From: Stephen Boyd <swboyd@xxxxxxxxxxxx> Subject: buildid: stash away kernels build ID on init Parse the kernel's build ID at initialization so that other code can print a hex format string representation of the running kernel's build ID. This will be used in the kdump and dump_stack code so that developers can easily locate the vmlinux debug symbols for a crash/stacktrace. [swboyd@xxxxxxxxxxxx: fix implicit declaration of init_vmlinux_build_id()] Link: https://lkml.kernel.org/r/CAE-0n51UjTbay8N9FXAyE7_aR2+ePrQnKSRJ0gbmRsXtcLBVaw@xxxxxxxxxxxxxx Link: https://lkml.kernel.org/r/20210511003845.2429846-4-swboyd@xxxxxxxxxxxx Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> Acked-by: Baoquan He <bhe@xxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Jessica Yu <jeyu@xxxxxxxxxx> Cc: Evan Green <evgreen@xxxxxxxxxxxx> Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/buildid.h | 3 +++ init/main.c | 2 ++ lib/buildid.c | 15 +++++++++++++++ 3 files changed, 20 insertions(+) --- a/include/linux/buildid.h~buildid-stash-away-kernels-build-id-on-init +++ a/include/linux/buildid.h @@ -10,4 +10,7 @@ int build_id_parse(struct vm_area_struct __u32 *size); int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size); +extern unsigned char vmlinux_build_id[BUILD_ID_SIZE_MAX]; +void init_vmlinux_build_id(void); + #endif --- a/init/main.c~buildid-stash-away-kernels-build-id-on-init +++ a/init/main.c @@ -45,6 +45,7 @@ #include <linux/srcu.h> #include <linux/moduleparam.h> #include <linux/kallsyms.h> +#include <linux/buildid.h> #include <linux/writeback.h> #include <linux/cpu.h> #include <linux/cpuset.h> @@ -913,6 +914,7 @@ asmlinkage __visible void __init __no_sa set_task_stack_end_magic(&init_task); smp_setup_processor_id(); debug_objects_early_init(); + init_vmlinux_build_id(); cgroup_init_early(); --- a/lib/buildid.c~buildid-stash-away-kernels-build-id-on-init +++ a/lib/buildid.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include <linux/buildid.h> +#include <linux/cache.h> #include <linux/elf.h> #include <linux/kernel.h> #include <linux/pagemap.h> @@ -172,3 +173,17 @@ int build_id_parse_buf(const void *buf, { return parse_build_id_buf(build_id, NULL, buf, buf_size); } + +unsigned char vmlinux_build_id[BUILD_ID_SIZE_MAX] __ro_after_init; + +/** + * init_vmlinux_build_id - Compute and stash the running kernel's build ID + */ +void __init init_vmlinux_build_id(void) +{ + extern const void __start_notes __weak; + extern const void __stop_notes __weak; + unsigned int size = &__stop_notes - &__start_notes; + + build_id_parse_buf(&__start_notes, vmlinux_build_id, size); +} _
