[PATCH 4.9 41/42] objtool: Support GCC 9 cold subfunction naming scheme

From: Greg Kroah-Hartman
Date: Mon Aug 05 2019 - 09:06:19 EST

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

commit bcb6fb5da77c2a228adf07cc9cb1a0c2aa2001c6 upstream.

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:


are moved out to the following subfunction:


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


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

Reported-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/015e9544b1f188d36a7f02fa31e9e95629aa5f50.1541040800.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

tools/objtool/elf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -305,7 +305,7 @@ static int read_symbols(struct elf *elf)
if (sym->type != STT_FUNC)
sym->pfunc = sym->cfunc = sym;
- coldstr = strstr(sym->name, ".cold.");
+ coldstr = strstr(sym->name, ".cold");
if (!coldstr)