| Message ID | 20181031010934.3627-1-joel@jms.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 9c87156cce5a63735d1218f0096a65c50a7a32aa |
| Headers | show |
| Series | powerpc/xmon: Relax frame size for clang | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
| snowpatch_ozlabs/checkpatch | success | Test checkpatch on branch next |
| snowpatch_ozlabs/build-ppc64le | success | Test build-ppc64le on branch next |
| snowpatch_ozlabs/build-ppc64be | success | Test build-ppc64be on branch next |
| snowpatch_ozlabs/build-ppc64e | success | Test build-ppc64e on branch next |
| snowpatch_ozlabs/build-ppc32 | success | Test build-ppc32 on branch next |
On Wed, 2018-10-31 at 01:09:34 UTC, Joel Stanley wrote: > When building with clang (8 trunk, 7.0 release) the frame size limit is > hit: > > arch/powerpc/xmon/xmon.c:452:12: warning: stack frame size of 2576 > bytes in function 'xmon_core' [-Wframe-larger-than=] > > Some investigation by Naveen indicates this is due to clang saving the > addresses to printf format strings on the stack. > > While this issue is investigated, bump up the frame size limit for xmon > when building with clang. > > Link: https://github.com/ClangBuiltLinux/linux/issues/252 > Signed-off-by: Joel Stanley <joel@jms.id.au> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/9c87156cce5a63735d1218f0096a65 cheers
From: Linuxppc-dev [mailto:linuxppc-dev-bounces+david.laight=aculab.com@lists.ozlabs.org] On Behalf Of > Michael Ellerman > Subject: Re: powerpc/xmon: Relax frame size for clang > > On Wed, 2018-10-31 at 01:09:34 UTC, Joel Stanley wrote: > > When building with clang (8 trunk, 7.0 release) the frame size limit is > > hit: > > > > arch/powerpc/xmon/xmon.c:452:12: warning: stack frame size of 2576 > > bytes in function 'xmon_core' [-Wframe-larger-than=] > > > > Some investigation by Naveen indicates this is due to clang saving the > > addresses to printf format strings on the stack. > > > > While this issue is investigated, bump up the frame size limit for xmon > > when building with clang. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/252 > > Signed-off-by: Joel Stanley <joel@jms.id.au> Would it be better to stop some of the functions being inlined? Clearly clang shouldn't be using separate on-stack temporaries for every printf() call. That is indicative of a bigger problem. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile index 69e7fb47bcaa..878f9c1d3615 100644 --- a/arch/powerpc/xmon/Makefile +++ b/arch/powerpc/xmon/Makefile @@ -11,6 +11,12 @@ UBSAN_SANITIZE := n ORIG_CFLAGS := $(KBUILD_CFLAGS) KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS)) +ifdef CONFIG_CC_IS_CLANG +# clang stores addresses on the stack causing the frame size to blow +# out. See https://github.com/ClangBuiltLinux/linux/issues/252 +KBUILD_CFLAGS += -Wframe-larger-than=4096 +endif + ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC) obj-y += xmon.o nonstdio.o spr_access.o
When building with clang (8 trunk, 7.0 release) the frame size limit is hit: arch/powerpc/xmon/xmon.c:452:12: warning: stack frame size of 2576 bytes in function 'xmon_core' [-Wframe-larger-than=] Some investigation by Naveen indicates this is due to clang saving the addresses to printf format strings on the stack. While this issue is investigated, bump up the frame size limit for xmon when building with clang. Link: https://github.com/ClangBuiltLinux/linux/issues/252 Signed-off-by: Joel Stanley <joel@jms.id.au> --- arch/powerpc/xmon/Makefile | 6 ++++++ 1 file changed, 6 insertions(+)