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 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, context tracking,
74 * or rseq debug is enabled. As we will need to call out to some C functions,
75 * we save r0 first to avoid needing to save registers around each C function
82 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
83 #if IS_ENABLED(CONFIG_DEBUG_RSEQ)
84 /* do_rseq_syscall needs interrupts enabled. */
88 disable_irq_notrace @ disable interrupts
89 ldr r2, [tsk, #TI_ADDR_LIMIT]
91 blne addr_limit_check_failed
92 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
93 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
96 ENDPROC(ret_fast_syscall)
98 /* Slower path - fall through to work_pending */
101 tst r1, #_TIF_SYSCALL_WORK
102 bne __sys_trace_return_nosave
105 mov r2, why @ 'syscall'
109 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
110 ldmia sp, {r0 - r6} @ have to reload r0 - r6
111 b local_restart @ ... and off we go
112 ENDPROC(ret_fast_syscall)
115 * "slow" syscall return path. "why" tells us if this was a real syscall.
116 * IRQs may be enabled here, so always disable them. Note that we use the
117 * "notrace" version to avoid calling into the tracing code unnecessarily.
118 * do_work_pending() will update this state if necessary.
122 #if IS_ENABLED(CONFIG_DEBUG_RSEQ)
123 /* do_rseq_syscall needs interrupts enabled. */
124 enable_irq_notrace @ enable interrupts
128 disable_irq_notrace @ disable interrupts
129 ENTRY(ret_to_user_from_irq)
130 ldr r2, [tsk, #TI_ADDR_LIMIT]
132 blne addr_limit_check_failed
133 ldr r1, [tsk, #TI_FLAGS]
134 tst r1, #_TIF_WORK_MASK
135 bne slow_work_pending
137 asm_trace_hardirqs_on save = 0
139 /* perform architecture specific actions before user return */
140 arch_ret_to_user r1, lr
141 ct_user_enter save = 0
143 restore_user_regs fast = 0, offset = 0
144 ENDPROC(ret_to_user_from_irq)
148 * This is how we return from a fork.
156 1: get_thread_info tsk
158 ENDPROC(ret_from_fork)
160 /*=============================================================================
162 *-----------------------------------------------------------------------------
166 #ifdef CONFIG_HARDEN_BRANCH_HISTORY
167 ENTRY(vector_bhb_loop8_swi)
168 sub sp, sp, #PT_REGS_SIZE
177 ENDPROC(vector_bhb_loop8_swi)
180 ENTRY(vector_bhb_bpiall_swi)
181 sub sp, sp, #PT_REGS_SIZE
183 mcr p15, 0, r8, c7, c5, 6 @ BPIALL
186 ENDPROC(vector_bhb_bpiall_swi)
190 #ifdef CONFIG_CPU_V7M
193 sub sp, sp, #PT_REGS_SIZE
194 stmia sp, {r0 - r12} @ Calling r0 - r12
196 ARM( add r8, sp, #S_PC )
197 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
199 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
200 mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
201 TRACE( mov saved_pc, lr )
202 str saved_pc, [sp, #S_PC] @ Save calling PC
203 str saved_psr, [sp, #S_PSR] @ Save CPSR
204 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
207 alignment_trap r10, ip, __cr_alignment
208 asm_trace_hardirqs_on save=0
213 * Get the system call number.
216 #if defined(CONFIG_OABI_COMPAT)
219 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
220 * value to determine if it is an EABI or an old ABI call.
222 #ifdef CONFIG_ARM_THUMB
223 tst saved_psr, #PSR_T_BIT
224 movne r10, #0 @ no thumb OABI emulation
225 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
227 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
229 ARM_BE8(rev r10, r10) @ little endian instruction
231 #elif defined(CONFIG_AEABI)
234 * Pure EABI user space always put syscall number into scno (r7).
236 #elif defined(CONFIG_ARM_THUMB)
237 /* Legacy ABI only, possibly thumb mode. */
238 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
239 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
240 USER( ldreq scno, [saved_pc, #-4] )
243 /* Legacy ABI only. */
244 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
247 /* saved_psr and saved_pc are now dead */
251 adr tbl, sys_call_table @ load syscall table pointer
253 #if defined(CONFIG_OABI_COMPAT)
255 * If the swi argument is zero, this is an EABI call and we do nothing.
257 * If this is an old ABI call, get the syscall number into scno and
258 * get the old ABI syscall table address.
260 bics r10, r10, #0xff000000
261 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
262 ldrne tbl, =sys_oabi_call_table
263 #elif !defined(CONFIG_AEABI)
264 bic scno, scno, #0xff000000 @ mask off SWI op-code
265 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
269 * Reload the registers that may have been corrupted on entry to
270 * the syscall assembly (by tracing or context tracking.)
272 TRACE( ldmia sp, {r0 - r3} )
275 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
276 stmdb sp!, {r4, r5} @ push fifth and sixth args
278 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
281 invoke_syscall tbl, scno, r10, __ret_fast_syscall
284 2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
285 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
287 mov why, #0 @ no longer a real syscall
288 b sys_ni_syscall @ not private func
290 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
292 * We failed to handle a fault trying to access the page
293 * containing the swi instruction, but we're not really in a
294 * position to return -EFAULT. Instead, return back to the
295 * instruction and re-enter the user fault handling path trying
296 * to page it in. This will likely result in sending SEGV to the
308 * This is the really slow path. We're going to be doing
309 * context switches, and waiting for our parent to respond.
314 bl syscall_trace_enter
316 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
317 cmp scno, #-1 @ skip the syscall?
319 add sp, sp, #S_OFF @ restore stack
321 __sys_trace_return_nosave:
324 bl syscall_trace_exit
328 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
330 bl syscall_trace_exit
334 #ifdef CONFIG_ALIGNMENT_TRAP
335 .type __cr_alignment, #object
341 .macro syscall_table_start, sym
347 .macro syscall, nr, func
349 .error "Duplicated/unorded system call entry"
355 .equ __sys_nr, \nr + 1
358 .macro syscall_table_end, sym
359 .ifgt __sys_nr - __NR_syscalls
360 .error "System call table too big"
362 .rept __NR_syscalls - __sys_nr
368 #define NATIVE(nr, func) syscall nr, func
371 * This is the syscall table declaration for native ABI syscalls.
372 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
374 syscall_table_start sys_call_table
375 #define COMPAT(nr, native, compat) syscall nr, native
377 #include <calls-eabi.S>
379 #include <calls-oabi.S>
382 syscall_table_end sys_call_table
384 /*============================================================================
385 * Special system call wrappers
387 @ r0 = syscall number
390 bic scno, r0, #__NR_OABI_SYSCALL_BASE
391 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
392 cmpne scno, #NR_syscalls @ check range
393 #ifdef CONFIG_CPU_SPECTRE
397 stmialo sp, {r5, r6} @ shuffle args
402 ldrlo pc, [tbl, scno, lsl #2]
406 sys_sigreturn_wrapper:
408 mov why, #0 @ prevent syscall restart handling
410 ENDPROC(sys_sigreturn_wrapper)
412 sys_rt_sigreturn_wrapper:
414 mov why, #0 @ prevent syscall restart handling
416 ENDPROC(sys_rt_sigreturn_wrapper)
418 sys_statfs64_wrapper:
422 ENDPROC(sys_statfs64_wrapper)
424 sys_fstatfs64_wrapper:
428 ENDPROC(sys_fstatfs64_wrapper)
431 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
432 * offset, we return EINVAL.
439 #ifdef CONFIG_OABI_COMPAT
442 * These are syscalls with argument register differences
448 ENDPROC(sys_oabi_pread64)
453 ENDPROC(sys_oabi_pwrite64)
459 ENDPROC(sys_oabi_truncate64)
461 sys_oabi_ftruncate64:
465 ENDPROC(sys_oabi_ftruncate64)
472 ENDPROC(sys_oabi_readahead)
475 * Let's declare a second syscall table for old ABI binaries
476 * using the compatibility syscall entries.
478 syscall_table_start sys_oabi_call_table
479 #define COMPAT(nr, native, compat) syscall nr, compat
480 #include <calls-oabi.S>
481 syscall_table_end sys_oabi_call_table