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Subject[RFC][PATCH 06/13 v2] ftrace/x86: Add save_regs for i386 function calls
From: Steven Rostedt <srostedt@redhat.com>

Add saving full regs for function tracing on i386.
The saving of regs was influenced by patches sent out by
Masami Hiramatsu.

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
arch/x86/include/asm/ftrace.h | 2 --
arch/x86/kernel/entry_32.S | 53 +++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/ftrace.c | 4 ----
3 files changed, 53 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index fd10faf..2b396cf 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -40,10 +40,8 @@

#ifdef CONFIG_DYNAMIC_FTRACE
#define ARCH_SUPPORTS_FTRACE_OPS 1
-#ifdef CONFIG_X86_64
#define ARCH_SUPPORTS_FTRACE_SAVE_REGS
#endif
-#endif

#ifndef __ASSEMBLY__
extern void mcount(void);
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index acd4963..f22802c 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1123,6 +1123,7 @@ ftrace_call:
popl %edx
popl %ecx
popl %eax
+ftrace_ret:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
@@ -1134,6 +1135,58 @@ ftrace_stub:
ret
END(ftrace_caller)

+ENTRY(ftrace_regs_caller)
+ pushf /* push flags before compare */
+ cmpl $0, function_trace_stop
+ jne ftrace_exit
+
+ 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) /* Store CS */
+
+ movl 0x4(%ebp), %edx
+ lea 4(%esp), %ecx
+ pushl %ecx /* Save pt_regs as 4th parameter */
+ leal function_trace_op, %ecx
+
+GLOBAL(ftrace_regs_call)
+ call ftrace_stub
+
+ addl $4,%esp /* Skip pt_regs */
+ 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
+ftrace_exit:
+ addl $4, %esp /* Skip eflags */
+ jmp ftrace_ret
#else /* ! CONFIG_DYNAMIC_FTRACE */

ENTRY(mcount)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index b90eb1a..1d41402 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -206,7 +206,6 @@ static int
ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
unsigned const char *new_code);

-#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
/*
* Should never be called:
* As it is only called by __ftrace_replace_code() which is called by
@@ -221,7 +220,6 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
WARN_ON(1);
return -EINVAL;
}
-#endif

int ftrace_update_ftrace_func(ftrace_func_t func)
{
@@ -237,7 +235,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)

ret = ftrace_modify_code(ip, old, new);

-#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
/* Also update the regs callback function */
if (!ret) {
ip = (unsigned long)(&ftrace_regs_call);
@@ -245,7 +242,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
new = ftrace_call_replace(ip, (unsigned long)func);
ret = ftrace_modify_code(ip, old, new);
}
-#endif

atomic_dec(&modifying_ftrace_code);

--
1.7.10



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