[PATCH 7/7] kdump: Use vmlinux_build_id() to simplify

[Stephen Boyd <swboyd@xxxxxxxxxxxx>]

We can use the vmlinux_build_id() helper here now instead of open coding
it. This consolidates code and possibly avoids calculating the build ID
twice in the case of a crash with a stacktrace.

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: Baoquan He <bhe@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: <kexec@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
 kernel/crash_core.c | 46 ++++++++-------------------------------------
 1 file changed, 8 insertions(+), 38 deletions(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 825284baaf46..07d3e1109a8c 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -4,6 +4,7 @@
  * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xxxxxxxxxxxx>
  */
 
+#include <linux/buildid.h>
 #include <linux/crash_core.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
@@ -378,51 +379,20 @@ 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);
+	const char *build_id = vmlinux_build_id();
+
+	if (build_id[0] == '\0') {
+		pr_warn("Build ID cannot be included in vmcoreinfo\n");
+		return;
 	}
+
+	VMCOREINFO_BUILD_ID(build_id);
 }
 
 static int __init crash_save_vmcoreinfo_init(void)
-- 
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