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 *-----------------------------------------------------------------------------
146 #ifdef CONFIG_HARDEN_BRANCH_HISTORY
147 ENTRY(vector_bhb_loop8_swi)
148 sub sp, sp, #PT_REGS_SIZE
157 ENDPROC(vector_bhb_loop8_swi)
160 ENTRY(vector_bhb_bpiall_swi)
161 sub sp, sp, #PT_REGS_SIZE
163 mcr p15, 0, r8, c7, c5, 6 @ BPIALL
166 ENDPROC(vector_bhb_bpiall_swi)
170 #ifdef CONFIG_CPU_V7M
173 sub sp, sp, #PT_REGS_SIZE
174 stmia sp, {r0 - r12} @ Calling r0 - r12
176 ARM( add r8, sp, #S_PC )
177 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
179 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
180 mrs r8, spsr @ called from non-FIQ mode, so ok.
181 str lr, [sp, #S_PC] @ Save calling PC
182 str r8, [sp, #S_PSR] @ Save CPSR
183 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
186 alignment_trap r10, ip, __cr_alignment
192 * Get the system call number.
195 #if defined(CONFIG_OABI_COMPAT)
198 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
199 * value to determine if it is an EABI or an old ABI call.
201 #ifdef CONFIG_ARM_THUMB
203 movne r10, #0 @ no thumb OABI emulation
204 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction
206 USER( ldr r10, [lr, #-4] ) @ get SWI instruction
208 ARM_BE8(rev r10, r10) @ little endian instruction
210 #elif defined(CONFIG_AEABI)
213 * Pure EABI user space always put syscall number into scno (r7).
215 #elif defined(CONFIG_ARM_THUMB)
216 /* Legacy ABI only, possibly thumb mode. */
217 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
218 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
219 USER( ldreq scno, [lr, #-4] )
222 /* Legacy ABI only. */
223 USER( ldr scno, [lr, #-4] ) @ get SWI instruction
228 adr tbl, sys_call_table @ load syscall table pointer
230 #if defined(CONFIG_OABI_COMPAT)
232 * If the swi argument is zero, this is an EABI call and we do nothing.
234 * If this is an old ABI call, get the syscall number into scno and
235 * get the old ABI syscall table address.
237 bics r10, r10, #0xff000000
238 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
239 ldrne tbl, =sys_oabi_call_table
240 #elif !defined(CONFIG_AEABI)
241 bic scno, scno, #0xff000000 @ mask off SWI op-code
242 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
246 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
247 stmdb sp!, {r4, r5} @ push fifth and sixth args
249 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
252 invoke_syscall tbl, scno, r10, __ret_fast_syscall
255 2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
256 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
258 mov why, #0 @ no longer a real syscall
259 b sys_ni_syscall @ not private func
261 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
263 * We failed to handle a fault trying to access the page
264 * containing the swi instruction, but we're not really in a
265 * position to return -EFAULT. Instead, return back to the
266 * instruction and re-enter the user fault handling path trying
267 * to page it in. This will likely result in sending SEGV to the
278 * This is the really slow path. We're going to be doing
279 * context switches, and waiting for our parent to respond.
284 bl syscall_trace_enter
286 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
287 cmp scno, #-1 @ skip the syscall?
289 add sp, sp, #S_OFF @ restore stack
291 __sys_trace_return_nosave:
294 bl syscall_trace_exit
298 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
300 bl syscall_trace_exit
304 #ifdef CONFIG_ALIGNMENT_TRAP
305 .type __cr_alignment, #object
312 * This is the syscall table declaration for native ABI syscalls.
313 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
315 #define ABI(native, compat) native
317 #define OBSOLETE(syscall) sys_ni_syscall
319 #define OBSOLETE(syscall) syscall
322 .type sys_call_table, #object
323 ENTRY(sys_call_table)
328 /*============================================================================
329 * Special system call wrappers
331 @ r0 = syscall number
334 bic scno, r0, #__NR_OABI_SYSCALL_BASE
335 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
336 cmpne scno, #NR_syscalls @ check range
337 #ifdef CONFIG_CPU_SPECTRE
341 stmloia sp, {r5, r6} @ shuffle args
346 ldrlo pc, [tbl, scno, lsl #2]
350 sys_sigreturn_wrapper:
352 mov why, #0 @ prevent syscall restart handling
354 ENDPROC(sys_sigreturn_wrapper)
356 sys_rt_sigreturn_wrapper:
358 mov why, #0 @ prevent syscall restart handling
360 ENDPROC(sys_rt_sigreturn_wrapper)
362 sys_statfs64_wrapper:
366 ENDPROC(sys_statfs64_wrapper)
368 sys_fstatfs64_wrapper:
372 ENDPROC(sys_fstatfs64_wrapper)
375 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
376 * offset, we return EINVAL.
381 moveq r5, r5, lsr #PAGE_SHIFT - 12
392 #ifdef CONFIG_OABI_COMPAT
395 * These are syscalls with argument register differences
401 ENDPROC(sys_oabi_pread64)
406 ENDPROC(sys_oabi_pwrite64)
412 ENDPROC(sys_oabi_truncate64)
414 sys_oabi_ftruncate64:
418 ENDPROC(sys_oabi_ftruncate64)
425 ENDPROC(sys_oabi_readahead)
428 * Let's declare a second syscall table for old ABI binaries
429 * using the compatibility syscall entries.
431 #define ABI(native, compat) compat
432 #define OBSOLETE(syscall) syscall
434 .type sys_oabi_call_table, #object
435 ENTRY(sys_oabi_call_table)