linux-kernel - [tip:core/urgent] objtool: Support GCC 9 cold subfunction naming scheme

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Message-ID: <tip-bcb6fb5da77c2a228adf07cc9cb1a0c2aa2001c6@git.kernel.org>
Date:   Thu, 1 Nov 2018 01:58:26 -0700
From:   tip-bot for Josh Poimboeuf <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     jpoimboe@...hat.com, hpa@...or.com, mingo@...nel.org,
        peterz@...radead.org, tglx@...utronix.de,
        linux-kernel@...r.kernel.org
Subject: [tip:core/urgent] objtool: Support GCC 9 cold subfunction naming
 scheme

Commit-ID:  bcb6fb5da77c2a228adf07cc9cb1a0c2aa2001c6
Gitweb:     https://git.kernel.org/tip/bcb6fb5da77c2a228adf07cc9cb1a0c2aa2001c6
Author:     Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Wed, 31 Oct 2018 21:57:30 -0500
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 1 Nov 2018 09:55:38 +0100

objtool: Support GCC 9 cold subfunction naming scheme

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-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/015e9544b1f188d36a7f02fa31e9e95629aa5f50.1541040800.git.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 7ec85d567598..f8cef271dfc7 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;