[PATCH v6 13/13] kdump: Use vmlinux_build_id to simplify

From: Stephen Boyd
Date: Mon May 10 2021 - 20:39:45 EST


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

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>
---
include/linux/buildid.h | 2 +-
include/linux/crash_core.h | 12 ++++-----
kernel/crash_core.c | 50 ++------------------------------------
lib/buildid.c | 2 +-
4 files changed, 10 insertions(+), 56 deletions(-)

diff --git a/include/linux/buildid.h b/include/linux/buildid.h
index 3e8d77a93ec4..3b7a0ff4642f 100644
--- a/include/linux/buildid.h
+++ b/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
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 206bde8308b2..de62a722431e 100644
--- a/include/linux/crash_core.h
+++ b/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);
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 825284baaf46..29cc15398ee4 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>
@@ -378,53 +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);
diff --git a/lib/buildid.c b/lib/buildid.c
index 180a1a9b3b76..dfc62625cae4 100644
--- a/lib/buildid.c
+++ b/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;

/**
--
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