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. [[email protected]: fix implicit declaration of init_vmlinux_build_id()] Link: https://lkml.kernel.org/r/CAE-0n51UjTbay8N9FXAyE7_aR2+ePrQnKSRJ0gbmRsXtcLBVaw@mail.gmail.com Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Stephen Boyd <[email protected]> Acked-by: Baoquan He <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Jessica Yu <[email protected]> Cc: Evan Green <[email protected]> Cc: Hsin-Yi Wang <[email protected]> Cc: Dave Young <[email protected]> Cc: Vivek Goyal <[email protected]> Cc: Andy Shevchenko <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Konstantin Khlebnikov <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Petr Mladek <[email protected]> Cc: Rasmus Villemoes <[email protected]> Cc: Sasha Levin <[email protected]> Cc: Sergey Senozhatsky <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Will Deacon <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
mj22226 · Jul 8, 2021 · 83cc6fa · 83cc6fa
1 parent 7eaf3cf
commit 83cc6fa
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diff --git a/include/linux/buildid.h b/include/linux/buildid.h
@@ -10,4 +10,7 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id,
 		   __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
diff --git a/init/main.c b/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_sanitize_address start_kernel(void)
 	set_task_stack_end_magic(&init_task);
 	smp_setup_processor_id();
 	debug_objects_early_init();
+	init_vmlinux_build_id();
 
 	cgroup_init_early();
 

diff --git a/lib/buildid.c b/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, unsigned char *build_id, u32 buf_size)
 {
 	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);
+}