On 2022/07/28 16:11, Lianbo Jiang wrote:
> Kernel commit changes(see [1]/[2]) may cause the failure of crash-utility
> with the following error:
>
>    #./crash /home/vmlinux /home/vmcore
>    ...
>    For help, type "help".
>    Type "apropos word" to search for commands related to "word"...
>
>    crash: seek error: physical address: 8000760a14000  type: "p4d page"
>
> Let's get the "NUMBER(sme_mask)" from vmcoreinfo, and try to remove
> the C-bit from the page table entries, the intention is to get the
> true physical address.
>
> Related kernel commits:
> [1] aad983913d77 ("x86/mm/encrypt: Simplify sme_populate_pgd() and sme_populate_pgd_large()")
> [2] e7d445ab26db ("x86/sme: Use #define USE_EARLY_PGTABLE_L5 in mem_encrypt_identity.c")
>
> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
> ---
> Note: This issue also occurs in live debugging system.
>
>   defs.h   |  1 +
>   x86_64.c | 19 ++++++++++++++++---
>   2 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index 9b1b69a4f421..9d6d8916284b 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -6198,6 +6198,7 @@ struct machine_specific {
>       ulong cpu_entry_area_end;
>       ulong page_offset_force;
>       char **exception_functions;
> +     ulong sme_mask;
>   };
>   
>   #define KSYMS_START    (0x1)
> diff --git a/x86_64.c b/x86_64.c
> index cfafbcc4dabe..1dae39bcbb3c 100644
> --- a/x86_64.c
> +++ b/x86_64.c
> @@ -208,6 +208,10 @@ x86_64_init(int when)
>                       machdep->machspec->kernel_image_size = dtol(string, QUIET, NULL);
>                       free(string);
>               }
> +             if ((string = pc->read_vmcoreinfo("NUMBER(sme_mask)"))) {
> +                     machdep->machspec->sme_mask = dtol(string, QUIET, NULL);
> +                     free(string);
> +             }
>               if (SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO() ||
>                   VMSS_DUMPFILE())
>                       /* Need for calculation of kaslr_offset and phys_base */
> @@ -940,6 +944,7 @@ x86_64_dump_machdep_table(ulong arg)
>                       ms->kernel_image_size/MEGABYTES(1));
>       else
>               fprintf(fp, "(uninitialized)\n");
> +     fprintf(fp, "                 sme_mask: %lx\n", ms->sme_mask);
>       fprintf(fp, "      physical_mask_shift: %ld\n", ms->physical_mask_shift);
>       fprintf(fp, "              pgdir_shift: %ld\n", ms->pgdir_shift);
>       fprintf(fp, "               GART_start: %lx\n", ms->GART_start);
> @@ -1817,7 +1822,7 @@ x86_64_kpgd_offset(ulong kvaddr, int verbose, int IS_XEN)
>               if (IS_XEN)
>                       fprintf(fp, "PAGE DIRECTORY: %lx [machine]\n", *pgd);
>               else
> -                     fprintf(fp, "PAGE DIRECTORY: %lx\n", *pgd);
> +                     fprintf(fp, "PAGE DIRECTORY: %lx\n", *pgd & ~machdep->machspec->sme_mask);
>       }
>   
>       return pgd;
> @@ -1854,7 +1859,7 @@ x86_64_upgd_offset_legacy(struct task_context *tc, ulong uvaddr, int verbose, in
>               if (IS_XEN)
>                       fprintf(fp, "   PGD: %lx => %lx [machine]\n", (ulong)pud, pud_pte);
>               else
> -                     fprintf(fp, "   PGD: %lx => %lx\n", (ulong)pud, pud_pte);
> +                     fprintf(fp, "   PGD: %lx => %lx\n", (ulong)pud, pud_pte & ~machdep->machspec->sme_mask);
>           }
>   
>       return pud_pte;
> @@ -1885,7 +1890,7 @@ x86_64_upgd_offset(struct task_context *tc, ulong uvaddr, int verbose, int IS_XE
>               if (IS_XEN)
>                       fprintf(fp, "   PGD: %lx => %lx [machine]\n", (ulong)pgd, pgd_pte);
>               else
> -                     fprintf(fp, "   PGD: %lx => %lx\n", (ulong)pgd, pgd_pte);
> +                     fprintf(fp, "   PGD: %lx => %lx\n", (ulong)pgd, pgd_pte & ~machdep->machspec->sme_mask);
>           }
>   
>       return pgd_pte;
> @@ -1903,9 +1908,11 @@ x86_64_p4d_offset(ulong pgd_pte, ulong vaddr, int verbose, int IS_XEN)
>       ulong p4d_pte;
>   
>       p4d_paddr = pgd_pte & PHYSICAL_PAGE_MASK;
> +     p4d_paddr &= ~machdep->machspec->sme_mask;
>       FILL_P4D(p4d_paddr, PHYSADDR, PAGESIZE());
>       p4d = ((ulong *)p4d_paddr) + p4d_index(vaddr);
>       p4d_pte = ULONG(machdep->machspec->p4d + PAGEOFFSET(p4d));
> +     p4d_pte &= ~machdep->machspec->sme_mask;
>           if (verbose) {
>               if (IS_XEN)
>                       fprintf(fp, "   P4D: %lx => %lx [machine]\n", (ulong)p4d, p4d_pte);
> @@ -1928,6 +1935,7 @@ x86_64_pud_offset(ulong pgd_pte, ulong vaddr, int verbose, int IS_XEN)
>       ulong pud_pte;
>   
>       pud_paddr = pgd_pte & PHYSICAL_PAGE_MASK;
> +     pud_paddr &= ~machdep->machspec->sme_mask;
>   
>       if (IS_XEN) {
>               pud_paddr = xen_m2p(pud_paddr);
> @@ -1938,6 +1946,7 @@ x86_64_pud_offset(ulong pgd_pte, ulong vaddr, int verbose, int IS_XEN)
>       FILL_PUD(pud_paddr, PHYSADDR, PAGESIZE());
>       pud = ((ulong *)pud_paddr) + pud_index(vaddr);
>       pud_pte = ULONG(machdep->pud + PAGEOFFSET(pud));
> +     pud_pte &= ~machdep->machspec->sme_mask;

Taking this for example, the pud_pte is masked here..

         PUD: 761c02b28 => 16bea5063

                                            ^^^^^^^^^^

      Otherwise, it will display the address of PUD with the C-bit.

      Or Remove the C-bit when printing information?

+    fprintf(fp, "   PUD: %lx => %lx\n", (ulong)pud, pud_pte & ~machdep->machspec->sme_mask);

[2] consider the cases of using hugepage.

     -On this machine, it supports 1G and 2M hugepage according to the vmcore.

 

 >       if (verbose) {
>               if (IS_XEN)
>                       fprintf(fp, "   PUD: %lx => %lx [machine]\n", (ulong)pud, pud_pte);
> @@ -1960,6 +1969,7 @@ x86_64_pmd_offset(ulong pud_pte, ulong vaddr, int verbose, int IS_XEN)
>       ulong pmd_pte;
>   
>       pmd_paddr = pud_pte & PHYSICAL_PAGE_MASK;
> +     pmd_paddr &= ~machdep->machspec->sme_mask;

and also here the pud_pte is masked again.  Is this needed?

Thanks,
Kazu

>   
>       if (IS_XEN) {
>               pmd_paddr = xen_m2p(pmd_paddr);
> @@ -1970,6 +1980,7 @@ x86_64_pmd_offset(ulong pud_pte, ulong vaddr, int verbose, int IS_XEN)
>       FILL_PMD(pmd_paddr, PHYSADDR, PAGESIZE());
>       pmd = ((ulong *)pmd_paddr) + pmd_index(vaddr);
>       pmd_pte = ULONG(machdep->pmd + PAGEOFFSET(pmd));
> +     pmd_pte &= ~machdep->machspec->sme_mask;
>           if (verbose) {
>               if (IS_XEN)
>                       fprintf(fp, "   PMD: %lx => %lx [machine]\n", (ulong)pmd, pmd_pte);
> @@ -1991,6 +2002,7 @@ x86_64_pte_offset(ulong pmd_pte, ulong vaddr, int verbose, int IS_XEN)
>       ulong pte;
>   
>       pte_paddr = pmd_pte & PHYSICAL_PAGE_MASK;
> +     pte_paddr &= ~machdep->machspec->sme_mask;
>   
>       if (IS_XEN) {
>               pte_paddr = xen_m2p(pte_paddr);
> @@ -2001,6 +2013,7 @@ x86_64_pte_offset(ulong pmd_pte, ulong vaddr, int verbose, int IS_XEN)
>       FILL_PTBL(pte_paddr, PHYSADDR, PAGESIZE());
>       ptep = ((ulong *)pte_paddr) + pte_index(vaddr);
>       pte = ULONG(machdep->ptbl + PAGEOFFSET(ptep));
> +     pte &= ~machdep->machspec->sme_mask;
>       if (verbose) {
>               if (IS_XEN)
>                       fprintf(fp, "   PTE: %lx => %lx [machine]\n", (ulong)ptep, pte);