[PATCH RESEND] Fix stack protector Makefile breakage on x86_64

From: George Spelvin
Date: Wed May 07 2014 - 17:06:04 EST


If you are using a 64-bit kernel with 32-bit userland, then
scripts/gcc-x86_64-has-stack-protector.sh invokes 32-bit gcc
with -mcmodel=kernel, which produces:

<stdin>:1:0: error: code model 'kernel' not supported in the 32 bit mode

and trips the "broken compiler" test at arch/x86/Makefile:120.

There are several places a fix is possible, but the following seems
cleanest. (But it's minimal; it would also be possible to factor
out a bunch of stuff from the two branches of the if.)

Signed-off-by: George Spelvin <linux@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.14.x
---
Originally sent March 19 (but elicited no response), this is still an
issue with 3.15-rc4, and still applies without changes.

Sending to some general Linux-x86 people as well as the authors of the
stack-protector patch that caused the problem. Feel free to fix it a
different way, but could we please fix it?


diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index eeda43abed..c6c61361c3 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -79,6 +79,7 @@ else
UTS_MACHINE := x86_64
CHECKFLAGS += -D__x86_64__ -m64

+ biarch := -m64
KBUILD_AFLAGS += -m64
KBUILD_CFLAGS += -m64

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