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(+)
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
--
2.19.1
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:
quoted
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
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