On Wed, Sep 27, 2023 at 06:32:44AM +0000, HAGIO KAZUHITO(萩尾 一仁) wrote:
> On 2023/09/14 18:22, Aditya Gupta wrote:
> > Currently 'makedumpfile' fails to collect vmcore on upstream kernel,
> > with the errors:
> >
> > readpage_elf: Attempt to read non-existent page at 0x4000000000000000.
> > readmem: type_addr: 0, addr:0, size:8
> > get_vmemmap_list_info: Can't get vmemmap region addresses
> > get_machdep_info_ppc64: Can't get vmemmap list info.
> >
> > This occurs since makedumpfile depends on 'vmemmap_list' for translating
> > vmemmap addresses. But with below commit in Linux, vmemmap_list can be
> > empty, in case of Radix MMU on PowerPC64
> >
> > 368a0590d954: (powerpc/book3s64/vmemmap: switch radix to use a
> > different vmemmap handling function)
> >
> > In case vmemmap_list is empty, then it's head is NULL, which causes
> > makedumpfile to fail with above error.
> >
> > Since with above commit, 'vmemmap_list' is not populated (when MMU is
> > Radix MMU), kernel populates corresponding page table entries in kernel
> > page table. Hence, instead of depending on 'vmemmap_list' for address
> > translation for vmemmap addresses, do a kernel pagetable walk.
> >
> > And since the pte can also be introduced at higher levels in the page
> > table, such as at PMD level, add hugepage support, by checking for
> > PAGE_PTE flag
> >
> > Reported-by: Sachin Sant <sach...@linux.ibm.com>
> > Signed-off-by: Aditya Gupta <adit...@linux.ibm.com>
>
> Thank you for the patch, applied.
>
> https://github.com/makedumpfile/makedumpfile/commit/a34f017965583e89c4cb0b00117c200a6c191e54
Thanks for the update.
>
> Sorry for the delay, exceptionally busy this month..
No issues :)
Thanks,
- Aditya Gupta
>
> Thanks,
> Kazu
>
> > ---
> > arch/ppc64.c | 111 ++++++++++++++++++++++++++++++++++---------------
> > makedumpfile.h | 6 +++
> > 2 files changed, 84 insertions(+), 33 deletions(-)
> >
> > diff --git a/arch/ppc64.c b/arch/ppc64.c
> > index 5e70acb51aba..9456b8b570c5 100644
> > --- a/arch/ppc64.c
> > +++ b/arch/ppc64.c
> > @@ -196,6 +196,10 @@ ppc64_vmemmap_init(void)
> > int psize, shift;
> > ulong head;
> >
> > + /* initialise vmemmap_list in case SYMBOL(vmemmap_list) is not found */
> > + info->vmemmap_list = NULL;
> > + info->vmemmap_cnt = 0;
> > +
> > if ((SYMBOL(vmemmap_list) == NOT_FOUND_SYMBOL)
> > || (SYMBOL(mmu_psize_defs) == NOT_FOUND_SYMBOL)
> > || (SYMBOL(mmu_vmemmap_psize) == NOT_FOUND_SYMBOL)
> > @@ -216,15 +220,24 @@ ppc64_vmemmap_init(void)
> > return FALSE;
> > info->vmemmap_psize = 1 << shift;
> >
> > - if (!readmem(VADDR, SYMBOL(vmemmap_list), &head, sizeof(unsigned long)))
> > - return FALSE;
> > -
> > /*
> > - * Get vmemmap list count and populate vmemmap regions info
> > - */
> > - info->vmemmap_cnt = get_vmemmap_list_info(head);
> > - if (info->vmemmap_cnt == 0)
> > - return FALSE;
> > + * vmemmap_list symbol can be missing or set to 0 in the kernel.
> > + * This would imply vmemmap region is mapped in the kernel pagetable.
> > + *
> > + * So, read vmemmap_list anyway, and use 'vmemmap_list' if it's not
> > empty
> > + * (head != NULL), or we will do a kernel pagetable walk for vmemmap
> > address
> > + * translation later
> > + **/
> > + readmem(VADDR, SYMBOL(vmemmap_list), &head, sizeof(unsigned long));
> > +
> > + if (head) {
> > + /*
> > + * Get vmemmap list count and populate vmemmap regions info
> > + */
> > + info->vmemmap_cnt = get_vmemmap_list_info(head);
> > + if (info->vmemmap_cnt == 0)
> > + return FALSE;
> > + }
> >
> > info->flag_vmemmap = TRUE;
> > return TRUE;
> > @@ -347,29 +360,6 @@ ppc64_vmalloc_init(void)
> > return TRUE;
> > }
> >
> > -/*
> > - * If the vmemmap address translation information is stored in the kernel,
> > - * make the translation.
> > - */
> > -static unsigned long long
> > -ppc64_vmemmap_to_phys(unsigned long vaddr)
> > -{
> > - int i;
> > - ulong offset;
> > - unsigned long long paddr = NOT_PADDR;
> > -
> > - for (i = 0; i < info->vmemmap_cnt; i++) {
> > - if ((vaddr >= info->vmemmap_list[i].virt) && (vaddr <
> > - (info->vmemmap_list[i].virt + info->vmemmap_psize))) {
> > - offset = vaddr - info->vmemmap_list[i].virt;
> > - paddr = info->vmemmap_list[i].phys + offset;
> > - break;
> > - }
> > - }
> > -
> > - return paddr;
> > -}
> > -
> > static unsigned long long
> > ppc64_vtop_level4(unsigned long vaddr)
> > {
> > @@ -379,6 +369,8 @@ ppc64_vtop_level4(unsigned long vaddr)
> > unsigned long long pgd_pte, pud_pte;
> > unsigned long long pmd_pte, pte;
> > unsigned long long paddr = NOT_PADDR;
> > + uint is_hugepage = 0;
> > + uint pdshift;
> > uint swap = 0;
> >
> > if (info->page_buf == NULL) {
> > @@ -413,6 +405,13 @@ ppc64_vtop_level4(unsigned long vaddr)
> > if (!pgd_pte)
> > return NOT_PADDR;
> >
> > + if (IS_HUGEPAGE(pgd_pte)) {
> > + is_hugepage = 1;
> > + pte = pgd_pte;
> > + pdshift = info->l4_shift;
> > + goto out;
> > + }
> > +
> > /*
> > * Sometimes we don't have level3 pagetable entries
> > */
> > @@ -426,6 +425,13 @@ ppc64_vtop_level4(unsigned long vaddr)
> > pud_pte = swap64(ULONG((info->page_buf +
> > PAGEOFFSET(page_upper))), swap);
> > if (!pud_pte)
> > return NOT_PADDR;
> > +
> > + if (IS_HUGEPAGE(pud_pte)) {
> > + is_hugepage = 1;
> > + pte = pud_pte;
> > + pdshift = info->l3_shift;
> > + goto out;
> > + }
> > } else {
> > pud_pte = pgd_pte;
> > }
> > @@ -440,6 +446,13 @@ ppc64_vtop_level4(unsigned long vaddr)
> > if (!(pmd_pte))
> > return NOT_PADDR;
> >
> > + if (IS_HUGEPAGE(pmd_pte)) {
> > + is_hugepage = 1;
> > + pte = pmd_pte;
> > + pdshift = info->l2_shift;
> > + goto out;
> > + }
> > +
> > pmd_pte = pmd_page_vaddr_l4(pmd_pte);
> > page_table = (ulong *)(pmd_pte)
> > + (BTOP(vaddr) & (info->ptrs_per_l1 - 1));
> > @@ -456,8 +469,40 @@ ppc64_vtop_level4(unsigned long vaddr)
> > if (!pte)
> > return NOT_PADDR;
> >
> > - paddr = PAGEBASE(PTOB((pte & info->pte_rpn_mask) >>
> > info->pte_rpn_shift))
> > +out:
> > + if (is_hugepage) {
> > + paddr = PAGEBASE(PTOB((pte & info->pte_rpn_mask) >>
> > info->pte_rpn_shift))
> > + + (vaddr & ((1UL << pdshift) - 1));
> > + } else {
> > + paddr = PAGEBASE(PTOB((pte & info->pte_rpn_mask) >>
> > info->pte_rpn_shift))
> > + PAGEOFFSET(vaddr);
> > + }
> > +
> > + return paddr;
> > +}
> > +
> > +/*
> > + * If the vmemmap address translation information is stored in the kernel,
> > + * make the translation.
> > + */
> > +static unsigned long long
> > +ppc64_vmemmap_to_phys(unsigned long vaddr)
> > +{
> > + int i;
> > + ulong offset;
> > + unsigned long long paddr = NOT_PADDR;
> > +
> > + if (!info->vmemmap_list)
> > + return ppc64_vtop_level4(vaddr);
> > +
> > + for (i = 0; i < info->vmemmap_cnt; i++) {
> > + if ((vaddr >= info->vmemmap_list[i].virt) && (vaddr <
> > + (info->vmemmap_list[i].virt + info->vmemmap_psize))) {
> > + offset = vaddr - info->vmemmap_list[i].virt;
> > + paddr = info->vmemmap_list[i].phys + offset;
> > + break;
> > + }
> > + }
> >
> > return paddr;
> > }
> > @@ -567,8 +612,8 @@ get_machdep_info_ppc64(void)
> > return FALSE;
> > }
> >
> > + info->vmemmap_start = VMEMMAP_REGION_ID << REGION_SHIFT;
> > if (SYMBOL(vmemmap_list) != NOT_FOUND_SYMBOL) {
> > - info->vmemmap_start = VMEMMAP_REGION_ID << REGION_SHIFT;
> > info->vmemmap_end = info->vmemmap_start;
> > if (ppc64_vmemmap_init() == FALSE) {
> > ERRMSG("Can't get vmemmap list info.\n");
> > diff --git a/makedumpfile.h b/makedumpfile.h
> > index 85e5a4932983..056aee191519 100644
> > --- a/makedumpfile.h
> > +++ b/makedumpfile.h
> > @@ -678,6 +678,12 @@ unsigned long get_kvbase_arm64(void);
> > #define REGION_SHIFT (60UL)
> > #define VMEMMAP_REGION_ID (0xfUL)
> >
> > +/*
> > + * If PAGE_PTE is set, then it's a leaf PTE for hugepage
> > + */
> > +#define PAGE_PTE (1UL << 62)
> > +#define IS_HUGEPAGE(pte) (!!((pte) & PAGE_PTE))
> > +
> > /* 4-level page table support */
> >
> > /* 4K pagesize */
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