lkml.org 
[lkml]   [2018]   [Feb]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [RFC PATCH 4/7] kconfig: support new special property shell=
On Sun, Feb 11, 2018 at 10:13:44AM -0800, Linus Torvalds wrote:

> That actually sounds like we could just
>
> (a) make gcc 4.5 be the minimum required version
>
> (b) actually error out if we find a bad compiler

So the unofficial plan was to enforce asm-goto and -fentry support by
hard failure to build, which would get us at gcc-4.6 and then remove all
the fallback cruft needed for those features -- for x86. If we want to
do this tree wide, that's obviously OK with me too ;-)

The below is the two force-asm-goto and force-fentry patches folded.

---
Makefile | 17 +++++++++++------
arch/x86/Makefile | 25 +++++--------------------
2 files changed, 16 insertions(+), 26 deletions(-)

diff --git a/Makefile b/Makefile
index d192dd826cce..1a46f23d0974 100644
--- a/Makefile
+++ b/Makefile
@@ -489,6 +489,17 @@ KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
endif

+# check for 'asm goto'
+ifeq ($(shell $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
+ CC_HAVE_ASM_GOTO := 1
+ KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+ KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
+ifeq ($(call cc-option-yn, -mfentry), y)
+ CC_HAVE_FENTRY := 1
+endif
+
ifeq ($(config-targets),1)
# ===========================================================================
# *config targets only - make sure prerequisites are updated, and descend
@@ -654,12 +665,6 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
# Tell gcc to never replace conditional load with a non-conditional one
KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)

-# check for 'asm goto'
-ifeq ($(call shell-cached,$(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
- KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
- KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
-endif
-
include scripts/Makefile.kcov
include scripts/Makefile.gcc-plugins

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index fad55160dcb9..35cea458a7be 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -158,27 +158,12 @@ ifdef CONFIG_X86_X32
endif
export CONFIG_X86_X32_ABI

-#
-# If the function graph tracer is used with mcount instead of fentry,
-# '-maccumulate-outgoing-args' is needed to prevent a GCC bug
-# (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
-#
-ifdef CONFIG_FUNCTION_GRAPH_TRACER
- ifndef CONFIG_HAVE_FENTRY
- ACCUMULATE_OUTGOING_ARGS := 1
- else
- ifeq ($(call cc-option-yn, -mfentry), n)
- ACCUMULATE_OUTGOING_ARGS := 1
-
- # GCC ignores '-maccumulate-outgoing-args' when used with '-Os'.
- # If '-Os' is enabled, disable it and print a warning.
- ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
- undefine CONFIG_CC_OPTIMIZE_FOR_SIZE
- $(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE. Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.)
- endif
+ifndef CC_HAVE_ASM_GOTO
+ $(error Compiler lacks asm-goto support.)
+endif

- endif
- endif
+ifndef CC_HAVE_FENTRY
+ $(error Compiler lacks -mfentry support.)
endif

#
\
 
 \ /
  Last update: 2018-02-12 09:27    [W:0.161 / U:0.228 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site