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 #ifdef CONFIG_DYNAMIC_FTRACE
145 ENTRY(__gnu_mcount_nc)
149 ENDPROC(__gnu_mcount_nc)
152 stmdb sp!, {r0-r3, lr}
154 sub r0, r0, #MCOUNT_INSN_SIZE
160 ldmia sp!, {r0-r3, ip, lr}
162 ENDPROC(ftrace_caller)
164 #ifdef CONFIG_OLD_MCOUNT
171 ENTRY(ftrace_caller_old)
172 stmdb sp!, {r0-r3, lr}
175 sub r0, r0, #MCOUNT_INSN_SIZE
177 .globl ftrace_call_old
180 ldr lr, [fp, #-4] @ restore lr
181 ldmia sp!, {r0-r3, pc}
182 ENDPROC(ftrace_caller_old)
187 ENTRY(__gnu_mcount_nc)
188 stmdb sp!, {r0-r3, lr}
189 ldr r0, =ftrace_trace_function
191 adr r0, .Lftrace_stub
194 ldmia sp!, {r0-r3, ip, lr}
198 ldr r1, [sp, #20] @ lr of instrumented routine
200 sub r0, r0, #MCOUNT_INSN_SIZE
204 ldmia sp!, {r0-r3, ip, lr}
206 ENDPROC(__gnu_mcount_nc)
208 #ifdef CONFIG_OLD_MCOUNT
210 * This is under an ifdef in order to force link-time errors for people trying
211 * to build with !FRAME_POINTER with a GCC which doesn't use the new-style
215 stmdb sp!, {r0-r3, lr}
216 ldr r0, =ftrace_trace_function
221 ldr lr, [fp, #-4] @ restore lr
222 ldmia sp!, {r0-r3, pc}
225 ldr r1, [fp, #-4] @ lr of instrumented routine
227 sub r0, r0, #MCOUNT_INSN_SIZE
230 ldr lr, [fp, #-4] @ restore lr
231 ldmia sp!, {r0-r3, pc}
235 #endif /* CONFIG_DYNAMIC_FTRACE */
242 #endif /* CONFIG_FUNCTION_TRACER */
244 /*=============================================================================
246 *-----------------------------------------------------------------------------
249 /* If we're optimising for StrongARM the resulting code won't
250 run on an ARM7 and we can save a couple of instructions.
252 #ifdef CONFIG_CPU_ARM710
253 #define A710(code...) code
255 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr
257 add sp, sp, #S_FRAME_SIZE
260 #define A710(code...)
265 sub sp, sp, #S_FRAME_SIZE
266 stmia sp, {r0 - r12} @ Calling r0 - r12
267 ARM( add r8, sp, #S_PC )
268 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
270 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
271 mrs r8, spsr @ called from non-FIQ mode, so ok.
272 str lr, [sp, #S_PC] @ Save calling PC
273 str r8, [sp, #S_PSR] @ Save CPSR
274 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
278 * Get the system call number.
281 #if defined(CONFIG_OABI_COMPAT)
284 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
285 * value to determine if it is an EABI or an old ABI call.
287 #ifdef CONFIG_ARM_THUMB
289 movne r10, #0 @ no thumb OABI emulation
290 ldreq r10, [lr, #-4] @ get SWI instruction
292 ldr r10, [lr, #-4] @ get SWI instruction
293 A710( and ip, r10, #0x0f000000 @ check for SWI )
294 A710( teq ip, #0x0f000000 )
295 A710( bne .Larm710bug )
297 #ifdef CONFIG_CPU_ENDIAN_BE8
298 rev r10, r10 @ little endian instruction
301 #elif defined(CONFIG_AEABI)
304 * Pure EABI user space always put syscall number into scno (r7).
306 A710( ldr ip, [lr, #-4] @ get SWI instruction )
307 A710( and ip, ip, #0x0f000000 @ check for SWI )
308 A710( teq ip, #0x0f000000 )
309 A710( bne .Larm710bug )
311 #elif defined(CONFIG_ARM_THUMB)
313 /* Legacy ABI only, possibly thumb mode. */
314 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
315 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
316 ldreq scno, [lr, #-4]
320 /* Legacy ABI only. */
321 ldr scno, [lr, #-4] @ get SWI instruction
322 A710( and ip, scno, #0x0f000000 @ check for SWI )
323 A710( teq ip, #0x0f000000 )
324 A710( bne .Larm710bug )
328 #ifdef CONFIG_ALIGNMENT_TRAP
329 ldr ip, __cr_alignment
331 mcr p15, 0, ip, c1, c0 @ update control register
336 adr tbl, sys_call_table @ load syscall table pointer
337 ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing
339 #if defined(CONFIG_OABI_COMPAT)
341 * If the swi argument is zero, this is an EABI call and we do nothing.
343 * If this is an old ABI call, get the syscall number into scno and
344 * get the old ABI syscall table address.
346 bics r10, r10, #0xff000000
347 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
348 ldrne tbl, =sys_oabi_call_table
349 #elif !defined(CONFIG_AEABI)
350 bic scno, scno, #0xff000000 @ mask off SWI op-code
351 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
354 stmdb sp!, {r4, r5} @ push fifth and sixth args
355 tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
358 cmp scno, #NR_syscalls @ check upper syscall limit
359 adr lr, BSYM(ret_fast_syscall) @ return address
360 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
363 2: mov why, #0 @ no longer a real syscall
364 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
365 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
367 b sys_ni_syscall @ not private func
371 * This is the really slow path. We're going to be doing
372 * context switches, and waiting for our parent to respond.
377 mov r0, #0 @ trace entry [IP = 0]
380 adr lr, BSYM(__sys_trace_return) @ return address
381 mov scno, r0 @ syscall number (possibly new)
382 add r1, sp, #S_R0 + S_OFF @ pointer to regs
383 cmp scno, #NR_syscalls @ check upper syscall limit
384 ldmccia r1, {r0 - r3} @ have to reload r0 - r3
385 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
389 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
392 mov r0, #1 @ trace exit [IP = 1]
397 #ifdef CONFIG_ALIGNMENT_TRAP
398 .type __cr_alignment, #object
405 * This is the syscall table declaration for native ABI syscalls.
406 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
408 #define ABI(native, compat) native
410 #define OBSOLETE(syscall) sys_ni_syscall
412 #define OBSOLETE(syscall) syscall
415 .type sys_call_table, #object
416 ENTRY(sys_call_table)
421 /*============================================================================
422 * Special system call wrappers
424 @ r0 = syscall number
427 bic scno, r0, #__NR_OABI_SYSCALL_BASE
428 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
429 cmpne scno, #NR_syscalls @ check range
430 stmloia sp, {r5, r6} @ shuffle args
435 ldrlo pc, [tbl, scno, lsl #2]
442 ENDPROC(sys_fork_wrapper)
447 ENDPROC(sys_vfork_wrapper)
452 ENDPROC(sys_execve_wrapper)
458 ENDPROC(sys_clone_wrapper)
460 sys_sigreturn_wrapper:
462 mov why, #0 @ prevent syscall restart handling
464 ENDPROC(sys_sigreturn_wrapper)
466 sys_rt_sigreturn_wrapper:
468 mov why, #0 @ prevent syscall restart handling
470 ENDPROC(sys_rt_sigreturn_wrapper)
472 sys_sigaltstack_wrapper:
473 ldr r2, [sp, #S_OFF + S_SP]
475 ENDPROC(sys_sigaltstack_wrapper)
477 sys_statfs64_wrapper:
481 ENDPROC(sys_statfs64_wrapper)
483 sys_fstatfs64_wrapper:
487 ENDPROC(sys_fstatfs64_wrapper)
490 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
491 * offset, we return EINVAL.
496 moveq r5, r5, lsr #PAGE_SHIFT - 12
507 #ifdef CONFIG_OABI_COMPAT
510 * These are syscalls with argument register differences
516 ENDPROC(sys_oabi_pread64)
521 ENDPROC(sys_oabi_pwrite64)
527 ENDPROC(sys_oabi_truncate64)
529 sys_oabi_ftruncate64:
533 ENDPROC(sys_oabi_ftruncate64)
540 ENDPROC(sys_oabi_readahead)
543 * Let's declare a second syscall table for old ABI binaries
544 * using the compatibility syscall entries.
546 #define ABI(native, compat) compat
547 #define OBSOLETE(syscall) syscall
549 .type sys_oabi_call_table, #object
550 ENTRY(sys_oabi_call_table)