linux-kernel - [PATCH] lib: remove redundant ftrace flag removal

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Date:   Tue,  6 Aug 2019 17:25:39 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Mark Rutland <mark.rutland@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Borislav Petkov <bp@...en8.de>,
        Gary R Hook <gary.hook@....com>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH] lib: remove redundant ftrace flag removal

Since architectures can implement ftrace using a variety of mechanisms,
generic code should always use CC_FLAGS_FTRACE rather than assuming that
ftrace is built using -pg.

Since commit:

  2464a609ded09420 ("ftrace: do not trace library functions")

... lib/Makefile has removed CC_FLAGS_FTRACE from KBUILD_CFLAGS, so ftrace is
disabled for all files under lib/.

Given that, we shouldn't explicitly remove -pg when building
lib/string.o, as this is redundant and bad form.

This patch cleans things up accordingly.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Gary R Hook <gary.hook@....com>
Cc: Ingo Molnar <mingo@...nel.org>
---
 lib/Makefile | 4 ----
 1 file changed, 4 deletions(-)

I've verified this atop of v5.3-rc3, where the Makefile removes all of
CC_FLAGS_FTRACE (containing "-pg -mrecord-mcount -mfentry") from the CFLAGS for
building string.o

Mark.

diff --git a/lib/Makefile b/lib/Makefile
index 29c02a924973..c5892807e06f 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -21,10 +21,6 @@ KCOV_INSTRUMENT_dynamic_debug.o := n
 ifdef CONFIG_AMD_MEM_ENCRYPT
 KASAN_SANITIZE_string.o := n
 
-ifdef CONFIG_FUNCTION_TRACER
-CFLAGS_REMOVE_string.o = -pg
-endif
-
 CFLAGS_string.o := $(call cc-option, -fno-stack-protector)
 endif
 
-- 
2.11.0