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s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations 

ftrace_regs_caller is an alias to ftrace_caller - making ftrace_caller
quite heavyweight. Split the function and provide an ftrace_caller
implementation which comes with fewer instructions. Especially getting
rid of 'stosm' on each function entry should help here, e.g. to
have less performance impact on live patched functions.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2021-10-04 20:24:12 +02:00 committed by Vasily Gorbik
parent 176510ebec
commit 894979689d
2 changed files with 29 additions and 13 deletions
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1
arch/s390/include/asm/ftrace.h
View File

@ -17,7 +17,6 @@
void ftrace_caller(void);
extern char ftrace_graph_caller_end;
extern void *ftrace_func;
struct dyn_arch_ftrace { };

41
arch/s390/kernel/mcount.S
View File

@ -33,13 +33,15 @@ ENDPROC(ftrace_stub)
#define TRACED_FUNC_FRAME_SIZE STACK_FRAME_OVERHEAD
#endif
ENTRY(ftrace_caller)
.globl ftrace_regs_caller
.set ftrace_regs_caller,ftrace_caller
.macro ftrace_regs_entry, allregs=0
stg %r14,(__SF_GPRS+8*8)(%r15) # save traced function caller
.if \allregs == 1
lghi %r14,0 # save condition code
ipm %r14 # don't put any instructions
sllg %r14,%r14,16 # clobbering CC before this point
.endif
lgr %r1,%r15
# allocate stack frame for ftrace_caller to contain traced function
aghi %r15,-TRACED_FUNC_FRAME_SIZE
@ -49,13 +51,30 @@ ENTRY(ftrace_caller)
# allocate pt_regs and stack frame for ftrace_trace_function
aghi %r15,-STACK_FRAME_SIZE
stg %r1,(STACK_PTREGS_GPRS+15*8)(%r15)
.if \allregs == 1
stg %r14,(STACK_PTREGS_PSW)(%r15)
lg %r14,(__SF_GPRS+8*8)(%r1) # restore original return address
stosm (STACK_PTREGS_PSW)(%r15),0
.endif
lg %r14,(__SF_GPRS+8*8)(%r1) # restore original return address
aghi %r1,-TRACED_FUNC_FRAME_SIZE
stg %r1,__SF_BACKCHAIN(%r15)
stg %r0,(STACK_PTREGS_PSW+8)(%r15)
stmg %r2,%r14,(STACK_PTREGS_GPRS+2*8)(%r15)
.endm
SYM_CODE_START(ftrace_regs_caller)
ftrace_regs_entry 1
j ftrace_common
SYM_CODE_END(ftrace_regs_caller)
SYM_CODE_START(ftrace_caller)
ftrace_regs_entry 0
j ftrace_common
SYM_CODE_END(ftrace_caller)
SYM_CODE_START(ftrace_common)
#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
aghik %r2,%r0,-MCOUNT_INSN_SIZE
lgrl %r4,function_trace_op
@ -74,24 +93,22 @@ ENTRY(ftrace_caller)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
# The j instruction gets runtime patched to a nop instruction.
# See ftrace_enable_ftrace_graph_caller.
.globl ftrace_graph_caller
ftrace_graph_caller:
j ftrace_graph_caller_end
SYM_INNER_LABEL(ftrace_graph_caller, SYM_L_GLOBAL)
j .Lftrace_graph_caller_end
lmg %r2,%r3,(STACK_PTREGS_GPRS+14*8)(%r15)
lg %r4,(STACK_PTREGS_PSW+8)(%r15)
brasl %r14,prepare_ftrace_return
stg %r2,(STACK_PTREGS_GPRS+14*8)(%r15)
ftrace_graph_caller_end:
.globl ftrace_graph_caller_end
.Lftrace_graph_caller_end:
#endif
lg %r1,(STACK_PTREGS_PSW+8)(%r15)
lmg %r2,%r15,(STACK_PTREGS_GPRS+2*8)(%r15)
BR_EX %r1
ENDPROC(ftrace_caller)
SYM_CODE_END(ftrace_common)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(return_to_handler)
SYM_FUNC_START(return_to_handler)
stmg %r2,%r5,32(%r15)
lgr %r1,%r15
aghi %r15,-STACK_FRAME_OVERHEAD
@ -101,6 +118,6 @@ ENTRY(return_to_handler)
lgr %r14,%r2
lmg %r2,%r5,32(%r15)
BR_EX %r14
ENDPROC(return_to_handler)
SYM_FUNC_END(return_to_handler)
#endif