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>
---
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 */
--
2.41.0
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