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author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2014-08-15 13:01:46 +0200 |
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committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-09-09 08:53:28 +0200 |
commit | 10dec7dbd50ab0be96dda085d625d54ce800e426 (patch) | |
tree | a293f2b0d4cc1e68cd09770dfcd284356d3bb932 /arch/s390/include/asm | |
parent | s390/ftrace: optimize function graph caller code (diff) | |
download | linux-10dec7dbd50ab0be96dda085d625d54ce800e426.tar.xz linux-10dec7dbd50ab0be96dda085d625d54ce800e426.zip |
s390/ftrace: add HAVE_DYNAMIC_FTRACE_WITH_REGS support
This code is based on a patch from Vojtech Pavlik.
http://marc.info/?l=linux-s390&m=140438885114413&w=2
The actual implementation now differs significantly:
Instead of adding a second function "ftrace_regs_caller" which would be nearly
identical to the existing ftrace_caller function, the current ftrace_caller
function is now an alias to ftrace_regs_caller and always passes the needed
pt_regs structure and function_trace_op parameters unconditionally.
Besides that also use asm offsets to correctly allocate and access the new
struct pt_regs on the stack.
While at it we can make use of new instruction to get rid of some indirect
loads if compiled for new machines.
The passed struct pt_regs can be changed by the called function and it's new
contents will replace the current contents.
Note: to change the return address the embedded psw member of the pt_regs
structure must be changed. The psw member is right now incomplete, since
the mask part is missing. For all current use cases this should be sufficent.
Providing and restoring a sane mask would mean we need to add an epsw/lpswe
pair to the mcount code. Only these two instruction would cost us ~120 cycles
which currently seems not necessary.
Cc: Vojtech Pavlik <vojtech@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm')
-rw-r--r-- | arch/s390/include/asm/ftrace.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h index 7b8e456d76c9..1759d73fb95b 100644 --- a/arch/s390/include/asm/ftrace.h +++ b/arch/s390/include/asm/ftrace.h @@ -24,4 +24,8 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) #define MCOUNT_INSN_SIZE 22 #endif +#ifdef CONFIG_64BIT +#define ARCH_SUPPORTS_FTRACE_OPS 1 +#endif + #endif /* _ASM_S390_FTRACE_H */ |