11:16 a.m.
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.
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>
---
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