[Crash-utility] Re: [PATCH] riscv64: handle leaf page table entries in vtop

RISC-V page table entries at any level may be leaf entries when V is set and any of R/W/X is set. The riscv64 vtop walkers currently treat non-zero intermediate entries as pointers to the next page table, so a PMD leaf can be used as a page table address and make vtop fail with a physical seek error. Detect leaf entries at PGD/P4D/PUD/PMD levels and translate them using the page size implied by that level. Continue walking only for non-leaf table entries. Signed-off-by: Rui Qi <qirui.001(a)bytedance.com&gt; --- riscv64.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/riscv64.c b/riscv64.c index 4dcecc2f6b2c..ca26965421d7 100644 --- a/riscv64.c +++ b/riscv64.c @@ -602,6 +602,33 @@ riscv64_translate_pte(ulong pte, void *physaddr, ulonglong unused) return page_present; } +static int +riscv64_pte_is_leaf(ulong pte) +{ + return ((pte & _PAGE_PRESENT) && + (pte & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC))); +} + +static int +riscv64_handle_leaf_pte(ulong pte, ulong vaddr, int shift, + physaddr_t *paddr, int verbose) +{ + physaddr_t paddr_base, page_mask; + + pte &= PTE_PFN_PROT_MASK; + paddr_base = PTOB(pte >> _PAGE_PFN_SHIFT); + page_mask = ~(((physaddr_t)1 << shift) - 1); + *paddr = (paddr_base & page_mask) + (vaddr & ~page_mask); + + if (verbose) { + fprintf(fp, " PAGE: %016llx\n\n", + (ulonglong)(*paddr & page_mask)); + riscv64_translate_pte(pte, 0, 0); + } + + return TRUE; +} + static void riscv64_page_type_init(void) { @@ -655,6 +682,9 @@ riscv64_vtop_3level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PGD: %lx => %lx\n", (ulong)pgd_ptr, pgd_val); if (!pgd_val) goto no_page; + if (riscv64_pte_is_leaf(pgd_val)) + return riscv64_handle_leaf_pte(pgd_val, vaddr, + PGD_SHIFT_L3, paddr, verbose); pgd_val &= PTE_PFN_PROT_MASK; pmd_base = (pgd_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -666,6 +696,9 @@ riscv64_vtop_3level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PMD: %016lx => %016lx\n", pmd_addr, pmd_val); if (!pmd_val) goto no_page; + if (riscv64_pte_is_leaf(pmd_val)) + return riscv64_handle_leaf_pte(pmd_val, vaddr, + PMD_SHIFT, paddr, verbose); pmd_val &= PTE_PFN_PROT_MASK; pte_base = (pmd_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -1237,6 +1270,9 @@ riscv64_vtop_4level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PGD: %lx => %lx\n", (ulong)pgd_ptr, pgd_val); if (!pgd_val) goto no_page; + if (riscv64_pte_is_leaf(pgd_val)) + return riscv64_handle_leaf_pte(pgd_val, vaddr, + PGD_SHIFT_L4, paddr, verbose); pgd_val &= PTE_PFN_PROT_MASK; pud_base = (pgd_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -1248,6 +1284,9 @@ riscv64_vtop_4level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PUD: %016lx => %016lx\n", pud_addr, pud_val); if (!pud_val) goto no_page; + if (riscv64_pte_is_leaf(pud_val)) + return riscv64_handle_leaf_pte(pud_val, vaddr, + PUD_SHIFT, paddr, verbose); pud_val &= PTE_PFN_PROT_MASK; pmd_base = (pud_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -1259,6 +1298,9 @@ riscv64_vtop_4level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PMD: %016lx => %016lx\n", pmd_addr, pmd_val); if (!pmd_val) goto no_page; + if (riscv64_pte_is_leaf(pmd_val)) + return riscv64_handle_leaf_pte(pmd_val, vaddr, + PMD_SHIFT, paddr, verbose); pmd_val &= PTE_PFN_PROT_MASK; pte_base = (pmd_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -1316,6 +1358,9 @@ riscv64_vtop_5level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PGD: %lx => %lx\n", (ulong)pgd_ptr, pgd_val); if (!pgd_val) goto no_page; + if (riscv64_pte_is_leaf(pgd_val)) + return riscv64_handle_leaf_pte(pgd_val, vaddr, + PGD_SHIFT_L5, paddr, verbose); pgd_val &= PTE_PFN_PROT_MASK; p4d_base = (pgd_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -1327,6 +1372,9 @@ riscv64_vtop_5level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " P4D: %016lx => %016lx\n", p4d_addr, p4d_val); if (!p4d_val) goto no_page; + if (riscv64_pte_is_leaf(p4d_val)) + return riscv64_handle_leaf_pte(p4d_val, vaddr, + P4D_SHIFT, paddr, verbose); p4d_val &= PTE_PFN_PROT_MASK; pud_base = (p4d_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -1338,6 +1386,9 @@ riscv64_vtop_5level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PUD: %016lx => %016lx\n", pud_addr, pud_val); if (!pud_val) goto no_page; + if (riscv64_pte_is_leaf(pud_val)) + return riscv64_handle_leaf_pte(pud_val, vaddr, + PUD_SHIFT, paddr, verbose); pud_val &= PTE_PFN_PROT_MASK; pmd_base = (pud_val >> _PAGE_PFN_SHIFT) << PAGESHIFT(); @@ -1349,6 +1400,9 @@ riscv64_vtop_5level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) fprintf(fp, " PMD: %016lx => %016lx\n", pmd_addr, pmd_val); if (!pmd_val) goto no_page; + if (riscv64_pte_is_leaf(pmd_val)) + return riscv64_handle_leaf_pte(pmd_val, vaddr, + PMD_SHIFT, paddr, verbose); pmd_val &= PTE_PFN_PROT_MASK; pte_base = (pmd_val >> _PAGE_PFN_SHIFT) << PAGESHIFT();