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Message-ID: <20240719-92015016b960e7153e97b39d@orel>
Date: Fri, 19 Jul 2024 09:32:13 -0500
From: Andrew Jones <ajones@...tanamicro.com>
To: Yunhui Cui <cuiyunhui@...edance.com>
Cc: punit.agrawal@...edance.com, paul.walmsley@...ive.com,
palmer@...belt.com, aou@...s.berkeley.edu, akpm@...ux-foundation.org,
surenb@...gle.com, peterx@...hat.com, alexghiti@...osinc.com, willy@...radead.org,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv/mm/fault: add show_pte() before die()
On Thu, Jul 18, 2024 at 10:09:35AM GMT, Yunhui Cui wrote:
> 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@...edance.com>
> ---
> arch/riscv/mm/fault.c | 47 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 47 insertions(+)
>
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index 90d4ba36d1d0..dfe3ce38e16b 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -22,6 +22,52 @@
>
> #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;
arm64 show_pte starts with a summary line where the pgtable type (swapper
vs. user), number of VA bits, and physical address of the pgd are
displayed. Should we add that too?
Thanks,
drew
> + pgdp = pgd_offset(mm, addr);
> + pgd = READ_ONCE(*pgdp);
> + pr_alert("[%016lx] pgd=%016lx", addr, pgd_val(pgd));
> + if (pgd_none(pgd) || pgd_bad(pgd))
> + goto out;
> +
> + p4dp = p4d_offset(pgdp, addr);
> + p4d = READ_ONCE(*p4dp);
> + pr_cont(", p4d=%016lx", p4d_val(p4d));
> + if (p4d_none(p4d) || p4d_bad(p4d))
> + goto out;
> +
> + pudp = pud_offset(p4dp, addr);
> + pud = READ_ONCE(*pudp);
> + pr_cont(", pud=%016lx", pud_val(pud));
> + if (pud_none(pud) || pud_bad(pud))
> + goto out;
> +
> + pmdp = pmd_offset(pudp, addr);
> + pmd = READ_ONCE(*pmdp);
> + pr_cont(", pmd=%016lx", pmd_val(pmd));
> + if (pmd_none(pmd) || pmd_bad(pmd))
> + goto out;
> +
> + ptep = pte_offset_map(pmdp, addr);
> + if (!ptep)
> + goto out;
> +
> + pte = READ_ONCE(*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 +77,7 @@ 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);
> }
> --
> 2.39.2
>
>
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