riscv/mm/fault: add show_pte() before die()

When the kernel displays "Unable to handle kernel paging request at
virtual address", we would like to confirm the status of the virtual
address in the page table. So add show_pte() before die().

Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240723021820.87718-1-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index a9f2b4af8f3f18442117f79855cfe89b39ce4d7e..0194324a0c5060dd6e205166c34c79480e0f7960 100644 (file)
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -22,6 +22,57 @@
 
 #include "../kernel/head.h"
 
+static void show_pte(unsigned long addr)
+{
+       pgd_t *pgdp, pgd;
+       p4d_t *p4dp, p4d;
+       pud_t *pudp, pud;
+       pmd_t *pmdp, pmd;
+       pte_t *ptep, pte;
+       struct mm_struct *mm = current->mm;
+
+       if (!mm)
+               mm = &init_mm;
+
+       pr_alert("Current %s pgtable: %luK pagesize, %d-bit VAs, pgdp=0x%016llx\n",
+                current->comm, PAGE_SIZE / SZ_1K, VA_BITS,
+                mm == &init_mm ? (u64)__pa_symbol(mm->pgd) : virt_to_phys(mm->pgd));
+
+       pgdp = pgd_offset(mm, addr);
+       pgd = pgdp_get(pgdp);
+       pr_alert("[%016lx] pgd=%016lx", addr, pgd_val(pgd));
+       if (pgd_none(pgd) || pgd_bad(pgd) || pgd_leaf(pgd))
+               goto out;
+
+       p4dp = p4d_offset(pgdp, addr);
+       p4d = p4dp_get(p4dp);
+       pr_cont(", p4d=%016lx", p4d_val(p4d));
+       if (p4d_none(p4d) || p4d_bad(p4d) || p4d_leaf(p4d))
+               goto out;
+
+       pudp = pud_offset(p4dp, addr);
+       pud = pudp_get(pudp);
+       pr_cont(", pud=%016lx", pud_val(pud));
+       if (pud_none(pud) || pud_bad(pud) || pud_leaf(pud))
+               goto out;
+
+       pmdp = pmd_offset(pudp, addr);
+       pmd = pmdp_get(pmdp);
+       pr_cont(", pmd=%016lx", pmd_val(pmd));
+       if (pmd_none(pmd) || pmd_bad(pmd) || pmd_leaf(pmd))
+               goto out;
+
+       ptep = pte_offset_map(pmdp, addr);
+       if (!ptep)
+               goto out;
+
+       pte = ptep_get(ptep);
+       pr_cont(", pte=%016lx", pte_val(pte));
+       pte_unmap(ptep);
+out:
+       pr_cont("\n");
+}
+
 static void die_kernel_fault(const char *msg, unsigned long addr,
                struct pt_regs *regs)
 {
@@ -31,6 +82,7 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
                addr);
 
        bust_spinlocks(0);
+       show_pte(addr);
        die(regs, "Oops");
        make_task_dead(SIGKILL);
 }