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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>
This commit is contained in:
Heiko Carstens 2014-08-15 13:01:46 +02:00 committed by Martin Schwidefsky
parent 2481a87b02
commit 10dec7dbd5
4 changed files with 43 additions and 12 deletions
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1
arch/s390/Kconfig
View File

@ -114,6 +114,7 @@ config S390
select HAVE_C_RECORDMCOUNT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_REGS if 64BIT
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER

4
arch/s390/include/asm/ftrace.h
View File

@ -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 */

7
arch/s390/kernel/ftrace.c
View File

@ -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)

43
arch/s390/kernel/mcount64.S
View File

@ -8,28 +8,47 @@
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/ftrace.h>
#include <asm/ptrace.h>
.section .kprobes.text, "ax"
ENTRY(ftrace_stub)
br %r14
#define STACK_FRAME_SIZE (STACK_FRAME_OVERHEAD + __PT_SIZE)
#define STACK_PARENT_IP (STACK_FRAME_SIZE + 8)
#define STACK_PTREGS (STACK_FRAME_OVERHEAD)
#define STACK_PTREGS_GPRS (STACK_PTREGS + __PT_GPRS)
#define STACK_PTREGS_PSW (STACK_PTREGS + __PT_PSW)
ENTRY(_mcount)
#ifdef CONFIG_DYNAMIC_FTRACE
br %r14
ENTRY(ftrace_caller)
.globl ftrace_regs_caller
.set ftrace_regs_caller,ftrace_caller
#endif
stmg %r2,%r5,32(%r15)
stg %r14,112(%r15)
lgr %r1,%r15
aghi %r15,-160
aghi %r15,-STACK_FRAME_SIZE
stg %r1,__SF_BACKCHAIN(%r15)
stg %r1,(STACK_PTREGS_GPRS+15*8)(%r15)
stmg %r0,%r13,STACK_PTREGS_GPRS(%r15)
stg %r14,(STACK_PTREGS_PSW+8)(%r15)
#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
aghik %r2,%r14,-MCOUNT_INSN_SIZE
lgrl %r4,function_trace_op
lgrl %r14,ftrace_trace_function
#else
lgr %r2,%r14
lg %r3,168(%r15)
aghi %r2,-MCOUNT_INSN_SIZE
larl %r4,function_trace_op
lg %r4,0(%r4)
larl %r14,ftrace_trace_function
lg %r14,0(%r14)
#endif
lg %r3,STACK_PARENT_IP(%r15)
la %r5,STACK_PTREGS(%r15)
basr %r14,%r14
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
# The j instruction gets runtime patched to a nop instruction.
@ -37,16 +56,16 @@ ENTRY(ftrace_caller)
# j .+4
ENTRY(ftrace_graph_caller)
j ftrace_graph_caller_end
lg %r2,168(%r15)
lg %r3,272(%r15)
lg %r2,STACK_PARENT_IP(%r15)
lg %r3,(STACK_PTREGS_PSW+8)(%r15)
brasl %r14,prepare_ftrace_return
stg %r2,168(%r15)
stg %r2,STACK_PARENT_IP(%r15)
ftrace_graph_caller_end:
.globl ftrace_graph_caller_end
#endif
aghi %r15,160
lmg %r2,%r5,32(%r15)
lg %r14,112(%r15)
lmg %r0,%r13,STACK_PTREGS_GPRS(%r15)
lg %r14,(STACK_PTREGS_PSW+8)(%r15)
aghi %r15,STACK_FRAME_SIZE
br %r14
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@ -54,10 +73,10 @@ ftrace_graph_caller_end:
ENTRY(return_to_handler)
stmg %r2,%r5,32(%r15)
lgr %r1,%r15
aghi %r15,-160
aghi %r15,-STACK_FRAME_OVERHEAD
stg %r1,__SF_BACKCHAIN(%r15)
brasl %r14,ftrace_return_to_handler
aghi %r15,160
aghi %r15,STACK_FRAME_OVERHEAD
lgr %r14,%r2
lmg %r2,%r5,32(%r15)
br %r14