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

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Message-ID: <CAEEQ3wmOKtfMyRYnmEcHcczuRhPjMC8g_rxQc9y3X9gOuaqS0Q@mail.gmail.com>
Date: Wed, 18 Sep 2024 11:44:05 +0800
From: yunhui cui <cuiyunhui@...edance.com>
To: conor@...nel.org, 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
Cc: Andrew Jones <ajones@...tanamicro.com>
Subject: Re: [PATCH v3] riscv/mm/fault: add show_pte() before die()

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(+)
> >
> > 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