Re: [Crash-utility] [PATCH v2] arm64/x86_64: show zero pfn information when using vtop

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