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 <asm/unwind.h>
15 #ifdef CONFIG_NEED_RET_TO_USER
16 #include <mach/entry-macro.S>
18 .macro arch_ret_to_user, tmp1, tmp2
22 #include "entry-header.S"
27 * This is the fast syscall return path. We do as little as
28 * possible here, and this includes saving r0 back into the SVC
34 disable_irq @ disable interrupts
35 ldr r1, [tsk, #TI_FLAGS]
36 tst r1, #_TIF_WORK_MASK
38 #if defined(CONFIG_IRQSOFF_TRACER)
42 /* perform architecture specific actions before user return */
43 arch_ret_to_user r1, lr
45 restore_user_regs fast = 1, offset = S_OFF
49 * Ok, we need to do extra processing, enter the slow path.
52 str r0, [sp, #S_R0+S_OFF]! @ returned r0
54 tst r1, #_TIF_NEED_RESCHED
57 * TIF_SIGPENDING or TIF_NOTIFY_RESUME must've been set if we got here
61 tst r2, #15 @ are we returning to user mode?
62 bne no_work_pending @ no? just leave, then...
63 mov r2, why @ 'syscall'
64 tst r1, #_TIF_SIGPENDING @ delivering a signal?
65 movne why, #0 @ prevent further restarts
67 b ret_slow_syscall @ Check work again
72 * "slow" syscall return path. "why" tells us if this was a real syscall.
76 disable_irq @ disable interrupts
77 ENTRY(ret_to_user_from_irq)
78 ldr r1, [tsk, #TI_FLAGS]
79 tst r1, #_TIF_WORK_MASK
82 #if defined(CONFIG_IRQSOFF_TRACER)
85 /* perform architecture specific actions before user return */
86 arch_ret_to_user r1, lr
88 restore_user_regs fast = 0, offset = 0
89 ENDPROC(ret_to_user_from_irq)
93 * This is how we return from a fork.
98 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing
100 tst r1, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
103 mov r0, #1 @ trace exit [IP = 1]
106 ENDPROC(ret_from_fork)
109 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
112 #define CALL(x) .long x
114 #ifdef CONFIG_FUNCTION_TRACER
116 * When compiling with -pg, gcc inserts a call to the mcount routine at the
117 * start of every function. In mcount, apart from the function's address (in
118 * lr), we need to get hold of the function's caller's address.
120 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
124 * These versions have the limitation that in order for the mcount routine to
125 * be able to determine the function's caller's address, an APCS-style frame
126 * pointer (which is set up with something like the code below) is required.
129 * push {fp, ip, lr, pc}
132 * With EABI, these frame pointers are not available unless -mapcs-frame is
133 * specified, and if building as Thumb-2, not even then.
135 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
136 * with call sites like:
141 * With these compilers, frame pointers are not necessary.
143 * mcount can be thought of as a function called in the middle of a subroutine
144 * call. As such, it needs to be transparent for both the caller and the
145 * callee: the original lr needs to be restored when leaving mcount, and no
146 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we
147 * clobber the ip register. This is OK because the ARM calling convention
148 * allows it to be clobbered in subroutines and doesn't use it to hold
151 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
152 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
153 * arch/arm/kernel/ftrace.c).
156 #ifndef CONFIG_OLD_MCOUNT
157 #if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
158 #error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
162 .macro mcount_adjust_addr rd, rn
163 bic \rd, \rn, #1 @ clear the Thumb bit if present
164 sub \rd, \rd, #MCOUNT_INSN_SIZE
167 .macro __mcount suffix
169 ldr r0, =ftrace_trace_function
171 adr r0, .Lftrace_stub
175 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
176 ldr r1, =ftrace_graph_return
179 bne ftrace_graph_caller\suffix
181 ldr r1, =ftrace_graph_entry
183 ldr r0, =ftrace_graph_entry_stub
185 bne ftrace_graph_caller\suffix
190 1: mcount_get_lr r1 @ lr of instrumented func
191 mcount_adjust_addr r0, lr @ instrumented function
197 .macro __ftrace_caller suffix
200 mcount_get_lr r1 @ lr of instrumented func
201 mcount_adjust_addr r0, lr @ instrumented function
203 .globl ftrace_call\suffix
207 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
208 .globl ftrace_graph_call\suffix
209 ftrace_graph_call\suffix:
216 .macro __ftrace_graph_caller
217 sub r0, fp, #4 @ &lr of instrumented routine (&parent)
218 #ifdef CONFIG_DYNAMIC_FTRACE
219 @ called from __ftrace_caller, saved in mcount_enter
220 ldr r1, [sp, #16] @ instrumented routine (func)
221 mcount_adjust_addr r1, r1
223 @ called from __mcount, untouched in lr
224 mcount_adjust_addr r1, lr @ instrumented routine (func)
226 mov r2, fp @ frame pointer
227 bl prepare_ftrace_return
231 #ifdef CONFIG_OLD_MCOUNT
237 stmdb sp!, {r0-r3, lr}
240 .macro mcount_get_lr reg
246 ldmia sp!, {r0-r3, pc}
250 #ifdef CONFIG_DYNAMIC_FTRACE
259 #ifdef CONFIG_DYNAMIC_FTRACE
260 ENTRY(ftrace_caller_old)
262 ENDPROC(ftrace_caller_old)
265 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
266 ENTRY(ftrace_graph_caller_old)
267 __ftrace_graph_caller
268 ENDPROC(ftrace_graph_caller_old)
272 .purgem mcount_get_lr
281 stmdb sp!, {r0-r3, lr}
284 .macro mcount_get_lr reg
289 ldmia sp!, {r0-r3, ip, lr}
293 ENTRY(__gnu_mcount_nc)
294 #ifdef CONFIG_DYNAMIC_FTRACE
301 ENDPROC(__gnu_mcount_nc)
303 #ifdef CONFIG_DYNAMIC_FTRACE
306 ENDPROC(ftrace_caller)
309 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
310 ENTRY(ftrace_graph_caller)
311 __ftrace_graph_caller
312 ENDPROC(ftrace_graph_caller)
316 .purgem mcount_get_lr
319 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
320 .globl return_to_handler
323 mov r0, fp @ frame pointer
324 bl ftrace_return_to_handler
325 mov lr, r0 @ r0 has real ret addr
335 #endif /* CONFIG_FUNCTION_TRACER */
337 /*=============================================================================
339 *-----------------------------------------------------------------------------
344 sub sp, sp, #S_FRAME_SIZE
345 stmia sp, {r0 - r12} @ Calling r0 - r12
346 ARM( add r8, sp, #S_PC )
347 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
349 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
350 mrs r8, spsr @ called from non-FIQ mode, so ok.
351 str lr, [sp, #S_PC] @ Save calling PC
352 str r8, [sp, #S_PSR] @ Save CPSR
353 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
357 * Get the system call number.
360 #if defined(CONFIG_OABI_COMPAT)
363 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
364 * value to determine if it is an EABI or an old ABI call.
366 #ifdef CONFIG_ARM_THUMB
368 movne r10, #0 @ no thumb OABI emulation
369 ldreq r10, [lr, #-4] @ get SWI instruction
371 ldr r10, [lr, #-4] @ get SWI instruction
373 #ifdef CONFIG_CPU_ENDIAN_BE8
374 rev r10, r10 @ little endian instruction
377 #elif defined(CONFIG_AEABI)
380 * Pure EABI user space always put syscall number into scno (r7).
382 #elif defined(CONFIG_ARM_THUMB)
383 /* Legacy ABI only, possibly thumb mode. */
384 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
385 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
386 ldreq scno, [lr, #-4]
389 /* Legacy ABI only. */
390 ldr scno, [lr, #-4] @ get SWI instruction
393 #ifdef CONFIG_ALIGNMENT_TRAP
394 ldr ip, __cr_alignment
396 mcr p15, 0, ip, c1, c0 @ update control register
401 adr tbl, sys_call_table @ load syscall table pointer
403 #if defined(CONFIG_OABI_COMPAT)
405 * If the swi argument is zero, this is an EABI call and we do nothing.
407 * If this is an old ABI call, get the syscall number into scno and
408 * get the old ABI syscall table address.
410 bics r10, r10, #0xff000000
411 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
412 ldrne tbl, =sys_oabi_call_table
413 #elif !defined(CONFIG_AEABI)
414 bic scno, scno, #0xff000000 @ mask off SWI op-code
415 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
418 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
419 stmdb sp!, {r4, r5} @ push fifth and sixth args
421 #ifdef CONFIG_SECCOMP
422 tst r10, #_TIF_SECCOMP
425 bl __secure_computing
426 add r0, sp, #S_R0 + S_OFF @ pointer to regs
427 ldmia r0, {r0 - r3} @ have to reload r0 - r3
431 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
434 cmp scno, #NR_syscalls @ check upper syscall limit
435 adr lr, BSYM(ret_fast_syscall) @ return address
436 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
439 2: mov why, #0 @ no longer a real syscall
440 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
441 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
443 b sys_ni_syscall @ not private func
447 * This is the really slow path. We're going to be doing
448 * context switches, and waiting for our parent to respond.
453 mov r0, #0 @ trace entry [IP = 0]
456 adr lr, BSYM(__sys_trace_return) @ return address
457 mov scno, r0 @ syscall number (possibly new)
458 add r1, sp, #S_R0 + S_OFF @ pointer to regs
459 cmp scno, #NR_syscalls @ check upper syscall limit
460 ldmccia r1, {r0 - r3} @ have to reload r0 - r3
461 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
465 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
468 mov r0, #1 @ trace exit [IP = 1]
473 #ifdef CONFIG_ALIGNMENT_TRAP
474 .type __cr_alignment, #object
481 * This is the syscall table declaration for native ABI syscalls.
482 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
484 #define ABI(native, compat) native
486 #define OBSOLETE(syscall) sys_ni_syscall
488 #define OBSOLETE(syscall) syscall
491 .type sys_call_table, #object
492 ENTRY(sys_call_table)
497 /*============================================================================
498 * Special system call wrappers
500 @ r0 = syscall number
503 bic scno, r0, #__NR_OABI_SYSCALL_BASE
504 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
505 cmpne scno, #NR_syscalls @ check range
506 stmloia sp, {r5, r6} @ shuffle args
511 ldrlo pc, [tbl, scno, lsl #2]
518 ENDPROC(sys_fork_wrapper)
523 ENDPROC(sys_vfork_wrapper)
528 ENDPROC(sys_execve_wrapper)
534 ENDPROC(sys_clone_wrapper)
536 sys_sigreturn_wrapper:
538 mov why, #0 @ prevent syscall restart handling
540 ENDPROC(sys_sigreturn_wrapper)
542 sys_rt_sigreturn_wrapper:
544 mov why, #0 @ prevent syscall restart handling
546 ENDPROC(sys_rt_sigreturn_wrapper)
548 sys_sigaltstack_wrapper:
549 ldr r2, [sp, #S_OFF + S_SP]
551 ENDPROC(sys_sigaltstack_wrapper)
553 sys_statfs64_wrapper:
557 ENDPROC(sys_statfs64_wrapper)
559 sys_fstatfs64_wrapper:
563 ENDPROC(sys_fstatfs64_wrapper)
566 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
567 * offset, we return EINVAL.
572 moveq r5, r5, lsr #PAGE_SHIFT - 12
583 #ifdef CONFIG_OABI_COMPAT
586 * These are syscalls with argument register differences
592 ENDPROC(sys_oabi_pread64)
597 ENDPROC(sys_oabi_pwrite64)
603 ENDPROC(sys_oabi_truncate64)
605 sys_oabi_ftruncate64:
609 ENDPROC(sys_oabi_ftruncate64)
616 ENDPROC(sys_oabi_readahead)
619 * Let's declare a second syscall table for old ABI binaries
620 * using the compatibility syscall entries.
622 #define ABI(native, compat) compat
623 #define OBSOLETE(syscall) syscall
625 .type sys_oabi_call_table, #object
626 ENTRY(sys_oabi_call_table)