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/unistd.h>
12 #include <asm/ftrace.h>
13 #include <mach/entry-macro.S>
14 #include <asm/unwind.h>
16 #include "entry-header.S"
21 * This is the fast syscall return path. We do as little as
22 * possible here, and this includes saving r0 back into the SVC
28 disable_irq @ disable interrupts
29 ldr r1, [tsk, #TI_FLAGS]
30 tst r1, #_TIF_WORK_MASK
33 /* perform architecture specific actions before user return */
34 arch_ret_to_user r1, lr
36 restore_user_regs fast = 1, offset = S_OFF
40 * Ok, we need to do extra processing, enter the slow path.
43 str r0, [sp, #S_R0+S_OFF]! @ returned r0
45 tst r1, #_TIF_NEED_RESCHED
47 tst r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME
50 mov r2, why @ 'syscall'
51 tst r1, #_TIF_SIGPENDING @ delivering a signal?
52 movne why, #0 @ prevent further restarts
54 b ret_slow_syscall @ Check work again
59 * "slow" syscall return path. "why" tells us if this was a real syscall.
63 disable_irq @ disable interrupts
64 ldr r1, [tsk, #TI_FLAGS]
65 tst r1, #_TIF_WORK_MASK
68 /* perform architecture specific actions before user return */
69 arch_ret_to_user r1, lr
71 restore_user_regs fast = 0, offset = 0
75 * This is how we return from a fork.
80 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing
82 tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
85 mov r0, #1 @ trace exit [IP = 1]
88 ENDPROC(ret_from_fork)
91 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
94 #define CALL(x) .long x
96 #ifdef CONFIG_FUNCTION_TRACER
98 * When compiling with -pg, gcc inserts a call to the mcount routine at the
99 * start of every function. In mcount, apart from the function's address (in
100 * lr), we need to get hold of the function's caller's address.
102 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
106 * These versions have the limitation that in order for the mcount routine to
107 * be able to determine the function's caller's address, an APCS-style frame
108 * pointer (which is set up with something like the code below) is required.
111 * push {fp, ip, lr, pc}
114 * With EABI, these frame pointers are not available unless -mapcs-frame is
115 * specified, and if building as Thumb-2, not even then.
117 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
118 * with call sites like:
123 * With these compilers, frame pointers are not necessary.
125 * mcount can be thought of as a function called in the middle of a subroutine
126 * call. As such, it needs to be transparent for both the caller and the
127 * callee: the original lr needs to be restored when leaving mcount, and no
128 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we
129 * clobber the ip register. This is OK because the ARM calling convention
130 * allows it to be clobbered in subroutines and doesn't use it to hold
133 #ifdef CONFIG_DYNAMIC_FTRACE
135 stmdb sp!, {r0-r3, lr}
137 sub r0, r0, #MCOUNT_INSN_SIZE
142 ldr lr, [fp, #-4] @ restore lr
143 ldmia sp!, {r0-r3, pc}
146 stmdb sp!, {r0-r3, lr}
149 sub r0, r0, #MCOUNT_INSN_SIZE
154 ldr lr, [fp, #-4] @ restore lr
155 ldmia sp!, {r0-r3, pc}
159 ENTRY(__gnu_mcount_nc)
160 stmdb sp!, {r0-r3, lr}
161 ldr r0, =ftrace_trace_function
166 ldmia sp!, {r0-r3, ip, lr}
170 ldr r1, [sp, #20] @ lr of instrumented routine
172 sub r0, r0, #MCOUNT_INSN_SIZE
175 ldmia sp!, {r0-r3, ip, lr}
179 stmdb sp!, {r0-r3, lr}
180 ldr r0, =ftrace_trace_function
185 ldr lr, [fp, #-4] @ restore lr
186 ldmia sp!, {r0-r3, pc}
189 ldr r1, [fp, #-4] @ lr of instrumented routine
191 sub r0, r0, #MCOUNT_INSN_SIZE
194 ldr lr, [fp, #-4] @ restore lr
195 ldmia sp!, {r0-r3, pc}
197 #endif /* CONFIG_DYNAMIC_FTRACE */
203 #endif /* CONFIG_FUNCTION_TRACER */
205 /*=============================================================================
207 *-----------------------------------------------------------------------------
210 /* If we're optimising for StrongARM the resulting code won't
211 run on an ARM7 and we can save a couple of instructions.
213 #ifdef CONFIG_CPU_ARM710
214 #define A710(code...) code
216 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr
218 add sp, sp, #S_FRAME_SIZE
221 #define A710(code...)
226 sub sp, sp, #S_FRAME_SIZE
227 stmia sp, {r0 - r12} @ Calling r0 - r12
228 ARM( add r8, sp, #S_PC )
229 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
231 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
232 mrs r8, spsr @ called from non-FIQ mode, so ok.
233 str lr, [sp, #S_PC] @ Save calling PC
234 str r8, [sp, #S_PSR] @ Save CPSR
235 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
239 * Get the system call number.
242 #if defined(CONFIG_OABI_COMPAT)
245 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
246 * value to determine if it is an EABI or an old ABI call.
248 #ifdef CONFIG_ARM_THUMB
250 movne r10, #0 @ no thumb OABI emulation
251 ldreq r10, [lr, #-4] @ get SWI instruction
253 ldr r10, [lr, #-4] @ get SWI instruction
254 A710( and ip, r10, #0x0f000000 @ check for SWI )
255 A710( teq ip, #0x0f000000 )
256 A710( bne .Larm710bug )
258 #ifdef CONFIG_CPU_ENDIAN_BE8
259 rev r10, r10 @ little endian instruction
262 #elif defined(CONFIG_AEABI)
265 * Pure EABI user space always put syscall number into scno (r7).
267 A710( ldr ip, [lr, #-4] @ get SWI instruction )
268 A710( and ip, ip, #0x0f000000 @ check for SWI )
269 A710( teq ip, #0x0f000000 )
270 A710( bne .Larm710bug )
272 #elif defined(CONFIG_ARM_THUMB)
274 /* Legacy ABI only, possibly thumb mode. */
275 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
276 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
277 ldreq scno, [lr, #-4]
281 /* Legacy ABI only. */
282 ldr scno, [lr, #-4] @ get SWI instruction
283 A710( and ip, scno, #0x0f000000 @ check for SWI )
284 A710( teq ip, #0x0f000000 )
285 A710( bne .Larm710bug )
289 #ifdef CONFIG_ALIGNMENT_TRAP
290 ldr ip, __cr_alignment
292 mcr p15, 0, ip, c1, c0 @ update control register
297 adr tbl, sys_call_table @ load syscall table pointer
298 ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing
300 #if defined(CONFIG_OABI_COMPAT)
302 * If the swi argument is zero, this is an EABI call and we do nothing.
304 * If this is an old ABI call, get the syscall number into scno and
305 * get the old ABI syscall table address.
307 bics r10, r10, #0xff000000
308 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
309 ldrne tbl, =sys_oabi_call_table
310 #elif !defined(CONFIG_AEABI)
311 bic scno, scno, #0xff000000 @ mask off SWI op-code
312 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
315 stmdb sp!, {r4, r5} @ push fifth and sixth args
316 tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
319 cmp scno, #NR_syscalls @ check upper syscall limit
320 adr lr, BSYM(ret_fast_syscall) @ return address
321 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
324 2: mov why, #0 @ no longer a real syscall
325 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
326 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
328 b sys_ni_syscall @ not private func
332 * This is the really slow path. We're going to be doing
333 * context switches, and waiting for our parent to respond.
338 mov r0, #0 @ trace entry [IP = 0]
341 adr lr, BSYM(__sys_trace_return) @ return address
342 mov scno, r0 @ syscall number (possibly new)
343 add r1, sp, #S_R0 + S_OFF @ pointer to regs
344 cmp scno, #NR_syscalls @ check upper syscall limit
345 ldmccia r1, {r0 - r3} @ have to reload r0 - r3
346 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
350 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
353 mov r0, #1 @ trace exit [IP = 1]
358 #ifdef CONFIG_ALIGNMENT_TRAP
359 .type __cr_alignment, #object
366 * This is the syscall table declaration for native ABI syscalls.
367 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
369 #define ABI(native, compat) native
371 #define OBSOLETE(syscall) sys_ni_syscall
373 #define OBSOLETE(syscall) syscall
376 .type sys_call_table, #object
377 ENTRY(sys_call_table)
382 /*============================================================================
383 * Special system call wrappers
385 @ r0 = syscall number
388 bic scno, r0, #__NR_OABI_SYSCALL_BASE
389 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
390 cmpne scno, #NR_syscalls @ check range
391 stmloia sp, {r5, r6} @ shuffle args
396 ldrlo pc, [tbl, scno, lsl #2]
403 ENDPROC(sys_fork_wrapper)
408 ENDPROC(sys_vfork_wrapper)
413 ENDPROC(sys_execve_wrapper)
419 ENDPROC(sys_clone_wrapper)
421 sys_sigreturn_wrapper:
423 mov why, #0 @ prevent syscall restart handling
425 ENDPROC(sys_sigreturn_wrapper)
427 sys_rt_sigreturn_wrapper:
429 mov why, #0 @ prevent syscall restart handling
431 ENDPROC(sys_rt_sigreturn_wrapper)
433 sys_sigaltstack_wrapper:
434 ldr r2, [sp, #S_OFF + S_SP]
436 ENDPROC(sys_sigaltstack_wrapper)
438 sys_statfs64_wrapper:
442 ENDPROC(sys_statfs64_wrapper)
444 sys_fstatfs64_wrapper:
448 ENDPROC(sys_fstatfs64_wrapper)
451 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
452 * offset, we return EINVAL.
457 moveq r5, r5, lsr #PAGE_SHIFT - 12
468 #ifdef CONFIG_OABI_COMPAT
471 * These are syscalls with argument register differences
477 ENDPROC(sys_oabi_pread64)
482 ENDPROC(sys_oabi_pwrite64)
488 ENDPROC(sys_oabi_truncate64)
490 sys_oabi_ftruncate64:
494 ENDPROC(sys_oabi_ftruncate64)
501 ENDPROC(sys_oabi_readahead)
504 * Let's declare a second syscall table for old ABI binaries
505 * using the compatibility syscall entries.
507 #define ABI(native, compat) compat
508 #define OBSOLETE(syscall) syscall
510 .type sys_oabi_call_table, #object
511 ENTRY(sys_oabi_call_table)