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] @ re-check for syscall tracing
36 tst r1, #_TIF_SYSCALL_WORK
37 bne __sys_trace_return
38 tst r1, #_TIF_WORK_MASK
42 /* perform architecture specific actions before user return */
43 arch_ret_to_user r1, lr
46 restore_user_regs fast = 1, offset = S_OFF
50 * Ok, we need to do extra processing, enter the slow path.
53 str r0, [sp, #S_R0+S_OFF]! @ returned r0
56 mov r2, why @ 'syscall'
60 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
61 ldmia sp, {r0 - r6} @ have to reload r0 - r6
62 b local_restart @ ... and off we go
65 * "slow" syscall return path. "why" tells us if this was a real syscall.
69 disable_irq @ disable interrupts
70 ENTRY(ret_to_user_from_irq)
71 ldr r1, [tsk, #TI_FLAGS]
72 tst r1, #_TIF_WORK_MASK
77 /* perform architecture specific actions before user return */
78 arch_ret_to_user r1, lr
79 ct_user_enter save = 0
81 restore_user_regs fast = 0, offset = 0
82 ENDPROC(ret_to_user_from_irq)
86 * This is how we return from a fork.
94 1: get_thread_info tsk
96 ENDPROC(ret_from_fork)
99 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
103 * Ensure that the system call table is equal to __NR_syscalls,
104 * which is the value the rest of the system sees
106 .ifne NR_syscalls - __NR_syscalls
107 .error "__NR_syscalls is not equal to the size of the syscall table"
111 #define CALL(x) .long x
113 #ifdef CONFIG_FUNCTION_TRACER
115 * When compiling with -pg, gcc inserts a call to the mcount routine at the
116 * start of every function. In mcount, apart from the function's address (in
117 * lr), we need to get hold of the function's caller's address.
119 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
123 * These versions have the limitation that in order for the mcount routine to
124 * be able to determine the function's caller's address, an APCS-style frame
125 * pointer (which is set up with something like the code below) is required.
128 * push {fp, ip, lr, pc}
131 * With EABI, these frame pointers are not available unless -mapcs-frame is
132 * specified, and if building as Thumb-2, not even then.
134 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
135 * with call sites like:
140 * With these compilers, frame pointers are not necessary.
142 * mcount can be thought of as a function called in the middle of a subroutine
143 * call. As such, it needs to be transparent for both the caller and the
144 * callee: the original lr needs to be restored when leaving mcount, and no
145 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we
146 * clobber the ip register. This is OK because the ARM calling convention
147 * allows it to be clobbered in subroutines and doesn't use it to hold
150 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
151 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
152 * arch/arm/kernel/ftrace.c).
155 #ifndef CONFIG_OLD_MCOUNT
156 #if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
157 #error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
161 .macro mcount_adjust_addr rd, rn
162 bic \rd, \rn, #1 @ clear the Thumb bit if present
163 sub \rd, \rd, #MCOUNT_INSN_SIZE
166 .macro __mcount suffix
168 ldr r0, =ftrace_trace_function
170 adr r0, .Lftrace_stub
174 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
175 ldr r1, =ftrace_graph_return
178 bne ftrace_graph_caller\suffix
180 ldr r1, =ftrace_graph_entry
182 ldr r0, =ftrace_graph_entry_stub
184 bne ftrace_graph_caller\suffix
189 1: mcount_get_lr r1 @ lr of instrumented func
190 mcount_adjust_addr r0, lr @ instrumented function
196 .macro __ftrace_caller suffix
199 mcount_get_lr r1 @ lr of instrumented func
200 mcount_adjust_addr r0, lr @ instrumented function
202 .globl ftrace_call\suffix
206 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
207 .globl ftrace_graph_call\suffix
208 ftrace_graph_call\suffix:
215 .macro __ftrace_graph_caller
216 sub r0, fp, #4 @ &lr of instrumented routine (&parent)
217 #ifdef CONFIG_DYNAMIC_FTRACE
218 @ called from __ftrace_caller, saved in mcount_enter
219 ldr r1, [sp, #16] @ instrumented routine (func)
220 mcount_adjust_addr r1, r1
222 @ called from __mcount, untouched in lr
223 mcount_adjust_addr r1, lr @ instrumented routine (func)
225 mov r2, fp @ frame pointer
226 bl prepare_ftrace_return
230 #ifdef CONFIG_OLD_MCOUNT
236 stmdb sp!, {r0-r3, lr}
239 .macro mcount_get_lr reg
245 ldmia sp!, {r0-r3, pc}
249 #ifdef CONFIG_DYNAMIC_FTRACE
258 #ifdef CONFIG_DYNAMIC_FTRACE
259 ENTRY(ftrace_caller_old)
261 ENDPROC(ftrace_caller_old)
264 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
265 ENTRY(ftrace_graph_caller_old)
266 __ftrace_graph_caller
267 ENDPROC(ftrace_graph_caller_old)
271 .purgem mcount_get_lr
281 * This pad compensates for the push {lr} at the call site. Note that we are
282 * unable to unwind through a function which does not otherwise save its lr.
285 stmdb sp!, {r0-r3, lr}
286 UNWIND(.save {r0-r3, lr})
289 .macro mcount_get_lr reg
294 ldmia sp!, {r0-r3, ip, lr}
298 ENTRY(__gnu_mcount_nc)
300 #ifdef CONFIG_DYNAMIC_FTRACE
308 ENDPROC(__gnu_mcount_nc)
310 #ifdef CONFIG_DYNAMIC_FTRACE
315 ENDPROC(ftrace_caller)
318 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
319 ENTRY(ftrace_graph_caller)
321 __ftrace_graph_caller
323 ENDPROC(ftrace_graph_caller)
327 .purgem mcount_get_lr
330 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
331 .globl return_to_handler
334 mov r0, fp @ frame pointer
335 bl ftrace_return_to_handler
336 mov lr, r0 @ r0 has real ret addr
346 #endif /* CONFIG_FUNCTION_TRACER */
348 /*=============================================================================
350 *-----------------------------------------------------------------------------
355 sub sp, sp, #S_FRAME_SIZE
356 stmia sp, {r0 - r12} @ Calling r0 - r12
357 ARM( add r8, sp, #S_PC )
358 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
360 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
361 mrs r8, spsr @ called from non-FIQ mode, so ok.
362 str lr, [sp, #S_PC] @ Save calling PC
363 str r8, [sp, #S_PSR] @ Save CPSR
364 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
367 #ifdef CONFIG_ALIGNMENT_TRAP
368 ldr ip, __cr_alignment
370 mcr p15, 0, ip, c1, c0 @ update control register
378 * Get the system call number.
381 #if defined(CONFIG_OABI_COMPAT)
384 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
385 * value to determine if it is an EABI or an old ABI call.
387 #ifdef CONFIG_ARM_THUMB
389 movne r10, #0 @ no thumb OABI emulation
390 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction
392 USER( ldr r10, [lr, #-4] ) @ get SWI instruction
394 ARM_BE8(rev r10, r10) @ little endian instruction
396 #elif defined(CONFIG_AEABI)
399 * Pure EABI user space always put syscall number into scno (r7).
401 #elif defined(CONFIG_ARM_THUMB)
402 /* Legacy ABI only, possibly thumb mode. */
403 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
404 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
405 USER( ldreq scno, [lr, #-4] )
408 /* Legacy ABI only. */
409 USER( ldr scno, [lr, #-4] ) @ get SWI instruction
412 adr tbl, sys_call_table @ load syscall table pointer
414 #if defined(CONFIG_OABI_COMPAT)
416 * If the swi argument is zero, this is an EABI call and we do nothing.
418 * If this is an old ABI call, get the syscall number into scno and
419 * get the old ABI syscall table address.
421 bics r10, r10, #0xff000000
422 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
423 ldrne tbl, =sys_oabi_call_table
424 #elif !defined(CONFIG_AEABI)
425 bic scno, scno, #0xff000000 @ mask off SWI op-code
426 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
430 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
431 stmdb sp!, {r4, r5} @ push fifth and sixth args
433 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
436 cmp scno, #NR_syscalls @ check upper syscall limit
437 adr lr, BSYM(ret_fast_syscall) @ return address
438 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
441 2: mov why, #0 @ no longer a real syscall
442 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
443 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
445 b sys_ni_syscall @ not private func
447 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
449 * We failed to handle a fault trying to access the page
450 * containing the swi instruction, but we're not really in a
451 * position to return -EFAULT. Instead, return back to the
452 * instruction and re-enter the user fault handling path trying
453 * to page it in. This will likely result in sending SEGV to the
464 * This is the really slow path. We're going to be doing
465 * context switches, and waiting for our parent to respond.
470 bl syscall_trace_enter
472 adr lr, BSYM(__sys_trace_return) @ return address
473 mov scno, r0 @ syscall number (possibly new)
474 add r1, sp, #S_R0 + S_OFF @ pointer to regs
475 cmp scno, #NR_syscalls @ check upper syscall limit
476 ldmccia r1, {r0 - r6} @ have to reload r0 - r6
477 stmccia sp, {r4, r5} @ and update the stack args
478 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
479 cmp scno, #-1 @ skip the syscall?
481 add sp, sp, #S_OFF @ restore stack
485 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
487 bl syscall_trace_exit
491 #ifdef CONFIG_ALIGNMENT_TRAP
492 .type __cr_alignment, #object
499 * This is the syscall table declaration for native ABI syscalls.
500 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
502 #define ABI(native, compat) native
504 #define OBSOLETE(syscall) sys_ni_syscall
506 #define OBSOLETE(syscall) syscall
509 .type sys_call_table, #object
510 ENTRY(sys_call_table)
515 /*============================================================================
516 * Special system call wrappers
518 @ r0 = syscall number
521 bic scno, r0, #__NR_OABI_SYSCALL_BASE
522 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
523 cmpne scno, #NR_syscalls @ check range
524 stmloia sp, {r5, r6} @ shuffle args
529 ldrlo pc, [tbl, scno, lsl #2]
533 sys_sigreturn_wrapper:
535 mov why, #0 @ prevent syscall restart handling
537 ENDPROC(sys_sigreturn_wrapper)
539 sys_rt_sigreturn_wrapper:
541 mov why, #0 @ prevent syscall restart handling
543 ENDPROC(sys_rt_sigreturn_wrapper)
545 sys_statfs64_wrapper:
549 ENDPROC(sys_statfs64_wrapper)
551 sys_fstatfs64_wrapper:
555 ENDPROC(sys_fstatfs64_wrapper)
558 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
559 * offset, we return EINVAL.
564 moveq r5, r5, lsr #PAGE_SHIFT - 12
575 #ifdef CONFIG_OABI_COMPAT
578 * These are syscalls with argument register differences
584 ENDPROC(sys_oabi_pread64)
589 ENDPROC(sys_oabi_pwrite64)
595 ENDPROC(sys_oabi_truncate64)
597 sys_oabi_ftruncate64:
601 ENDPROC(sys_oabi_ftruncate64)
608 ENDPROC(sys_oabi_readahead)
611 * Let's declare a second syscall table for old ABI binaries
612 * using the compatibility syscall entries.
614 #define ABI(native, compat) compat
615 #define OBSOLETE(syscall) syscall
617 .type sys_oabi_call_table, #object
618 ENTRY(sys_oabi_call_table)