Re: [Crash-utility] [PATCH] x86_64_init: Refresh vmalloc region addresses in POST_RELOC instead of POST_GDB phase

Previously for x86_64, when memory is randomized, the region addresses such as vmalloc_start_addr/vmemmap_vaddr/modules_vaddr are firstly set to a default value before POST_RELOC phase, then get refreshed with the actual value in POST_GDB phase. However for crash mininal mode, POST_GDB phase is not called, which leaving the region addresses unrefreshed and incorrect. As a consequence, the x86_64_IS_VMALLOC_ADDR check will give a faulty result when value_search tries to search a symbol by address. For example, in crash minimal mode we can observe the following issue: crash> dis -f panic dis: cannot resolve address: ffffffffb20e0d30 crash> sym panic ffffffffb20e0d30 (T) panic /usr/src/debug/kernel-4.18.0-290/linux-4.18.0-290/kernel/panic.c: 168 crash> sym ffffffffb20e0d30 symbol not found: ffffffffb20e0d30 In this patch, we will move the code which update the region addresses into POST_RELOC phase, so in mininal mode the regions can get the correct addresses. Signed-off-by: Tao Liu <ltao(a)redhat.com&gt;

--- x86_64.c | 52 ++++++++++++++++++++++++++-------------------------- 1 file changed, 26 insertions(+), 26 deletions(-) diff --git a/x86_64.c b/x86_64.c index 552d619..2fb1277 100644 --- a/x86_64.c +++ b/x86_64.c @@ -384,6 +384,31 @@ x86_64_init(int when) "page_offset_base", QUIET|FAULT_ON_ERROR); machdep->kvbase = machdep->machspec->page_offset; machdep->identity_map_base = machdep->machspec->page_offset; + + readmem(symbol_value("vmalloc_base"), KVADDR, + &machdep->machspec->vmalloc_start_addr, + sizeof(ulong), "vmalloc_base", FAULT_ON_ERROR); + if (machdep->flags & VM_5LEVEL) + machdep->machspec->vmalloc_end = + machdep->machspec->vmalloc_start_addr + TERABYTES(1280) - 1; + else + machdep->machspec->vmalloc_end = + machdep->machspec->vmalloc_start_addr + TERABYTES(32) - 1; + if (kernel_symbol_exists("vmemmap_base")) { + readmem(symbol_value("vmemmap_base"), KVADDR, + &machdep->machspec->vmemmap_vaddr, sizeof(ulong), + "vmemmap_base", FAULT_ON_ERROR); + machdep->machspec->vmemmap_end = + machdep->machspec->vmemmap_vaddr + + TERABYTES(1) - 1; + } else { + machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_2_6_31; + machdep->machspec->vmemmap_end = VMEMMAP_END_2_6_31; + } + machdep->machspec->modules_vaddr = __START_KERNEL_map + + (machdep->machspec->kernel_image_size ? + machdep->machspec->kernel_image_size : GIGABYTES(1)); + machdep->machspec->modules_end = MODULES_END_2_6_31; } break; @@ -414,32 +439,7 @@ x86_64_init(int when) machdep->machspec->modules_end = MODULES_END_2_6_27; } if (THIS_KERNEL_VERSION >= LINUX(2,6,31)) { - if (machdep->flags & RANDOMIZED) { - readmem(symbol_value("vmalloc_base"), KVADDR, - &machdep->machspec->vmalloc_start_addr, - sizeof(ulong), "vmalloc_base", FAULT_ON_ERROR); - if (machdep->flags & VM_5LEVEL) - machdep->machspec->vmalloc_end = - machdep->machspec->vmalloc_start_addr + TERABYTES(1280) - 1; - else - machdep->machspec->vmalloc_end = - machdep->machspec->vmalloc_start_addr + TERABYTES(32) - 1; - if (kernel_symbol_exists("vmemmap_base")) { - readmem(symbol_value("vmemmap_base"), KVADDR, - &machdep->machspec->vmemmap_vaddr, sizeof(ulong), - "vmemmap_base", FAULT_ON_ERROR); - machdep->machspec->vmemmap_end = - machdep->machspec->vmemmap_vaddr + - TERABYTES(1) - 1; - } else { - machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_2_6_31; - machdep->machspec->vmemmap_end = VMEMMAP_END_2_6_31; - } - machdep->machspec->modules_vaddr = __START_KERNEL_map + - (machdep->machspec->kernel_image_size ? - machdep->machspec->kernel_image_size : GIGABYTES(1)); - machdep->machspec->modules_end = MODULES_END_2_6_31; - } else { + if (!(machdep->flags & RANDOMIZED)) { machdep->machspec->vmalloc_start_addr = VMALLOC_START_ADDR_2_6_31; machdep->machspec->vmalloc_end = VMALLOC_END_2_6_31; machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_2_6_31; -- 2.33.1 -- Crash-utility mailing list Crash-utility(a)redhat.com https://listman.redhat.com/mailman/listinfo/crash-utility