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Commit 4de72395 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
Browse files

ftrace/x86: Add save_regs for i386 function calls 

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

Link: Link: http://lkml.kernel.org/r/20120711195745.379060003@goodmis.org



Reviewed-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 08f6fba5

arch/x86/include/asm/ftrace.h

+0 −2
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/entry_32.S

+68 −0
Original line number Diff line number Diff line
@@ -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 +1135,73 @@ ftrace_stub: 
	ret

END(ftrace_caller)



ENTRY(ftrace_regs_caller)

	pushf	/* push flags before compare (in cs location) */

	cmpl $0, function_trace_stop

	jne ftrace_restore_flags



	/*

	 * i386 does not save SS and ESP when coming from kernel.

	 * Instead, to get sp, &regs->sp is used (see ptrace.h).

	 * Unfortunately, that means eflags must be at the same location

	 * as the current return ip is. We move the return ip into the

	 * ip location, and move flags into the return ip location.

	 */

	pushl 4(%esp)	/* save return ip into ip slot */

	subl $MCOUNT_INSN_SIZE, (%esp)	/* Adjust ip */



	pushl $0	/* Load 0 into 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 13*4(%esp), %eax	/* Get the saved flags */

	movl %eax, 14*4(%esp)	/* Move saved flags into regs->flags location */

				/* clobbering return ip */

	movl $__KERNEL_CS,13*4(%esp)



	movl 12*4(%esp), %eax	/* Load ip (1st parameter) */

	movl 0x4(%ebp), %edx	/* Load parent ip (2cd parameter) */

	lea  (%esp), %ecx

	pushl %ecx		/* Save pt_regs as 4th parameter */

	leal function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */



GLOBAL(ftrace_regs_call)

	call ftrace_stub



	addl $4, %esp		/* Skip pt_regs */

	movl 14*4(%esp), %eax	/* Move flags back into cs */

	movl %eax, 13*4(%esp)	/* Needed to keep addl from modifying flags */

	movl 12*4(%esp), %eax	/* Get return ip from regs->ip */

	addl $MCOUNT_INSN_SIZE, %eax

	movl %eax, 14*4(%esp)	/* Put return ip back for ret */



	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		/* Skip orig_ax and ip */

	popf			/* Pop flags at end (no addl to corrupt flags) */

	jmp ftrace_ret



ftrace_restore_flags:

	popf

	jmp  ftrace_stub

#else /* ! CONFIG_DYNAMIC_FTRACE */



ENTRY(mcount)

arch/x86/kernel/ftrace.c

+0 −4
Original line number Diff line number Diff line
@@ -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);