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/*
* linux/arch/arm/kernel/entry-common.S
*
* Copyright (C) 2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <asm/unistd.h>
#include <asm/ftrace.h>
#include <mach/entry-macro.S>
#include <asm/unwind.h>
#include "entry-header.S"
.align 5
/*
* This is the fast syscall return path. We do as little as
* possible here, and this includes saving r0 back into the SVC
* stack.
*/
ret_fast_syscall:
UNWIND(.fnstart )
UNWIND(.cantunwind )
disable_irq @ disable interrupts
ldr r1, [tsk, #TI_FLAGS]
tst r1, #_TIF_WORK_MASK
bne fast_work_pending
#if defined(CONFIG_IRQSOFF_TRACER)
asm_trace_hardirqs_on
#endif
/* perform architecture specific actions before user return */
arch_ret_to_user r1, lr
restore_user_regs fast = 1, offset = S_OFF
UNWIND(.fnend )
/*
* Ok, we need to do extra processing, enter the slow path.
*/
fast_work_pending:
str r0, [sp, #S_R0+S_OFF]! @ returned r0
work_pending:
tst r1, #_TIF_NEED_RESCHED
bne work_resched
tst r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME
beq no_work_pending
mov r0, sp @ 'regs'
mov r2, why @ 'syscall'
tst r1, #_TIF_SIGPENDING @ delivering a signal?
movne why, #0 @ prevent further restarts
bl do_notify_resume
b ret_slow_syscall @ Check work again
work_resched:
bl schedule
/*
* "slow" syscall return path. "why" tells us if this was a real syscall.
*/
ENTRY(ret_to_user)
ret_slow_syscall:
disable_irq @ disable interrupts
ENTRY(ret_to_user_from_irq)
ldr r1, [tsk, #TI_FLAGS]
tst r1, #_TIF_WORK_MASK
bne work_pending
no_work_pending:
#if defined(CONFIG_IRQSOFF_TRACER)
asm_trace_hardirqs_on
#endif
/* perform architecture specific actions before user return */
arch_ret_to_user r1, lr
restore_user_regs fast = 0, offset = 0
ENDPROC(ret_to_user_from_irq)
ENDPROC(ret_to_user)
/*
* This is how we return from a fork.
*/
ENTRY(ret_from_fork)
bl schedule_tail
get_thread_info tsk
ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing
mov why, #1
tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
beq ret_slow_syscall
mov r1, sp
mov r0, #1 @ trace exit [IP = 1]
bl syscall_trace
b ret_slow_syscall
ENDPROC(ret_from_fork)
.equ NR_syscalls,0
#define CALL(x) .equ NR_syscalls,NR_syscalls+1
#include "calls.S"
#undef CALL
#define CALL(x) .long x
#ifdef CONFIG_FUNCTION_TRACER
/*
* When compiling with -pg, gcc inserts a call to the mcount routine at the
* start of every function. In mcount, apart from the function's address (in
* lr), we need to get hold of the function's caller's address.
*
* Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
*
* bl mcount
*
* These versions have the limitation that in order for the mcount routine to
* be able to determine the function's caller's address, an APCS-style frame
* pointer (which is set up with something like the code below) is required.
*
* mov ip, sp
* push {fp, ip, lr, pc}
* sub fp, ip, #4
*
* With EABI, these frame pointers are not available unless -mapcs-frame is
* specified, and if building as Thumb-2, not even then.
*
* Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
* with call sites like:
*
* push {lr}
* bl __gnu_mcount_nc
*
* With these compilers, frame pointers are not necessary.
*
* mcount can be thought of as a function called in the middle of a subroutine
* call. As such, it needs to be transparent for both the caller and the
* callee: the original lr needs to be restored when leaving mcount, and no
* registers should be clobbered. (In the __gnu_mcount_nc implementation, we
* clobber the ip register. This is OK because the ARM calling convention
* allows it to be clobbered in subroutines and doesn't use it to hold
* parameters.)
*
* When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
* for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
* arch/arm/kernel/ftrace.c).
*/
#ifndef CONFIG_OLD_MCOUNT
#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
#endif
#endif
.macro __mcount suffix
mcount_enter
ldr r0, =ftrace_trace_function
ldr r2, [r0]
adr r0, .Lftrace_stub
cmp r0, r2
bne 1f
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ldr r1, =ftrace_graph_return
ldr r2, [r1]
cmp r0, r2
bne ftrace_graph_caller\suffix
ldr r1, =ftrace_graph_entry
ldr r2, [r1]
ldr r0, =ftrace_graph_entry_stub
cmp r0, r2
bne ftrace_graph_caller\suffix
#endif
mcount_exit
1: mcount_get_lr r1 @ lr of instrumented func
mov r0, lr @ instrumented function
sub r0, r0, #MCOUNT_INSN_SIZE
adr lr, BSYM(2f)
mov pc, r2
2: mcount_exit
.endm
.macro __ftrace_caller suffix
mcount_enter
mcount_get_lr r1 @ lr of instrumented func
mov r0, lr @ instrumented function
sub r0, r0, #MCOUNT_INSN_SIZE
.globl ftrace_call\suffix
ftrace_call\suffix:
bl ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call\suffix
ftrace_graph_call\suffix:
mov r0, r0
#endif
mcount_exit
.endm
.macro __ftrace_graph_caller
sub r0, fp, #4 @ &lr of instrumented routine (&parent)
#ifdef CONFIG_DYNAMIC_FTRACE
@ called from __ftrace_caller, saved in mcount_enter
ldr r1, [sp, #16] @ instrumented routine (func)
#else
@ called from __mcount, untouched in lr
mov r1, lr @ instrumented routine (func)
#endif
sub r1, r1, #MCOUNT_INSN_SIZE
mov r2, fp @ frame pointer
bl prepare_ftrace_return
mcount_exit
.endm
#ifdef CONFIG_OLD_MCOUNT
/*
* mcount
*/
.macro mcount_enter
stmdb sp!, {r0-r3, lr}
.endm
.macro mcount_get_lr reg
ldr \reg, [fp, #-4]
.endm
.macro mcount_exit
ldr lr, [fp, #-4]
ldmia sp!, {r0-r3, pc}
.endm
ENTRY(mcount)
#ifdef CONFIG_DYNAMIC_FTRACE
stmdb sp!, {lr}
ldr lr, [fp, #-4]
ldmia sp!, {pc}
#else
__mcount _old
#endif
ENDPROC(mcount)
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(ftrace_caller_old)
__ftrace_caller _old
ENDPROC(ftrace_caller_old)
#endif
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller_old)
__ftrace_graph_caller
ENDPROC(ftrace_graph_caller_old)
#endif
.purgem mcount_enter
.purgem mcount_get_lr
.purgem mcount_exit
#endif
/*
* __gnu_mcount_nc
*/
.macro mcount_enter
stmdb sp!, {r0-r3, lr}
.endm
.macro mcount_get_lr reg
ldr \reg, [sp, #20]
.endm
.macro mcount_exit
ldmia sp!, {r0-r3, ip, lr}
mov pc, ip
.endm
ENTRY(__gnu_mcount_nc)
#ifdef CONFIG_DYNAMIC_FTRACE
mov ip, lr
ldmia sp!, {lr}
mov pc, ip
#else
__mcount
#endif
ENDPROC(__gnu_mcount_nc)
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(ftrace_caller)
__ftrace_caller
ENDPROC(ftrace_caller)
#endif
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
__ftrace_graph_caller
ENDPROC(ftrace_graph_caller)
#endif
.purgem mcount_enter
.purgem mcount_get_lr
.purgem mcount_exit
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl return_to_handler
return_to_handler:
stmdb sp!, {r0-r3}
mov r0, fp @ frame pointer
bl ftrace_return_to_handler
mov lr, r0 @ r0 has real ret addr
ldmia sp!, {r0-r3}
mov pc, lr
#endif
ENTRY(ftrace_stub)
.Lftrace_stub:
mov <
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