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| author |   Josh Poimboeuf <jpoimboe@redhat.com> | 2017-07-24 18:36:57 -0500 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2017-07-26 13:18:20 +0200 |
| commit | ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67 (patch) | |
| tree | be03fe86edb9ebd70b4d29ca2bc8a4d972ff6644 /arch/x86/kernel/module.c | |
| parent | x86/asm: Make objtool unreachable macros independent from GCC version (diff) | |
| download | linux-dev-ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67.tar.xz linux-dev-ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67.zip | |
x86/unwind: Add the ORC unwinder
Add the new ORC unwinder which is enabled by CONFIG_ORC_UNWINDER=y.
It plugs into the existing x86 unwinder framework.
It relies on objtool to generate the needed .orc_unwind and
.orc_unwind_ip sections.
For more details on why ORC is used instead of DWARF, see
Documentation/x86/orc-unwinder.txt - but the short version is
that it's a simplified, fundamentally more robust debugninfo
data structure, which also allows up to two orders of magnitude
faster lookups than the DWARF unwinder - which matters to
profiling workloads like perf.
Thanks to Andy Lutomirski for the performance improvement ideas:
splitting the ORC unwind table into two parallel arrays and creating a
fast lookup table to search a subset of the unwind table.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/0a6cbfb40f8da99b7a45a1a8302dc6aef16ec812.1500938583.git.jpoimboe@redhat.com
[ Extended the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/module.c')
| -rw-r--r-- | arch/x86/kernel/module.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c index f67bd3205df7..62e7d70aadd5 100644 --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -35,6 +35,7 @@ #include <asm/page.h> #include <asm/pgtable.h> #include <asm/setup.h> +#include <asm/unwind.h> #if 0 #define DEBUGP(fmt, ...) \ @@ -213,7 +214,7 @@ int module_finalize(const Elf_Ehdr *hdr, struct module *me) { const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL, - *para = NULL; + *para = NULL, *orc = NULL, *orc_ip = NULL; char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { @@ -225,6 +226,10 @@ int module_finalize(const Elf_Ehdr *hdr, locks = s; if (!strcmp(".parainstructions", secstrings + s->sh_name)) para = s; + if (!strcmp(".orc_unwind", secstrings + s->sh_name)) + orc = s; + if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name)) + orc_ip = s; } if (alt) { @@ -248,6 +253,10 @@ int module_finalize(const Elf_Ehdr *hdr, /* make jump label nops */ jump_label_apply_nops(me); + if (orc && orc_ip) + unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size, + (void *)orc->sh_addr, orc->sh_size); + return 0; } |