linux-kernel - Re: [PATCH v3] riscv/mm/fault: add show

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Message-ID: <87ed46galb.fsf@bytedance.com>
Date: Wed, 23 Oct 2024 15:25:36 +0100
From: Punit Agrawal <punit.agrawal@...edance.com>
To: palmer@...belt.com
Cc: conor@...nel.org,  punit.agrawal@...edance.com,
  paul.walmsley@...ive.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,  Andrew
 Jones <ajones@...tanamicro.com>, yunhui cui <cuiyunhui@...edance.com>
Subject: Re: [PATCH v3] riscv/mm/fault: add show_pte() before die()

yunhui cui <cuiyunhui@...edance.com> writes:

> Hi Palmer,
>
> A gentle ping for this patch.
>
> On Thu, Aug 15, 2024 at 10:05 AM yunhui cui <cuiyunhui@...edance.com> wrote:
>>
>> Hi All,
>>
>> A gentle ping, Any more comments on this patch?
>>
>> On Tue, Jul 23, 2024 at 10:18 AM Yunhui Cui <cuiyunhui@...edance.com> 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>
>> > Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>
>> > Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
>> > ---
>> >  arch/riscv/mm/fault.c | 52 +++++++++++++++++++++++++++++++++++++++++++
>> >  1 file changed, 52 insertions(+)

Another one that seems to have slipped through the cracks. If there are
no further comments, please merge the patch.

Thanks,
Punit

>> >
>> > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
>> > index 5224f3733802..c72e6c7c09ef 100644
>> > --- 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);
>> >  }
>> > --
>> > 2.39.2
>> >
>>
>> Thanks,
>> Yunhui
>
>
> Thanks,
> Yunhui