2 * linux/arch/arm/kernel/entry-common.S
4 * Copyright (C) 2000 Russell King
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <asm/assembler.h>
12 #include <asm/unistd.h>
13 #include <asm/ftrace.h>
14 #include <asm/unwind.h>
16 #ifdef CONFIG_NEED_RET_TO_USER
17 #include <mach/entry-macro.S>
19 .macro arch_ret_to_user, tmp1, tmp2
23 #include "entry-header.S"
27 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING))
29 * This is the fast syscall return path. We do as little as possible here,
30 * such as avoiding writing r0 to the stack. We only use this path if we
31 * have tracing and context tracking disabled - the overheads from those
32 * features make this path too inefficient.
37 disable_irq_notrace @ disable interrupts
38 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
39 tst r1, #((_TIF_SYSCALL_WORK | _TIF_WORK_MASK) & ~_TIF_SECCOMP)
44 /* perform architecture specific actions before user return */
45 arch_ret_to_user r1, lr
47 restore_user_regs fast = 1, offset = S_OFF
49 ENDPROC(ret_fast_syscall)
51 /* Ok, we need to do extra processing, enter the slow path. */
53 str r0, [sp, #S_R0+S_OFF]! @ returned r0
54 /* fall through to work_pending */
57 * The "replacement" ret_fast_syscall for when tracing or context tracking
58 * is enabled. As we will need to call out to some C functions, we save
59 * r0 first to avoid needing to save registers around each C function call.
64 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
65 disable_irq_notrace @ disable interrupts
66 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
67 tst r1, #((_TIF_SYSCALL_WORK | _TIF_WORK_MASK) & ~_TIF_SECCOMP)
73 ENDPROC(ret_fast_syscall)
75 /* Slower path - fall through to work_pending */
78 tst r1, #_TIF_SYSCALL_WORK
79 bne __sys_trace_return_nosave
82 mov r2, why @ 'syscall'
86 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
87 ldmia sp, {r0 - r6} @ have to reload r0 - r6
88 b local_restart @ ... and off we go
89 ENDPROC(ret_fast_syscall)
92 * "slow" syscall return path. "why" tells us if this was a real syscall.
93 * IRQs may be enabled here, so always disable them. Note that we use the
94 * "notrace" version to avoid calling into the tracing code unnecessarily.
95 * do_work_pending() will update this state if necessary.
99 disable_irq_notrace @ disable interrupts
100 ENTRY(ret_to_user_from_irq)
101 ldr r1, [tsk, #TI_FLAGS]
102 tst r1, #_TIF_WORK_MASK
103 bne slow_work_pending
105 asm_trace_hardirqs_on save = 0
107 /* perform architecture specific actions before user return */
108 arch_ret_to_user r1, lr
109 ct_user_enter save = 0
111 restore_user_regs fast = 0, offset = 0
112 ENDPROC(ret_to_user_from_irq)
116 * This is how we return from a fork.
124 1: get_thread_info tsk
126 ENDPROC(ret_from_fork)
129 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
133 * Ensure that the system call table is equal to __NR_syscalls,
134 * which is the value the rest of the system sees
136 .ifne NR_syscalls - __NR_syscalls
137 .error "__NR_syscalls is not equal to the size of the syscall table"
141 #define CALL(x) .long x
143 /*=============================================================================
145 *-----------------------------------------------------------------------------
150 #ifdef CONFIG_CPU_V7M
153 sub sp, sp, #S_FRAME_SIZE
154 stmia sp, {r0 - r12} @ Calling r0 - r12
155 ARM( add r8, sp, #S_PC )
156 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
158 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
159 mrs r8, spsr @ called from non-FIQ mode, so ok.
160 str lr, [sp, #S_PC] @ Save calling PC
161 str r8, [sp, #S_PSR] @ Save CPSR
162 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
165 alignment_trap r10, ip, __cr_alignment
171 * Get the system call number.
174 #if defined(CONFIG_OABI_COMPAT)
177 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
178 * value to determine if it is an EABI or an old ABI call.
180 #ifdef CONFIG_ARM_THUMB
182 movne r10, #0 @ no thumb OABI emulation
183 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction
185 USER( ldr r10, [lr, #-4] ) @ get SWI instruction
187 ARM_BE8(rev r10, r10) @ little endian instruction
189 #elif defined(CONFIG_AEABI)
192 * Pure EABI user space always put syscall number into scno (r7).
194 #elif defined(CONFIG_ARM_THUMB)
195 /* Legacy ABI only, possibly thumb mode. */
196 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
197 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
198 USER( ldreq scno, [lr, #-4] )
201 /* Legacy ABI only. */
202 USER( ldr scno, [lr, #-4] ) @ get SWI instruction
207 adr tbl, sys_call_table @ load syscall table pointer
209 #if defined(CONFIG_OABI_COMPAT)
211 * If the swi argument is zero, this is an EABI call and we do nothing.
213 * If this is an old ABI call, get the syscall number into scno and
214 * get the old ABI syscall table address.
216 bics r10, r10, #0xff000000
217 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
218 ldrne tbl, =sys_oabi_call_table
219 #elif !defined(CONFIG_AEABI)
220 bic scno, scno, #0xff000000 @ mask off SWI op-code
221 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
225 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
226 stmdb sp!, {r4, r5} @ push fifth and sixth args
228 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
231 cmp scno, #NR_syscalls @ check upper syscall limit
232 badr lr, ret_fast_syscall @ return address
233 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
236 2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
237 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
239 mov why, #0 @ no longer a real syscall
240 b sys_ni_syscall @ not private func
242 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
244 * We failed to handle a fault trying to access the page
245 * containing the swi instruction, but we're not really in a
246 * position to return -EFAULT. Instead, return back to the
247 * instruction and re-enter the user fault handling path trying
248 * to page it in. This will likely result in sending SEGV to the
259 * This is the really slow path. We're going to be doing
260 * context switches, and waiting for our parent to respond.
265 bl syscall_trace_enter
267 badr lr, __sys_trace_return @ return address
268 mov scno, r0 @ syscall number (possibly new)
269 add r1, sp, #S_R0 + S_OFF @ pointer to regs
270 cmp scno, #NR_syscalls @ check upper syscall limit
271 ldmccia r1, {r0 - r6} @ have to reload r0 - r6
272 stmccia sp, {r4, r5} @ and update the stack args
273 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
274 cmp scno, #-1 @ skip the syscall?
276 add sp, sp, #S_OFF @ restore stack
280 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
282 bl syscall_trace_exit
285 __sys_trace_return_nosave:
288 bl syscall_trace_exit
292 #ifdef CONFIG_ALIGNMENT_TRAP
293 .type __cr_alignment, #object
300 * This is the syscall table declaration for native ABI syscalls.
301 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
303 #define ABI(native, compat) native
305 #define OBSOLETE(syscall) sys_ni_syscall
307 #define OBSOLETE(syscall) syscall
310 .type sys_call_table, #object
311 ENTRY(sys_call_table)
316 /*============================================================================
317 * Special system call wrappers
319 @ r0 = syscall number
322 bic scno, r0, #__NR_OABI_SYSCALL_BASE
323 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
324 cmpne scno, #NR_syscalls @ check range
325 stmloia sp, {r5, r6} @ shuffle args
330 ldrlo pc, [tbl, scno, lsl #2]
334 sys_sigreturn_wrapper:
336 mov why, #0 @ prevent syscall restart handling
338 ENDPROC(sys_sigreturn_wrapper)
340 sys_rt_sigreturn_wrapper:
342 mov why, #0 @ prevent syscall restart handling
344 ENDPROC(sys_rt_sigreturn_wrapper)
346 sys_statfs64_wrapper:
350 ENDPROC(sys_statfs64_wrapper)
352 sys_fstatfs64_wrapper:
356 ENDPROC(sys_fstatfs64_wrapper)
359 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
360 * offset, we return EINVAL.
365 moveq r5, r5, lsr #PAGE_SHIFT - 12
376 #ifdef CONFIG_OABI_COMPAT
379 * These are syscalls with argument register differences
385 ENDPROC(sys_oabi_pread64)
390 ENDPROC(sys_oabi_pwrite64)
396 ENDPROC(sys_oabi_truncate64)
398 sys_oabi_ftruncate64:
402 ENDPROC(sys_oabi_ftruncate64)
409 ENDPROC(sys_oabi_readahead)
412 * Let's declare a second syscall table for old ABI binaries
413 * using the compatibility syscall entries.
415 #define ABI(native, compat) compat
416 #define OBSOLETE(syscall) syscall
418 .type sys_oabi_call_table, #object
419 ENTRY(sys_oabi_call_table)