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Subject[RFC] x86: entry_64 - introduce FTRACE_ frame macro
Impact: clean up

Itroduce FTRACE_SAVE/RESTORE_FRAME which allow us to
save a number of lines on source level.

Also fix a comment in ftrace.h.

---
Actually I'm not that sure about bringing new macros there
since we already have a lot so feel free to just drop it.
Maybe it would be good to comment args passed
to ftrace_call on ABI level :)

Ah, the patch is on top of -tip e3bdf48

arch/x86/include/asm/ftrace.h | 2 -
arch/x86/kernel/entry_64.S | 70 +++++++++++++++---------------------------
2 files changed, 26 insertions(+), 46 deletions(-)
Index: linux-2.6.git/arch/x86/include/asm/ftrace.h
===================================================================
--- linux-2.6.git.orig/arch/x86/include/asm/ftrace.h
+++ linux-2.6.git/arch/x86/include/asm/ftrace.h
@@ -46,7 +46,7 @@ struct ftrace_ret_stack {
/*
* Primary handler of a function return.
* It relays on ftrace_return_to_handler.
- * Defined in entry32.S
+ * Defined in entry_32/64.S
*/
extern void return_to_handler(void);

Index: linux-2.6.git/arch/x86/kernel/entry_64.S
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/entry_64.S
+++ linux-2.6.git/arch/x86/kernel/entry_64.S
@@ -66,10 +66,7 @@ ENTRY(mcount)
retq
END(mcount)

-ENTRY(ftrace_caller)
- cmpl $0, function_trace_stop
- jne ftrace_stub
-
+ .macro FTRACE_SAVE_FRAME
/* taken from glibc */
subq $0x38, %rsp
movq %rax, (%rsp)
@@ -79,15 +76,9 @@ ENTRY(ftrace_caller)
movq %rdi, 32(%rsp)
movq %r8, 40(%rsp)
movq %r9, 48(%rsp)
+ .endm

- movq 0x38(%rsp), %rdi
- movq 8(%rbp), %rsi
- subq $MCOUNT_INSN_SIZE, %rdi
-
-.globl ftrace_call
-ftrace_call:
- call ftrace_stub
-
+ .macro FTRACE_RESTORE_FRAME
movq 48(%rsp), %r9
movq 40(%rsp), %r8
movq 32(%rsp), %rdi
@@ -96,6 +87,23 @@ ftrace_call:
movq 8(%rsp), %rcx
movq (%rsp), %rax
addq $0x38, %rsp
+ .endm
+
+ENTRY(ftrace_caller)
+ cmpl $0, function_trace_stop
+ jne ftrace_stub
+
+ FTRACE_SAVE_FRAME
+
+ movq 0x38(%rsp), %rdi
+ movq 8(%rbp), %rsi
+ subq $MCOUNT_INSN_SIZE, %rdi
+
+.globl ftrace_call
+ftrace_call:
+ call ftrace_stub
+
+ FTRACE_RESTORE_FRAME

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
@@ -129,15 +137,7 @@ ftrace_stub:
retq

trace:
- /* taken from glibc */
- subq $0x38, %rsp
- movq %rax, (%rsp)
- movq %rcx, 8(%rsp)
- movq %rdx, 16(%rsp)
- movq %rsi, 24(%rsp)
- movq %rdi, 32(%rsp)
- movq %r8, 40(%rsp)
- movq %r9, 48(%rsp)
+ FTRACE_SAVE_FRAME

movq 0x38(%rsp), %rdi
movq 8(%rbp), %rsi
@@ -145,14 +145,7 @@ trace:

call *ftrace_trace_function

- movq 48(%rsp), %r9
- movq 40(%rsp), %r8
- movq 32(%rsp), %rdi
- movq 24(%rsp), %rsi
- movq 16(%rsp), %rdx
- movq 8(%rsp), %rcx
- movq (%rsp), %rax
- addq $0x38, %rsp
+ FTRACE_RESTORE_FRAME

jmp ftrace_stub
END(mcount)
@@ -164,14 +157,7 @@ ENTRY(ftrace_graph_caller)
cmpl $0, function_trace_stop
jne ftrace_stub

- subq $0x38, %rsp
- movq %rax, (%rsp)
- movq %rcx, 8(%rsp)
- movq %rdx, 16(%rsp)
- movq %rsi, 24(%rsp)
- movq %rdi, 32(%rsp)
- movq %r8, 40(%rsp)
- movq %r9, 48(%rsp)
+ FTRACE_SAVE_FRAME

leaq 8(%rbp), %rdi
movq 0x38(%rsp), %rsi
@@ -179,14 +165,8 @@ ENTRY(ftrace_graph_caller)

call prepare_ftrace_return

- movq 48(%rsp), %r9
- movq 40(%rsp), %r8
- movq 32(%rsp), %rdi
- movq 24(%rsp), %rsi
- movq 16(%rsp), %rdx
- movq 8(%rsp), %rcx
- movq (%rsp), %rax
- addq $0x38, %rsp
+ FTRACE_RESTORE_FRAME
+
retq
END(ftrace_graph_caller)


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