android_kernel_xiaomi_sm8350/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.h>
#include <asm/vfpmacros.h>
#include <asm/arch/entry-macro.S>
#include <asm/thread_notify.h>
#include "entry-header.S"
/*
* Interrupt handling. Preserves r7, r8, r9
*/
.macro irq_handler
get_irqnr_preamble r5, lr
1: get_irqnr_and_base r0, r6, r5, lr
movne r1, sp
@
@ routine called with r0 = irq number, r1 = struct pt_regs *
@
adrne lr, 1b
bne asm_do_IRQ
#ifdef CONFIG_SMP
/*
* XXX
*
* this macro assumes that irqstat (r6) and base (r5) are
* preserved from get_irqnr_and_base above
*/
test_for_ipi r0, r6, r5, lr
movne r0, sp
adrne lr, 1b
bne do_IPI
#ifdef CONFIG_LOCAL_TIMERS
test_for_ltirq r0, r6, r5, lr
movne r0, sp
adrne lr, 1b
bne do_local_timer
#endif
#endif
.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
stmib sp, {r1 - lr}
mov r1, #\reason
.endm
__pabt_invalid:
inv_entry BAD_PREFETCH
b common_invalid
__dabt_invalid:
inv_entry BAD_DATA
b common_invalid
__irq_invalid:
inv_entry BAD_IRQ
b common_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
/*
* 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
sub sp, sp, #(S_FRAME_SIZE + \stack_hole)
SPFIX( tst sp, #4 )
SPFIX( bicne sp, sp, #4 )
stmib sp, {r1 - r12}
ldmia r0, {r1 - r3}
add r5, sp, #S_SP @ here for interlock avoidance
mov r4, #-1 @ "" "" "" ""
add r0, sp, #(S_FRAME_SIZE + \stack_hole)
SPFIX( addne r0, r0, #4 )
str r1, [sp] @ 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
@
msr cpsr_c, r9
mov r2, sp
bl do_DataAbort
@
@ IRQs off again before pulling preserved data off the stack
@
disable_irq
@
@ restore SPSR and restart the instruction
@
ldr r0, [sp, #S_PSR]
msr spsr_cxsf, r0
ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
.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 r0, [sp, #S_PSR] @ irqs are already disabled
msr spsr_cxsf, r0
#ifdef CONFIG_TRACE_IRQFLAGS
tst r0, #PSR_I_BIT
bleq trace_hardirqs_on
#endif
ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
.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
@
ldr r0, [r2, #-4]
adr r9, 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
@
@ restore SPSR and restart the instruction
@
ldr lr, [sp, #S_PSR] @ Get SVC cpsr
msr spsr_cxsf, lr
ldmia sp, {r0 - pc}^ @ Restore SVC registers
.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
@
@ set args, then call main handler
@
@ r0 - address of faulting instruction
@ r1 - pointer to registers on stack
@
#ifdef MULTI_PABORT
mov r0, r2 @ pass address of aborted instruction.
ldr r4, .LCprocfns
mov lr, pc
ldr pc, [r4, #PROCESSOR_PABT_FUNC]
#else
CPU_PABORT_HANDLER(r0, r2)
#endif
msr cpsr_c, r9 @ Maybe enable interrupts
mov r1, sp @ regs
bl do_PrefetchAbort @ call abort handler
@
@ IRQs off again before pulling preserved data off the stack
@
disable_irq
@
@ restore SPSR and restart the instruction
@
ldr r0, [sp, #S_PSR]
msr spsr_cxsf, r0
ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
.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
sub sp, sp, #S_FRAME_SIZE
stmib sp, {r1 - 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}
stmdb r0, {sp, lr}^
@
@ 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
@
enable_irq
mov r2, sp
adr lr, ret_from_exception
b do_DataAbort
.align 5
__irq_usr:
usr_entry
kuser_cmpxchg_check
#ifdef CONFIG_TRACE_IRQFLAGS
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
strne r0, [r0, -r0]
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_on
#endif
mov why, #0
b ret_to_user
.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, ret_from_exception
adr lr, __und_usr_unknown
tst r3, #PSR_T_BIT @ Thumb mode?
subeq r4, r2, #4 @ ARM instr at LR - 4
subne r4, r2, #2 @ Thumb instr at LR - 2
1: ldreqt r0, [r4]
beq call_fpe
@ Thumb instruction
#if __LINUX_ARM_ARCH__ >= 7
2: ldrht r5, [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
@
@ fallthrough to call_fpe
@
/*
* The out of line fixup for the ldrt above.
*/
.section .fixup, "ax"
4: mov pc, r9
.previous
.section __ex_table,"a"
.long 1b, 4b
#if __LINUX_ARM_ARCH__ >= 7
.long 2b, 4b
.long 3b, 4b
#endif
.previous
/*
* 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
mov r7, #1
add r6, r10, #TI_USED_CP
strb r7, [r6, r8, lsr #8] @ 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
add pc, pc, r8, lsr #6
mov r0, r0
mov pc, lr @ CP#0
b do_fpe @ CP#1 (FPE)
b do_fpe @ CP#2 (FPE)
mov 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
mov pc, lr @ CP#4
mov pc, lr @ CP#5
mov pc, lr @ CP#6
#endif
mov pc, lr @ CP#7
mov pc, lr @ CP#8
mov pc, lr @ CP#9
#ifdef CONFIG_VFP
b do_vfp @ CP#10 (VFP)
b do_vfp @ CP#11 (VFP)
#else
mov pc, lr @ CP#10 (VFP)
mov pc, lr @ CP#11 (VFP)
#endif
mov pc, lr @ CP#12
mov pc, lr @ CP#13
mov pc, lr @ CP#14 (Debug)
mov 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
*/
.data
ENTRY(fp_enter)
.word no_fp
.previous
no_fp: mov pc, lr
__und_usr_unknown:
mov r0, sp
adr lr, ret_from_exception
b do_undefinstr
.align 5
__pabt_usr:
usr_entry
#ifdef MULTI_PABORT
mov r0, r2 @ pass address of aborted instruction.
ldr r4, .LCprocfns
mov lr, pc
ldr pc, [r4, #PROCESSOR_PABT_FUNC]
#else
CPU_PABORT_HANDLER(r0, r2)
#endif
enable_irq @ Enable interrupts
mov r1, sp @ regs
bl do_PrefetchAbort @ call abort handler
/* fall through */
/*
* This is the return code to user mode for abort handlers
*/
ENTRY(ret_from_exception)
get_thread_info tsk
mov why, #0
b ret_to_user
/*
* 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)
add ip, r1, #TI_CPU_SAVE
ldr r3, [r2, #TI_TP_VALUE]
stmia ip!, {r4 - sl, fp, sp, lr} @ Store most regs on stack
#ifdef CONFIG_MMU
ldr r6, [r2, #TI_CPU_DOMAIN]
#endif
#if __LINUX_ARM_ARCH__ >= 6
#ifdef CONFIG_CPU_32v6K
clrex
#else
strex r5, r4, [ip] @ Clear exclusive monitor
#endif
#endif
#if defined(CONFIG_HAS_TLS_REG)
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
mcr p15, 0, r3, c13, c0, 3 @ set TLS register
#elif !defined(CONFIG_TLS_REG_EMUL)
mov r4, #0xffff0fff
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
str r3, [r4, #-15] @ TLS val at 0xffff0ff0
#endif
#ifdef CONFIG_MMU
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
mov r0, r5
ldmia r4, {r4 - sl, fp, sp, pc} @ Load all regs saved previously
__INIT
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
/*
* 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.
*/
.macro usr_ret, reg
#ifdef CONFIG_ARM_THUMB
bx \reg
#else
mov pc, \reg
#endif
.endm
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
.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
#if __LINUX_ARM_ARCH__ >= 6 && defined(CONFIG_SMP)
mcr p15, 0, r0, c7, c10, 5 @ dmb
#endif
usr_ret lr
.align 5
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
/*
* 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.
*
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
* 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)
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
/*
* 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}
mov r7, #0xff00 @ 0xfff0 into r7 for EABI
orr r7, r7, #0xf0
swi #0x9ffff0
ldmfd sp!, {r7, pc}
#elif __LINUX_ARM_ARCH__ < 6
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
#ifdef CONFIG_MMU
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
/*
* 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).
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
*/
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
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
#else
#ifdef CONFIG_SMP
mcr p15, 0, r0, c7, c10, 5 @ dmb
#endif
1: ldrex r3, [r2]
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
subs r3, r3, r0
strexeq r3, r1, [r2]
teqeq r3, #1
beq 1b
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
rsbs r0, r3, #0
/* beware -- each __kuser slot must be 8 instructions max */
#ifdef CONFIG_SMP
b __kuser_memory_barrier
#else
usr_ret lr
#endif
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
#endif
.align 5
/*
* Reference prototype:
*
* int __kernel_get_tls(void)
*
* Input:
*
* lr = return address
*
* Output:
*
* r0 = TLS value
*
* Clobbered:
*
* none
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
*
* 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
#if !defined(CONFIG_HAS_TLS_REG) && !defined(CONFIG_TLS_REG_EMUL)
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
ldr r0, [pc, #(16 - 8)] @ TLS stored at 0xffff0ff0
#else
mrc p15, 0, r0, c13, c0, 3 @ read TLS register
#endif
usr_ret lr
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-29 17:08:33 -04:00
.rep 5
.word 0 @ pad up to __kuser_helper_version
.endr
/*
* 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:
/*
* 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)
msr spsr_cxsf, r0
@
@ the branch table must immediately follow this code
@
and lr, lr, #0x0f
mov r0, sp
ldr lr, [pc, lr, lsl #2]
movs pc, lr @ branch to handler in SVC mode
.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:
swi SYS_ERROR0
b vector_und + stubs_offset
ldr pc, .LCvswi + stubs_offset
b vector_pabt + stubs_offset
b vector_dabt + stubs_offset
b vector_addrexcptn + stubs_offset
b vector_irq + stubs_offset
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