diff options
| author | Omar Sandoval <osandov@fb.com> | 2023-06-13 14:14:56 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-06-16 17:17:42 +0200 |
| commit | b9f174c811e3ae4ae8959dc57e6adb9990e913f4 (patch) | |
| tree | 3306ec83cfcfb8a59c8770d04e974469f3a2c6a6 /scripts | |
| parent | 858fd168a95c5b9669aac8db6c14a9aeab446375 (diff) | |
x86/unwind/orc: Add ELF section with ORC version identifier
Commits ffb1b4a41016 ("x86/unwind/orc: Add 'signal' field to ORC
metadata") and fb799447ae29 ("x86,objtool: Split UNWIND_HINT_EMPTY in
two") changed the ORC format. Although ORC is internal to the kernel,
it's the only way for external tools to get reliable kernel stack traces
on x86-64. In particular, the drgn debugger [1] uses ORC for stack
unwinding, and these format changes broke it [2]. As the drgn
maintainer, I don't care how often or how much the kernel changes the
ORC format as long as I have a way to detect the change.
It suffices to store a version identifier in the vmlinux and kernel
module ELF files (to use when parsing ORC sections from ELF), and in
kernel memory (to use when parsing ORC from a core dump+symbol table).
Rather than hard-coding a version number that needs to be manually
bumped, Peterz suggested hashing the definitions from orc_types.h. If
there is a format change that isn't caught by this, the hashing script
can be updated.
This patch adds an .orc_header allocated ELF section containing the
20-byte hash to vmlinux and kernel modules, along with the corresponding
__start_orc_header and __stop_orc_header symbols in vmlinux.
1: https://github.com/osandov/drgn
2: https://github.com/osandov/drgn/issues/303
Fixes: ffb1b4a41016 ("x86/unwind/orc: Add 'signal' field to ORC metadata")
Fixes: fb799447ae29 ("x86,objtool: Split UNWIND_HINT_EMPTY in two")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lkml.kernel.org/r/aef9c8dc43915b886a8c48509a12ec1b006ca1ca.1686690801.git.osandov@osandov.com
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/mod/modpost.c | 5 | ||||
| -rw-r--r-- | scripts/orc_hash.sh | 16 |
2 files changed, 21 insertions, 0 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index d4531d09984d..c12150f96b88 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1979,6 +1979,11 @@ static void add_header(struct buffer *b, struct module *mod) buf_printf(b, "#include <linux/vermagic.h>\n"); buf_printf(b, "#include <linux/compiler.h>\n"); buf_printf(b, "\n"); + buf_printf(b, "#ifdef CONFIG_UNWINDER_ORC\n"); + buf_printf(b, "#include <asm/orc_header.h>\n"); + buf_printf(b, "ORC_HEADER;\n"); + buf_printf(b, "#endif\n"); + buf_printf(b, "\n"); buf_printf(b, "BUILD_SALT;\n"); buf_printf(b, "BUILD_LTO_INFO;\n"); buf_printf(b, "\n"); diff --git a/scripts/orc_hash.sh b/scripts/orc_hash.sh new file mode 100644 index 000000000000..466611aa0053 --- /dev/null +++ b/scripts/orc_hash.sh @@ -0,0 +1,16 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-or-later +# Copyright (c) Meta Platforms, Inc. and affiliates. + +set -e + +printf '%s' '#define ORC_HASH ' + +awk ' +/^#define ORC_(REG|TYPE)_/ { print } +/^struct orc_entry {$/ { p=1 } +p { print } +/^}/ { p=0 }' | + sha1sum | + cut -d " " -f 1 | + sed 's/\([0-9a-f]\{2\}\)/0x\1,/g' |