linux-kernel - [PATCH] Disable -Wframe-larger-than warnings with KASAN=y

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Message-ID: <1445011330-22698-1-git-send-email-aryabinin@virtuozzo.com>
Date:	Fri, 16 Oct 2015 19:02:10 +0300
From:	Andrey Ryabinin <aryabinin@...tuozzo.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Ingo Molnar <mingo@...nel.org>, Andi Kleen <ak@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	Kozlov Sergey <serjk@...up.ru>, <kbuild-all@...org>,
	<linux-media@...r.kernel.org>, Abylay Ospan <aospan@...up.ru>,
	Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: [PATCH] Disable -Wframe-larger-than warnings with KASAN=y

When the kernel compiled with KASAN=y, GCC adds redzones
for each variable on stack. This enlarges function's stack
frame and causes:
	'warning: the frame size of X bytes is larger than Y bytes'

The worst case I've seen for now is following:
 ../net/wireless/nl80211.c: In function ‘nl80211_send_wiphy’:
 ../net/wireless/nl80211.c:1731:1: warning: the frame size of 5448 bytes is larger than 2048 bytes [-Wframe-larger-than=]
  }
   ^
That kind of warning becomes useless with KASAN=y. It doesn't necessarily
indicate that there is some problem in the code, thus we should turn it off.

Reported-by: Fengguang Wu <fengguang.wu@...el.com>
Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
---
 lib/Kconfig.debug | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ab76b99..1d1521c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -197,6 +197,7 @@ config ENABLE_MUST_CHECK
 config FRAME_WARN
 	int "Warn for stack frames larger than (needs gcc 4.4)"
 	range 0 8192
+	default 0 if KASAN
 	default 1024 if !64BIT
 	default 2048 if 64BIT
 	help
-- 
2.4.9

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