Re: [PATCH 7/7 v4] sh: mcount.S: fix build error when PRINTK is not enabled

[John Paul Adrian Glaubitz]

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@xxxxxxxxxxxxx>
> Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
> Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
> Cc: Rich Felker <dalias@xxxxxxxx>
> Suggested-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> 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 to

I 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?

Adrian

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