1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * linux/arch/arm/kernel/entry-common.S
5 * Copyright (C) 2000 Russell King
8 #include <asm/assembler.h>
9 #include <asm/unistd.h>
10 #include <asm/ftrace.h>
11 #include <asm/unwind.h>
12 #include <asm/memory.h>
14 #include <asm/unistd-oabi.h>
17 .equ NR_syscalls, __NR_syscalls
19 #ifdef CONFIG_NEED_RET_TO_USER
20 #include <mach/entry-macro.S>
22 .macro arch_ret_to_user, tmp1, tmp2
26 #include "entry-header.S"
29 #if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
37 .section .entry.text,"ax",%progbits
39 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
40 IS_ENABLED(CONFIG_DEBUG_RSEQ))
42 * This is the fast syscall return path. We do as little as possible here,
43 * such as avoiding writing r0 to the stack. We only use this path if we
44 * have tracing, context tracking and rseq debug disabled - the overheads
45 * from those features make this path too inefficient.
51 disable_irq_notrace @ disable interrupts
52 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
57 /* perform architecture specific actions before user return */
58 arch_ret_to_user r1, lr
60 restore_user_regs fast = 1, offset = S_OFF
62 ENDPROC(ret_fast_syscall)
64 /* Ok, we need to do extra processing, enter the slow path. */
66 str r0, [sp, #S_R0+S_OFF]! @ returned r0
67 /* fall through to work_pending */
70 * The "replacement" ret_fast_syscall for when tracing, context tracking,
71 * or rseq debug is enabled. As we will need to call out to some C functions,
72 * we save r0 first to avoid needing to save registers around each C function
79 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
80 #if IS_ENABLED(CONFIG_DEBUG_RSEQ)
81 /* do_rseq_syscall needs interrupts enabled. */
85 disable_irq_notrace @ disable interrupts
86 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
90 ENDPROC(ret_fast_syscall)
92 /* Slower path - fall through to work_pending */
95 tst r1, #_TIF_SYSCALL_WORK
96 bne __sys_trace_return_nosave
99 mov r2, why @ 'syscall'
103 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
104 ldmia sp, {r0 - r6} @ have to reload r0 - r6
105 b local_restart @ ... and off we go
106 ENDPROC(ret_fast_syscall)
109 * "slow" syscall return path. "why" tells us if this was a real syscall.
110 * IRQs may be enabled here, so always disable them. Note that we use the
111 * "notrace" version to avoid calling into the tracing code unnecessarily.
112 * do_work_pending() will update this state if necessary.
116 #if IS_ENABLED(CONFIG_DEBUG_RSEQ)
117 /* do_rseq_syscall needs interrupts enabled. */
118 enable_irq_notrace @ enable interrupts
122 disable_irq_notrace @ disable interrupts
123 ENTRY(ret_to_user_from_irq)
124 ldr r1, [tsk, #TI_FLAGS]
126 bne slow_work_pending
128 asm_trace_hardirqs_on save = 0
130 /* perform architecture specific actions before user return */
131 arch_ret_to_user r1, lr
132 ct_user_enter save = 0
134 restore_user_regs fast = 0, offset = 0
135 ENDPROC(ret_to_user_from_irq)
139 * This is how we return from a fork.
147 1: get_thread_info tsk
149 ENDPROC(ret_from_fork)
151 /*=============================================================================
153 *-----------------------------------------------------------------------------
158 #ifdef CONFIG_CPU_V7M
161 sub sp, sp, #PT_REGS_SIZE
162 stmia sp, {r0 - r12} @ Calling r0 - r12
163 ARM( add r8, sp, #S_PC )
164 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
166 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
167 mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
168 TRACE( mov saved_pc, lr )
169 str saved_pc, [sp, #S_PC] @ Save calling PC
170 str saved_psr, [sp, #S_PSR] @ Save CPSR
171 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
174 alignment_trap r10, ip, __cr_alignment
175 asm_trace_hardirqs_on save=0
180 * Get the system call number.
183 #if defined(CONFIG_OABI_COMPAT)
186 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
187 * value to determine if it is an EABI or an old ABI call.
189 #ifdef CONFIG_ARM_THUMB
190 tst saved_psr, #PSR_T_BIT
191 movne r10, #0 @ no thumb OABI emulation
192 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
194 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
196 ARM_BE8(rev r10, r10) @ little endian instruction
198 #elif defined(CONFIG_AEABI)
201 * Pure EABI user space always put syscall number into scno (r7).
203 #elif defined(CONFIG_ARM_THUMB)
204 /* Legacy ABI only, possibly thumb mode. */
205 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
206 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
207 USER( ldreq scno, [saved_pc, #-4] )
210 /* Legacy ABI only. */
211 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
214 /* saved_psr and saved_pc are now dead */
219 adr tbl, sys_call_table @ load syscall table pointer
221 #if defined(CONFIG_OABI_COMPAT)
223 * If the swi argument is zero, this is an EABI call and we do nothing.
225 * If this is an old ABI call, get the syscall number into scno and
226 * get the old ABI syscall table address.
228 bics r10, r10, #0xff000000
229 strne r10, [tsk, #TI_ABI_SYSCALL]
230 streq scno, [tsk, #TI_ABI_SYSCALL]
231 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
232 ldrne tbl, =sys_oabi_call_table
233 #elif !defined(CONFIG_AEABI)
234 bic scno, scno, #0xff000000 @ mask off SWI op-code
235 str scno, [tsk, #TI_ABI_SYSCALL]
236 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
238 str scno, [tsk, #TI_ABI_SYSCALL]
241 * Reload the registers that may have been corrupted on entry to
242 * the syscall assembly (by tracing or context tracking.)
244 TRACE( ldmia sp, {r0 - r3} )
247 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
248 stmdb sp!, {r4, r5} @ push fifth and sixth args
250 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
253 invoke_syscall tbl, scno, r10, __ret_fast_syscall
256 2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
257 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
259 mov why, #0 @ no longer a real syscall
260 b sys_ni_syscall @ not private func
262 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
264 * We failed to handle a fault trying to access the page
265 * containing the swi instruction, but we're not really in a
266 * position to return -EFAULT. Instead, return back to the
267 * instruction and re-enter the user fault handling path trying
268 * to page it in. This will likely result in sending SEGV to the
280 * This is the really slow path. We're going to be doing
281 * context switches, and waiting for our parent to respond.
285 bl syscall_trace_enter
287 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
288 cmp scno, #-1 @ skip the syscall?
290 add sp, sp, #S_OFF @ restore stack
292 __sys_trace_return_nosave:
295 bl syscall_trace_exit
299 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
301 bl syscall_trace_exit
305 #ifdef CONFIG_ALIGNMENT_TRAP
306 .type __cr_alignment, #object
312 .macro syscall_table_start, sym
318 .macro syscall, nr, func
320 .error "Duplicated/unorded system call entry"
326 .equ __sys_nr, \nr + 1
329 .macro syscall_table_end, sym
330 .ifgt __sys_nr - __NR_syscalls
331 .error "System call table too big"
333 .rept __NR_syscalls - __sys_nr
339 #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
340 #define __SYSCALL(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
348 #include <calls-eabi.S>
350 #include <calls-oabi.S>
352 syscall_table_end sys_call_table
354 /*============================================================================
355 * Special system call wrappers
357 @ r0 = syscall number
360 bic scno, r0, #__NR_OABI_SYSCALL_BASE
361 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
362 cmpne scno, #NR_syscalls @ check range
363 #ifdef CONFIG_CPU_SPECTRE
367 stmialo sp, {r5, r6} @ shuffle args
372 ldrlo pc, [tbl, scno, lsl #2]
376 sys_sigreturn_wrapper:
378 mov why, #0 @ prevent syscall restart handling
380 ENDPROC(sys_sigreturn_wrapper)
382 sys_rt_sigreturn_wrapper:
384 mov why, #0 @ prevent syscall restart handling
386 ENDPROC(sys_rt_sigreturn_wrapper)
388 sys_statfs64_wrapper:
392 ENDPROC(sys_statfs64_wrapper)
394 sys_fstatfs64_wrapper:
398 ENDPROC(sys_fstatfs64_wrapper)
401 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
402 * offset, we return EINVAL.
409 #ifdef CONFIG_OABI_COMPAT
412 * These are syscalls with argument register differences
418 ENDPROC(sys_oabi_pread64)
423 ENDPROC(sys_oabi_pwrite64)
429 ENDPROC(sys_oabi_truncate64)
431 sys_oabi_ftruncate64:
435 ENDPROC(sys_oabi_ftruncate64)
442 ENDPROC(sys_oabi_readahead)
445 * Let's declare a second syscall table for old ABI binaries
446 * using the compatibility syscall entries.
448 syscall_table_start sys_oabi_call_table
449 #undef __SYSCALL_WITH_COMPAT
450 #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat)
451 #include <calls-oabi.S>
452 syscall_table_end sys_oabi_call_table