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 <sachinp@xxxxxxxxxxxxx> > Signed-off-by: Aditya Gupta <adityag@xxxxxxxxxxxxx> Thank you for the patch, applied. https://github.com/makedumpfile/makedumpfile/commit/a34f017965583e89c4cb0b00117c200a6c191e54 Sorry for the delay, exceptionally busy this month.. 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 */ _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
