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Subject[PATCH -tip v2 3/9] ftrace/x86: Support SAVE_REGS feature on i386
Date
Add register saving/restoring sequence in ftrace_caller
on i386 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 | 2 +
arch/x86/kernel/entry_32.S | 64 +++++++++++++++++++++++++++++++++++------
2 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index ffb9564..e2f7269 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -32,7 +32,7 @@
#define MCOUNT_ADDR ((long)(mcount))
#define MCOUNT_INSN_SIZE 5 /* sizeof mcount call */

-#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_X86_64)
+#if defined(CONFIG_DYNAMIC_FTRACE)
#define ARCH_SUPPORTS_FTRACE_SAVE_REGS 1
#endif

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 01ccf9b..79c45a2 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1095,24 +1095,66 @@ ENTRY(mcount)
ret
END(mcount)

+ .macro FTRACE_SAVE_ALL
+ /* eflags is saved on cs */
+ subl $8, %esp /* skip ip and orig_ax */
+ pushl %gs
+ pushl %fs
+ pushl %es
+ pushl %ds
+ pushl %eax
+ pushl %ebp
+ pushl %edi
+ pushl %esi
+ pushl %edx
+ pushl %ecx
+ pushl %ebx
+ movl 14*4(%esp), %eax /* Load return address */
+ pushl %eax /* Save return address (+4) */
+ subl $MCOUNT_INSN_SIZE, %eax
+ movl %eax, 12*4+4(%esp) /* Store IP */
+ movl 13*4+4(%esp), %edx /* Load flags */
+ movl %edx, 14*4+4(%esp) /* Store flags */
+ movl $__KERNEL_CS, %edx
+ movl %edx, 13*4+4(%esp)
+ .endm
+
+ .macro FTRACE_RESTORE_ALL
+ movl 14*4+4(%esp), %eax /* Load flags */
+ movl %eax, 13*4+4(%esp) /* Restore flags */
+ popl %eax
+ movl %eax, 14*4(%esp) /* Restore return address */
+ popl %ebx
+ popl %ecx
+ popl %edx
+ popl %esi
+ popl %edi
+ popl %ebp
+ popl %eax
+ popl %ds
+ popl %es
+ popl %fs
+ popl %gs
+ addl $8, %esp
+ .endm
+
ENTRY(ftrace_caller)
+ pushf /* flags on regs->cs */
cmpl $0, function_trace_stop
- jne ftrace_stub
+ jne ftrace_exit
+
+ FTRACE_SAVE_ALL

- pushl %eax
- pushl %ecx
- pushl %edx
- movl 0xc(%esp), %eax
movl 0x4(%ebp), %edx
- subl $MCOUNT_INSN_SIZE, %eax
+ lea 4(%esp), %ecx

.globl ftrace_call
ftrace_call:
call ftrace_stub

- popl %edx
- popl %ecx
- popl %eax
+ FTRACE_RESTORE_ALL
+
+ popf
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
@@ -1122,6 +1164,10 @@ ftrace_graph_call:
.globl ftrace_stub
ftrace_stub:
ret
+
+ftrace_exit:
+ popf
+ ret
END(ftrace_caller)

#else /* ! CONFIG_DYNAMIC_FTRACE */


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