| blob | 271cb8a1eba1eefe4469db9ae5a677385fa8c2cc |
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * linux/arch/arm/kernel/entry-common.S
4 *
5 * Copyright (C) 2000 Russell King
6 */
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>
13 #ifdef CONFIG_AEABI
14 #include <asm/unistd-oabi.h>
15 #endif
17 .equ NR_syscalls, __NR_syscalls
19 #ifdef CONFIG_NEED_RET_TO_USER
20 #include <mach/entry-macro.S>
21 #else
22 .macro arch_ret_to_user, tmp1, tmp2
23 .endm
24 #endif
26 #include "entry-header.S"
28 saved_psr .req r8
29 #if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
30 saved_pc .req r9
31 #define TRACE(x...) x
32 #else
33 saved_pc .req lr
34 #define TRACE(x...)
35 #endif
37 .section .entry.text,"ax",%progbits
38 .align 5
39 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
40 IS_ENABLED(CONFIG_DEBUG_RSEQ))
41 /*
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.
46 */
47 ret_fast_syscall:
48 __ret_fast_syscall:
49 UNWIND(.fnstart )
50 UNWIND(.cantunwind )
51 disable_irq_notrace @ disable interrupts
52 ldr r2, [tsk, #TI_ADDR_LIMIT]
53 cmp r2, #TASK_SIZE
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
57 bne fast_work_pending
60 /* perform architecture specific actions before user return */
61 arch_ret_to_user r1, lr
63 restore_user_regs fast = 1, offset = S_OFF
64 UNWIND(.fnend )
65 ENDPROC(ret_fast_syscall)
67 /* Ok, we need to do extra processing, enter the slow path. */
68 fast_work_pending:
69 str r0, [sp, #S_R0+S_OFF]! @ returned r0
70 /* fall through to work_pending */
71 #else
72 /*
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
76 * call.
77 */
78 ret_fast_syscall:
79 __ret_fast_syscall:
80 UNWIND(.fnstart )
81 UNWIND(.cantunwind )
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. */
85 mov r0, sp @ 'regs'
86 bl do_rseq_syscall
87 #endif
88 disable_irq_notrace @ disable interrupts
89 ldr r2, [tsk, #TI_ADDR_LIMIT]
90 cmp r2, #TASK_SIZE
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
94 beq no_work_pending
95 UNWIND(.fnend )
96 ENDPROC(ret_fast_syscall)
98 /* Slower path - fall through to work_pending */
99 #endif
101 tst r1, #_TIF_SYSCALL_WORK
102 bne __sys_trace_return_nosave
103 slow_work_pending:
104 mov r0, sp @ 'regs'
105 mov r2, why @ 'syscall'
106 bl do_work_pending
107 cmp r0, #0
108 beq no_work_pending
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)
114 /*
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.
119 */
120 ENTRY(ret_to_user)
121 ret_slow_syscall:
122 #if IS_ENABLED(CONFIG_DEBUG_RSEQ)
123 /* do_rseq_syscall needs interrupts enabled. */
124 enable_irq_notrace @ enable interrupts
125 mov r0, sp @ 'regs'
126 bl do_rseq_syscall
127 #endif
128 disable_irq_notrace @ disable interrupts
129 ENTRY(ret_to_user_from_irq)
130 ldr r2, [tsk, #TI_ADDR_LIMIT]
131 cmp r2, #TASK_SIZE
132 blne addr_limit_check_failed
133 ldr r1, [tsk, #TI_FLAGS]
134 tst r1, #_TIF_WORK_MASK
135 bne slow_work_pending
136 no_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)
145 ENDPROC(ret_to_user)
147 /*
148 * This is how we return from a fork.
149 */
150 ENTRY(ret_from_fork)
151 bl schedule_tail
152 cmp r5, #0
153 movne r0, r4
154 badrne lr, 1f
155 retne r5
156 1: get_thread_info tsk
157 b ret_slow_syscall
158 ENDPROC(ret_from_fork)
160 /*=============================================================================
161 * SWI handler
162 *-----------------------------------------------------------------------------
163 */
165 .align 5
166 ENTRY(vector_swi)
167 #ifdef CONFIG_CPU_V7M
168 v7m_exception_entry
169 #else
170 sub sp, sp, #PT_REGS_SIZE
171 stmia sp, {r0 - r12} @ Calling r0 - r12
172 ARM( add r8, sp, #S_PC )
173 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
174 THUMB( mov r8, sp )
175 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
176 mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
177 TRACE( mov saved_pc, lr )
178 str saved_pc, [sp, #S_PC] @ Save calling PC
179 str saved_psr, [sp, #S_PSR] @ Save CPSR
180 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
181 #endif
182 zero_fp
183 alignment_trap r10, ip, __cr_alignment
184 asm_trace_hardirqs_on save=0
185 enable_irq_notrace
186 ct_user_exit save=0
188 /*
189 * Get the system call number.
190 */
192 #if defined(CONFIG_OABI_COMPAT)
194 /*
195 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
196 * value to determine if it is an EABI or an old ABI call.
197 */
198 #ifdef CONFIG_ARM_THUMB
199 tst saved_psr, #PSR_T_BIT
200 movne r10, #0 @ no thumb OABI emulation
201 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
202 #else
203 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
204 #endif
205 ARM_BE8(rev r10, r10) @ little endian instruction
207 #elif defined(CONFIG_AEABI)
209 /*
210 * Pure EABI user space always put syscall number into scno (r7).
211 */
212 #elif defined(CONFIG_ARM_THUMB)
213 /* Legacy ABI only, possibly thumb mode. */
214 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
215 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
216 USER( ldreq scno, [saved_pc, #-4] )
218 #else
219 /* Legacy ABI only. */
220 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
221 #endif
223 /* saved_psr and saved_pc are now dead */
225 uaccess_disable tbl
227 adr tbl, sys_call_table @ load syscall table pointer
229 #if defined(CONFIG_OABI_COMPAT)
230 /*
231 * If the swi argument is zero, this is an EABI call and we do nothing.
232 *
233 * If this is an old ABI call, get the syscall number into scno and
234 * get the old ABI syscall table address.
235 */
236 bics r10, r10, #0xff000000
237 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
238 ldrne tbl, =sys_oabi_call_table
239 #elif !defined(CONFIG_AEABI)
240 bic scno, scno, #0xff000000 @ mask off SWI op-code
241 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
242 #endif
243 get_thread_info tsk
244 /*
245 * Reload the registers that may have been corrupted on entry to
246 * the syscall assembly (by tracing or context tracking.)
247 */
248 TRACE( ldmia sp, {r0 - r3} )
250 local_restart:
251 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
252 stmdb sp!, {r4, r5} @ push fifth and sixth args
254 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
255 bne __sys_trace
257 invoke_syscall tbl, scno, r10, __ret_fast_syscall
259 add r1, sp, #S_OFF
260 2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
261 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
262 bcs arm_syscall
263 mov why, #0 @ no longer a real syscall
264 b sys_ni_syscall @ not private func
266 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
267 /*
268 * We failed to handle a fault trying to access the page
269 * containing the swi instruction, but we're not really in a
270 * position to return -EFAULT. Instead, return back to the
271 * instruction and re-enter the user fault handling path trying
272 * to page it in. This will likely result in sending SEGV to the
273 * current task.
274 */
275 9001:
276 sub lr, saved_pc, #4
277 str lr, [sp, #S_PC]
278 get_thread_info tsk
279 b ret_fast_syscall
280 #endif
281 ENDPROC(vector_swi)
283 /*
284 * This is the really slow path. We're going to be doing
285 * context switches, and waiting for our parent to respond.
286 */
287 __sys_trace:
288 mov r1, scno
289 add r0, sp, #S_OFF
290 bl syscall_trace_enter
291 mov scno, r0
292 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
293 cmp scno, #-1 @ skip the syscall?
294 bne 2b
295 add sp, sp, #S_OFF @ restore stack
297 __sys_trace_return_nosave:
298 enable_irq_notrace
299 mov r0, sp
300 bl syscall_trace_exit
301 b ret_slow_syscall
303 __sys_trace_return:
304 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
305 mov r0, sp
306 bl syscall_trace_exit
307 b ret_slow_syscall
309 .align 5
310 #ifdef CONFIG_ALIGNMENT_TRAP
311 .type __cr_alignment, #object
312 __cr_alignment:
313 .word cr_alignment
314 #endif
315 .ltorg
317 .macro syscall_table_start, sym
318 .equ __sys_nr, 0
319 .type \sym, #object
320 ENTRY(\sym)
321 .endm
323 .macro syscall, nr, func
324 .ifgt __sys_nr - \nr
325 .error "Duplicated/unorded system call entry"
326 .endif
327 .rept \nr - __sys_nr
328 .long sys_ni_syscall
329 .endr
330 .long \func
331 .equ __sys_nr, \nr + 1
332 .endm
334 .macro syscall_table_end, sym
335 .ifgt __sys_nr - __NR_syscalls
336 .error "System call table too big"
337 .endif
338 .rept __NR_syscalls - __sys_nr
339 .long sys_ni_syscall
340 .endr
341 .size \sym, . - \sym
342 .endm
344 #define NATIVE(nr, func) syscall nr, func
346 /*
347 * This is the syscall table declaration for native ABI syscalls.
348 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
349 */
350 syscall_table_start sys_call_table
351 #define COMPAT(nr, native, compat) syscall nr, native
352 #ifdef CONFIG_AEABI
353 #include <calls-eabi.S>
354 #else
355 #include <calls-oabi.S>
356 #endif
357 #undef COMPAT
358 syscall_table_end sys_call_table
360 /*============================================================================
361 * Special system call wrappers
362 */
363 @ r0 = syscall number
364 @ r8 = syscall table
365 sys_syscall:
366 bic scno, r0, #__NR_OABI_SYSCALL_BASE
367 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
368 cmpne scno, #NR_syscalls @ check range
369 #ifdef CONFIG_CPU_SPECTRE
370 movhs scno, #0
371 csdb
372 #endif
373 stmialo sp, {r5, r6} @ shuffle args
374 movlo r0, r1
375 movlo r1, r2
376 movlo r2, r3
377 movlo r3, r4
378 ldrlo pc, [tbl, scno, lsl #2]
379 b sys_ni_syscall
380 ENDPROC(sys_syscall)
382 sys_sigreturn_wrapper:
383 add r0, sp, #S_OFF
384 mov why, #0 @ prevent syscall restart handling
385 b sys_sigreturn
386 ENDPROC(sys_sigreturn_wrapper)
388 sys_rt_sigreturn_wrapper:
389 add r0, sp, #S_OFF
390 mov why, #0 @ prevent syscall restart handling
391 b sys_rt_sigreturn
392 ENDPROC(sys_rt_sigreturn_wrapper)
394 sys_statfs64_wrapper:
395 teq r1, #88
396 moveq r1, #84
397 b sys_statfs64
398 ENDPROC(sys_statfs64_wrapper)
400 sys_fstatfs64_wrapper:
401 teq r1, #88
402 moveq r1, #84
403 b sys_fstatfs64
404 ENDPROC(sys_fstatfs64_wrapper)
406 /*
407 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
408 * offset, we return EINVAL.
409 */
410 sys_mmap2:
411 str r5, [sp, #4]
412 b sys_mmap_pgoff
413 ENDPROC(sys_mmap2)
415 #ifdef CONFIG_OABI_COMPAT
417 /*
418 * These are syscalls with argument register differences
419 */
421 sys_oabi_pread64:
422 stmia sp, {r3, r4}
423 b sys_pread64
424 ENDPROC(sys_oabi_pread64)
426 sys_oabi_pwrite64:
427 stmia sp, {r3, r4}
428 b sys_pwrite64
429 ENDPROC(sys_oabi_pwrite64)
431 sys_oabi_truncate64:
432 mov r3, r2
433 mov r2, r1
434 b sys_truncate64
435 ENDPROC(sys_oabi_truncate64)
437 sys_oabi_ftruncate64:
438 mov r3, r2
439 mov r2, r1
440 b sys_ftruncate64
441 ENDPROC(sys_oabi_ftruncate64)
443 sys_oabi_readahead:
444 str r3, [sp]
445 mov r3, r2
446 mov r2, r1
447 b sys_readahead
448 ENDPROC(sys_oabi_readahead)
450 /*
451 * Let's declare a second syscall table for old ABI binaries
452 * using the compatibility syscall entries.
453 */
454 syscall_table_start sys_oabi_call_table
455 #define COMPAT(nr, native, compat) syscall nr, compat
456 #include <calls-oabi.S>
457 syscall_table_end sys_oabi_call_table
459 #endif