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>

diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index 3baceb4a7d3c2d21a442e290117f3406eeb8ee1f..4a721b44d4f406e5f9fca5b227a2614384232c28 100644 (file)
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -17,7 +17,6 @@
 
 void ftrace_caller(void);
 
-extern char ftrace_graph_caller_end;
 extern void *ftrace_func;
 
 struct dyn_arch_ftrace { };

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 6b13797143a72acc0b476cf87e566752b321f826..cc25fbd75ea9ba6fecbf3dfc9b3c4f4a32bc7b42 100644 (file)
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -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