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authorJosh Poimboeuf <jpoimboe@redhat.com>2017-07-25 02:36:57 +0300
committerIngo Molnar <mingo@kernel.org>2017-07-26 14:18:20 +0300
commitee9f8fce99640811b2b8e79d0d1dbe8bab69ba67 (patch)
treebe03fe86edb9ebd70b4d29ca2bc8a4d972ff6644 /include/asm-generic
parent1ee6f00d1164955b7bdadd36fc0f2736754784d9 (diff)
downloadlinux-ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67.tar.xz
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')
-rw-r--r--include/asm-generic/vmlinux.lds.h27
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); \