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Subject[PATCH -tip v2 2/9] ftrace/x86-64: support SAVE_REGS feature on x86-64
Date
Add register saving/restoring sequence in ftrace_caller
on x86-64 for enabling SAVE_REGS feature.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
---

arch/x86/include/asm/ftrace.h | 4 ++++
arch/x86/kernel/entry_64.S | 38 +++++++++++++++++++++++++++++++++-----
2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 18d9005..ffb9564 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -32,6 +32,10 @@
#define MCOUNT_ADDR ((long)(mcount))
#define MCOUNT_INSN_SIZE 5 /* sizeof mcount call */

+#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_X86_64)
+#define ARCH_SUPPORTS_FTRACE_SAVE_REGS 1
+#endif
+
#ifndef __ASSEMBLY__
extern void mcount(void);
extern int modifying_ftrace_code;
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 320852d..6d0545b 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -73,21 +73,44 @@ ENTRY(mcount)
retq
END(mcount)

+ .macro MCOUNT_SAVE_ALL
+ SAVE_ARGS (RSP-ORIG_RAX)
+ SAVE_REST
+ /* Adjust eflags, rsp and rip */
+ movq RSP(%rsp), %rdx
+ movq %rdx, EFLAGS(%rsp)
+ leaq SS+8(%rsp), %rdx
+ movq %rdx, RSP(%rsp)
+ movq SS(%rsp), %rdi
+ subq $MCOUNT_INSN_SIZE, %rdi
+ movq %rdi, RIP(%rsp)
+ .endm
+
+ .macro MCOUNT_RESTORE_ALL
+ /* store eflags into regs->rsp */
+ movq EFLAGS(%rsp), %rax
+ movq %rax, RSP(%rsp)
+ RESTORE_REST
+ RESTORE_ARGS 1, (RSP-ORIG_RAX)
+ .endm
+
ENTRY(ftrace_caller)
+ CFI_STARTPROC simple
+ pushfq_cfi
cmpl $0, function_trace_stop
- jne ftrace_stub
+ jne ftrace_exit

- MCOUNT_SAVE_FRAME
+ MCOUNT_SAVE_ALL

- movq 0x38(%rsp), %rdi
movq 8(%rbp), %rsi
- subq $MCOUNT_INSN_SIZE, %rdi
+ movq %rsp, %rdx

GLOBAL(ftrace_call)
call ftrace_stub

- MCOUNT_RESTORE_FRAME
+ MCOUNT_RESTORE_ALL

+ popfq_cfi
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
GLOBAL(ftrace_graph_call)
jmp ftrace_stub
@@ -95,6 +118,11 @@ GLOBAL(ftrace_graph_call)

GLOBAL(ftrace_stub)
retq
+
+ftrace_exit:
+ popfq_cfi
+ retq
+ CFI_ENDPROC
END(ftrace_caller)

#else /* ! CONFIG_DYNAMIC_FTRACE */


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