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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 /include/asm-generic/vmlinux.lds.h | |
| parent | 1ee6f00d1164955b7bdadd36fc0f2736754784d9 (diff) | |
| download | lwn-ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67.tar.gz lwn-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 'include/asm-generic/vmlinux.lds.h')
| -rw-r--r-- | include/asm-generic/vmlinux.lds.h | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index da0be9a8d1de..fffc9bdae025 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -680,6 +680,31 @@ #define BUG_TABLE #endif +#ifdef CONFIG_ORC_UNWINDER +#define ORC_UNWIND_TABLE \ + . = ALIGN(4); \ + .orc_unwind_ip : AT(ADDR(.orc_unwind_ip) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(__start_orc_unwind_ip) = .; \ + KEEP(*(.orc_unwind_ip)) \ + VMLINUX_SYMBOL(__stop_orc_unwind_ip) = .; \ + } \ + . = ALIGN(6); \ + .orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(__start_orc_unwind) = .; \ + KEEP(*(.orc_unwind)) \ + VMLINUX_SYMBOL(__stop_orc_unwind) = .; \ + } \ + . = ALIGN(4); \ + .orc_lookup : AT(ADDR(.orc_lookup) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(orc_lookup) = .; \ + . += (((SIZEOF(.text) + LOOKUP_BLOCK_SIZE - 1) / \ + LOOKUP_BLOCK_SIZE) + 1) * 4; \ + VMLINUX_SYMBOL(orc_lookup_end) = .; \ + } +#else +#define ORC_UNWIND_TABLE +#endif + #ifdef CONFIG_PM_TRACE #define TRACEDATA \ . = ALIGN(4); \ @@ -866,7 +891,7 @@ DATA_DATA \ CONSTRUCTORS \ } \ - BUG_TABLE + BUG_TABLE \ #define INIT_TEXT_SECTION(inittext_align) \ . = ALIGN(inittext_align); \ |