kdump: use vmlinux_build_id to simplify

We can use the vmlinux_build_id array here now instead of open coding it.
This mostly consolidates code.

Link: https://lkml.kernel.org/r/20210511003845.2429846-14-swboyd@chromium.orgSigned-off-by: Stephen Boyd <swboyd@chromium.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Evan Green <evgreen@chromium.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/buildid.h

@@ -10,7 +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);
 
-#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) || IS_ENABLED(CONFIG_CRASH_CORE)
 extern unsigned char vmlinux_build_id[BUILD_ID_SIZE_MAX];
 void init_vmlinux_build_id(void);
 #else

include/linux/crash_core.h

@@ -38,8 +38,12 @@ phys_addr_t paddr_vmcoreinfo_note(void);
 
 #define VMCOREINFO_OSRELEASE(value) \
 	vmcoreinfo_append_str("OSRELEASE=%s\n", value)
-#define VMCOREINFO_BUILD_ID(value) \
-	vmcoreinfo_append_str("BUILD-ID=%s\n", value)
+#define VMCOREINFO_BUILD_ID()						\
+	({								\
+		static_assert(sizeof(vmlinux_build_id) == 20);		\
+		vmcoreinfo_append_str("BUILD-ID=%20phN\n", vmlinux_build_id); \
+	})
+
 #define VMCOREINFO_PAGESIZE(value) \
 	vmcoreinfo_append_str("PAGESIZE=%ld\n", value)
 #define VMCOREINFO_SYMBOL(name) \
@@ -69,10 +73,6 @@ extern unsigned char *vmcoreinfo_data;
 extern size_t vmcoreinfo_size;
 extern u32 *vmcoreinfo_note;
 
-/* raw contents of kernel .notes section */
-extern const void __start_notes __weak;
-extern const void __stop_notes __weak;
-
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
 void final_note(Elf_Word *buf);

kernel/crash_core.c

@@ -4,6 +4,7 @@
  * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
  */
 
+#include <linux/buildid.h>
 #include <linux/crash_core.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
@@ -378,53 +379,6 @@ phys_addr_t __weak paddr_vmcoreinfo_note(void)
 }
 EXPORT_SYMBOL(paddr_vmcoreinfo_note);
 
-#define NOTES_SIZE (&__stop_notes - &__start_notes)
-#define BUILD_ID_MAX SHA1_DIGEST_SIZE
-#define NT_GNU_BUILD_ID 3
-
-struct elf_note_section {
-	struct elf_note	n_hdr;
-	u8 n_data[];
-};
-
-/*
- * Add build ID from .notes section as generated by the GNU ld(1)
- * or LLVM lld(1) --build-id option.
- */
-static void add_build_id_vmcoreinfo(void)
-{
-	char build_id[BUILD_ID_MAX * 2 + 1];
-	int n_remain = NOTES_SIZE;
-
-	while (n_remain >= sizeof(struct elf_note)) {
-		const struct elf_note_section *note_sec =
-			&__start_notes + NOTES_SIZE - n_remain;
-		const u32 n_namesz = note_sec->n_hdr.n_namesz;
-
-		if (note_sec->n_hdr.n_type == NT_GNU_BUILD_ID &&
-		    n_namesz != 0 &&
-		    !strcmp((char *)&note_sec->n_data[0], "GNU")) {
-			if (note_sec->n_hdr.n_descsz <= BUILD_ID_MAX) {
-				const u32 n_descsz = note_sec->n_hdr.n_descsz;
-				const u8 *s = &note_sec->n_data[n_namesz];
-
-				s = PTR_ALIGN(s, 4);
-				bin2hex(build_id, s, n_descsz);
-				build_id[2 * n_descsz] = '\0';
-				VMCOREINFO_BUILD_ID(build_id);
-				return;
-			}
-			pr_warn("Build ID is too large to include in vmcoreinfo: %u > %u\n",
-				note_sec->n_hdr.n_descsz,
-				BUILD_ID_MAX);
-			return;
-		}
-		n_remain -= sizeof(struct elf_note) +
-			ALIGN(note_sec->n_hdr.n_namesz, 4) +
-			ALIGN(note_sec->n_hdr.n_descsz, 4);
-	}
-}
-
 static int __init crash_save_vmcoreinfo_init(void)
 {
 	vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL);
@@ -443,7 +397,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 	}
 
 	VMCOREINFO_OSRELEASE(init_uts_ns.name.release);
-	add_build_id_vmcoreinfo();
+	VMCOREINFO_BUILD_ID();
 	VMCOREINFO_PAGESIZE(PAGE_SIZE);
 
 	VMCOREINFO_SYMBOL(init_uts_ns);

lib/buildid.c

@@ -174,7 +174,7 @@ 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);
 }
 
-#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) || IS_ENABLED(CONFIG_CRASH_CORE)
 unsigned char vmlinux_build_id[BUILD_ID_SIZE_MAX] __ro_after_init;
 
 /**