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 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
134 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
135 * arch/arm/kernel/ftrace.c).
138 #ifndef CONFIG_OLD_MCOUNT
139 #if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
140 #error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
144 .macro __mcount suffix
146 ldr r0, =ftrace_trace_function
148 adr r0, .Lftrace_stub
152 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
153 ldr r1, =ftrace_graph_return
156 bne ftrace_graph_caller\suffix
158 ldr r1, =ftrace_graph_entry
160 ldr r0, =ftrace_graph_entry_stub
162 bne ftrace_graph_caller\suffix
167 1: mcount_get_lr r1 @ lr of instrumented func
168 mov r0, lr @ instrumented function
169 sub r0, r0, #MCOUNT_INSN_SIZE
175 .macro __ftrace_caller suffix
178 mcount_get_lr r1 @ lr of instrumented func
179 mov r0, lr @ instrumented function
180 sub r0, r0, #MCOUNT_INSN_SIZE
182 .globl ftrace_call\suffix
186 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
187 .globl ftrace_graph_call\suffix
188 ftrace_graph_call\suffix:
195 .macro __ftrace_graph_caller
196 sub r0, fp, #4 @ &lr of instrumented routine (&parent)
197 #ifdef CONFIG_DYNAMIC_FTRACE
198 @ called from __ftrace_caller, saved in mcount_enter
199 ldr r1, [sp, #16] @ instrumented routine (func)
201 @ called from __mcount, untouched in lr
202 mov r1, lr @ instrumented routine (func)
204 sub r1, r1, #MCOUNT_INSN_SIZE
205 mov r2, fp @ frame pointer
206 bl prepare_ftrace_return
210 #ifdef CONFIG_OLD_MCOUNT
216 stmdb sp!, {r0-r3, lr}
219 .macro mcount_get_lr reg
225 ldmia sp!, {r0-r3, pc}
229 #ifdef CONFIG_DYNAMIC_FTRACE
238 #ifdef CONFIG_DYNAMIC_FTRACE
239 ENTRY(ftrace_caller_old)
241 ENDPROC(ftrace_caller_old)
244 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
245 ENTRY(ftrace_graph_caller_old)
246 __ftrace_graph_caller
247 ENDPROC(ftrace_graph_caller_old)
251 .purgem mcount_get_lr
260 stmdb sp!, {r0-r3, lr}
263 .macro mcount_get_lr reg
268 ldmia sp!, {r0-r3, ip, lr}
272 ENTRY(__gnu_mcount_nc)
273 #ifdef CONFIG_DYNAMIC_FTRACE
280 ENDPROC(__gnu_mcount_nc)
282 #ifdef CONFIG_DYNAMIC_FTRACE
285 ENDPROC(ftrace_caller)
288 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
289 ENTRY(ftrace_graph_caller)
290 __ftrace_graph_caller
291 ENDPROC(ftrace_graph_caller)
295 .purgem mcount_get_lr
298 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
299 .globl return_to_handler
302 mov r0, fp @ frame pointer
303 bl ftrace_return_to_handler
304 mov lr, r0 @ r0 has real ret addr
314 #endif /* CONFIG_FUNCTION_TRACER */
316 /*=============================================================================
318 *-----------------------------------------------------------------------------
321 /* If we're optimising for StrongARM the resulting code won't
322 run on an ARM7 and we can save a couple of instructions.
324 #ifdef CONFIG_CPU_ARM710
325 #define A710(code...) code
327 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr
329 add sp, sp, #S_FRAME_SIZE
332 #define A710(code...)
337 sub sp, sp, #S_FRAME_SIZE
338 stmia sp, {r0 - r12} @ Calling r0 - r12
339 ARM( add r8, sp, #S_PC )
340 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
342 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
343 mrs r8, spsr @ called from non-FIQ mode, so ok.
344 str lr, [sp, #S_PC] @ Save calling PC
345 str r8, [sp, #S_PSR] @ Save CPSR
346 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
350 * Get the system call number.
353 #if defined(CONFIG_OABI_COMPAT)
356 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
357 * value to determine if it is an EABI or an old ABI call.
359 #ifdef CONFIG_ARM_THUMB
361 movne r10, #0 @ no thumb OABI emulation
362 ldreq r10, [lr, #-4] @ get SWI instruction
364 ldr r10, [lr, #-4] @ get SWI instruction
365 A710( and ip, r10, #0x0f000000 @ check for SWI )
366 A710( teq ip, #0x0f000000 )
367 A710( bne .Larm710bug )
369 #ifdef CONFIG_CPU_ENDIAN_BE8
370 rev r10, r10 @ little endian instruction
373 #elif defined(CONFIG_AEABI)
376 * Pure EABI user space always put syscall number into scno (r7).
378 A710( ldr ip, [lr, #-4] @ get SWI instruction )
379 A710( and ip, ip, #0x0f000000 @ check for SWI )
380 A710( teq ip, #0x0f000000 )
381 A710( bne .Larm710bug )
383 #elif defined(CONFIG_ARM_THUMB)
385 /* Legacy ABI only, possibly thumb mode. */
386 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
387 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
388 ldreq scno, [lr, #-4]
392 /* Legacy ABI only. */
393 ldr scno, [lr, #-4] @ get SWI instruction
394 A710( and ip, scno, #0x0f000000 @ check for SWI )
395 A710( teq ip, #0x0f000000 )
396 A710( bne .Larm710bug )
400 #ifdef CONFIG_ALIGNMENT_TRAP
401 ldr ip, __cr_alignment
403 mcr p15, 0, ip, c1, c0 @ update control register
408 adr tbl, sys_call_table @ load syscall table pointer
410 #if defined(CONFIG_OABI_COMPAT)
412 * If the swi argument is zero, this is an EABI call and we do nothing.
414 * If this is an old ABI call, get the syscall number into scno and
415 * get the old ABI syscall table address.
417 bics r10, r10, #0xff000000
418 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
419 ldrne tbl, =sys_oabi_call_table
420 #elif !defined(CONFIG_AEABI)
421 bic scno, scno, #0xff000000 @ mask off SWI op-code
422 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
425 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
426 stmdb sp!, {r4, r5} @ push fifth and sixth args
428 #ifdef CONFIG_SECCOMP
429 tst r10, #_TIF_SECCOMP
432 bl __secure_computing
433 add r0, sp, #S_R0 + S_OFF @ pointer to regs
434 ldmia r0, {r0 - r3} @ have to reload r0 - r3
438 tst r10, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
441 cmp scno, #NR_syscalls @ check upper syscall limit
442 adr lr, BSYM(ret_fast_syscall) @ return address
443 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
446 2: mov why, #0 @ no longer a real syscall
447 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
448 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
450 b sys_ni_syscall @ not private func
454 * This is the really slow path. We're going to be doing
455 * context switches, and waiting for our parent to respond.
460 mov r0, #0 @ trace entry [IP = 0]
463 adr lr, BSYM(__sys_trace_return) @ return address
464 mov scno, r0 @ syscall number (possibly new)
465 add r1, sp, #S_R0 + S_OFF @ pointer to regs
466 cmp scno, #NR_syscalls @ check upper syscall limit
467 ldmccia r1, {r0 - r3} @ have to reload r0 - r3
468 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
472 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
475 mov r0, #1 @ trace exit [IP = 1]
480 #ifdef CONFIG_ALIGNMENT_TRAP
481 .type __cr_alignment, #object
488 * This is the syscall table declaration for native ABI syscalls.
489 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
491 #define ABI(native, compat) native
493 #define OBSOLETE(syscall) sys_ni_syscall
495 #define OBSOLETE(syscall) syscall
498 .type sys_call_table, #object
499 ENTRY(sys_call_table)
504 /*============================================================================
505 * Special system call wrappers
507 @ r0 = syscall number
510 bic scno, r0, #__NR_OABI_SYSCALL_BASE
511 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
512 cmpne scno, #NR_syscalls @ check range
513 stmloia sp, {r5, r6} @ shuffle args
518 ldrlo pc, [tbl, scno, lsl #2]
525 ENDPROC(sys_fork_wrapper)
530 ENDPROC(sys_vfork_wrapper)
535 ENDPROC(sys_execve_wrapper)
541 ENDPROC(sys_clone_wrapper)
543 sys_sigreturn_wrapper:
545 mov why, #0 @ prevent syscall restart handling
547 ENDPROC(sys_sigreturn_wrapper)
549 sys_rt_sigreturn_wrapper:
551 mov why, #0 @ prevent syscall restart handling
553 ENDPROC(sys_rt_sigreturn_wrapper)
555 sys_sigaltstack_wrapper:
556 ldr r2, [sp, #S_OFF + S_SP]
558 ENDPROC(sys_sigaltstack_wrapper)
560 sys_statfs64_wrapper:
564 ENDPROC(sys_statfs64_wrapper)
566 sys_fstatfs64_wrapper:
570 ENDPROC(sys_fstatfs64_wrapper)
573 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
574 * offset, we return EINVAL.
579 moveq r5, r5, lsr #PAGE_SHIFT - 12
590 #ifdef CONFIG_OABI_COMPAT
593 * These are syscalls with argument register differences
599 ENDPROC(sys_oabi_pread64)
604 ENDPROC(sys_oabi_pwrite64)
610 ENDPROC(sys_oabi_truncate64)
612 sys_oabi_ftruncate64:
616 ENDPROC(sys_oabi_ftruncate64)
623 ENDPROC(sys_oabi_readahead)
626 * Let's declare a second syscall table for old ABI binaries
627 * using the compatibility syscall entries.
629 #define ABI(native, compat) compat
630 #define OBSOLETE(syscall) syscall
632 .type sys_oabi_call_table, #object
633 ENTRY(sys_oabi_call_table)