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

Josh Poimboeuf
2018-11-01T02:57:36Z

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