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 .macro arch_ret_to_user, tmp
20 #ifdef CONFIG_ARCH_IOP32X
21 mrc p15, 0, \tmp, c15, c1, 0
23 bicne \tmp, \tmp, #(1 << 6)
24 mcrne p15, 0, \tmp, c15, c1, 0 @ Disable cp6 access
28 #include "entry-header.S"
31 #if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER)
39 .section .entry.text,"ax",%progbits
41 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING_USER) || \
42 IS_ENABLED(CONFIG_DEBUG_RSEQ))
44 * This is the fast syscall return path. We do as little as possible here,
45 * such as avoiding writing r0 to the stack. We only use this path if we
46 * have tracing, context tracking and rseq debug disabled - the overheads
47 * from those features make this path too inefficient.
53 disable_irq_notrace @ disable interrupts
54 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
59 /* perform architecture specific actions before user return */
62 restore_user_regs fast = 1, offset = S_OFF
64 ENDPROC(ret_fast_syscall)
66 /* Ok, we need to do extra processing, enter the slow path. */
68 str r0, [sp, #S_R0+S_OFF]! @ returned r0
69 /* fall through to work_pending */
72 * The "replacement" ret_fast_syscall for when tracing, context tracking,
73 * or rseq debug is enabled. As we will need to call out to some C functions,
74 * we save r0 first to avoid needing to save registers around each C function
81 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
82 #if IS_ENABLED(CONFIG_DEBUG_RSEQ)
83 /* do_rseq_syscall needs interrupts enabled. */
87 disable_irq_notrace @ disable interrupts
88 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
92 ENDPROC(ret_fast_syscall)
94 /* Slower path - fall through to work_pending */
97 tst r1, #_TIF_SYSCALL_WORK
98 bne __sys_trace_return_nosave
101 mov r2, why @ 'syscall'
105 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
106 str scno, [tsk, #TI_ABI_SYSCALL] @ make sure tracers see update
107 ldmia sp, {r0 - r6} @ have to reload r0 - r6
108 b local_restart @ ... and off we go
109 ENDPROC(ret_fast_syscall)
112 * "slow" syscall return path. "why" tells us if this was a real syscall.
113 * IRQs may be enabled here, so always disable them. Note that we use the
114 * "notrace" version to avoid calling into the tracing code unnecessarily.
115 * do_work_pending() will update this state if necessary.
119 #if IS_ENABLED(CONFIG_DEBUG_RSEQ)
120 /* do_rseq_syscall needs interrupts enabled. */
121 enable_irq_notrace @ enable interrupts
125 disable_irq_notrace @ disable interrupts
126 ENTRY(ret_to_user_from_irq)
127 ldr r1, [tsk, #TI_FLAGS]
129 bne slow_work_pending
131 asm_trace_hardirqs_on save = 0
133 /* perform architecture specific actions before user return */
135 ct_user_enter save = 0
137 restore_user_regs fast = 0, offset = 0
138 ENDPROC(ret_to_user_from_irq)
142 * This is how we return from a fork.
150 1: get_thread_info tsk
152 ENDPROC(ret_from_fork)
154 /*=============================================================================
156 *-----------------------------------------------------------------------------
160 #ifdef CONFIG_HARDEN_BRANCH_HISTORY
161 ENTRY(vector_bhb_loop8_swi)
162 sub sp, sp, #PT_REGS_SIZE
171 ENDPROC(vector_bhb_loop8_swi)
174 ENTRY(vector_bhb_bpiall_swi)
175 sub sp, sp, #PT_REGS_SIZE
177 mcr p15, 0, r8, c7, c5, 6 @ BPIALL
180 ENDPROC(vector_bhb_bpiall_swi)
184 #ifdef CONFIG_CPU_V7M
187 sub sp, sp, #PT_REGS_SIZE
188 stmia sp, {r0 - r12} @ Calling r0 - r12
190 ARM( add r8, sp, #S_PC )
191 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
193 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
194 mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
195 TRACE( mov saved_pc, lr )
196 str saved_pc, [sp, #S_PC] @ Save calling PC
197 str saved_psr, [sp, #S_PSR] @ Save CPSR
198 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
200 reload_current r10, ip
202 alignment_trap r10, ip, cr_alignment
203 asm_trace_hardirqs_on save=0
208 * Get the system call number.
211 #if defined(CONFIG_OABI_COMPAT)
214 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
215 * value to determine if it is an EABI or an old ABI call.
217 #ifdef CONFIG_ARM_THUMB
218 tst saved_psr, #PSR_T_BIT
219 movne r10, #0 @ no thumb OABI emulation
220 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
222 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
224 ARM_BE8(rev r10, r10) @ little endian instruction
226 #elif defined(CONFIG_AEABI)
229 * Pure EABI user space always put syscall number into scno (r7).
231 #elif defined(CONFIG_ARM_THUMB)
232 /* Legacy ABI only, possibly thumb mode. */
233 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
234 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
235 USER( ldreq scno, [saved_pc, #-4] )
238 /* Legacy ABI only. */
239 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
242 /* saved_psr and saved_pc are now dead */
247 adr tbl, sys_call_table @ load syscall table pointer
249 #if defined(CONFIG_OABI_COMPAT)
251 * If the swi argument is zero, this is an EABI call and we do nothing.
253 * If this is an old ABI call, get the syscall number into scno and
254 * get the old ABI syscall table address.
256 bics r10, r10, #0xff000000
257 strne r10, [tsk, #TI_ABI_SYSCALL]
258 streq scno, [tsk, #TI_ABI_SYSCALL]
259 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
260 ldrne tbl, =sys_oabi_call_table
261 #elif !defined(CONFIG_AEABI)
262 bic scno, scno, #0xff000000 @ mask off SWI op-code
263 str scno, [tsk, #TI_ABI_SYSCALL]
264 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
266 str scno, [tsk, #TI_ABI_SYSCALL]
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
309 * This is the really slow path. We're going to be doing
310 * 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
333 .macro syscall_table_start, sym
339 .macro syscall, nr, func
341 .error "Duplicated/unorded system call entry"
347 .equ __sys_nr, \nr + 1
350 .macro syscall_table_end, sym
351 .ifgt __sys_nr - __NR_syscalls
352 .error "System call table too big"
354 .rept __NR_syscalls - __sys_nr
360 #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
361 #define __SYSCALL(nr, func) syscall nr, func
364 * This is the syscall table declaration for native ABI syscalls.
365 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
367 syscall_table_start sys_call_table
369 #include <calls-eabi.S>
371 #include <calls-oabi.S>
373 syscall_table_end sys_call_table
375 /*============================================================================
376 * Special system call wrappers
378 @ r0 = syscall number
381 bic scno, r0, #__NR_OABI_SYSCALL_BASE
382 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
383 cmpne scno, #NR_syscalls @ check range
384 #ifdef CONFIG_CPU_SPECTRE
388 stmialo sp, {r5, r6} @ shuffle args
393 ldrlo pc, [tbl, scno, lsl #2]
397 sys_sigreturn_wrapper:
399 mov why, #0 @ prevent syscall restart handling
401 ENDPROC(sys_sigreturn_wrapper)
403 sys_rt_sigreturn_wrapper:
405 mov why, #0 @ prevent syscall restart handling
407 ENDPROC(sys_rt_sigreturn_wrapper)
409 sys_statfs64_wrapper:
413 ENDPROC(sys_statfs64_wrapper)
415 sys_fstatfs64_wrapper:
419 ENDPROC(sys_fstatfs64_wrapper)
422 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
423 * offset, we return EINVAL.
430 #ifdef CONFIG_OABI_COMPAT
433 * These are syscalls with argument register differences
439 ENDPROC(sys_oabi_pread64)
444 ENDPROC(sys_oabi_pwrite64)
450 ENDPROC(sys_oabi_truncate64)
452 sys_oabi_ftruncate64:
456 ENDPROC(sys_oabi_ftruncate64)
463 ENDPROC(sys_oabi_readahead)
466 * Let's declare a second syscall table for old ABI binaries
467 * using the compatibility syscall entries.
469 syscall_table_start sys_oabi_call_table
470 #undef __SYSCALL_WITH_COMPAT
471 #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat)
472 #include <calls-oabi.S>
473 syscall_table_end sys_oabi_call_table