Hi Adrian,
On Mon, Mar 20, 2023 at 10:13 AM John Paul Adrian Glaubitz glaubitz@physik.fu-berlin.de wrote:
On Mon, 2023-03-20 at 09:16 +0100, Geert Uytterhoeven wrote:
On Sun, Mar 19, 2023 at 9:49 PM John Paul Adrian Glaubitz glaubitz@physik.fu-berlin.de wrote:
On Sun, 2023-03-05 at 20:00 -0800, Randy Dunlap wrote:
Fix a build error in mcount.S when CONFIG_PRINTK is not enabled. Fixes this build error:
sh2-linux-ld: arch/sh/lib/mcount.o: in function `stack_panic': (.text+0xec): undefined reference to `dump_stack'
Fixes: e460ab27b6c3 ("sh: Fix up stack overflow check with ftrace disabled.") Signed-off-by: Randy Dunlap rdunlap@infradead.org Cc: John Paul Adrian Glaubitz glaubitz@physik.fu-berlin.de Cc: Yoshinori Sato ysato@users.sourceforge.jp Cc: Rich Felker dalias@libc.org Suggested-by: Geert Uytterhoeven geert@linux-m68k.org Cc: stable@vger.kernel.org
v2: add PRINTK to STACK_DEBUG dependency (thanks, Geert) v3: skipped v4: refresh & resend
arch/sh/Kconfig.debug | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff -- a/arch/sh/Kconfig.debug b/arch/sh/Kconfig.debug --- a/arch/sh/Kconfig.debug +++ b/arch/sh/Kconfig.debug @@ -15,7 +15,7 @@ config SH_STANDARD_BIOS
config STACK_DEBUG bool "Check for stack overflows"
depends on DEBUG_KERNEL
depends on DEBUG_KERNEL && PRINTK help This option will cause messages to be printed if free stack space drops below a certain limit. Saying Y here will add overhead toI can't really test this change as the moment I am enabling CONFIG_STACK_DEBUG, the build fails with:
CC scripts/mod/devicetable-offsets.s sh4-linux-gcc: error: -pg and -fomit-frame-pointer are incompatible make[1]: *** [scripts/Makefile.build:252: scripts/mod/empty.o] Error 1 make[1]: *** Waiting for unfinished jobs.... sh4-linux-gcc: error: -pg and -fomit-frame-pointer are incompatible make[1]: *** [scripts/Makefile.build:114: scripts/mod/devicetable-offsets.s] Error 1 make: *** [Makefile:1286: prepare0] Error 2
So, I assume we need to strip -fomit-frame-pointer from KBUILD_CFLAGS, correct?
I tried this change, but that doesn't fix it for me:
diff --git a/arch/sh/Makefile b/arch/sh/Makefile index 5c8776482530..83f535b73835 100644 --- a/arch/sh/Makefile +++ b/arch/sh/Makefile @@ -173,6 +173,7 @@ KBUILD_AFLAGS += $(cflags-y)
ifeq ($(CONFIG_MCOUNT),y) KBUILD_CFLAGS += -pg
- KBUILD_CFLAGS := $(subst -fomit-frame-pointer,,$(KBUILD_CFLAGS))
endif
ifeq ($(CONFIG_DWARF_UNWINDER),y)
Any ideas?
Please try with "+=" instead of ":=".
That doesn't work either. I tried the following, but that didn't strip -fomit-frame-pointer:
Oops, obviously all of that happened before my morning coffee ;-)
Makefile has:
ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls KBUILD_RUSTFLAGS += -Cforce-frame-pointers=y else # Some targets (ARM with Thumb2, for example), can't be built with frame # pointers. For those, we don't have FUNCTION_TRACER automatically # select FRAME_POINTER. However, FUNCTION_TRACER adds -pg, and this is # incompatible with -fomit-frame-pointer with current GCC, so we don't use # -fomit-frame-pointer with FUNCTION_TRACER. # In the Rust target specification, "frame-pointer" is set explicitly # to "may-omit". ifndef CONFIG_FUNCTION_TRACER KBUILD_CFLAGS += -fomit-frame-pointer endif endif
Your config probably has CONFIG_FRAME_POINTER set?
arch/sh/Kconfig.debug=config DWARF_UNWINDER arch/sh/Kconfig.debug- bool "Enable the DWARF unwinder for stacktraces" arch/sh/Kconfig.debug- depends on DEBUG_KERNEL arch/sh/Kconfig.debug: select FRAME_POINTER
You should make sure that cannot happen when CONFIG_FUNCTION_TRACER is enabled. I.e. make DWARF_UNWINDER depend on !FUNCTION_TRACER?
Other architectures do something similar:
arch/sparc/Kconfig.debug:config FRAME_POINTER arch/sparc/Kconfig.debug- bool arch/sparc/Kconfig.debug- depends on MCOUNT
arch/x86/Kconfig.debug:config FRAME_POINTER arch/x86/Kconfig.debug- depends on !UNWINDER_ORC && !UNWINDER_GUESS arch/x86/Kconfig.debug- bool
Probably you need to adjust the following, too:
lib/Kconfig.debug:config FRAME_POINTER lib/Kconfig.debug- bool "Compile the kernel with frame pointers" lib/Kconfig.debug- depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS lib/Kconfig.debug- default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
i.e. drop SUPERH from the list above, and select ARCH_WANT_FRAME_POINTERS if !FUNCTION_TRACER.
Gr{oetje,eeting}s,
Geert