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>
15 #include <asm/memory.h>
17 #include <asm/unistd-oabi.h>
20 .equ NR_syscalls, __NR_syscalls
22 #ifdef CONFIG_NEED_RET_TO_USER
23 #include <mach/entry-macro.S>
25 .macro arch_ret_to_user, tmp1, tmp2
29 #include "entry-header.S"
32 #if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
41 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING))
43 * This is the fast syscall return path. We do as little as possible here,
44 * such as avoiding writing r0 to the stack. We only use this path if we
45 * have tracing and context tracking disabled - the overheads from those
46 * features make this path too inefficient.
51 disable_irq_notrace @ disable interrupts
52 ldr r2, [tsk, #TI_ADDR_LIMIT]
54 blne addr_limit_check_failed
55 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
56 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
60 /* perform architecture specific actions before user return */
61 arch_ret_to_user r1, lr
63 restore_user_regs fast = 1, offset = S_OFF
65 ENDPROC(ret_fast_syscall)
67 /* Ok, we need to do extra processing, enter the slow path. */
69 str r0, [sp, #S_R0+S_OFF]! @ returned r0
70 /* fall through to work_pending */
73 * The "replacement" ret_fast_syscall for when tracing or context tracking
74 * is enabled. As we will need to call out to some C functions, we save
75 * r0 first to avoid needing to save registers around each C function call.
80 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
81 disable_irq_notrace @ disable interrupts
82 ldr r2, [tsk, #TI_ADDR_LIMIT]
84 blne addr_limit_check_failed
85 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
86 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
89 ENDPROC(ret_fast_syscall)
91 /* Slower path - fall through to work_pending */
94 tst r1, #_TIF_SYSCALL_WORK
95 bne __sys_trace_return_nosave
98 mov r2, why @ 'syscall'
102 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
103 ldmia sp, {r0 - r6} @ have to reload r0 - r6
104 b local_restart @ ... and off we go
105 ENDPROC(ret_fast_syscall)
108 * "slow" syscall return path. "why" tells us if this was a real syscall.
109 * IRQs may be enabled here, so always disable them. Note that we use the
110 * "notrace" version to avoid calling into the tracing code unnecessarily.
111 * do_work_pending() will update this state if necessary.
115 disable_irq_notrace @ disable interrupts
116 ENTRY(ret_to_user_from_irq)
117 ldr r2, [tsk, #TI_ADDR_LIMIT]
119 blne addr_limit_check_failed
120 ldr r1, [tsk, #TI_FLAGS]
121 tst r1, #_TIF_WORK_MASK
122 bne slow_work_pending
124 asm_trace_hardirqs_on save = 0
126 /* perform architecture specific actions before user return */
127 arch_ret_to_user r1, lr
128 ct_user_enter save = 0
130 restore_user_regs fast = 0, offset = 0
131 ENDPROC(ret_to_user_from_irq)
135 * This is how we return from a fork.
143 1: get_thread_info tsk
145 ENDPROC(ret_from_fork)
147 /*=============================================================================
149 *-----------------------------------------------------------------------------
154 #ifdef CONFIG_CPU_V7M
157 sub sp, sp, #PT_REGS_SIZE
158 stmia sp, {r0 - r12} @ Calling r0 - r12
159 ARM( add r8, sp, #S_PC )
160 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
162 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
163 mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
164 TRACE( mov saved_pc, lr )
165 str saved_pc, [sp, #S_PC] @ Save calling PC
166 str saved_psr, [sp, #S_PSR] @ Save CPSR
167 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
170 alignment_trap r10, ip, __cr_alignment
171 asm_trace_hardirqs_on save=0
176 * Get the system call number.
179 #if defined(CONFIG_OABI_COMPAT)
182 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
183 * value to determine if it is an EABI or an old ABI call.
185 #ifdef CONFIG_ARM_THUMB
186 tst saved_psr, #PSR_T_BIT
187 movne r10, #0 @ no thumb OABI emulation
188 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
190 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
192 ARM_BE8(rev r10, r10) @ little endian instruction
194 #elif defined(CONFIG_AEABI)
197 * Pure EABI user space always put syscall number into scno (r7).
199 #elif defined(CONFIG_ARM_THUMB)
200 /* Legacy ABI only, possibly thumb mode. */
201 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
202 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
203 USER( ldreq scno, [saved_pc, #-4] )
206 /* Legacy ABI only. */
207 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
210 /* saved_psr and saved_pc are now dead */
214 adr tbl, sys_call_table @ load syscall table pointer
216 #if defined(CONFIG_OABI_COMPAT)
218 * If the swi argument is zero, this is an EABI call and we do nothing.
220 * If this is an old ABI call, get the syscall number into scno and
221 * get the old ABI syscall table address.
223 bics r10, r10, #0xff000000
224 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
225 ldrne tbl, =sys_oabi_call_table
226 #elif !defined(CONFIG_AEABI)
227 bic scno, scno, #0xff000000 @ mask off SWI op-code
228 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
232 * Reload the registers that may have been corrupted on entry to
233 * the syscall assembly (by tracing or context tracking.)
235 TRACE( ldmia sp, {r0 - r3} )
238 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
239 stmdb sp!, {r4, r5} @ push fifth and sixth args
241 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
244 cmp scno, #NR_syscalls @ check upper syscall limit
245 badr lr, ret_fast_syscall @ return address
246 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
249 2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
250 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
252 mov why, #0 @ no longer a real syscall
253 b sys_ni_syscall @ not private func
255 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
257 * We failed to handle a fault trying to access the page
258 * containing the swi instruction, but we're not really in a
259 * position to return -EFAULT. Instead, return back to the
260 * instruction and re-enter the user fault handling path trying
261 * to page it in. This will likely result in sending SEGV to the
273 * This is the really slow path. We're going to be doing
274 * context switches, and waiting for our parent to respond.
279 bl syscall_trace_enter
281 badr lr, __sys_trace_return @ return address
282 mov scno, r0 @ syscall number (possibly new)
283 add r1, sp, #S_R0 + S_OFF @ pointer to regs
284 cmp scno, #NR_syscalls @ check upper syscall limit
285 ldmccia r1, {r0 - r6} @ have to reload r0 - r6
286 stmccia sp, {r4, r5} @ and update the stack args
287 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
288 cmp scno, #-1 @ skip the syscall?
290 add sp, sp, #S_OFF @ restore stack
294 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
296 bl syscall_trace_exit
299 __sys_trace_return_nosave:
302 bl syscall_trace_exit
306 #ifdef CONFIG_ALIGNMENT_TRAP
307 .type __cr_alignment, #object
313 .macro syscall_table_start, sym
319 .macro syscall, nr, func
321 .error "Duplicated/unorded system call entry"
327 .equ __sys_nr, \nr + 1
330 .macro syscall_table_end, sym
331 .ifgt __sys_nr - __NR_syscalls
332 .error "System call table too big"
334 .rept __NR_syscalls - __sys_nr
340 #define NATIVE(nr, func) syscall nr, func
343 * This is the syscall table declaration for native ABI syscalls.
344 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
346 syscall_table_start sys_call_table
347 #define COMPAT(nr, native, compat) syscall nr, native
349 #include <calls-eabi.S>
351 #include <calls-oabi.S>
354 syscall_table_end sys_call_table
356 /*============================================================================
357 * Special system call wrappers
359 @ r0 = syscall number
362 bic scno, r0, #__NR_OABI_SYSCALL_BASE
363 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
364 cmpne scno, #NR_syscalls @ check range
365 stmloia sp, {r5, r6} @ shuffle args
370 ldrlo pc, [tbl, scno, lsl #2]
374 sys_sigreturn_wrapper:
376 mov why, #0 @ prevent syscall restart handling
378 ENDPROC(sys_sigreturn_wrapper)
380 sys_rt_sigreturn_wrapper:
382 mov why, #0 @ prevent syscall restart handling
384 ENDPROC(sys_rt_sigreturn_wrapper)
386 sys_statfs64_wrapper:
390 ENDPROC(sys_statfs64_wrapper)
392 sys_fstatfs64_wrapper:
396 ENDPROC(sys_fstatfs64_wrapper)
399 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
400 * offset, we return EINVAL.
405 moveq r5, r5, lsr #PAGE_SHIFT - 12
416 #ifdef CONFIG_OABI_COMPAT
419 * These are syscalls with argument register differences
425 ENDPROC(sys_oabi_pread64)
430 ENDPROC(sys_oabi_pwrite64)
436 ENDPROC(sys_oabi_truncate64)
438 sys_oabi_ftruncate64:
442 ENDPROC(sys_oabi_ftruncate64)
449 ENDPROC(sys_oabi_readahead)
452 * Let's declare a second syscall table for old ABI binaries
453 * using the compatibility syscall entries.
455 syscall_table_start sys_oabi_call_table
456 #define COMPAT(nr, native, compat) syscall nr, compat
457 #include <calls-oabi.S>
458 syscall_table_end sys_oabi_call_table