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s390/ftrace: provide working ftrace_return_address() 

The common code ftrace_return_address(n), which is just a wrapper for
__builtin_return_address(n), will only work for n > 0 if CONFIG_FRAME_POINTER
is set to 'y'. Otherwise it will return 0.
Since on s390 we will never have that config option set to 'y'
ftrace_return_address() won't work at all for n > 0.

Luckily we always compile the kernel with -mkernel-backchain which
in turn means that __builtin_return_address(n) will always work.

So let ftrace_return_address(n) map to __builtin_return_address(n).

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2014-11-24 14:30:32 +01:00 committed by Martin Schwidefsky
parent b3e06dc3f0
commit 7eed2e09ab
1 changed files with 2 additions and 0 deletions
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2
arch/s390/include/asm/ftrace.h
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@ -8,6 +8,8 @@
#ifndef __ASSEMBLY__
#define ftrace_return_address(n) __builtin_return_address(n)
void _mcount(void);
void ftrace_caller(void);