[PATCH] objtool: Support GCC 9 cold subfunction naming scheme

* [PATCH] objtool: Support GCC 9 cold subfunction naming scheme
@ 2018-11-01  2:57 Josh Poimboeuf
  2018-11-01  8:58 ` [tip:core/urgent] " tip-bot for Josh Poimboeuf
  0 siblings, 1 reply; 2+ messages in thread
From: Josh Poimboeuf @ 2018-11-01  2:57 UTC (permalink / raw)
  To: x86; +Cc: linux-kernel, Peter Zijlstra

Starting with GCC 8, a lot of unlikely code was moved out of line to
"cold" subfunctions in .text.unlikely.

For example, the unlikely bits of:

  irq_do_set_affinity()

are moved out to the following subfunction:

  irq_do_set_affinity.cold.49()

Starting with GCC 9, the numbered suffix has been removed.  So in the
above example, the cold subfunction is instead:

  irq_do_set_affinity.cold()

Tweak the objtool subfunction detection logic so that it detects both
GCC 8 and GCC 9 naming schemes.

Reported-and-tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 tools/objtool/elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index f7082de1ee82..6dbb9fae0f9d 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -301,7 +301,7 @@ static int read_symbols(struct elf *elf)
 			if (sym->type != STT_FUNC)
 				continue;
 			sym->pfunc = sym->cfunc = sym;
-			coldstr = strstr(sym->name, ".cold.");
+			coldstr = strstr(sym->name, ".cold");
 			if (!coldstr)
 				continue;
 
-- 
2.17.2


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