Now vtop can not show us the page is zero pfn when PTE or PMD has attached ZERO PAGE. This patch supports show this information directly when using vtop, likes: crash> vtop -c 13674 ffff8917e000 VIRTUAL PHYSICAL ffff8917e000 836e71000 PAGE DIRECTORY: ffff000802f8d000 PGD: ffff000802f8dff8 => 884e29003 PUD: ffff000844e29ff0 => 884e93003 PMD: ffff000844e93240 => 840413003 PTE: ffff000800413bf0 => 160000836e71fc3 PAGE: 836e71000 (ZERO PAGE) PTE PHYSICAL FLAGS 160000836e71fc3 836e71000 (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN|SPECIAL) VMA START END FLAGS FILE ffff000844f51860 ffff8917c000 ffff8957d000 100073 PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffffe001fbb9c40 836e71000 0 0 1 2ffffc000001000 reserved If huge page found: crash> vtop -c 14538 ffff95800000 VIRTUAL PHYSICAL ffff95800000 910c00000 PAGE DIRECTORY: ffff000801fa0000 PGD: ffff000801fa0ff8 => 884f53003 PUD: ffff000844f53ff0 => 8426cb003 PMD: ffff0008026cb560 => 60000910c00fc1 PAGE: 910c00000 (2MB, ZERO PAGE) PTE PHYSICAL FLAGS 60000910c00fc1 910c00000 (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN) VMA START END FLAGS FILE ffff0000caa711e0 ffff956a9000 ffff95aaa000 100073 PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffffe0023230000 910c00000 0 0 1 6ffffc000010000 head That seems be sensible with this patch. Signed-off-by: Rongwei Wang <rongwei.wang(a)linux.alibaba.com&gt; --- arm64.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++------ defs.h | 5 ++++ 2 files changed, 88 insertions(+), 9 deletions(-) diff --git a/arm64.c b/arm64.c index 56fb841..264572d 100644 --- a/arm64.c +++ b/arm64.c @@ -419,7 +419,25 @@ arm64_init(int when) /* use machdep parameters */ arm64_calc_phys_offset(); arm64_calc_physvirt_offset(); - + + if (kernel_symbol_exists("zero_pfn")) { + ulong zero_pfn = 0; + + if (readmem(symbol_value("zero_pfn"), KVADDR, + &zero_pfn, sizeof(zero_pfn), + "read zero_pfn", QUIET|RETURN_ON_ERROR)) + machdep->zero_pfn = zero_pfn; + } + + if (kernel_symbol_exists("huge_zero_pfn")) { + ulong huge_zero_pfn = 0; + + if (readmem(symbol_value("huge_zero_pfn"), KVADDR, + &huge_zero_pfn, sizeof(huge_zero_pfn), + "read huge_zero_pfn", QUIET|RETURN_ON_ERROR)) + machdep->huge_zero_pfn = huge_zero_pfn; + } + if (CRASHDEBUG(1)) { if (machdep->flags & NEW_VMEMMAP) fprintf(fp, "kimage_voffset: %lx\n", @@ -1787,7 +1805,14 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pgd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pgd_val & SECTION_PAGE_MASK_512MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + if (kernel_symbol_exists("huge_zero_pfn")) { + if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (512MB, ZERO PAGE)\n\n", + HUGE_ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + } else + fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); arm64_translate_pte(pgd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); @@ -1806,7 +1831,14 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + if (kernel_symbol_exists("zero_pfn")) { + if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (ZERO PAGE)\n\n", + ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + } else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -1859,7 +1891,14 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = PTE_TO_PHYS(pmd_val) & SECTION_PAGE_MASK_512MB; if (verbose) { - fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + if (kernel_symbol_exists("huge_zero_pfn")) { + if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (512MB, ZERO PAGE)\n\n", + HUGE_ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + } else + fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); @@ -1878,7 +1917,14 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = PTE_TO_PHYS(pte_val) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + if (kernel_symbol_exists("zero_pfn")) { + if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (ZERO PAGE)\n\n", + ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + } else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -1940,7 +1986,14 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + if (kernel_symbol_exists("huge_zero_pfn")) { + if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (2MB, ZERO PAGE)\n\n", + HUGE_ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + } else + fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); @@ -1959,7 +2012,14 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + if (kernel_symbol_exists("zero_pfn")) { + if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (ZERO PAGE)\n\n", + ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + } else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -2029,7 +2089,14 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + if (kernel_symbol_exists("huge_zero_pfn")) { + if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (2MB, ZERO PAGE)\n\n", + HUGE_ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + } else + fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); @@ -2048,7 +2115,14 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + if (kernel_symbol_exists("zero_pfn")) { + if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) + fprintf(fp, " PAGE: %lx (ZERO PAGE)\n\n", + ZEROPFN() << PAGESHIFT()); + else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + } else + fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); arm64_translate_pte(pte_val, 0, 0); } } else { diff --git a/defs.h b/defs.h index 12ad6aa..4ed2d0a 100644 --- a/defs.h +++ b/defs.h @@ -1071,6 +1071,8 @@ struct machdep_table { void (*show_interrupts)(int, ulong *); int (*is_page_ptr)(ulong, physaddr_t *); int (*get_cpu_reg)(int, int, const char *, int, void *); + ulong zero_pfn; + ulong huge_zero_pfn; }; /* @@ -2999,6 +3001,9 @@ struct load_module { #define VIRTPAGEBASE(X) (((ulong)(X)) & (ulong)machdep->pagemask) #define PHYSPAGEBASE(X) (((physaddr_t)(X)) & (physaddr_t)machdep->pagemask) +#define ZEROPFN() (machdep->zero_pfn) +#define HUGE_ZEROPFN() (machdep->huge_zero_pfn) + /* * Sparse memory stuff * These must follow the definitions in the kernel mmzone.h

On 2023/05/01 1:16, Rongwei Wang wrote: > Hello, > > Recently I handle some stuff about zero page with crash. I'm always use > vtop to check > > whether an virtual address has been set the zero page. But, it can not > directly show whether a page > > is zero page or not. So I try to add this patch to support this. > > And I'm not sure this idea is nice to be accepted, so just realize it on > arm64 platform. I can finish others > > arch if it accepted. Sorry for the delay, I had been on holidays last week. I think this is a nice suggestion and would like to accept it also for other architectures.

> > Thanks for your time. > > On 2023/5/1 00:02, Rongwei Wang wrote: >> Now vtop can not show us the page is zero pfn >> when PTE or PMD has attached ZERO PAGE. This >> patch supports show this information directly >> when using vtop, likes: >> >> crash> vtop -c 13674 ffff8917e000 >> VIRTUAL     PHYSICAL >> ffff8917e000  836e71000 >> >> PAGE DIRECTORY: ffff000802f8d000 >>     PGD: ffff000802f8dff8 => 884e29003 >>     PUD: ffff000844e29ff0 => 884e93003 >>     PMD: ffff000844e93240 => 840413003 >>     PTE: ffff000800413bf0 => 160000836e71fc3 >>    PAGE: 836e71000  (ZERO PAGE) >> >>        PTE        PHYSICAL   FLAGS >> 160000836e71fc3  836e71000 >> (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN|SPECIAL) >> >>        VMA           START       END     FLAGS FILE >> ffff000844f51860 ffff8917c000 ffff8957d000 100073 >> >>        PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS >> fffffe001fbb9c40  836e71000                0        0  1 >> 2ffffc000001000 reserved >> >> If huge page found: >> >> crash> vtop -c 14538 ffff95800000 >> VIRTUAL     PHYSICAL >> ffff95800000  910c00000 >> >> PAGE DIRECTORY: ffff000801fa0000 >>     PGD: ffff000801fa0ff8 => 884f53003 >>     PUD: ffff000844f53ff0 => 8426cb003 >>     PMD: ffff0008026cb560 => 60000910c00fc1 >>    PAGE: 910c00000  (2MB, ZERO PAGE) >> >>       PTE        PHYSICAL   FLAGS >> 60000910c00fc1  910c00000  (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN) >> >>        VMA           START       END     FLAGS FILE >> ffff0000caa711e0 ffff956a9000 ffff95aaa000 100073 >> >>        PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS >> fffffe0023230000  910c00000                0        0  1 >> 6ffffc000010000 head >> >> That seems be sensible with this patch. >> >> Signed-off-by: Rongwei Wang <rongwei.wang(a)linux.alibaba.com&gt; >> --- >>   arm64.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++------ >>   defs.h  |  5 ++++ >>   2 files changed, 88 insertions(+), 9 deletions(-) >> >> diff --git a/arm64.c b/arm64.c >> index 56fb841..264572d 100644 >> --- a/arm64.c >> +++ b/arm64.c >> @@ -419,7 +419,25 @@ arm64_init(int when) >>           /* use machdep parameters */ >>           arm64_calc_phys_offset(); >>           arm64_calc_physvirt_offset(); >> - >> + >> +        if (kernel_symbol_exists("zero_pfn")) { >> +                ulong zero_pfn = 0; >> + >> +                if (readmem(symbol_value("zero_pfn"), KVADDR, >> +                          &zero_pfn, sizeof(zero_pfn), >> +                          "read zero_pfn", QUIET|RETURN_ON_ERROR)) >> +                    machdep->zero_pfn = zero_pfn; >> +        } >> + >> +        if (kernel_symbol_exists("huge_zero_pfn")) { >> +                ulong huge_zero_pfn = 0; >> + >> +                if (readmem(symbol_value("huge_zero_pfn"), KVADDR, >> +                          &huge_zero_pfn, sizeof(huge_zero_pfn), >> +                          "read huge_zero_pfn", QUIET|RETURN_ON_ERROR)) >> +                    machdep->huge_zero_pfn = huge_zero_pfn; >> +        } so, for other architectures, are you going to move these to vm_init() or somewhere?

And zero_paddr might be better than zero_pfn to reduce the calculation on printing, e.g. vt->zero_paddr = zero_pfn << PAGESHIFT().

>> + >>           if (CRASHDEBUG(1)) { >>               if (machdep->flags & NEW_VMEMMAP) >>                   fprintf(fp, "kimage_voffset: %lx\n", >> @@ -1787,7 +1805,14 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if ((pgd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = (pgd_val & SECTION_PAGE_MASK_512MB) & >> PHYS_MASK; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >> +            if (kernel_symbol_exists("huge_zero_pfn")) { >> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (512MB, ZERO PAGE)\n\n", >> +                        HUGE_ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx  (512MB)\n\n", >> sectionbase); >> +            } else >> +                fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >>               arm64_translate_pte(pgd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); >> @@ -1806,7 +1831,14 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            if (kernel_symbol_exists("zero_pfn")) { >> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >> +                        ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            } else >> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); These blocks look a bit verbose and it would be better to not call kernel_symbol_exists() each time, if possible.

Can it be changed to something like this? if (vt->zero_paddr && PAGEBASE(*paddr) == vt->zero_paddr) { or this. fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), vt->zero_paddr && PAGEBASE(*paddr) == vt->zero_paddr ? "(ZERO PAGE)" : "");

Thanks, Kazu

>>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> @@ -1859,7 +1891,14 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = PTE_TO_PHYS(pmd_val) & >> SECTION_PAGE_MASK_512MB; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >> +            if (kernel_symbol_exists("huge_zero_pfn")) { >> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (512MB, ZERO PAGE)\n\n", >> +                        HUGE_ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx  (512MB)\n\n", >> sectionbase); >> +            } else >> +                fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >>               arm64_translate_pte(pmd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); >> @@ -1878,7 +1917,14 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = PTE_TO_PHYS(pte_val) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            if (kernel_symbol_exists("zero_pfn")) { >> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >> +                        ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            } else >> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> @@ -1940,7 +1986,14 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & >> PHYS_MASK; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >> +            if (kernel_symbol_exists("huge_zero_pfn")) { >> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (2MB, ZERO PAGE)\n\n", >> +                        HUGE_ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >> +            } else >> +                fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >>               arm64_translate_pte(pmd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); >> @@ -1959,7 +2012,14 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            if (kernel_symbol_exists("zero_pfn")) { >> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >> +                        ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            } else >> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> @@ -2029,7 +2089,14 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & >> PHYS_MASK; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >> +            if (kernel_symbol_exists("huge_zero_pfn")) { >> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (2MB, ZERO PAGE)\n\n", >> +                        HUGE_ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >> +            } else >> +                fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >>               arm64_translate_pte(pmd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); >> @@ -2048,7 +2115,14 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, >> physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            if (kernel_symbol_exists("zero_pfn")) { >> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >> +                        ZEROPFN() << PAGESHIFT()); >> +                else >> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            } else >> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> diff --git a/defs.h b/defs.h >> index 12ad6aa..4ed2d0a 100644 >> --- a/defs.h >> +++ b/defs.h >> @@ -1071,6 +1071,8 @@ struct machdep_table { >>           void (*show_interrupts)(int, ulong *); >>       int (*is_page_ptr)(ulong, physaddr_t *); >>       int (*get_cpu_reg)(int, int, const char *, int, void *); >> +    ulong zero_pfn; >> +    ulong huge_zero_pfn; >>   }; >>   /* >> @@ -2999,6 +3001,9 @@ struct load_module { >>   #define VIRTPAGEBASE(X)  (((ulong)(X)) & (ulong)machdep->pagemask) >>   #define PHYSPAGEBASE(X)  (((physaddr_t)(X)) & >> (physaddr_t)machdep->pagemask) >> +#define ZEROPFN()    (machdep->zero_pfn) >> +#define HUGE_ZEROPFN()   (machdep->huge_zero_pfn) >> + >>   /* >>    * Sparse memory stuff >>    *  These must follow the definitions in the kernel mmzone.h

On 2023/05/08 21:07, Rongwei Wang wrote: > On 2023/5/8 15:46, HAGIO KAZUHITO(萩尾 一仁) wrote: >> On 2023/05/01 1:16, Rongwei Wang wrote: >>> Hello, >>> >>> Recently I handle some stuff about zero page with crash. I'm always use >>> vtop to check >>> >>> whether an virtual address has been set the zero page. But, it can not >>> directly show whether a page >>> >>> is zero page or not. So I try to add this patch to support this. >>> >>> And I'm not sure this idea is nice to be accepted, so just realize it on >>> arm64 platform. I can finish others >>> >>> arch if it accepted. >> Sorry for the delay, I had been on holidays last week. >> >> I think this is a nice suggestion and would like to accept it also for >> other architectures. > Thanks for your reply. > > I will continue to finish this patch for other arches. ;) > >>> Thanks for your time. >>> >>> On 2023/5/1 00:02, Rongwei Wang wrote: >>>> Now vtop can not show us the page is zero pfn >>>> when PTE or PMD has attached ZERO PAGE. This >>>> patch supports show this information directly >>>> when using vtop, likes: >>>> >>>> crash> vtop -c 13674 ffff8917e000 >>>> VIRTUAL     PHYSICAL >>>> ffff8917e000  836e71000 >>>> >>>> PAGE DIRECTORY: ffff000802f8d000 >>>>      PGD: ffff000802f8dff8 => 884e29003 >>>>      PUD: ffff000844e29ff0 => 884e93003 >>>>      PMD: ffff000844e93240 => 840413003 >>>>      PTE: ffff000800413bf0 => 160000836e71fc3 >>>>     PAGE: 836e71000  (ZERO PAGE) >>>> >>>>         PTE        PHYSICAL   FLAGS >>>> 160000836e71fc3  836e71000 >>>> (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN|SPECIAL) >>>> >>>>         VMA           START       END     FLAGS FILE >>>> ffff000844f51860 ffff8917c000 ffff8957d000 100073 >>>> >>>>         PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS >>>> fffffe001fbb9c40  836e71000                0        0  1 >>>> 2ffffc000001000 reserved >>>> >>>> If huge page found: >>>> >>>> crash> vtop -c 14538 ffff95800000 >>>> VIRTUAL     PHYSICAL >>>> ffff95800000  910c00000 >>>> >>>> PAGE DIRECTORY: ffff000801fa0000 >>>>      PGD: ffff000801fa0ff8 => 884f53003 >>>>      PUD: ffff000844f53ff0 => 8426cb003 >>>>      PMD: ffff0008026cb560 => 60000910c00fc1 >>>>     PAGE: 910c00000  (2MB, ZERO PAGE) >>>> >>>>        PTE        PHYSICAL   FLAGS >>>> 60000910c00fc1  910c00000  (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN) >>>> >>>>         VMA           START       END     FLAGS FILE >>>> ffff0000caa711e0 ffff956a9000 ffff95aaa000 100073 >>>> >>>>         PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS >>>> fffffe0023230000  910c00000                0        0  1 >>>> 6ffffc000010000 head >>>> >>>> That seems be sensible with this patch. >>>> >>>> Signed-off-by: Rongwei Wang <rongwei.wang(a)linux.alibaba.com&gt; >>>> --- >>>>    arm64.c | 92 >>>> +++++++++++++++++++++++++++++++++++++++++++++++++++------ >>>>    defs.h  |  5 ++++ >>>>    2 files changed, 88 insertions(+), 9 deletions(-) >>>> >>>> diff --git a/arm64.c b/arm64.c >>>> index 56fb841..264572d 100644 >>>> --- a/arm64.c >>>> +++ b/arm64.c >>>> @@ -419,7 +419,25 @@ arm64_init(int when) >>>>            /* use machdep parameters */ >>>>            arm64_calc_phys_offset(); >>>>            arm64_calc_physvirt_offset(); >>>> - >>>> + >>>> +        if (kernel_symbol_exists("zero_pfn")) { >>>> +                ulong zero_pfn = 0; >>>> + >>>> +                if (readmem(symbol_value("zero_pfn"), KVADDR, >>>> +                          &zero_pfn, sizeof(zero_pfn), >>>> +                          "read zero_pfn", QUIET|RETURN_ON_ERROR)) >>>> +                    machdep->zero_pfn = zero_pfn; >>>> +        } >>>> + >>>> +        if (kernel_symbol_exists("huge_zero_pfn")) { >>>> +                ulong huge_zero_pfn = 0; >>>> + >>>> +                if (readmem(symbol_value("huge_zero_pfn"), KVADDR, >>>> +                          &huge_zero_pfn, sizeof(huge_zero_pfn), >>>> +                          "read huge_zero_pfn", >>>> QUIET|RETURN_ON_ERROR)) >>>> +                    machdep->huge_zero_pfn = huge_zero_pfn; >>>> +        } >> so, for other architectures, are you going to move these to vm_init() or >> somewhere? > Good idea, it looks better than arm64_init(). Next version will fix here. >> And zero_paddr might be better than zero_pfn to reduce the calculation >> on printing, e.g. vt->zero_paddr = zero_pfn << PAGESHIFT(). > OK, next version will fix here. >>>> + >>>>            if (CRASHDEBUG(1)) { >>>>                if (machdep->flags & NEW_VMEMMAP) >>>>                    fprintf(fp, "kimage_voffset: %lx\n", >>>> @@ -1787,7 +1805,14 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if ((pgd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>>>            ulong sectionbase = (pgd_val & SECTION_PAGE_MASK_512MB) & >>>> PHYS_MASK; >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >>>> +            if (kernel_symbol_exists("huge_zero_pfn")) { >>>> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (512MB, ZERO PAGE)\n\n", >>>> +                        HUGE_ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx  (512MB)\n\n", >>>> sectionbase); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >>>>                arm64_translate_pte(pgd_val, 0, 0); >>>>            } >>>>            *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); >>>> @@ -1806,7 +1831,14 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if (pte_val & PTE_VALID) { >>>>            *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + >>>> PAGEOFFSET(vaddr); >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            if (kernel_symbol_exists("zero_pfn")) { >>>> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >>>> +                        ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> These blocks look a bit verbose and it would be better to not call >> kernel_symbol_exists() each time, if possible. > Actually, I'm not sure this 'zero_paddr' has possibility of equal to 0 > (seems unlikely). > > Anyway, I will try to make sure that. Thanks! If 0 cannot be used, ~0 might be good. And you can also use macros if possible. For example, #define IS_ZEROPAGE(paddr) (vt->zero_paddr != ~0UL && ...

or something. Just an idea, not tried. One more thing, it's hard for us to test all of arches that crash supports, so it would be ok to implement it first for arches that you can test. For the other arches, each arch user can reuse the patch if they want it.

Thanks, Kazu >> Can it be changed to something like this? >> >>     if (vt->zero_paddr && PAGEBASE(*paddr) == vt->zero_paddr) { >> >> or this. >> >>     fprintf(fp, "  PAGE: %lx  %s\n\n", PAGEBASE(*paddr), >>             vt->zero_paddr && PAGEBASE(*paddr) == vt->zero_paddr ? >>                 "(ZERO PAGE)" : ""); > Nice, I'm also think my above style is verbose, but have no idea at that > time. > > I will update here at next version. > >> Thanks, >> Kazu > Thanks for your time. > > -wrw > >>>>                arm64_translate_pte(pte_val, 0, 0); >>>>            } >>>>        } else { >>>> @@ -1859,7 +1891,14 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>>>            ulong sectionbase = PTE_TO_PHYS(pmd_val) & >>>> SECTION_PAGE_MASK_512MB; >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >>>> +            if (kernel_symbol_exists("huge_zero_pfn")) { >>>> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (512MB, ZERO PAGE)\n\n", >>>> +                        HUGE_ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx  (512MB)\n\n", >>>> sectionbase); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >>>>                arm64_translate_pte(pmd_val, 0, 0); >>>>            } >>>>            *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); >>>> @@ -1878,7 +1917,14 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if (pte_val & PTE_VALID) { >>>>            *paddr = PTE_TO_PHYS(pte_val) + PAGEOFFSET(vaddr); >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            if (kernel_symbol_exists("zero_pfn")) { >>>> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >>>> +                        ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>>                arm64_translate_pte(pte_val, 0, 0); >>>>            } >>>>        } else { >>>> @@ -1940,7 +1986,14 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>>>            ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & >>>> PHYS_MASK; >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >>>> +            if (kernel_symbol_exists("huge_zero_pfn")) { >>>> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (2MB, ZERO PAGE)\n\n", >>>> +                        HUGE_ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx  (2MB)\n\n", >>>> sectionbase); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >>>>                arm64_translate_pte(pmd_val, 0, 0); >>>>            } >>>>            *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); >>>> @@ -1959,7 +2012,14 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if (pte_val & PTE_VALID) { >>>>            *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + >>>> PAGEOFFSET(vaddr); >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            if (kernel_symbol_exists("zero_pfn")) { >>>> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >>>> +                        ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>>                arm64_translate_pte(pte_val, 0, 0); >>>>            } >>>>        } else { >>>> @@ -2029,7 +2089,14 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>>>            ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & >>>> PHYS_MASK; >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >>>> +            if (kernel_symbol_exists("huge_zero_pfn")) { >>>> +                if (sectionbase == (HUGE_ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (2MB, ZERO PAGE)\n\n", >>>> +                        HUGE_ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx  (2MB)\n\n", >>>> sectionbase); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >>>>                arm64_translate_pte(pmd_val, 0, 0); >>>>            } >>>>            *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); >>>> @@ -2048,7 +2115,14 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, >>>> physaddr_t *paddr, int verbose) >>>>        if (pte_val & PTE_VALID) { >>>>            *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + >>>> PAGEOFFSET(vaddr); >>>>            if (verbose) { >>>> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            if (kernel_symbol_exists("zero_pfn")) { >>>> +                if (PAGEBASE(*paddr) == (ZEROPFN() << PAGESHIFT())) >>>> +                    fprintf(fp, "  PAGE: %lx  (ZERO PAGE)\n\n", >>>> +                        ZEROPFN() << PAGESHIFT()); >>>> +                else >>>> +                    fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>> +            } else >>>> +                fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >>>>                arm64_translate_pte(pte_val, 0, 0); >>>>            } >>>>        } else { >>>> diff --git a/defs.h b/defs.h >>>> index 12ad6aa..4ed2d0a 100644 >>>> --- a/defs.h >>>> +++ b/defs.h >>>> @@ -1071,6 +1071,8 @@ struct machdep_table { >>>>            void (*show_interrupts)(int, ulong *); >>>>        int (*is_page_ptr)(ulong, physaddr_t *); >>>>        int (*get_cpu_reg)(int, int, const char *, int, void *); >>>> +    ulong zero_pfn; >>>> +    ulong huge_zero_pfn; >>>>    }; >>>>    /* >>>> @@ -2999,6 +3001,9 @@ struct load_module { >>>>    #define VIRTPAGEBASE(X)  (((ulong)(X)) & (ulong)machdep->pagemask) >>>>    #define PHYSPAGEBASE(X)  (((physaddr_t)(X)) & >>>> (physaddr_t)machdep->pagemask) >>>> +#define ZEROPFN()    (machdep->zero_pfn) >>>> +#define HUGE_ZEROPFN()   (machdep->huge_zero_pfn) >>>> + >>>>    /* >>>>     * Sparse memory stuff >>>>     *  These must follow the definitions in the kernel mmzone.h

Now vtop can not show us the page is zero pfn when PTE or PMD has attached ZERO PAGE. This patch supports show this information directly when using vtop, likes: crash> vtop -c 13674 ffff8917e000 VIRTUAL PHYSICAL ffff8917e000 836e71000 PAGE DIRECTORY: ffff000802f8d000 PGD: ffff000802f8dff8 => 884e29003 PUD: ffff000844e29ff0 => 884e93003 PMD: ffff000844e93240 => 840413003 PTE: ffff000800413bf0 => 160000836e71fc3 PAGE: 836e71000 (ZERO PAGE) PTE PHYSICAL FLAGS 160000836e71fc3 836e71000 (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN|SPECIAL) VMA START END FLAGS FILE ffff000844f51860 ffff8917c000 ffff8957d000 100073 PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffffe001fbb9c40 836e71000 0 0 1 2ffffc000001000 reserved If huge page found: crash> vtop -c 14538 ffff95800000 VIRTUAL PHYSICAL ffff95800000 910c00000 PAGE DIRECTORY: ffff000801fa0000 PGD: ffff000801fa0ff8 => 884f53003 PUD: ffff000844f53ff0 => 8426cb003 PMD: ffff0008026cb560 => 60000910c00fc1 PAGE: 910c00000 (2MB, ZERO PAGE) PTE PHYSICAL FLAGS 60000910c00fc1 910c00000 (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN) VMA START END FLAGS FILE ffff0000caa711e0 ffff956a9000 ffff95aaa000 100073 PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffffe0023230000 910c00000 0 0 1 6ffffc000010000 head That seems be sensible with this patch. Signed-off-by: Rongwei Wang <rongwei.wang(a)linux.alibaba.com&gt; --- arm64.c | 26 +++++++++++++++++--------- defs.h | 6 ++++++ memory.c | 20 ++++++++++++++++++++ x86_64.c | 9 +++++---- 4 files changed, 48 insertions(+), 13 deletions(-) diff --git a/arm64.c b/arm64.c index 56fb841..d70f202 100644 --- a/arm64.c +++ b/arm64.c @@ -419,7 +419,7 @@ arm64_init(int when) /* use machdep parameters */ arm64_calc_phys_offset(); arm64_calc_physvirt_offset(); - + if (CRASHDEBUG(1)) { if (machdep->flags & NEW_VMEMMAP) fprintf(fp, "kimage_voffset: %lx\n", @@ -1787,7 +1787,8 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pgd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pgd_val & SECTION_PAGE_MASK_512MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (512MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pgd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); @@ -1806,7 +1807,8 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -1859,7 +1861,8 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = PTE_TO_PHYS(pmd_val) & SECTION_PAGE_MASK_512MB; if (verbose) { - fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (512MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); @@ -1878,7 +1881,8 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = PTE_TO_PHYS(pte_val) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -1940,7 +1944,8 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (2MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); @@ -1959,7 +1964,8 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -2029,7 +2035,8 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (2MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); @@ -2048,7 +2055,8 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { diff --git a/defs.h b/defs.h index 12ad6aa..1be5a68 100644 --- a/defs.h +++ b/defs.h @@ -2618,6 +2618,8 @@ struct vm_table { /* kernel VM-related data */ char *name; } *pageflags_data; ulong max_mem_section_nr; + ulong zero_paddr; + ulong huge_zero_paddr; }; #define NODES (0x1) @@ -2999,6 +3001,10 @@ struct load_module { #define VIRTPAGEBASE(X) (((ulong)(X)) & (ulong)machdep->pagemask) #define PHYSPAGEBASE(X) (((physaddr_t)(X)) & (physaddr_t)machdep->pagemask) +#define IS_ZEROPAGE(paddr) ((paddr) != ~0UL && \ + ((paddr) == vt->zero_paddr || \ + (paddr) == vt->huge_zero_paddr)) + /* * Sparse memory stuff * These must follow the definitions in the kernel mmzone.h diff --git a/memory.c b/memory.c index 0568f18..4ad5959 100644 --- a/memory.c +++ b/memory.c @@ -1208,6 +1208,26 @@ vm_init(void) machdep->memory_size())); vt->paddr_prlen = strlen(buf); + if (kernel_symbol_exists("zero_pfn")) { + ulong zero_pfn; + + vt->zero_paddr = ~0UL; + if (readmem(symbol_value("zero_pfn"), KVADDR, + &zero_pfn, sizeof(zero_pfn), + "read zero_pfn", QUIET|RETURN_ON_ERROR)) + vt->zero_paddr = zero_pfn << PAGESHIFT(); + } + + if (kernel_symbol_exists("huge_zero_pfn")) { + ulong huge_zero_pfn; + + vt->huge_zero_paddr = ~0UL; + if (readmem(symbol_value("huge_zero_pfn"), KVADDR, + &huge_zero_pfn, sizeof(huge_zero_pfn), + "read huge_zero_pfn", QUIET|RETURN_ON_ERROR)) + vt->huge_zero_paddr = huge_zero_pfn << PAGESHIFT(); + } + if (vt->flags & PERCPU_KMALLOC_V1) vt->dump_kmem_cache = dump_kmem_cache_percpu_v1; else if (vt->flags & PERCPU_KMALLOC_V2) diff --git a/x86_64.c b/x86_64.c index 5019c69..693a08b 100644 --- a/x86_64.c +++ b/x86_64.c @@ -2114,8 +2114,9 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in goto no_upage; if (pmd_pte & _PAGE_PSE) { if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", - PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK); + fprintf(fp, " PAGE: %lx (2MB%s)\n\n", + PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK, + IS_ZEROPAGE(PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK) ? ", ZERO PAGE" : ""); x86_64_translate_pte(pmd_pte, 0, 0); } @@ -2143,8 +2144,8 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in *paddr = (PAGEBASE(pte) & PHYSICAL_PAGE_MASK) + PAGEOFFSET(uvaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", - PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK, + IS_ZEROPAGE(PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK) ? "(ZERO PAGE)" : ""); x86_64_translate_pte(pte, 0, 0); }

On 2023/05/10 20:39, Rongwei Wang wrote: > Hi, Kazu > > As we discussed in previous email, I re-code this patch under x86_64 and arm64 env. > > The change log as belows. > > change log: > v1->v2: > - rename and move zero_paddr and huge_zero_paddr into vm_init(); > - simplify fprintf() code block; > - support x86_64 arch; Thank you for the update. > And if I miss something, please let me know. > > > Thanks, > -wrw > > On 2023/5/10 19:32, Rongwei Wang wrote: >> Now vtop can not show us the page is zero pfn >> when PTE or PMD has attached ZERO PAGE. This >> patch supports show this information directly >> when using vtop, likes: >> >> crash> vtop -c 13674 ffff8917e000 >> VIRTUAL     PHYSICAL >> ffff8917e000  836e71000 >> >> PAGE DIRECTORY: ffff000802f8d000 >>     PGD: ffff000802f8dff8 => 884e29003 >>     PUD: ffff000844e29ff0 => 884e93003 >>     PMD: ffff000844e93240 => 840413003 >>     PTE: ffff000800413bf0 => 160000836e71fc3 >>    PAGE: 836e71000  (ZERO PAGE) btw, how can I create this situation seeing zero page easily? I also would like to test the patch.

>>        PTE        PHYSICAL   FLAGS >> 160000836e71fc3  836e71000  (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN|SPECIAL) >> >>        VMA           START       END     FLAGS FILE >> ffff000844f51860 ffff8917c000 ffff8957d000 100073 >> >>        PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS >> fffffe001fbb9c40  836e71000                0        0  1 2ffffc000001000 reserved a bit verbose, please replace these with "..."

>> If huge page found: >> >> crash> vtop -c 14538 ffff95800000 >> VIRTUAL     PHYSICAL >> ffff95800000  910c00000 >> >> PAGE DIRECTORY: ffff000801fa0000 >>     PGD: ffff000801fa0ff8 => 884f53003 >>     PUD: ffff000844f53ff0 => 8426cb003 >>     PMD: ffff0008026cb560 => 60000910c00fc1 >>    PAGE: 910c00000  (2MB, ZERO PAGE) >> >>       PTE        PHYSICAL   FLAGS >> 60000910c00fc1  910c00000  (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN) >> >>        VMA           START       END     FLAGS FILE >> ffff0000caa711e0 ffff956a9000 ffff95aaa000 100073 >> >>        PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS >> fffffe0023230000  910c00000                0        0  1 6ffffc000010000 head >> >> That seems be sensible with this patch. Same as above. >> Signed-off-by: Rongwei Wang <rongwei.wang(a)linux.alibaba.com&gt; >> --- >>   arm64.c  | 26 +++++++++++++++++--------- >>   defs.h   |  6 ++++++ >>   memory.c | 20 ++++++++++++++++++++ >>   x86_64.c |  9 +++++---- >>   4 files changed, 48 insertions(+), 13 deletions(-) >> >> diff --git a/arm64.c b/arm64.c >> index 56fb841..d70f202 100644 >> --- a/arm64.c >> +++ b/arm64.c >> @@ -419,7 +419,7 @@ arm64_init(int when) >>           /* use machdep parameters */ >>           arm64_calc_phys_offset(); >>           arm64_calc_physvirt_offset(); >> - >> + >>           if (CRASHDEBUG(1)) { >>               if (machdep->flags & NEW_VMEMMAP) >>                   fprintf(fp, "kimage_voffset: %lx\n", >> @@ -1787,7 +1787,8 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if ((pgd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = (pgd_val & SECTION_PAGE_MASK_512MB) & PHYS_MASK; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >> +            fprintf(fp, "  PAGE: %lx  (512MB%s)\n\n", sectionbase, >> +                IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); >>               arm64_translate_pte(pgd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); >> @@ -1806,7 +1807,8 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            fprintf(fp, "  PAGE: %lx  %s\n\n", PAGEBASE(*paddr), >> +                IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); >>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> @@ -1859,7 +1861,8 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = PTE_TO_PHYS(pmd_val) & SECTION_PAGE_MASK_512MB; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (512MB)\n\n", sectionbase); >> +            fprintf(fp, "  PAGE: %lx  (512MB%s)\n\n", sectionbase, >> +                IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); >>               arm64_translate_pte(pmd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); >> @@ -1878,7 +1881,8 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = PTE_TO_PHYS(pte_val) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            fprintf(fp, "  PAGE: %lx  %s\n\n", PAGEBASE(*paddr), >> +                IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); >>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> @@ -1940,7 +1944,8 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >> +            fprintf(fp, "  PAGE: %lx  (2MB%s)\n\n", sectionbase, >> +                IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); >>               arm64_translate_pte(pmd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); >> @@ -1959,7 +1964,8 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            fprintf(fp, "  PAGE: %lx  %s\n\n", PAGEBASE(*paddr), >> +                IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); >>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> @@ -2029,7 +2035,8 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { >>           ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx  (2MB)\n\n", sectionbase); >> +            fprintf(fp, "  PAGE: %lx  (2MB%s)\n\n", sectionbase, >> +                IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); >>               arm64_translate_pte(pmd_val, 0, 0); >>           } >>           *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); >> @@ -2048,7 +2055,8 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) >>       if (pte_val & PTE_VALID) { >>           *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); >>           if (verbose) { >> -            fprintf(fp, "  PAGE: %lx\n\n", PAGEBASE(*paddr)); >> +            fprintf(fp, "  PAGE: %lx  %s\n\n", PAGEBASE(*paddr), >> +                IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); >>               arm64_translate_pte(pte_val, 0, 0); >>           } >>       } else { >> diff --git a/defs.h b/defs.h >> index 12ad6aa..1be5a68 100644 >> --- a/defs.h >> +++ b/defs.h >> @@ -2618,6 +2618,8 @@ struct vm_table {                /* kernel VM-related data */ >>           char *name; >>       } *pageflags_data; >>       ulong max_mem_section_nr; >> +    ulong zero_paddr; >> +    ulong huge_zero_paddr; Please print these with "help -v", for example, here. node_online_map_len: 16 node_online_map: [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] zero_paddr: 10ef9000 huge_zero_paddr: fffffffffffff000 nr_vm_stat_items: 0 vm_stat_items: (not used)

>>   }; >>   #define NODES                       (0x1) >> @@ -2999,6 +3001,10 @@ struct load_module { >>   #define VIRTPAGEBASE(X)  (((ulong)(X)) & (ulong)machdep->pagemask) >>   #define PHYSPAGEBASE(X)  (((physaddr_t)(X)) & (physaddr_t)machdep->pagemask) >> +#define IS_ZEROPAGE(paddr)   ((paddr) != ~0UL && \ >> +                  ((paddr) == vt->zero_paddr || \ >> +                  (paddr) == vt->huge_zero_paddr)) Ah, (paddr) != ~0UL would be unnecessary, if we use ~0UL as the invalid address.

>> + >>   /* >>    * Sparse memory stuff >>    *  These must follow the definitions in the kernel mmzone.h >> diff --git a/memory.c b/memory.c >> index 0568f18..4ad5959 100644 >> --- a/memory.c >> +++ b/memory.c >> @@ -1208,6 +1208,26 @@ vm_init(void) >>           machdep->memory_size())); >>       vt->paddr_prlen = strlen(buf); >> +    if (kernel_symbol_exists("zero_pfn")) { >> +        ulong zero_pfn; >> + >> +        vt->zero_paddr = ~0UL; Please move this out of the if block to initialize it even if the symbol does not exist.

>> +        if (readmem(symbol_value("zero_pfn"), KVADDR, >> +                &zero_pfn, sizeof(zero_pfn), >> +                "read zero_pfn", QUIET|RETURN_ON_ERROR)) >> +            vt->zero_paddr = zero_pfn << PAGESHIFT(); >> +    } >> + >> +    if (kernel_symbol_exists("huge_zero_pfn")) { >> +        ulong huge_zero_pfn; >> + >> +        vt->huge_zero_paddr = ~0UL; Same as above. >> +        if (readmem(symbol_value("huge_zero_pfn"), KVADDR, >> +                &huge_zero_pfn, sizeof(huge_zero_pfn), >> +                "read huge_zero_pfn", QUIET|RETURN_ON_ERROR)) >> +            vt->huge_zero_paddr = huge_zero_pfn << PAGESHIFT(); In kernel, huge_zero_pfn is initialized as ~0UL and set to a pfn when get_huge_zero_page() is called. crash> p -x huge_zero_pfn huge_zero_pfn = $4 = 0xffffffffffffffff so if huge_zero_pfn is ~0UL, vt->huge_zero_paddr should not be set.

>> +    } >> + >>       if (vt->flags & PERCPU_KMALLOC_V1) >>                   vt->dump_kmem_cache = dump_kmem_cache_percpu_v1; >>       else if (vt->flags & PERCPU_KMALLOC_V2) >> diff --git a/x86_64.c b/x86_64.c >> index 5019c69..693a08b 100644 >> --- a/x86_64.c >> +++ b/x86_64.c >> @@ -2114,8 +2114,9 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in >>           goto no_upage; >>           if (pmd_pte & _PAGE_PSE) { >>           if (verbose) { >> -                        fprintf(fp, "  PAGE: %lx  (2MB)\n\n", >> -                PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK); >> +            fprintf(fp, "  PAGE: %lx  (2MB%s)\n\n", >> +                PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK, >> +                IS_ZEROPAGE(PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK) ? ", ZERO PAGE" : ""); >>                           x86_64_translate_pte(pmd_pte, 0, 0); >>                   } >> @@ -2143,8 +2144,8 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in >>       *paddr = (PAGEBASE(pte) & PHYSICAL_PAGE_MASK) + PAGEOFFSET(uvaddr); >>       if (verbose) { >> -        fprintf(fp, "  PAGE: %lx\n\n", >> -            PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK); >> +        fprintf(fp, "  PAGE: %lx  %s\n\n", PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK, >> +            IS_ZEROPAGE(PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK) ? "(ZERO PAGE)" : ""); >>           x86_64_translate_pte(pte, 0, 0); >>       } why only for uvtop_level4?

Thanks, Kazu

On 2023/05/12 0:32, Rongwei Wang wrote: >> btw, how can I create this situation seeing zero page easily? >> I also would like to test the patch. > Here a testcase that I used to allocate zero page: Thanks! I could see it on x86_64. crash> vtop -c 638970 7f018fb11000 VIRTUAL PHYSICAL 7f018fb11000 3af648000 PGD: 4646ca7f0 => 5b1ba7067 PUD: 5b1ba7030 => 5f9e63067 PMD: 5f9e633e8 => b45b7d067 PTE: b45b7d888 => 80000003af648225 PAGE: 3af648000 (ZERO PAGE) > z.c: > > #include <string.h> > #include <stdio.h> > #include <stdlib.h> > #include <unistd.h> > #include <errno.h> > #include <ctype.h> > > unsigned long *zero_data; > > void read_only(void) > { >         unsigned long i, val, count = 0; > >         printf("hello\n"); >         while (count++ < 10) { >                 for (i=0; i<(4 * 1024 * 1024) / sizeof(unsigned long); i+=1024) { >                         val = zero_data[i]; >                 } >         } > >         return; > } > > int main(int argc, char *argv[]) > { >         char c; > >         zero_data = (unsigned long *)malloc(1024 * 1024 * 4); >         if (!zero_data) { >                 printf("malloc fail: exit\n"); >                 return -1; >         } >         printf("zero: %lx\n", zero_data); > >         read_only(); > >         c = getchar(); > >         free(zero_data); >         exit(EXIT_SUCCESS); > } > > When you test in arm64 with 64k base pagesize, the size of allocating memory is needed to set more than 512MB. I see. >>>>         PTE        PHYSICAL   FLAGS >>>> 160000836e71fc3  836e71000  (VALID|USER|RDONLY|SHARED|AF|NG|PXN|UXN|SPECIAL) >>>> >>>>         VMA           START       END     FLAGS FILE >>>> ffff000844f51860 ffff8917c000 ffff8957d000 100073 >>>> >>>>         PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS >>>> fffffe001fbb9c40  836e71000                0        0  1 2ffffc000001000 reserved >> a bit verbose, please replace these with "..." > Your mean comment as below is OK? Yes. > crash> vtop -c 13674 ffff8917e000 > VIRTUAL     PHYSICAL > ffff8917e000  836e71000 > > PAGE DIRECTORY: ffff000802f8d000 >    PGD: ffff000802f8dff8 => 884e29003 >    PUD: ffff000844e29ff0 => 884e93003 >    PMD: ffff000844e93240 => 840413003 >    PTE: ffff000800413bf0 => 160000836e71fc3 >   PAGE: 836e71000  (ZERO PAGE) > > ... > >>>> +        if (readmem(symbol_value("huge_zero_pfn"), KVADDR, >>>> +                &huge_zero_pfn, sizeof(huge_zero_pfn), >>>> +                "read huge_zero_pfn", QUIET|RETURN_ON_ERROR)) >>>> +            vt->huge_zero_paddr = huge_zero_pfn << PAGESHIFT(); >> In kernel, huge_zero_pfn is initialized as ~0UL and set to a pfn when >> get_huge_zero_page() is called. >> >>     crash> p -x huge_zero_pfn >>     huge_zero_pfn = $4 = 0xffffffffffffffff >> >> so if huge_zero_pfn is ~0UL, vt->huge_zero_paddr should not be set. > Good catch. > > How about following modification: > > +        if (readmem(symbol_value("huge_zero_pfn"), KVADDR, > +                &huge_zero_pfn, sizeof(huge_zero_pfn), > +                "read huge_zero_pfn", QUIET|RETURN_ON_ERROR)) > +            vt->huge_zero_paddr = (huge_zero_pfn != ~0UL) ? (huge_zero_pfn << PAGESHIFT()); hmm, this looks wrong, needs ':'?

I would prefer this simply: if (readmem(symbol_value("huge_zero_pfn"), KVADDR, &huge_zero_pfn, sizeof(huge_zero_pfn), - "read huge_zero_pfn", QUIET|RETURN_ON_ERROR)) + "read huge_zero_pfn", QUIET|RETURN_ON_ERROR) && + huge_zero_pfn != ~0UL) vt->huge_zero_paddr = huge_zero_pfn << PAGESHIFT();

>>>> +    } >>>> + >>>>        if (vt->flags & PERCPU_KMALLOC_V1) >>>>                    vt->dump_kmem_cache = dump_kmem_cache_percpu_v1; >>>>        else if (vt->flags & PERCPU_KMALLOC_V2) >>>> diff --git a/x86_64.c b/x86_64.c >>>> index 5019c69..693a08b 100644 >>>> --- a/x86_64.c >>>> +++ b/x86_64.c >>>> @@ -2114,8 +2114,9 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in >>>>            goto no_upage; >>>>            if (pmd_pte & _PAGE_PSE) { >>>>            if (verbose) { >>>> -                        fprintf(fp, "  PAGE: %lx  (2MB)\n\n", >>>> -                PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK); >>>> +            fprintf(fp, "  PAGE: %lx  (2MB%s)\n\n", >>>> +                PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK, >>>> +                IS_ZEROPAGE(PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK) ? ", ZERO PAGE" : ""); >>>>                            x86_64_translate_pte(pmd_pte, 0, 0); >>>>                    } >>>> @@ -2143,8 +2144,8 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in >>>>        *paddr = (PAGEBASE(pte) & PHYSICAL_PAGE_MASK) + PAGEOFFSET(uvaddr); >>>>        if (verbose) { >>>> -        fprintf(fp, "  PAGE: %lx\n\n", >>>> -            PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK); >>>> +        fprintf(fp, "  PAGE: %lx  %s\n\n", PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK, >>>> +            IS_ZEROPAGE(PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK) ? "(ZERO PAGE)" : ""); >>>>            x86_64_translate_pte(pte, 0, 0); >>>>        } >> why only for uvtop_level4? > That because I have no idea about xyz_xen_wpt and similar target. In addition, I have no environment to test that, so... > > How about doing this when someone need it in these environment? Or I can do it if you think just complete it directly is ok. Ah ok, I see. Your patch is good enough for now. Thanks, Kazu

Now vtop can not show us the page is zero pfn when PTE or PMD has attached ZERO PAGE. This patch supports show this information directly when using vtop, likes: crash> vtop -c 13674 ffff8917e000 VIRTUAL PHYSICAL ffff8917e000 836e71000 PAGE DIRECTORY: ffff000802f8d000 PGD: ffff000802f8dff8 => 884e29003 PUD: ffff000844e29ff0 => 884e93003 PMD: ffff000844e93240 => 840413003 PTE: ffff000800413bf0 => 160000836e71fc3 PAGE: 836e71000 (ZERO PAGE) ... If huge page found: crash> vtop -c 14538 ffff95800000 VIRTUAL PHYSICAL ffff95800000 910c00000 PAGE DIRECTORY: ffff000801fa0000 PGD: ffff000801fa0ff8 => 884f53003 PUD: ffff000844f53ff0 => 8426cb003 PMD: ffff0008026cb560 => 60000910c00fc1 PAGE: 910c00000 (2MB, ZERO PAGE) ... That seems be sensible with this patch. Signed-off-by: Rongwei Wang <rongwei.wang(a)linux.alibaba.com&gt; --- arm64.c | 24 ++++++++++++++++-------- defs.h | 5 +++++ memory.c | 23 +++++++++++++++++++++++ x86_64.c | 9 +++++---- 4 files changed, 49 insertions(+), 12 deletions(-) diff --git a/arm64.c b/arm64.c index 56fb841..efbdccb 100644 --- a/arm64.c +++ b/arm64.c @@ -1787,7 +1787,8 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pgd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pgd_val & SECTION_PAGE_MASK_512MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (512MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pgd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); @@ -1806,7 +1807,8 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -1859,7 +1861,8 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = PTE_TO_PHYS(pmd_val) & SECTION_PAGE_MASK_512MB; if (verbose) { - fprintf(fp, " PAGE: %lx (512MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (512MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_512MB); @@ -1878,7 +1881,8 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = PTE_TO_PHYS(pte_val) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -1940,7 +1944,8 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (2MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); @@ -1959,7 +1964,8 @@ arm64_vtop_3level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { @@ -2029,7 +2035,8 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if ((pmd_val & PMD_TYPE_MASK) == PMD_TYPE_SECT) { ulong sectionbase = (pmd_val & SECTION_PAGE_MASK_2MB) & PHYS_MASK; if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", sectionbase); + fprintf(fp, " PAGE: %lx (2MB%s)\n\n", sectionbase, + IS_ZEROPAGE(sectionbase) ? ", ZERO PAGE" : ""); arm64_translate_pte(pmd_val, 0, 0); } *paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_2MB); @@ -2048,7 +2055,8 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose) if (pte_val & PTE_VALID) { *paddr = (PAGEBASE(pte_val) & PHYS_MASK) + PAGEOFFSET(vaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", PAGEBASE(*paddr)); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr), + IS_ZEROPAGE(PAGEBASE(*paddr)) ? "(ZERO PAGE)" : ""); arm64_translate_pte(pte_val, 0, 0); } } else { diff --git a/defs.h b/defs.h index 12ad6aa..a6e4ef3 100644 --- a/defs.h +++ b/defs.h @@ -2618,6 +2618,8 @@ struct vm_table { /* kernel VM-related data */ char *name; } *pageflags_data; ulong max_mem_section_nr; + ulong zero_paddr; + ulong huge_zero_paddr; }; #define NODES (0x1) @@ -2999,6 +3001,9 @@ struct load_module { #define VIRTPAGEBASE(X) (((ulong)(X)) & (ulong)machdep->pagemask) #define PHYSPAGEBASE(X) (((physaddr_t)(X)) & (physaddr_t)machdep->pagemask) +#define IS_ZEROPAGE(paddr) ((paddr) == vt->zero_paddr || \ + (paddr) == vt->huge_zero_paddr) + /* * Sparse memory stuff * These must follow the definitions in the kernel mmzone.h diff --git a/memory.c b/memory.c index 0568f18..d791283 100644 --- a/memory.c +++ b/memory.c @@ -1208,6 +1208,27 @@ vm_init(void) machdep->memory_size())); vt->paddr_prlen = strlen(buf); + vt->zero_paddr = ~0UL; + if (kernel_symbol_exists("zero_pfn")) { + ulong zero_pfn; + + if (readmem(symbol_value("zero_pfn"), KVADDR, + &zero_pfn, sizeof(zero_pfn), + "read zero_pfn", QUIET|RETURN_ON_ERROR)) + vt->zero_paddr = zero_pfn << PAGESHIFT(); + } + + vt->huge_zero_paddr = ~0UL; + if (kernel_symbol_exists("huge_zero_pfn")) { + ulong huge_zero_pfn; + + if (readmem(symbol_value("huge_zero_pfn"), KVADDR, + &huge_zero_pfn, sizeof(huge_zero_pfn), + "read huge_zero_pfn", QUIET|RETURN_ON_ERROR) && + huge_zero_pfn != ~0UL) + vt->huge_zero_paddr = huge_zero_pfn << PAGESHIFT(); + } + if (vt->flags & PERCPU_KMALLOC_V1) vt->dump_kmem_cache = dump_kmem_cache_percpu_v1; else if (vt->flags & PERCPU_KMALLOC_V2) @@ -14063,6 +14084,8 @@ dump_vm_table(int verbose) } else { fprintf(fp, " node_online_map: (unused)\n"); } + fprintf(fp, " zero_paddr: %lx\n", vt->zero_paddr); + fprintf(fp, " huge_zero_paddr: %lx\n", vt->huge_zero_paddr); fprintf(fp, " nr_vm_stat_items: %d\n", vt->nr_vm_stat_items); fprintf(fp, " vm_stat_items: %s", (vt->flags & VM_STAT) ? "\n" : "(not used)\n"); diff --git a/x86_64.c b/x86_64.c index 5019c69..693a08b 100644 --- a/x86_64.c +++ b/x86_64.c @@ -2114,8 +2114,9 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in goto no_upage; if (pmd_pte & _PAGE_PSE) { if (verbose) { - fprintf(fp, " PAGE: %lx (2MB)\n\n", - PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK); + fprintf(fp, " PAGE: %lx (2MB%s)\n\n", + PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK, + IS_ZEROPAGE(PAGEBASE(pmd_pte) & PHYSICAL_PAGE_MASK) ? ", ZERO PAGE" : ""); x86_64_translate_pte(pmd_pte, 0, 0); } @@ -2143,8 +2144,8 @@ x86_64_uvtop_level4(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, in *paddr = (PAGEBASE(pte) & PHYSICAL_PAGE_MASK) + PAGEOFFSET(uvaddr); if (verbose) { - fprintf(fp, " PAGE: %lx\n\n", - PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK); + fprintf(fp, " PAGE: %lx %s\n\n", PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK, + IS_ZEROPAGE(PAGEBASE(*paddr) & PHYSICAL_PAGE_MASK) ? "(ZERO PAGE)" : ""); x86_64_translate_pte(pte, 0, 0); }