linux/arch/mips/kernel/mcount.S
Corey Minyard 05f226391d MIPS: Ftrace: Fix function tracing return address to match
Dynamic function tracing was not working on MIPS.  When doing dynamic
tracing, the tracer attempts to match up the passed in address with
the one the compiler creates in the mcount tables.  The MIPS code was
passing in the return address from the tracing function call, but the
compiler tables were the address of the function call.  So they
wouldn't match.

Just subtracting 8 from the return address will give the address of
the function call.  Easy enough.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
[david.daney@cavium.com: Adjusted code comment and patch Subject.]
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/5592/
2013-09-03 14:46:27 +02:00

203 lines
3.9 KiB
ArmAsm

/*
* MIPS specific _mcount support
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive for
* more details.
*
* Copyright (C) 2009 Lemote Inc. & DSLab, Lanzhou University, China
* Copyright (C) 2010 DSLab, Lanzhou University, China
* Author: Wu Zhangjin <wuzhangjin@gmail.com>
*/
#include <asm/regdef.h>
#include <asm/stackframe.h>
#include <asm/ftrace.h>
.text
.set noreorder
.set noat
.macro MCOUNT_SAVE_REGS
PTR_SUBU sp, PT_SIZE
PTR_S ra, PT_R31(sp)
PTR_S AT, PT_R1(sp)
PTR_S a0, PT_R4(sp)
PTR_S a1, PT_R5(sp)
PTR_S a2, PT_R6(sp)
PTR_S a3, PT_R7(sp)
#ifdef CONFIG_64BIT
PTR_S a4, PT_R8(sp)
PTR_S a5, PT_R9(sp)
PTR_S a6, PT_R10(sp)
PTR_S a7, PT_R11(sp)
#endif
.endm
.macro MCOUNT_RESTORE_REGS
PTR_L ra, PT_R31(sp)
PTR_L AT, PT_R1(sp)
PTR_L a0, PT_R4(sp)
PTR_L a1, PT_R5(sp)
PTR_L a2, PT_R6(sp)
PTR_L a3, PT_R7(sp)
#ifdef CONFIG_64BIT
PTR_L a4, PT_R8(sp)
PTR_L a5, PT_R9(sp)
PTR_L a6, PT_R10(sp)
PTR_L a7, PT_R11(sp)
#endif
PTR_ADDIU sp, PT_SIZE
.endm
.macro RETURN_BACK
jr ra
move ra, AT
.endm
/*
* The -mmcount-ra-address option of gcc 4.5 uses register $12 to pass
* the location of the parent's return address.
*/
#define MCOUNT_RA_ADDRESS_REG $12
#ifdef CONFIG_DYNAMIC_FTRACE
NESTED(ftrace_caller, PT_SIZE, ra)
.globl _mcount
_mcount:
b ftrace_stub
#ifdef CONFIG_32BIT
addiu sp,sp,8
#else
nop
#endif
/* When tracing is activated, it calls ftrace_caller+8 (aka here) */
lw t1, function_trace_stop
bnez t1, ftrace_stub
nop
MCOUNT_SAVE_REGS
#ifdef KBUILD_MCOUNT_RA_ADDRESS
PTR_S MCOUNT_RA_ADDRESS_REG, PT_R12(sp)
#endif
PTR_SUBU a0, ra, 8 /* arg1: self address */
.globl ftrace_call
ftrace_call:
nop /* a placeholder for the call to a real tracing function */
move a1, AT /* arg2: parent's return address */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
nop
nop
#endif
MCOUNT_RESTORE_REGS
.globl ftrace_stub
ftrace_stub:
RETURN_BACK
END(ftrace_caller)
#else /* ! CONFIG_DYNAMIC_FTRACE */
NESTED(_mcount, PT_SIZE, ra)
lw t1, function_trace_stop
bnez t1, ftrace_stub
nop
PTR_LA t1, ftrace_stub
PTR_L t2, ftrace_trace_function /* Prepare t2 for (1) */
bne t1, t2, static_trace
nop
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
PTR_L t3, ftrace_graph_return
bne t1, t3, ftrace_graph_caller
nop
PTR_LA t1, ftrace_graph_entry_stub
PTR_L t3, ftrace_graph_entry
bne t1, t3, ftrace_graph_caller
nop
#endif
b ftrace_stub
nop
static_trace:
MCOUNT_SAVE_REGS
move a0, ra /* arg1: self return address */
jalr t2 /* (1) call *ftrace_trace_function */
move a1, AT /* arg2: parent's return address */
MCOUNT_RESTORE_REGS
.globl ftrace_stub
ftrace_stub:
RETURN_BACK
END(_mcount)
#endif /* ! CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
NESTED(ftrace_graph_caller, PT_SIZE, ra)
#ifndef CONFIG_DYNAMIC_FTRACE
MCOUNT_SAVE_REGS
#endif
/* arg1: Get the location of the parent's return address */
#ifdef KBUILD_MCOUNT_RA_ADDRESS
#ifdef CONFIG_DYNAMIC_FTRACE
PTR_L a0, PT_R12(sp)
#else
move a0, MCOUNT_RA_ADDRESS_REG
#endif
bnez a0, 1f /* non-leaf func: stored in MCOUNT_RA_ADDRESS_REG */
nop
#endif
PTR_LA a0, PT_R1(sp) /* leaf func: the location in current stack */
1:
/* arg2: Get self return address */
#ifdef CONFIG_DYNAMIC_FTRACE
PTR_L a1, PT_R31(sp)
#else
move a1, ra
#endif
/* arg3: Get frame pointer of current stack */
#ifdef CONFIG_64BIT
PTR_LA a2, PT_SIZE(sp)
#else
PTR_LA a2, (PT_SIZE+8)(sp)
#endif
jal prepare_ftrace_return
nop
MCOUNT_RESTORE_REGS
RETURN_BACK
END(ftrace_graph_caller)
.align 2
.globl return_to_handler
return_to_handler:
PTR_SUBU sp, PT_SIZE
PTR_S v0, PT_R2(sp)
jal ftrace_return_to_handler
PTR_S v1, PT_R3(sp)
/* restore the real parent address: v0 -> ra */
move ra, v0
PTR_L v0, PT_R2(sp)
PTR_L v1, PT_R3(sp)
jr ra
PTR_ADDIU sp, PT_SIZE
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
.set at
.set reorder