Hello Dou,
This patch was failing on most -- but not all -- of my test dumpfiles, because of
fatal read or seek errors during session initialization.
As it turns out, the "l5_enabled" local variable needs to be zeroed-out, because
if neither the "if" or the "else" are true, it uses whatever old stack garbage
that l5_enabled contains:
> + /* Check for 5-level paging */
> + if (!(machdep->flags & VM_5LEVEL)) {
> + int l5_enabled;
> + if ((string = pc->read_vmcoreinfo("NUMBER(pgtable_l5_enabled)"))) {
> + l5_enabled = 1;
> + free(string);
> + } else if (kernel_symbol_exists("__pgtable_l5_enabled"))
> + readmem(symbol_value("__pgtable_l5_enabled"), KVADDR,
> + &l5_enabled, sizeof(int), "__pgtable_l5_enabled",
> + FAULT_ON_ERROR);
> +
> + if (l5_enabled)
> + machdep->flags |= VM_5LEVEL;
> + }
I'll fix that and retest.
Thanks,
Dave
----- Original Message -----
> Currently, Crash only enable support for kernel-only 5-level page tables by
> entering the command line option "--machdep vm=5level". Since Linux 4.17,
> the Linux kernel can be both 4level and 5level page tables. This command line
> can't work well for this.
>
> Using the "pgtable_l5_enabled" to detect whether the kernel proper for 5
> level
> page tables automatically. Also move the 5-level paging setup from
> machdep_init(PRE_GDB)
> to machdep_init(POST_RELOC).
>
> Signed-off-by: Dave Anderson <anderson@xxxxxxxxxx>
> Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
> ---
> Changelog v1 --> v2
>
> 1. Make it support live systems suggested by Dave
> 2. Using __pgtable_l5_enabled for check.
> 3. Do some tests in both kdump(5level and 4level) and virsh dump(5level and
> 4level)
> ---
> x86_64.c | 56 +++++++++++++++++++++++++++++++++++++-------------------
> 1 file changed, 37 insertions(+), 19 deletions(-)
>
> diff --git a/x86_64.c b/x86_64.c
> index 6d1ae2f..07b6aa9 100644
> --- a/x86_64.c
> +++ b/x86_64.c
> @@ -294,25 +294,6 @@ x86_64_init(int when)
> machdep->machspec->pgdir_shift = PGDIR_SHIFT;
> machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD;
> break;
> -
> - case VM_5LEVEL:
> - machdep->machspec->userspace_top = USERSPACE_TOP_5LEVEL;
> - machdep->machspec->page_offset = PAGE_OFFSET_5LEVEL;
> - machdep->machspec->vmalloc_start_addr = VMALLOC_START_ADDR_5LEVEL;
> - machdep->machspec->vmalloc_end = VMALLOC_END_5LEVEL;
> - machdep->machspec->modules_vaddr = MODULES_VADDR_5LEVEL;
> - machdep->machspec->modules_end = MODULES_END_5LEVEL;
> - machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_5LEVEL;
> - machdep->machspec->vmemmap_end = VMEMMAP_END_5LEVEL;
> - if (symbol_exists("vmemmap_populate"))
> - machdep->flags |= VMEMMAP;
> - machdep->machspec->physical_mask_shift = __PHYSICAL_MASK_SHIFT_5LEVEL;
> - machdep->machspec->pgdir_shift = PGDIR_SHIFT_5LEVEL;
> - machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD_5LEVEL;
> - if ((machdep->machspec->p4d = (char *)malloc(PAGESIZE())) == NULL)
> - error(FATAL, "cannot malloc p4d space.");
> - machdep->machspec->last_p4d_read = 0;
> - machdep->uvtop = x86_64_uvtop_level4; /* 5-level is optional per-task */
> }
> machdep->kvbase = (ulong)PAGE_OFFSET;
> machdep->identity_map_base = (ulong)PAGE_OFFSET;
> @@ -346,6 +327,43 @@ x86_64_init(int when)
> break;
>
> case POST_RELOC:
> + /* Check for 5-level paging */
> + if (!(machdep->flags & VM_5LEVEL)) {
> + int l5_enabled;
> + if ((string = pc->read_vmcoreinfo("NUMBER(pgtable_l5_enabled)"))) {
> + l5_enabled = 1;
> + free(string);
> + } else if (kernel_symbol_exists("__pgtable_l5_enabled"))
> + readmem(symbol_value("__pgtable_l5_enabled"), KVADDR,
> + &l5_enabled, sizeof(int), "__pgtable_l5_enabled",
> + FAULT_ON_ERROR);
> +
> + if (l5_enabled)
> + machdep->flags |= VM_5LEVEL;
> + }
> + if (machdep->flags & VM_5LEVEL) {
> + machdep->machspec->userspace_top = USERSPACE_TOP_5LEVEL;
> + machdep->machspec->page_offset = PAGE_OFFSET_5LEVEL;
> + machdep->machspec->vmalloc_start_addr = VMALLOC_START_ADDR_5LEVEL;
> + machdep->machspec->vmalloc_end = VMALLOC_END_5LEVEL;
> + machdep->machspec->modules_vaddr = MODULES_VADDR_5LEVEL;
> + machdep->machspec->modules_end = MODULES_END_5LEVEL;
> + machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_5LEVEL;
> + machdep->machspec->vmemmap_end = VMEMMAP_END_5LEVEL;
> + if (symbol_exists("vmemmap_populate"))
> + machdep->flags |= VMEMMAP;
> + machdep->machspec->physical_mask_shift = __PHYSICAL_MASK_SHIFT_5LEVEL;
> + machdep->machspec->pgdir_shift = PGDIR_SHIFT_5LEVEL;
> + machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD_5LEVEL;
> + if ((machdep->machspec->p4d = (char *)malloc(PAGESIZE())) == NULL)
> + error(FATAL, "cannot malloc p4d space.");
> + machdep->machspec->last_p4d_read = 0;
> + machdep->uvtop = x86_64_uvtop_level4; /* 5-level is optional per-task */
> + machdep->kvbase = (ulong)PAGE_OFFSET;
> + machdep->identity_map_base = (ulong)PAGE_OFFSET;
> +
> + }
> +
> /*
> * Check for CONFIG_RANDOMIZE_MEMORY, and set page_offset here.
> * The remainder of the virtual address range setups will get
> --
> 2.14.3
>
>
>
>
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