Re: [Crash-utility] [PATCH v2] x86_64: Make the conversion between 4level and 5level paging automatically

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(a)redhat.com&gt; > Signed-off-by: Dou Liyang <douly.fnst(a)cn.fujitsu.com&gt; > --- > 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 > > > > -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility