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linux/arch/arm/kernel/entry-armv.S

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/*
* linux/arch/arm/kernel/entry-armv.S
*
* Copyright (C) 1996,1997,1998 Russell King.
* ARM700 fix by Matthew Godbolt (linux-user@willothewisp.demon.co.uk)
* nommu support by Hyok S. Choi (hyok.choi@samsung.com)
*
* 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.
*
* Low-level vector interface routines
*
* Note: there is a StrongARM bug in the STMIA rn, {regs}^ instruction
* that causes it to save wrong values... Be aware!
*/
#include <asm/memory.h>
#include <asm/glue-df.h>
#include <asm/glue-pf.h>
#include <asm/vfpmacros.h>
#include <mach/entry-macro.S>
#include <asm/thread_notify.h>
#include <asm/unwind.h>
#include <asm/unistd.h>
#include <asm/tls.h>
#include "entry-header.S"
#include <asm/entry-macro-multi.S>
/*
* Interrupt handling. Preserves r7, r8, r9
*/
.macro irq_handler
#ifdef CONFIG_MULTI_IRQ_HANDLER
ldr r5, =handle_arch_irq
mov r0, sp
ldr r5, [r5]
adr lr, BSYM(9997f)
teq r5, #0
movne pc, r5
#endif
arch_irq_handler_default
9997:
.endm
#ifdef CONFIG_KPROBES
.section .kprobes.text,"ax",%progbits
#else
.text
#endif
/*
* Invalid mode handlers
*/
.macro inv_entry, reason
sub sp, sp, #S_FRAME_SIZE
ARM( stmib sp, {r1 - lr} )
THUMB( stmia sp, {r0 - r12} )
THUMB( str sp, [sp, #S_SP] )
THUMB( str lr, [sp, #S_LR] )
mov r1, #\reason
.endm
__pabt_invalid:
inv_entry BAD_PREFETCH
b common_invalid
ENDPROC(__pabt_invalid)
__dabt_invalid:
inv_entry BAD_DATA
b common_invalid
ENDPROC(__dabt_invalid)
__irq_invalid:
inv_entry BAD_IRQ
b common_invalid
ENDPROC(__irq_invalid)
__und_invalid:
inv_entry BAD_UNDEFINSTR
@
@ XXX fall through to common_invalid
@
@
@ common_invalid - generic code for failed exception (re-entrant version of handlers)
@
common_invalid:
zero_fp
ldmia r0, {r4 - r6}
add r0, sp, #S_PC @ here for interlock avoidance
mov r7, #-1 @ "" "" "" ""
str r4, [sp] @ save preserved r0
stmia r0, {r5 - r7} @ lr_<exception>,
@ cpsr_<exception>, "old_r0"
mov r0, sp
b bad_mode
ENDPROC(__und_invalid)
/*
* SVC mode handlers
*/
#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
#define SPFIX(code...) code
#else
#define SPFIX(code...)
#endif
.macro svc_entry, stack_hole=0
UNWIND(.fnstart )
UNWIND(.save {r0 - pc} )
sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
#ifdef CONFIG_THUMB2_KERNEL
SPFIX( str r0, [sp] ) @ temporarily saved
SPFIX( mov r0, sp )
SPFIX( tst r0, #4 ) @ test original stack alignment
SPFIX( ldr r0, [sp] ) @ restored
#else
SPFIX( tst sp, #4 )
#endif
SPFIX( subeq sp, sp, #4 )
stmia sp, {r1 - r12}
ldmia r0, {r1 - r3}
add r5, sp, #S_SP - 4 @ here for interlock avoidance
mov r4, #-1 @ "" "" "" ""
add r0, sp, #(S_FRAME_SIZE + \stack_hole - 4)
SPFIX( addeq r0, r0, #4 )
str r1, [sp, #-4]! @ save the "real" r0 copied
@ from the exception stack
mov r1, lr
@
@ We are now ready to fill in the remaining blanks on the stack:
@
@ r0 - sp_svc
@ r1 - lr_svc
@ r2 - lr_<exception>, already fixed up for correct return/restart
@ r3 - spsr_<exception>
@ r4 - orig_r0 (see pt_regs definition in ptrace.h)
@
stmia r5, {r0 - r4}
.endm
.align 5
__dabt_svc:
svc_entry
@
@ get ready to re-enable interrupts if appropriate
@
mrs r9, cpsr
tst r3, #PSR_I_BIT
biceq r9, r9, #PSR_I_BIT
@
@ Call the processor-specific abort handler:
@
@ r2 - aborted context pc
@ r3 - aborted context cpsr
@
@ The abort handler must return the aborted address in r0, and
@ the fault status register in r1. r9 must be preserved.
@
#ifdef MULTI_DABORT
ldr r4, .LCprocfns
mov lr, pc
ldr pc, [r4, #PROCESSOR_DABT_FUNC]
#else
bl CPU_DABORT_HANDLER
#endif
@
@ set desired IRQ state, then call main handler
@
debug_entry r1
msr cpsr_c, r9
mov r2, sp
bl do_DataAbort
@
@ IRQs off again before pulling preserved data off the stack
@
disable_irq_notrace
@
@ restore SPSR and restart the instruction
@
ldr r2, [sp, #S_PSR]
svc_exit r2 @ return from exception
UNWIND(.fnend )
ENDPROC(__dabt_svc)
.align 5
__irq_svc:
svc_entry
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
#ifdef CONFIG_PREEMPT
get_thread_info tsk
ldr r8, [tsk, #TI_PREEMPT] @ get preempt count
add r7, r8, #1 @ increment it
str r7, [tsk, #TI_PREEMPT]
#endif
irq_handler
#ifdef CONFIG_PREEMPT
str r8, [tsk, #TI_PREEMPT] @ restore preempt count
ldr r0, [tsk, #TI_FLAGS] @ get flags
teq r8, #0 @ if preempt count != 0
movne r0, #0 @ force flags to 0
tst r0, #_TIF_NEED_RESCHED
blne svc_preempt
#endif
ldr r4, [sp, #S_PSR] @ irqs are already disabled
#ifdef CONFIG_TRACE_IRQFLAGS
tst r4, #PSR_I_BIT
bleq trace_hardirqs_on
#endif
svc_exit r4 @ return from exception
UNWIND(.fnend )
ENDPROC(__irq_svc)
.ltorg
#ifdef CONFIG_PREEMPT
svc_preempt:
mov r8, lr
1: bl preempt_schedule_irq @ irq en/disable is done inside
ldr r0, [tsk, #TI_FLAGS] @ get new tasks TI_FLAGS
tst r0, #_TIF_NEED_RESCHED
moveq pc, r8 @ go again
b 1b
#endif
.align 5
__und_svc:
#ifdef CONFIG_KPROBES
@ If a kprobe is about to simulate a "stmdb sp..." instruction,
@ it obviously needs free stack space which then will belong to
@ the saved context.
svc_entry 64
#else
svc_entry
#endif
@
@ call emulation code, which returns using r9 if it has emulated
@ the instruction, or the more conventional lr if we are to treat
@ this as a real undefined instruction
@
@ r0 - instruction
@
#ifndef CONFIG_THUMB2_KERNEL
ldr r0, [r2, #-4]
#else
ldrh r0, [r2, #-2] @ Thumb instruction at LR - 2
and r9, r0, #0xf800
cmp r9, #0xe800 @ 32-bit instruction if xx >= 0
ldrhhs r9, [r2] @ bottom 16 bits
orrhs r0, r9, r0, lsl #16
#endif
adr r9, BSYM(1f)
bl call_fpe
mov r0, sp @ struct pt_regs *regs
bl do_undefinstr
@
@ IRQs off again before pulling preserved data off the stack
@
1: disable_irq_notrace
@
@ restore SPSR and restart the instruction
@
ldr r2, [sp, #S_PSR] @ Get SVC cpsr
svc_exit r2 @ return from exception
UNWIND(.fnend )
ENDPROC(__und_svc)
.align 5
__pabt_svc:
svc_entry
@
@ re-enable interrupts if appropriate
@
mrs r9, cpsr
tst r3, #PSR_I_BIT
biceq r9, r9, #PSR_I_BIT
mov r0, r2 @ pass address of aborted instruction.
#ifdef MULTI_PABORT
ldr r4, .LCprocfns
mov lr, pc
ldr pc, [r4, #PROCESSOR_PABT_FUNC]
#else
bl CPU_PABORT_HANDLER
#endif
debug_entry r1
msr cpsr_c, r9 @ Maybe enable interrupts
mov r2, sp @ regs
bl do_PrefetchAbort @ call abort handler
@
@ IRQs off again before pulling preserved data off the stack
@
disable_irq_notrace
@
@ restore SPSR and restart the instruction
@
ldr r2, [sp, #S_PSR]
svc_exit r2 @ return from exception
UNWIND(.fnend )
ENDPROC(__pabt_svc)
.align 5
.LCcralign:
.word cr_alignment
#ifdef MULTI_DABORT
.LCprocfns:
.word processor
#endif
.LCfp:
.word fp_enter
/*
* User mode handlers
*
* EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
*/
#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
#error "sizeof(struct pt_regs) must be a multiple of 8"
#endif
.macro usr_entry
UNWIND(.fnstart )
UNWIND(.cantunwind ) @ don't unwind the user space
sub sp, sp, #S_FRAME_SIZE
ARM( stmib sp, {r1 - r12} )
THUMB( stmia sp, {r0 - r12} )
ldmia r0, {r1 - r3}
add r0, sp, #S_PC @ here for interlock avoidance
mov r4, #-1 @ "" "" "" ""
str r1, [sp] @ save the "real" r0 copied
@ from the exception stack
@
@ We are now ready to fill in the remaining blanks on the stack:
@
@ r2 - lr_<exception>, already fixed up for correct return/restart
@ r3 - spsr_<exception>
@ r4 - orig_r0 (see pt_regs definition in ptrace.h)
@
@ Also, separately save sp_usr and lr_usr
@
stmia r0, {r2 - r4}
ARM( stmdb r0, {sp, lr}^ )
THUMB( store_user_sp_lr r0, r1, S_SP - S_PC )
@
@ Enable the alignment trap while in kernel mode
@
alignment_trap r0
@
@ Clear FP to mark the first stack frame
@
zero_fp
.endm
.macro kuser_cmpxchg_check
#if __LINUX_ARM_ARCH__ < 6 && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
#ifndef CONFIG_MMU
#warning "NPTL on non MMU needs fixing"
#else
@ Make sure our user space atomic helper is restarted
@ if it was interrupted in a critical region. Here we
@ perform a quick test inline since it should be false
@ 99.9999% of the time. The rest is done out of line.
cmp r2, #TASK_SIZE
blhs kuser_cmpxchg_fixup
#endif
#endif
.endm
.align 5
__dabt_usr:
usr_entry
kuser_cmpxchg_check
@
@ Call the processor-specific abort handler:
@
@ r2 - aborted context pc
@ r3 - aborted context cpsr
@
@ The abort handler must return the aborted address in r0, and
@ the fault status register in r1.
@
#ifdef MULTI_DABORT
ldr r4, .LCprocfns
mov lr, pc
ldr pc, [r4, #PROCESSOR_DABT_FUNC]
#else
bl CPU_DABORT_HANDLER
#endif
@
@ IRQs on, then call the main handler
@
debug_entry r1
enable_irq
mov r2, sp
adr lr, BSYM(ret_from_exception)
b do_DataAbort
UNWIND(.fnend )
ENDPROC(__dabt_usr)
.align 5
__irq_usr:
usr_entry
kuser_cmpxchg_check
#ifdef CONFIG_IRQSOFF_TRACER
bl trace_hardirqs_off
#endif
get_thread_info tsk
#ifdef CONFIG_PREEMPT
ldr r8, [tsk, #TI_PREEMPT] @ get preempt count
add r7, r8, #1 @ increment it
str r7, [tsk, #TI_PREEMPT]
#endif
irq_handler
#ifdef CONFIG_PREEMPT
ldr r0, [tsk, #TI_PREEMPT]
str r8, [tsk, #TI_PREEMPT]
teq r0, r7
ARM( strne r0, [r0, -r0] )
THUMB( movne r0, #0 )
THUMB( strne r0, [r0] )
#endif
mov why, #0
b ret_to_user_from_irq
UNWIND(.fnend )
ENDPROC(__irq_usr)
.ltorg
.align 5
__und_usr:
usr_entry
@
@ fall through to the emulation code, which returns using r9 if
@ it has emulated the instruction, or the more conventional lr
@ if we are to treat this as a real undefined instruction
@
@ r0 - instruction
@
adr r9, BSYM(ret_from_exception)
adr lr, BSYM(__und_usr_unknown)
tst r3, #PSR_T_BIT @ Thumb mode?
itet eq @ explicit IT needed for the 1f label
subeq r4, r2, #4 @ ARM instr at LR - 4
subne r4, r2, #2 @ Thumb instr at LR - 2
1: ldreqt r0, [r4]
#ifdef CONFIG_CPU_ENDIAN_BE8
reveq r0, r0 @ little endian instruction
#endif
beq call_fpe
@ Thumb instruction
#if __LINUX_ARM_ARCH__ >= 7
2:
ARM( ldrht r5, [r4], #2 )
THUMB( ldrht r5, [r4] )
THUMB( add r4, r4, #2 )
and r0, r5, #0xf800 @ mask bits 111x x... .... ....
cmp r0, #0xe800 @ 32bit instruction if xx != 0
blo __und_usr_unknown
3: ldrht r0, [r4]
add r2, r2, #2 @ r2 is PC + 2, make it PC + 4
orr r0, r0, r5, lsl #16
#else
b __und_usr_unknown
#endif
UNWIND(.fnend )
ENDPROC(__und_usr)
@
@ fallthrough to call_fpe
@
/*
* The out of line fixup for the ldrt above.
*/
.pushsection .fixup, "ax"
4: mov pc, r9
.popsection
.pushsection __ex_table,"a"
.long 1b, 4b
#if __LINUX_ARM_ARCH__ >= 7
.long 2b, 4b
.long 3b, 4b
#endif
.popsection
/*
* Check whether the instruction is a co-processor instruction.
* If yes, we need to call the relevant co-processor handler.
*
* Note that we don't do a full check here for the co-processor
* instructions; all instructions with bit 27 set are well
* defined. The only instructions that should fault are the
* co-processor instructions. However, we have to watch out
* for the ARM6/ARM7 SWI bug.
*
* NEON is a special case that has to be handled here. Not all
* NEON instructions are co-processor instructions, so we have
* to make a special case of checking for them. Plus, there's
* five groups of them, so we have a table of mask/opcode pairs
* to check against, and if any match then we branch off into the
* NEON handler code.
*
* Emulators may wish to make use of the following registers:
* r0 = instruction opcode.
* r2 = PC+4
* r9 = normal "successful" return address
* r10 = this threads thread_info structure.
* lr = unrecognised instruction return address
*/
@
@ Fall-through from Thumb-2 __und_usr
@
#ifdef CONFIG_NEON
adr r6, .LCneon_thumb_opcodes
b 2f
#endif
call_fpe:
#ifdef CONFIG_NEON
adr r6, .LCneon_arm_opcodes
2:
ldr r7, [r6], #4 @ mask value
cmp r7, #0 @ end mask?
beq 1f
and r8, r0, r7
ldr r7, [r6], #4 @ opcode bits matching in mask
cmp r8, r7 @ NEON instruction?
bne 2b
get_thread_info r10
mov r7, #1
strb r7, [r10, #TI_USED_CP + 10] @ mark CP#10 as used
strb r7, [r10, #TI_USED_CP + 11] @ mark CP#11 as used
b do_vfp @ let VFP handler handle this
1:
#endif
tst r0, #0x08000000 @ only CDP/CPRT/LDC/STC have bit 27
tstne r0, #0x04000000 @ bit 26 set on both ARM and Thumb-2
#if defined(CONFIG_CPU_ARM610) || defined(CONFIG_CPU_ARM710)
and r8, r0, #0x0f000000 @ mask out op-code bits
teqne r8, #0x0f000000 @ SWI (ARM6/7 bug)?
#endif
moveq pc, lr
get_thread_info r10 @ get current thread
and r8, r0, #0x00000f00 @ mask out CP number
THUMB( lsr r8, r8, #8 )
mov r7, #1
add r6, r10, #TI_USED_CP
ARM( strb r7, [r6, r8, lsr #8] ) @ set appropriate used_cp[]
THUMB( strb r7, [r6, r8] ) @ set appropriate used_cp[]
#ifdef CONFIG_IWMMXT
@ Test if we need to give access to iWMMXt coprocessors
ldr r5, [r10, #TI_FLAGS]
rsbs r7, r8, #(1 << 8) @ CP 0 or 1 only
movcss r7, r5, lsr #(TIF_USING_IWMMXT + 1)
bcs iwmmxt_task_enable
#endif
ARM( add pc, pc, r8, lsr #6 )
THUMB( lsl r8, r8, #2 )
THUMB( add pc, r8 )
nop
movw_pc lr @ CP#0
W(b) do_fpe @ CP#1 (FPE)
W(b) do_fpe @ CP#2 (FPE)
movw_pc lr @ CP#3
#ifdef CONFIG_CRUNCH
b crunch_task_enable @ CP#4 (MaverickCrunch)
b crunch_task_enable @ CP#5 (MaverickCrunch)
b crunch_task_enable @ CP#6 (MaverickCrunch)
#else
movw_pc lr @ CP#4
movw_pc lr @ CP#5
movw_pc lr @ CP#6
#endif
movw_pc lr @ CP#7
movw_pc lr @ CP#8
movw_pc lr @ CP#9
#ifdef CONFIG_VFP
W(b) do_vfp @ CP#10 (VFP)
W(b) do_vfp @ CP#11 (VFP)
#else
movw_pc lr @ CP#10 (VFP)
movw_pc lr @ CP#11 (VFP)
#endif
movw_pc lr @ CP#12
movw_pc lr @ CP#13
movw_pc lr @ CP#14 (Debug)
movw_pc lr @ CP#15 (Control)
#ifdef CONFIG_NEON
.align 6
.LCneon_arm_opcodes:
.word 0xfe000000 @ mask
.word 0xf2000000 @ opcode
.word 0xff100000 @ mask
.word 0xf4000000 @ opcode
.word 0x00000000 @ mask
.word 0x00000000 @ opcode
.LCneon_thumb_opcodes:
.word 0xef000000 @ mask
.word 0xef000000 @ opcode
.word 0xff100000 @ mask
.word 0xf9000000 @ opcode
.word 0x00000000 @ mask
.word 0x00000000 @ opcode
#endif
do_fpe:
enable_irq
ldr r4, .LCfp
add r10, r10, #TI_FPSTATE @ r10 = workspace
ldr pc, [r4] @ Call FP module USR entry point
/*
* The FP module is called with these registers set:
* r0 = instruction
* r2 = PC+4
* r9 = normal "successful" return address
* r10 = FP workspace
* lr = unrecognised FP instruction return address
*/
.pushsection .data
ENTRY(fp_enter)
.word no_fp
.popsection
ENTRY(no_fp)
mov pc, lr
ENDPROC(no_fp)
__und_usr_unknown:
enable_irq
mov r0, sp
adr lr, BSYM(ret_from_exception)
b do_undefinstr
ENDPROC(__und_usr_unknown)
.align 5
__pabt_usr:
usr_entry
mov r0, r2 @ pass address of aborted instruction.
#ifdef MULTI_PABORT
ldr r4, .LCprocfns
mov lr, pc
ldr pc, [r4, #PROCESSOR_PABT_FUNC]
#else
bl CPU_PABORT_HANDLER
#endif
debug_entry r1
enable_irq @ Enable interrupts
mov r2, sp @ regs
bl do_PrefetchAbort @ call abort handler
UNWIND(.fnend )
/* fall through */
/*
* This is the return code to user mode for abort handlers
*/
ENTRY(ret_from_exception)
UNWIND(.fnstart )
UNWIND(.cantunwind )
get_thread_info tsk
mov why, #0
b ret_to_user
UNWIND(.fnend )
ENDPROC(__pabt_usr)
ENDPROC(ret_from_exception)
/*
* Register switch for ARMv3 and ARMv4 processors
* r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info
* previous and next are guaranteed not to be the same.
*/
ENTRY(__switch_to)
UNWIND(.fnstart )
UNWIND(.cantunwind )
add ip, r1, #TI_CPU_SAVE
ldr r3, [r2, #TI_TP_VALUE]
ARM( stmia ip!, {r4 - sl, fp, sp, lr} ) @ Store most regs on stack
THUMB( stmia ip!, {r4 - sl, fp} ) @ Store most regs on stack
THUMB( str sp, [ip], #4 )
THUMB( str lr, [ip], #4 )
#ifdef CONFIG_CPU_USE_DOMAINS
ldr r6, [r2, #TI_CPU_DOMAIN]
#endif
set_tls r3, r4, r5
#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
ldr r7, [r2, #TI_TASK]
ldr r8, =__stack_chk_guard
ldr r7, [r7, #TSK_STACK_CANARY]
#endif
#ifdef CONFIG_CPU_USE_DOMAINS
mcr p15, 0, r6, c3, c0, 0 @ Set domain register
#endif
mov r5, r0
add r4, r2, #TI_CPU_SAVE
ldr r0, =thread_notify_head
mov r1, #THREAD_NOTIFY_SWITCH
bl atomic_notifier_call_chain
#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
str r7, [r8]
#endif
THUMB( mov ip, r4 )
mov r0, r5
ARM( ldmia r4, {r4 - sl, fp, sp, pc} ) @ Load all regs saved previously
THUMB( ldmia ip!, {r4 - sl, fp} ) @ Load all regs saved previously
THUMB( ldr sp, [ip], #4 )
THUMB( ldr pc, [ip] )
UNWIND(.fnend )
ENDPROC(__switch_to)
__INIT
/*
* User helpers.
*
* These are segment of kernel provided user code reachable from user space
* at a fixed address in kernel memory. This is used to provide user space
* with some operations which require kernel help because of unimplemented
* native feature and/or instructions in many ARM CPUs. The idea is for
* this code to be executed directly in user mode for best efficiency but
* which is too intimate with the kernel counter part to be left to user
* libraries. In fact this code might even differ from one CPU to another
* depending on the available instruction set and restrictions like on
* SMP systems. In other words, the kernel reserves the right to change
* this code as needed without warning. Only the entry points and their
* results are guaranteed to be stable.
*
* Each segment is 32-byte aligned and will be moved to the top of the high
* vector page. New segments (if ever needed) must be added in front of
* existing ones. This mechanism should be used only for things that are
* really small and justified, and not be abused freely.
*
* User space is expected to implement those things inline when optimizing
* for a processor that has the necessary native support, but only if such
* resulting binaries are already to be incompatible with earlier ARM
* processors due to the use of unsupported instructions other than what
* is provided here. In other words don't make binaries unable to run on
* earlier processors just for the sake of not using these kernel helpers
* if your compiled code is not going to use the new instructions for other
* purpose.
*/
THUMB( .arm )
.macro usr_ret, reg
#ifdef CONFIG_ARM_THUMB
bx \reg
#else
mov pc, \reg
#endif
.endm
.align 5
.globl __kuser_helper_start
__kuser_helper_start:
/*
* Reference prototype:
*
* void __kernel_memory_barrier(void)
*
* Input:
*
* lr = return address
*
* Output:
*
* none
*
* Clobbered:
*
* none
*
* Definition and user space usage example:
*
* typedef void (__kernel_dmb_t)(void);
* #define __kernel_dmb (*(__kernel_dmb_t *)0xffff0fa0)
*
* Apply any needed memory barrier to preserve consistency with data modified
* manually and __kuser_cmpxchg usage.
*
* This could be used as follows:
*
* #define __kernel_dmb() \
* asm volatile ( "mov r0, #0xffff0fff; mov lr, pc; sub pc, r0, #95" \
* : : : "r0", "lr","cc" )
*/
__kuser_memory_barrier: @ 0xffff0fa0
smp_dmb arm
usr_ret lr
.align 5
/*
* Reference prototype:
*
* int __kernel_cmpxchg(int oldval, int newval, int *ptr)
*
* Input:
*
* r0 = oldval
* r1 = newval
* r2 = ptr
* lr = return address
*
* Output:
*
* r0 = returned value (zero or non-zero)
* C flag = set if r0 == 0, clear if r0 != 0
*
* Clobbered:
*
* r3, ip, flags
*
* Definition and user space usage example:
*
* typedef int (__kernel_cmpxchg_t)(int oldval, int newval, int *ptr);
* #define __kernel_cmpxchg (*(__kernel_cmpxchg_t *)0xffff0fc0)
*
* Atomically store newval in *ptr if *ptr is equal to oldval for user space.
* Return zero if *ptr was changed or non-zero if no exchange happened.
* The C flag is also set if *ptr was changed to allow for assembly
* optimization in the calling code.
*
* Notes:
*
* - This routine already includes memory barriers as needed.
*
* For example, a user space atomic_add implementation could look like this:
*
* #define atomic_add(ptr, val) \
* ({ register unsigned int *__ptr asm("r2") = (ptr); \
* register unsigned int __result asm("r1"); \
* asm volatile ( \
* "1: @ atomic_add\n\t" \
* "ldr r0, [r2]\n\t" \
* "mov r3, #0xffff0fff\n\t" \
* "add lr, pc, #4\n\t" \
* "add r1, r0, %2\n\t" \
* "add pc, r3, #(0xffff0fc0 - 0xffff0fff)\n\t" \
* "bcc 1b" \
* : "=&r" (__result) \
* : "r" (__ptr), "rIL" (val) \
* : "r0","r3","ip","lr","cc","memory" ); \
* __result; })
*/
__kuser_cmpxchg: @ 0xffff0fc0
#if defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
/*
* Poor you. No fast solution possible...
* The kernel itself must perform the operation.
* A special ghost syscall is used for that (see traps.c).
*/
stmfd sp!, {r7, lr}
ldr r7, 1f @ it's 20 bits
swi __ARM_NR_cmpxchg
ldmfd sp!, {r7, pc}
1: .word __ARM_NR_cmpxchg
#elif __LINUX_ARM_ARCH__ < 6
#ifdef CONFIG_MMU
/*
* The only thing that can break atomicity in this cmpxchg
* implementation is either an IRQ or a data abort exception
* causing another process/thread to be scheduled in the middle
* of the critical sequence. To prevent this, code is added to
* the IRQ and data abort exception handlers to set the pc back
* to the beginning of the critical section if it is found to be
* within that critical section (see kuser_cmpxchg_fixup).
*/
1: ldr r3, [r2] @ load current val
subs r3, r3, r0 @ compare with oldval
2: streq r1, [r2] @ store newval if eq
rsbs r0, r3, #0 @ set return val and C flag
usr_ret lr
.text
kuser_cmpxchg_fixup:
@ Called from kuser_cmpxchg_check macro.
@ r2 = address of interrupted insn (must be preserved).
@ sp = saved regs. r7 and r8 are clobbered.
@ 1b = first critical insn, 2b = last critical insn.
@ If r2 >= 1b and r2 <= 2b then saved pc_usr is set to 1b.
mov r7, #0xffff0fff
sub r7, r7, #(0xffff0fff - (0xffff0fc0 + (1b - __kuser_cmpxchg)))
subs r8, r2, r7
rsbcss r8, r8, #(2b - 1b)
strcs r7, [sp, #S_PC]
mov pc, lr
.previous
#else
#warning "NPTL on non MMU needs fixing"
mov r0, #-1
adds r0, r0, #0
usr_ret lr
#endif
#else
smp_dmb arm
1: ldrex r3, [r2]
subs r3, r3, r0
strexeq r3, r1, [r2]
teqeq r3, #1
beq 1b
rsbs r0, r3, #0
/* beware -- each __kuser slot must be 8 instructions max */
ALT_SMP(b __kuser_memory_barrier)
ALT_UP(usr_ret lr)
#endif
.align 5
/*
* Reference prototype:
*
* int __kernel_get_tls(void)
*
* Input:
*
* lr = return address
*
* Output:
*
* r0 = TLS value
*
* Clobbered:
*
* none
*
* Definition and user space usage example:
*
* typedef int (__kernel_get_tls_t)(void);
* #define __kernel_get_tls (*(__kernel_get_tls_t *)0xffff0fe0)
*
* Get the TLS value as previously set via the __ARM_NR_set_tls syscall.
*
* This could be used as follows:
*
* #define __kernel_get_tls() \
* ({ register unsigned int __val asm("r0"); \
* asm( "mov r0, #0xffff0fff; mov lr, pc; sub pc, r0, #31" \
* : "=r" (__val) : : "lr","cc" ); \
* __val; })
*/
__kuser_get_tls: @ 0xffff0fe0
ldr r0, [pc, #(16 - 8)] @ read TLS, set in kuser_get_tls_init
usr_ret lr
mrc p15, 0, r0, c13, c0, 3 @ 0xffff0fe8 hardware TLS code
.rep 4
.word 0 @ 0xffff0ff0 software TLS value, then
.endr @ pad up to __kuser_helper_version
/*
* Reference declaration:
*
* extern unsigned int __kernel_helper_version;
*
* Definition and user space usage example:
*
* #define __kernel_helper_version (*(unsigned int *)0xffff0ffc)
*
* User space may read this to determine the curent number of helpers
* available.
*/
__kuser_helper_version: @ 0xffff0ffc
.word ((__kuser_helper_end - __kuser_helper_start) >> 5)
.globl __kuser_helper_end
__kuser_helper_end:
THUMB( .thumb )
/*
* Vector stubs.
*
* This code is copied to 0xffff0200 so we can use branches in the
* vectors, rather than ldr's. Note that this code must not
* exceed 0x300 bytes.
*
* Common stub entry macro:
* Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
*
* SP points to a minimal amount of processor-private memory, the address
* of which is copied into r0 for the mode specific abort handler.
*/
.macro vector_stub, name, mode, correction=0
.align 5
vector_\name:
.if \correction
sub lr, lr, #\correction
.endif
@
@ Save r0, lr_<exception> (parent PC) and spsr_<exception>
@ (parent CPSR)
@
stmia sp, {r0, lr} @ save r0, lr
mrs lr, spsr
str lr, [sp, #8] @ save spsr
@
@ Prepare for SVC32 mode. IRQs remain disabled.
@
mrs r0, cpsr
eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
msr spsr_cxsf, r0
@
@ the branch table must immediately follow this code
@
and lr, lr, #0x0f
THUMB( adr r0, 1f )
THUMB( ldr lr, [r0, lr, lsl #2] )
mov r0, sp
ARM( ldr lr, [pc, lr, lsl #2] )
movs pc, lr @ branch to handler in SVC mode
ENDPROC(vector_\name)
.align 2
@ handler addresses follow this label
1:
.endm
.globl __stubs_start
__stubs_start:
/*
* Interrupt dispatcher
*/
vector_stub irq, IRQ_MODE, 4
.long __irq_usr @ 0 (USR_26 / USR_32)
.long __irq_invalid @ 1 (FIQ_26 / FIQ_32)
.long __irq_invalid @ 2 (IRQ_26 / IRQ_32)
.long __irq_svc @ 3 (SVC_26 / SVC_32)
.long __irq_invalid @ 4
.long __irq_invalid @ 5
.long __irq_invalid @ 6
.long __irq_invalid @ 7
.long __irq_invalid @ 8
.long __irq_invalid @ 9
.long __irq_invalid @ a
.long __irq_invalid @ b
.long __irq_invalid @ c
.long __irq_invalid @ d
.long __irq_invalid @ e
.long __irq_invalid @ f
/*
* Data abort dispatcher
* Enter in ABT mode, spsr = USR CPSR, lr = USR PC
*/
vector_stub dabt, ABT_MODE, 8
.long __dabt_usr @ 0 (USR_26 / USR_32)
.long __dabt_invalid @ 1 (FIQ_26 / FIQ_32)
.long __dabt_invalid @ 2 (IRQ_26 / IRQ_32)
.long __dabt_svc @ 3 (SVC_26 / SVC_32)
.long __dabt_invalid @ 4
.long __dabt_invalid @ 5
.long __dabt_invalid @ 6
.long __dabt_invalid @ 7
.long __dabt_invalid @ 8
.long __dabt_invalid @ 9
.long __dabt_invalid @ a
.long __dabt_invalid @ b
.long __dabt_invalid @ c
.long __dabt_invalid @ d
.long __dabt_invalid @ e
.long __dabt_invalid @ f
/*
* Prefetch abort dispatcher
* Enter in ABT mode, spsr = USR CPSR, lr = USR PC
*/
vector_stub pabt, ABT_MODE, 4
.long __pabt_usr @ 0 (USR_26 / USR_32)
.long __pabt_invalid @ 1 (FIQ_26 / FIQ_32)
.long __pabt_invalid @ 2 (IRQ_26 / IRQ_32)
.long __pabt_svc @ 3 (SVC_26 / SVC_32)
.long __pabt_invalid @ 4
.long __pabt_invalid @ 5
.long __pabt_invalid @ 6
.long __pabt_invalid @ 7
.long __pabt_invalid @ 8
.long __pabt_invalid @ 9
.long __pabt_invalid @ a
.long __pabt_invalid @ b
.long __pabt_invalid @ c
.long __pabt_invalid @ d
.long __pabt_invalid @ e
.long __pabt_invalid @ f
/*
* Undef instr entry dispatcher
* Enter in UND mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
*/
vector_stub und, UND_MODE
.long __und_usr @ 0 (USR_26 / USR_32)
.long __und_invalid @ 1 (FIQ_26 / FIQ_32)
.long __und_invalid @ 2 (IRQ_26 / IRQ_32)
.long __und_svc @ 3 (SVC_26 / SVC_32)
.long __und_invalid @ 4
.long __und_invalid @ 5
.long __und_invalid @ 6
.long __und_invalid @ 7
.long __und_invalid @ 8
.long __und_invalid @ 9
.long __und_invalid @ a
.long __und_invalid @ b
.long __und_invalid @ c
.long __und_invalid @ d
.long __und_invalid @ e
.long __und_invalid @ f
.align 5
/*=============================================================================
* Undefined FIQs
*-----------------------------------------------------------------------------
* Enter in FIQ mode, spsr = ANY CPSR, lr = ANY PC
* MUST PRESERVE SVC SPSR, but need to switch to SVC mode to show our msg.
* Basically to switch modes, we *HAVE* to clobber one register... brain
* damage alert! I don't think that we can execute any code in here in any
* other mode than FIQ... Ok you can switch to another mode, but you can't
* get out of that mode without clobbering one register.
*/
vector_fiq:
disable_fiq
subs pc, lr, #4
/*=============================================================================
* Address exception handler
*-----------------------------------------------------------------------------
* These aren't too critical.
* (they're not supposed to happen, and won't happen in 32-bit data mode).
*/
vector_addrexcptn:
b vector_addrexcptn
/*
* We group all the following data together to optimise
* for CPUs with separate I & D caches.
*/
.align 5
.LCvswi:
.word vector_swi
.globl __stubs_end
__stubs_end:
.equ stubs_offset, __vectors_start + 0x200 - __stubs_start
.globl __vectors_start
__vectors_start:
ARM( swi SYS_ERROR0 )
THUMB( svc #0 )
THUMB( nop )
W(b) vector_und + stubs_offset
W(ldr) pc, .LCvswi + stubs_offset
W(b) vector_pabt + stubs_offset
W(b) vector_dabt + stubs_offset
W(b) vector_addrexcptn + stubs_offset
W(b) vector_irq + stubs_offset
W(b) vector_fiq + stubs_offset
.globl __vectors_end
__vectors_end:
.data
.globl cr_alignment
.globl cr_no_alignment
cr_alignment:
.space 4
cr_no_alignment:
.space 4
#ifdef CONFIG_MULTI_IRQ_HANDLER
.globl handle_arch_irq
handle_arch_irq:
.space 4
#endif
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