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Commit b8b7d791 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86: Use -maccumulate-outgoing-args for sane mcount prologues 



commit 746357d6 (x86: Prevent GCC 4.4.x (pentium-mmx et al) function
prologue wreckage) uses -mtune=generic to work around the function
prologue problem with mcount on -march=pentium-mmx and others.

Jakub pointed out that we can use -maccumulate-outgoing-args instead
which is selected by -mtune=generic and prevents the problem without
losing the -march specific optimizations.

Pointed-out-by: default avatarJakub Jelinek <jakub@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@kernel.org
parent 746357d6

arch/x86/Makefile_32.cpu

+3 −2
Original line number Original line Diff line number Diff line
@@ -49,8 +49,9 @@ cflags-$(CONFIG_X86_GENERIC) += $(call tune,generic,$(call tune,i686)) 
# Work around the pentium-mmx code generator madness of gcc4.4.x which

# Work around the pentium-mmx code generator madness of gcc4.4.x which

# does stack alignment by generating horrible code _before_ the mcount

# does stack alignment by generating horrible code _before_ the mcount

# prologue (push %ebp, mov %esp, %ebp) which breaks the function graph

# prologue (push %ebp, mov %esp, %ebp) which breaks the function graph

# tracer assumptions 

# tracer assumptions. For i686, generic, core2 this is set by the

cflags-$(CONFIG_FUNCTION_GRAPH_TRACER) += $(call cc-option,-mtune=generic)

# compiler anyway

cflags-$(CONFIG_FUNCTION_GRAPH_TRACER) += $(call cc-option,-maccumulate-outgoing-args)





# Bug fix for binutils: this option is required in order to keep

# Bug fix for binutils: this option is required in order to keep

# binutils from generating NOPL instructions against our will.

# binutils from generating NOPL instructions against our will.