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.
38 disable_irq_notrace @ disable interrupts
39 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
40 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
43 /* perform architecture specific actions before user return */
44 arch_ret_to_user r1, lr
46 restore_user_regs fast = 1, offset = S_OFF
48 ENDPROC(ret_fast_syscall)
50 /* Ok, we need to do extra processing, enter the slow path. */
52 str r0, [sp, #S_R0+S_OFF]! @ returned r0
53 /* fall through to work_pending */
56 * The "replacement" ret_fast_syscall for when tracing or context tracking
57 * is enabled. As we will need to call out to some C functions, we save
58 * 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
70 ENDPROC(ret_fast_syscall)
72 /* Slower path - fall through to work_pending */
75 tst r1, #_TIF_SYSCALL_WORK
76 bne __sys_trace_return_nosave
79 mov r2, why @ 'syscall'
83 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
84 ldmia sp, {r0 - r6} @ have to reload r0 - r6
85 b local_restart @ ... and off we go
86 ENDPROC(ret_fast_syscall)
89 * "slow" syscall return path. "why" tells us if this was a real syscall.
90 * IRQs may be enabled here, so always disable them. Note that we use the
91 * "notrace" version to avoid calling into the tracing code unnecessarily.
92 * do_work_pending() will update this state if necessary.
96 disable_irq_notrace @ disable interrupts
97 ENTRY(ret_to_user_from_irq)
98 ldr r1, [tsk, #TI_FLAGS]
99 tst r1, #_TIF_WORK_MASK
100 bne slow_work_pending
102 asm_trace_hardirqs_on save = 0
104 /* perform architecture specific actions before user return */
105 arch_ret_to_user r1, lr
106 ct_user_enter save = 0
108 restore_user_regs fast = 0, offset = 0
109 ENDPROC(ret_to_user_from_irq)
113 * This is how we return from a fork.
121 1: get_thread_info tsk
123 ENDPROC(ret_from_fork)
126 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
130 * Ensure that the system call table is equal to __NR_syscalls,
131 * which is the value the rest of the system sees
133 .ifne NR_syscalls - __NR_syscalls
134 .error "__NR_syscalls is not equal to the size of the syscall table"
138 #define CALL(x) .long x
140 /*=============================================================================
142 *-----------------------------------------------------------------------------
147 #ifdef CONFIG_CPU_V7M
150 sub sp, sp, #PT_REGS_SIZE
151 stmia sp, {r0 - r12} @ Calling r0 - r12
152 ARM( add r8, sp, #S_PC )
153 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
155 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
156 mrs r8, spsr @ called from non-FIQ mode, so ok.
157 str lr, [sp, #S_PC] @ Save calling PC
158 str r8, [sp, #S_PSR] @ Save CPSR
159 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
162 alignment_trap r10, ip, __cr_alignment
168 * Get the system call number.
171 #if defined(CONFIG_OABI_COMPAT)
174 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
175 * value to determine if it is an EABI or an old ABI call.
177 #ifdef CONFIG_ARM_THUMB
179 movne r10, #0 @ no thumb OABI emulation
180 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction
182 USER( ldr r10, [lr, #-4] ) @ get SWI instruction
184 ARM_BE8(rev r10, r10) @ little endian instruction
186 #elif defined(CONFIG_AEABI)
189 * Pure EABI user space always put syscall number into scno (r7).
191 #elif defined(CONFIG_ARM_THUMB)
192 /* Legacy ABI only, possibly thumb mode. */
193 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
194 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
195 USER( ldreq scno, [lr, #-4] )
198 /* Legacy ABI only. */
199 USER( ldr scno, [lr, #-4] ) @ get SWI instruction
204 adr tbl, sys_call_table @ load syscall table pointer
206 #if defined(CONFIG_OABI_COMPAT)
208 * If the swi argument is zero, this is an EABI call and we do nothing.
210 * If this is an old ABI call, get the syscall number into scno and
211 * get the old ABI syscall table address.
213 bics r10, r10, #0xff000000
214 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
215 ldrne tbl, =sys_oabi_call_table
216 #elif !defined(CONFIG_AEABI)
217 bic scno, scno, #0xff000000 @ mask off SWI op-code
218 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
222 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
223 stmdb sp!, {r4, r5} @ push fifth and sixth args
225 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
228 invoke_syscall tbl, scno, r10, __ret_fast_syscall
231 2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
232 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
234 mov why, #0 @ no longer a real syscall
235 b sys_ni_syscall @ not private func
237 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
239 * We failed to handle a fault trying to access the page
240 * containing the swi instruction, but we're not really in a
241 * position to return -EFAULT. Instead, return back to the
242 * instruction and re-enter the user fault handling path trying
243 * to page it in. This will likely result in sending SEGV to the
254 * This is the really slow path. We're going to be doing
255 * context switches, and waiting for our parent to respond.
260 bl syscall_trace_enter
262 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
263 cmp scno, #-1 @ skip the syscall?
265 add sp, sp, #S_OFF @ restore stack
267 __sys_trace_return_nosave:
270 bl syscall_trace_exit
274 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
276 bl syscall_trace_exit
280 #ifdef CONFIG_ALIGNMENT_TRAP
281 .type __cr_alignment, #object
288 * This is the syscall table declaration for native ABI syscalls.
289 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
291 #define ABI(native, compat) native
293 #define OBSOLETE(syscall) sys_ni_syscall
295 #define OBSOLETE(syscall) syscall
298 .type sys_call_table, #object
299 ENTRY(sys_call_table)
304 /*============================================================================
305 * Special system call wrappers
307 @ r0 = syscall number
310 bic scno, r0, #__NR_OABI_SYSCALL_BASE
311 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
312 cmpne scno, #NR_syscalls @ check range
313 #ifdef CONFIG_CPU_SPECTRE
317 stmloia sp, {r5, r6} @ shuffle args
322 ldrlo pc, [tbl, scno, lsl #2]
326 sys_sigreturn_wrapper:
328 mov why, #0 @ prevent syscall restart handling
330 ENDPROC(sys_sigreturn_wrapper)
332 sys_rt_sigreturn_wrapper:
334 mov why, #0 @ prevent syscall restart handling
336 ENDPROC(sys_rt_sigreturn_wrapper)
338 sys_statfs64_wrapper:
342 ENDPROC(sys_statfs64_wrapper)
344 sys_fstatfs64_wrapper:
348 ENDPROC(sys_fstatfs64_wrapper)
351 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
352 * offset, we return EINVAL.
357 moveq r5, r5, lsr #PAGE_SHIFT - 12
368 #ifdef CONFIG_OABI_COMPAT
371 * These are syscalls with argument register differences
377 ENDPROC(sys_oabi_pread64)
382 ENDPROC(sys_oabi_pwrite64)
388 ENDPROC(sys_oabi_truncate64)
390 sys_oabi_ftruncate64:
394 ENDPROC(sys_oabi_ftruncate64)
401 ENDPROC(sys_oabi_readahead)
404 * Let's declare a second syscall table for old ABI binaries
405 * using the compatibility syscall entries.
407 #define ABI(native, compat) compat
408 #define OBSOLETE(syscall) syscall
410 .type sys_oabi_call_table, #object
411 ENTRY(sys_oabi_call_table)