From f32360ef6608434a032dc7ad262d45e9693c27f3 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 10 Oct 2013 17:18:17 -0700 Subject: [PATCH] x86, kaslr: Report kernel offset on panic When the system panics, include the kernel offset in the report to assist in debugging. Signed-off-by: Kees Cook Link: http://lkml.kernel.org/r/1381450698-28710-6-git-send-email-keescook@chromium.org Signed-off-by: H. Peter Anvin --- arch/x86/kernel/setup.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index f0de6294b955..1708862fc40d 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -823,6 +823,20 @@ static void __init trim_low_memory_range(void) memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE)); } +/* + * Dump out kernel offset information on panic. + */ +static int +dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) +{ + pr_emerg("Kernel Offset: 0x%lx from 0x%lx " + "(relocation range: 0x%lx-0x%lx)\n", + (unsigned long)&_text - __START_KERNEL, __START_KERNEL, + __START_KERNEL_map, MODULES_VADDR-1); + + return 0; +} + /* * Determine if we were loaded by an EFI loader. If so, then we have also been * passed the efi memmap, systab, etc., so we should use these data structures @@ -1242,3 +1256,15 @@ void __init i386_reserve_resources(void) } #endif /* CONFIG_X86_32 */ + +static struct notifier_block kernel_offset_notifier = { + .notifier_call = dump_kernel_offset +}; + +static int __init register_kernel_offset_dumper(void) +{ + atomic_notifier_chain_register(&panic_notifier_list, + &kernel_offset_notifier); + return 0; +} +__initcall(register_kernel_offset_dumper); -- 2.45.2