next-0630: sparc64: build failed

next-0630: sparc64: build failed

[Alexander Beregalov]

Hi David, Abhishek

$ make CROSS_COMPILE=sparc64-unknown-linux-gnu- image modules && sudo
make modules_install
  CHK     include/linux/version.h
  CHK     include/linux/utsrelease.h
  CALL    scripts/checksyscalls.sh
  CHK     include/linux/compile.h
dnsdomainname: Unknown host
  CC      arch/sparc64/kernel/sparc64_ksyms.o
arch/sparc64/kernel/sparc64_ksyms.c:116: error: '_mcount' undeclared
here (not in a function)
cc1: warnings being treated as errors
arch/sparc64/kernel/sparc64_ksyms.c:116: error: type defaults to 'int'
in declaration of '_mcount'

This commit is cause.

commit 395a59d0f8e86bb39cd700c3d185d30c670bb958
Author: Abhishek Sagar <sagar.abhishek@gmail.com>
Date:   Sat Jun 21 23:47:27 2008 +0530

    ftrace: store mcount address in rec->ip

    Record the address of the mcount call-site. Currently all archs
except sparc64
    record the address of the instruction following the mcount call-site. Some
    general cleanups are entailed. Storing mcount addresses in rec->ip enables
    looking them up in the kprobe hash table later on to check if
they're kprobe'd.

    Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
    Cc: davem@davemloft.net
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/sparc64/kernel/sparc64_ksyms.c
b/arch/sparc64/kernel/sparc64_ksyms.c
index 8ac0b99..b80d982 100644
--- a/arch/sparc64/kernel/sparc64_ksyms.c
+++ b/arch/sparc64/kernel/sparc64_ksyms.c
@@ -53,6 +53,7 @@
 #include <asm/ns87303.h>
 #include <asm/timer.h>
 #include <asm/cpudata.h>
+#include <asm/ftrace.h>

 struct poll {
        int fd;
@@ -112,7 +113,6 @@ EXPORT_SYMBOL(smp_call_function);
 #endif /* CONFIG_SMP */

 #if defined(CONFIG_MCOUNT)
-extern void _mcount(void);
 EXPORT_SYMBOL(_mcount);
 #endif


gcc version 4.3.1 (Gentoo 4.3.1 p1.0)

Re: next-0630: sparc64: build failed

[Ingo Molnar]

* Alexander Beregalov <a.beregalov@gmail.com> wrote:

> Hi David, Abhishek
> 
> $ make CROSS_COMPILE=sparc64-unknown-linux-gnu- image modules && sudo
> make modules_install
>   CHK     include/linux/version.h
>   CHK     include/linux/utsrelease.h
>   CALL    scripts/checksyscalls.sh
>   CHK     include/linux/compile.h
> dnsdomainname: Unknown host
>   CC      arch/sparc64/kernel/sparc64_ksyms.o
> arch/sparc64/kernel/sparc64_ksyms.c:116: error: '_mcount' undeclared
> here (not in a function)
> cc1: warnings being treated as errors
> arch/sparc64/kernel/sparc64_ksyms.c:116: error: type defaults to 'int'
> in declaration of '_mcount'
> 
> This commit is cause.
> 
> commit 395a59d0f8e86bb39cd700c3d185d30c670bb958
> Author: Abhishek Sagar <sagar.abhishek@gmail.com>
> Date:   Sat Jun 21 23:47:27 2008 +0530
> 
>     ftrace: store mcount address in rec->ip

thanks Alexander - does the patch below fix it for you?

	Ingo

---------------->
commit 760378e1497841246ea7e42abad617d8a8ac0bcc
Author: Ingo Molnar <mingo@elte.hu>
Date:   Tue Jul 1 17:35:06 2008 +0200

    fix "ftrace: store mcount address in rec->ip"
    
    Alexander Beregalov reported this build failure:
    
    $ make CROSS_COMPILE=sparc64-unknown-linux-gnu- image modules && sudo
    make modules_install
      CHK     include/linux/version.h
      CHK     include/linux/utsrelease.h
      CALL    scripts/checksyscalls.sh
      CHK     include/linux/compile.h
    dnsdomainname: Unknown host
      CC      arch/sparc64/kernel/sparc64_ksyms.o
    arch/sparc64/kernel/sparc64_ksyms.c:116: error: '_mcount' undeclared
    here (not in a function)
    cc1: warnings being treated as errors
    arch/sparc64/kernel/sparc64_ksyms.c:116: error: type defaults to 'int'
    in declaration of '_mcount'
    
    And bisected it back to:
    
    | commit 395a59d0f8e86bb39cd700c3d185d30c670bb958
    | Author: Abhishek Sagar <sagar.abhishek@gmail.com>
    | Date:   Sat Jun 21 23:47:27 2008 +0530
    |
    |     ftrace: store mcount address in rec->ip
    
    the mcount prototype is only available under CONFIG_FTRACE,
    extend it to CONFIG_MCOUNT as well.
    
    Reported-and-bisected-by: Alexander Beregalov <a.beregalov@gmail.com>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/sparc64/kernel/sparc64_ksyms.c b/arch/sparc64/kernel/sparc64_ksyms.c
index b80d982..49d3ea5 100644
--- a/arch/sparc64/kernel/sparc64_ksyms.c
+++ b/arch/sparc64/kernel/sparc64_ksyms.c
@@ -112,7 +112,7 @@ EXPORT_SYMBOL(__write_trylock);
 EXPORT_SYMBOL(smp_call_function);
 #endif /* CONFIG_SMP */
 
-#if defined(CONFIG_MCOUNT)
+#ifdef CONFIG_MCOUNT
 EXPORT_SYMBOL(_mcount);
 #endif
 
diff --git a/include/asm-sparc64/ftrace.h b/include/asm-sparc64/ftrace.h
index f76a40a..d27716c 100644
--- a/include/asm-sparc64/ftrace.h
+++ b/include/asm-sparc64/ftrace.h
@@ -1,7 +1,7 @@
 #ifndef _ASM_SPARC64_FTRACE
 #define _ASM_SPARC64_FTRACE
 
-#ifdef CONFIG_FTRACE
+#ifdef CONFIG_MCOUNT
 #define MCOUNT_ADDR		((long)(_mcount))
 #define MCOUNT_INSN_SIZE	4 /* sizeof mcount call */
 

Re: next-0630: sparc64: build failed

[Abhishek Sagar]

Ingo Molnar wrote:
>     Alexander Beregalov reported this build failure:
>     
>     $ make CROSS_COMPILE=sparc64-unknown-linux-gnu- image modules && sudo
>     make modules_install
>       CHK     include/linux/version.h
>       CHK     include/linux/utsrelease.h
>       CALL    scripts/checksyscalls.sh
>       CHK     include/linux/compile.h
>     dnsdomainname: Unknown host
>       CC      arch/sparc64/kernel/sparc64_ksyms.o
>     arch/sparc64/kernel/sparc64_ksyms.c:116: error: '_mcount' undeclared
>     here (not in a function)
>     cc1: warnings being treated as errors
>     arch/sparc64/kernel/sparc64_ksyms.c:116: error: type defaults to 'int'
>     in declaration of '_mcount'
>     
>     And bisected it back to:
>     
>     | commit 395a59d0f8e86bb39cd700c3d185d30c670bb958
>     | Author: Abhishek Sagar <sagar.abhishek@gmail.com>
>     | Date:   Sat Jun 21 23:47:27 2008 +0530
>     |
>     |     ftrace: store mcount address in rec->ip
>     
>     the mcount prototype is only available under CONFIG_FTRACE,
>     extend it to CONFIG_MCOUNT as well.
>     
>     Reported-and-bisected-by: Alexander Beregalov <a.beregalov@gmail.com>
>     Signed-off-by: Ingo Molnar <mingo@elte.hu>

Hi Ingo/David,

CONFIG_MCOUNT currently controls the compilation with -pg flag and the export
of _mcount. But with ftrace, the former is redundant and the latter should be
made unconditional since _mcount is always defined. In which case, does the
inlined patch (untested) make sense? It should solve the build failure as well.

[for tip/master]

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
---
sparc64: get rid of CONFIG_MCOUNT

There are two possible (not necessarily exclusive) uses of the _mcount call:
1. To do stack usage debugging.
2. Function tracing.

Both have separate CONFIG_* options and don't require an alias such as
CONFIG_MCOUNT.

diff --git a/arch/sparc64/Kconfig.debug b/arch/sparc64/Kconfig.debug
index d6d32d1..6065be7 100644
--- a/arch/sparc64/Kconfig.debug
+++ b/arch/sparc64/Kconfig.debug
@@ -31,11 +31,6 @@ config DEBUG_PAGEALLOC
 	  This results in a large slowdown, but helps to find certain types
 	  of memory corruptions.
 
-config MCOUNT
-	bool
-	depends on STACK_DEBUG || FTRACE
-	default y
-
 config FRAME_POINTER
 	bool
 	depends on MCOUNT
diff --git a/arch/sparc64/Makefile b/arch/sparc64/Makefile
index 4b8f2b0..c182e5c 100644
--- a/arch/sparc64/Makefile
+++ b/arch/sparc64/Makefile
@@ -19,8 +19,10 @@ KBUILD_CFLAGS += -m64 -pipe -mno-fpu -mcpu=ultrasparc -mcmodel=medlow \
 KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
 
-ifeq ($(CONFIG_MCOUNT),y)
-  KBUILD_CFLAGS += -pg
+ifneq ($(CONFIG_FTRACE),y)
+ifeq ($(CONFIG_STACK_DEBUG),y)
+KBUILD_CFLAGS += -pg
+endif
 endif
 
 head-y := arch/sparc64/kernel/head.o arch/sparc64/kernel/init_task.o
diff --git a/arch/sparc64/kernel/sparc64_ksyms.c b/arch/sparc64/kernel/sparc64_ksyms.c
index b80d982..13c243c 100644
--- a/arch/sparc64/kernel/sparc64_ksyms.c
+++ b/arch/sparc64/kernel/sparc64_ksyms.c
@@ -112,10 +112,7 @@ EXPORT_SYMBOL(__write_trylock);
 EXPORT_SYMBOL(smp_call_function);
 #endif /* CONFIG_SMP */
 
-#if defined(CONFIG_MCOUNT)
 EXPORT_SYMBOL(_mcount);
-#endif
-
 EXPORT_SYMBOL(sparc64_get_clock_tick);
 
 /* RW semaphores */
diff --git a/include/asm-sparc64/ftrace.h b/include/asm-sparc64/ftrace.h
index f76a40a..51036c3 100644
--- a/include/asm-sparc64/ftrace.h
+++ b/include/asm-sparc64/ftrace.h
@@ -4,11 +4,10 @@
 #ifdef CONFIG_FTRACE
 #define MCOUNT_ADDR		((long)(_mcount))
 #define MCOUNT_INSN_SIZE	4 /* sizeof mcount call */
+#endif
 
 #ifndef __ASSEMBLY__
 extern void _mcount(void);
 #endif
 
-#endif
-
 #endif /* _ASM_SPARC64_FTRACE */

Re: next-0630: sparc64: build failed

[Ingo Molnar]

* Abhishek Sagar <sagar.abhishek@gmail.com> wrote:

> Hi Ingo/David,
> 
> CONFIG_MCOUNT currently controls the compilation with -pg flag and the 
> export of _mcount. But with ftrace, the former is redundant and the 
> latter should be made unconditional since _mcount is always defined. 
> In which case, does the inlined patch (untested) make sense? It should 
> solve the build failure as well.

hm, mcount is the facility - so it makes sense to have that defined. 
Here you basically hide CONFIG_MCOUNT:

> -ifeq ($(CONFIG_MCOUNT),y)
> -  KBUILD_CFLAGS += -pg
> +ifneq ($(CONFIG_FTRACE),y)
> +ifeq ($(CONFIG_STACK_DEBUG),y)
> +KBUILD_CFLAGS += -pg
> +endif
>  endif

via two conditions. I'm not sure that's a win and i found CONFIG_MCOUNT 
a logical switch - but it's David's call.

	Ingo

Re: next-0630: sparc64: build failed

[Abhishek Sagar]

On Wed, Jul 2, 2008 at 1:33 AM, Ingo Molnar <mingo@elte.hu> wrote:
> hm, mcount is the facility - so it makes sense to have that defined.
> Here you basically hide CONFIG_MCOUNT:
>
>> -ifeq ($(CONFIG_MCOUNT),y)
>> -  KBUILD_CFLAGS += -pg
>> +ifneq ($(CONFIG_FTRACE),y)
>> +ifeq ($(CONFIG_STACK_DEBUG),y)
>> +KBUILD_CFLAGS += -pg
>> +endif
>>  endif

Even with CONFIG_MCOUNT we'd have to do something like this to prevent
duplicate -pg flags (I hope there's a prettier way of writing this):

ifneq ($(CONFIG_FTRACE),y)
ifeq ($(CONFIG_MCOUNT),y)
KBUILD_CFLAGS += -pg
endif
endif

> via two conditions. I'm not sure that's a win and i found CONFIG_MCOUNT
> a logical switch - but it's David's call.

Ok, but it really doesn't allow end user to switch between anything
through any menu. It gets selected via:

config MCOUNT
        bool
        depends on STACK_DEBUG || FTRACE
        default y


I was attempting to decouple MCOUNT and STACK_DEBUG, which
incidentally made MCOUNT useless.

--
Regards,
Abhishek Sagar

Re: next-0630: sparc64: build failed

[Alexander Beregalov]

2008/7/1 Ingo Molnar <mingo@elte.hu>:
> thanks Alexander - does the patch below fix it for you?
> commit 760378e1497841246ea7e42abad617d8a8ac0bcc
> Author: Ingo Molnar <mingo@elte.hu>
> Date:   Tue Jul 1 17:35:06 2008 +0200
>
>    fix "ftrace: store mcount address in rec->ip"
>

Yes, it fixes the issue. I have tried next-0702 which already includes
your patch.
But it has a name a1d5d08eb4f5c76acd5bb115e13791ce87ec356b.