Commit e2414910 authored by Andi Kleen's avatar Andi Kleen Committed by Andi Kleen

[PATCH] x86: Detect CFI support in the assembler at runtime

... instead of using a CONFIG option. The config option still controls
if the resulting executable actually has unwind information.

This is useful to prevent compilation errors when users select
CONFIG_STACK_UNWIND on old binutils and also allows to use
CFI in the future for non kernel debugging applications.

Cc: jbeulich@novell.com
Cc: sam@ravnborg.org
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent fe7414a2
......@@ -421,6 +421,11 @@ more details, with real examples.
The second argument is optional, and if supplied will be used
if first argument is not supported.
as-instr
as-instr checks if the assembler reports a specific instruction
and then outputs either option1 or option2
C escapes are supported in the test instruction
cc-option
cc-option is used to check if $(CC) supports a given option, and not
supported to use an optional second option.
......
......@@ -46,6 +46,10 @@ cflags-y += -ffreestanding
# a lot more stack due to the lack of sharing of stacklots:
CFLAGS += $(shell if [ $(call cc-version) -lt 0400 ] ; then echo $(call cc-option,-fno-unit-at-a-time); fi ;)
# do binutils support CFI?
cflags-y += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)
AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)
CFLAGS += $(cflags-y)
# Default subarch .c files
......
......@@ -54,6 +54,9 @@ endif
cflags-y += $(call cc-option,-funit-at-a-time)
# prevent gcc from generating any FP code by mistake
cflags-y += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,)
# do binutils support CFI?
cflags-y += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)
AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)
CFLAGS += $(cflags-y)
CFLAGS_KERNEL += $(cflags-kernel-y)
......
......@@ -13,7 +13,7 @@
away for older version.
*/
#ifdef CONFIG_UNWIND_INFO
#ifdef CONFIG_AS_CFI
#define CFI_STARTPROC .cfi_startproc
#define CFI_ENDPROC .cfi_endproc
......
......@@ -63,6 +63,13 @@ as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
-xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
else echo "$(2)"; fi ;)
# as-instr
# Usage: cflags-y += $(call as-instr, instr, option1, option2)
as-instr = $(shell if echo -e "$(1)" | $(AS) -Z -o astest$$$$.out \
2>&1 >/dev/null ; then echo "$(2)"; else echo "$(3)"; fi; \
rm -f astest$$$$.out)
# cc-option
# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)
......
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