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|
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* linux/arch/arm/kernel/entry-common.S
*
* Copyright (C) 2000 Russell King
*/
#include <asm/assembler.h>
#include <asm/unistd.h>
#include <asm/ftrace.h>
#include <asm/unwind.h>
#include <asm/memory.h>
#ifdef CONFIG_AEABI
#include <asm/unistd-oabi.h>
#endif
.equ NR_syscalls, __NR_syscalls
#ifdef CONFIG_NEED_RET_TO_USER
#include <mach/entry-macro.S>
#else
.macro arch_ret_to_user, tmp1, tmp2
.endm
#endif
#include "entry-header.S"
saved_psr .req r8
#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
saved_pc .req r9
#define TRACE(x...) x
#else
saved_pc .req lr
#define TRACE(x...)
#endif
.section .entry.text,"ax",%progbits
.align 5
#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
IS_ENABLED(CONFIG_DEBUG_RSEQ))
/*
* This is the fast syscall return path. We do as little as possible here,
* such as avoiding writing r0 to the stack. We only use this path if we
* have tracing, context tracking and rseq debug disabled - the overheads
* from those features make this path too inefficient.
*/
ret_fast_syscall:
__ret_fast_syscall:
UNWIND(.fnstart )
UNWIND(.cantunwind )
disable_irq_notrace @ disable interrupts
ldr r2, [tsk, #TI_ADDR_LIMIT]
cmp r2, #TASK_SIZE
blne addr_limit_check_failed
ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
bne fast_work_pending
/* perform architecture specific actions before user return */
arch_ret_to_user r1, lr
restore_user_regs fast = 1, offset = S_OFF
UNWIND(.fnend )
ENDPROC(ret_fast_syscall)
/* Ok, we need to do extra processing, enter the slow path. */
fast_work_pending:
str r0, [sp, #S_R0+S_OFF]! @ returned r0
/* fall through to work_pending */
#else
/*
* The "replacement" ret_fast_syscall for when tracing, context tracking,
* or rseq debug is enabled. As we will need to call out to some C functions,
* we save r0 first to avoid needing to save registers around each C function
* call.
*/
ret_fast_syscall:
__ret_fast_syscall:
UNWIND(.fnstart )
UNWIND(.cantunwind )
str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
/* do_rseq_syscall needs interrupts enabled. */
mov r0, sp @ 'regs'
bl do_rseq_syscall
#endif
disable_irq_notrace @ disable interrupts
ldr r2, [tsk, #TI_ADDR_LIMIT]
cmp r2, #TASK_SIZE
blne addr_limit_check_failed
ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
beq no_work_pending
UNWIND(.fnend )
ENDPROC(ret_fast_syscall)
/* Slower path - fall through to work_pending */
#endif
tst r1, #_TIF_SYSCALL_WORK
bne __sys_trace_return_nosave
slow_work_pending:
mov r0, sp @ 'regs'
mov r2, why @ 'syscall'
bl do_work_pending
cmp r0, #0
beq no_work_pending
movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
ldmia sp, {r0 - r6} @ have to reload r0 - r6
b local_restart @ ... and off we go
ENDPROC(ret_fast_syscall)
/*
* "slow" syscall return path. "why" tells us if this was a real syscall.
* IRQs may be enabled here, so always disable them. Note that we use the
* "notrace" version to avoid calling into the tracing code unnecessarily.
* do_work_pending() will update this state if necessary.
*/
ENTRY(ret_to_user)
ret_slow_syscall:
#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
/* do_rseq_syscall needs interrupts enabled. */
enable_irq_notrace @ enable interrupts
mov r0, sp @ 'regs'
bl do_rseq_syscall
#endif
disable_irq_notrace @ disable interrupts
ENTRY(ret_to_user_from_irq)
ldr r2, [tsk, #TI_ADDR_LIMIT]
cmp r2, #TASK_SIZE
blne addr_limit_check_failed
ldr r1, [tsk, #TI_FLAGS]
tst r1, #_TIF_WORK_MASK
bne slow_work_pending
no_work_pending:
asm_trace_hardirqs_on save = 0
/* perform architecture specific actions before user return */
arch_ret_to_user r1, lr
ct_user_enter save = 0
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
cmp r5, #0
movne r0, r4
badrne lr, 1f
retne r5
1: get_thread_info tsk
b ret_slow_syscall
ENDPROC(ret_from_fork)
/*=============================================================================
* SWI handler
*-----------------------------------------------------------------------------
*/
.align 5
ENTRY(vector_swi)
#ifdef CONFIG_CPU_V7M
v7m_exception_entry
#else
sub sp, sp, #PT_REGS_SIZE
stmia sp, {r0 - r12} @ Calling r0 - r12
ARM( add r8, sp, #S_PC )
ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
THUMB( mov r8, sp )
THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
TRACE( mov saved_pc, lr )
str saved_pc, [sp, #S_PC] @ Save calling PC
str saved_psr, [sp, #S_PSR] @ Save CPSR
str r0, [sp, #S_OLD_R0] @ Save OLD_R0
#endif
zero_fp
alignment_trap r10, ip, __cr_alignment
asm_trace_hardirqs_on save=0
enable_irq_notrace
ct_user_exit save=0
/*
* Get the system call number.
*/
#if defined(CONFIG_OABI_COMPAT)
/*
* If we have CONFIG_OABI_COMPAT then we need to look at the swi
* value to determine if it is an EABI or an old ABI call.
*/
#ifdef CONFIG_ARM_THUMB
tst saved_psr, #PSR_T_BIT
movne r10, #0 @ no thumb OABI emulation
USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
#else
USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
#endif
ARM_BE8(rev r10, r10) @ little endian instruction
#elif defined(CONFIG_AEABI)
/*
* Pure EABI user space always put syscall number into scno (r7).
*/
#elif defined(CONFIG_ARM_THUMB)
/* Legacy ABI only, possibly thumb mode. */
tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
USER( ldreq scno, [saved_pc, #-4] )
#else
/* Legacy ABI only. */
USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
#endif
/*
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