diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2014-08-15 13:01:46 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-09-09 08:53:28 +0200 |
| commit | 10dec7dbd50ab0be96dda085d625d54ce800e426 (patch) | |
| tree | a293f2b0d4cc1e68cd09770dfcd284356d3bb932 /arch/s390/kernel/ftrace.c | |
| parent | 2481a87b0250bbf429fc8cdc78331efbc44a0221 (diff) | |
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/kernel/ftrace.c')
| -rw-r--r-- | arch/s390/kernel/ftrace.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index de55efa5b64e..14b61954d5a8 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -107,6 +107,13 @@ asm( #endif /* CONFIG_64BIT */ +#ifdef CONFIG_64BIT +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + return 0; +} +#endif int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) |