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'
52 b ret_slow_syscall @ Check work again
57 * "slow" syscall return path. "why" tells us if this was a real syscall.
61 disable_irq @ disable interrupts
62 ldr r1, [tsk, #TI_FLAGS]
63 tst r1, #_TIF_WORK_MASK
66 /* perform architecture specific actions before user return */
67 arch_ret_to_user r1, lr
69 restore_user_regs fast = 0, offset = 0
73 * This is how we return from a fork.
78 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing
80 tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
83 mov r0, #1 @ trace exit [IP = 1]
86 ENDPROC(ret_from_fork)
89 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
92 #define CALL(x) .long x
94 #ifdef CONFIG_FUNCTION_TRACER
96 * When compiling with -pg, gcc inserts a call to the mcount routine at the
97 * start of every function. In mcount, apart from the function's address (in
98 * lr), we need to get hold of the function's caller's address.
100 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
104 * These versions have the limitation that in order for the mcount routine to
105 * be able to determine the function's caller's address, an APCS-style frame
106 * pointer (which is set up with something like the code below) is required.
109 * push {fp, ip, lr, pc}
112 * With EABI, these frame pointers are not available unless -mapcs-frame is
113 * specified, and if building as Thumb-2, not even then.
115 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
116 * with call sites like:
121 * With these compilers, frame pointers are not necessary.
123 * mcount can be thought of as a function called in the middle of a subroutine
124 * call. As such, it needs to be transparent for both the caller and the
125 * callee: the original lr needs to be restored when leaving mcount, and no
126 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we
127 * clobber the ip register. This is OK because the ARM calling convention
128 * allows it to be clobbered in subroutines and doesn't use it to hold
131 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
132 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
133 * arch/arm/kernel/ftrace.c).
136 #ifndef CONFIG_OLD_MCOUNT
137 #if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
138 #error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
142 #ifdef CONFIG_DYNAMIC_FTRACE
143 ENTRY(__gnu_mcount_nc)
147 ENDPROC(__gnu_mcount_nc)
150 stmdb sp!, {r0-r3, lr}
152 sub r0, r0, #MCOUNT_INSN_SIZE
158 ldmia sp!, {r0-r3, ip, lr}
160 ENDPROC(ftrace_caller)
162 #ifdef CONFIG_OLD_MCOUNT
169 ENTRY(ftrace_caller_old)
170 stmdb sp!, {r0-r3, lr}
173 sub r0, r0, #MCOUNT_INSN_SIZE
175 .globl ftrace_call_old
178 ldr lr, [fp, #-4] @ restore lr
179 ldmia sp!, {r0-r3, pc}
180 ENDPROC(ftrace_caller_old)
185 ENTRY(__gnu_mcount_nc)
186 stmdb sp!, {r0-r3, lr}
187 ldr r0, =ftrace_trace_function
189 adr r0, .Lftrace_stub
192 ldmia sp!, {r0-r3, ip, lr}
196 ldr r1, [sp, #20] @ lr of instrumented routine
198 sub r0, r0, #MCOUNT_INSN_SIZE
202 ldmia sp!, {r0-r3, ip, lr}
204 ENDPROC(__gnu_mcount_nc)
206 #ifdef CONFIG_OLD_MCOUNT
208 * This is under an ifdef in order to force link-time errors for people trying
209 * to build with !FRAME_POINTER with a GCC which doesn't use the new-style
213 stmdb sp!, {r0-r3, lr}
214 ldr r0, =ftrace_trace_function
219 ldr lr, [fp, #-4] @ restore lr
220 ldmia sp!, {r0-r3, pc}
223 ldr r1, [fp, #-4] @ lr of instrumented routine
225 sub r0, r0, #MCOUNT_INSN_SIZE
228 ldr lr, [fp, #-4] @ restore lr
229 ldmia sp!, {r0-r3, pc}
233 #endif /* CONFIG_DYNAMIC_FTRACE */
240 #endif /* CONFIG_FUNCTION_TRACER */
242 /*=============================================================================
244 *-----------------------------------------------------------------------------
247 /* If we're optimising for StrongARM the resulting code won't
248 run on an ARM7 and we can save a couple of instructions.
250 #ifdef CONFIG_CPU_ARM710
251 #define A710(code...) code
253 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr
255 add sp, sp, #S_FRAME_SIZE
258 #define A710(code...)
263 sub sp, sp, #S_FRAME_SIZE
264 stmia sp, {r0 - r12} @ Calling r0 - r12
265 ARM( add r8, sp, #S_PC )
266 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
268 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
269 mrs r8, spsr @ called from non-FIQ mode, so ok.
270 str lr, [sp, #S_PC] @ Save calling PC
271 str r8, [sp, #S_PSR] @ Save CPSR
272 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
276 * Get the system call number.
279 #if defined(CONFIG_OABI_COMPAT)
282 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
283 * value to determine if it is an EABI or an old ABI call.
285 #ifdef CONFIG_ARM_THUMB
287 movne r10, #0 @ no thumb OABI emulation
288 ldreq r10, [lr, #-4] @ get SWI instruction
290 ldr r10, [lr, #-4] @ get SWI instruction
291 A710( and ip, r10, #0x0f000000 @ check for SWI )
292 A710( teq ip, #0x0f000000 )
293 A710( bne .Larm710bug )
295 #ifdef CONFIG_CPU_ENDIAN_BE8
296 rev r10, r10 @ little endian instruction
299 #elif defined(CONFIG_AEABI)
302 * Pure EABI user space always put syscall number into scno (r7).
304 A710( ldr ip, [lr, #-4] @ get SWI instruction )
305 A710( and ip, ip, #0x0f000000 @ check for SWI )
306 A710( teq ip, #0x0f000000 )
307 A710( bne .Larm710bug )
309 #elif defined(CONFIG_ARM_THUMB)
311 /* Legacy ABI only, possibly thumb mode. */
312 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
313 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
314 ldreq scno, [lr, #-4]
318 /* Legacy ABI only. */
319 ldr scno, [lr, #-4] @ get SWI instruction
320 A710( and ip, scno, #0x0f000000 @ check for SWI )
321 A710( teq ip, #0x0f000000 )
322 A710( bne .Larm710bug )
326 #ifdef CONFIG_ALIGNMENT_TRAP
327 ldr ip, __cr_alignment
329 mcr p15, 0, ip, c1, c0 @ update control register
334 adr tbl, sys_call_table @ load syscall table pointer
335 ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing
337 #if defined(CONFIG_OABI_COMPAT)
339 * If the swi argument is zero, this is an EABI call and we do nothing.
341 * If this is an old ABI call, get the syscall number into scno and
342 * get the old ABI syscall table address.
344 bics r10, r10, #0xff000000
345 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
346 ldrne tbl, =sys_oabi_call_table
347 #elif !defined(CONFIG_AEABI)
348 bic scno, scno, #0xff000000 @ mask off SWI op-code
349 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
352 stmdb sp!, {r4, r5} @ push fifth and sixth args
353 tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
356 cmp scno, #NR_syscalls @ check upper syscall limit
357 adr lr, BSYM(ret_fast_syscall) @ return address
358 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
361 2: mov why, #0 @ no longer a real syscall
362 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
363 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
365 b sys_ni_syscall @ not private func
369 * This is the really slow path. We're going to be doing
370 * context switches, and waiting for our parent to respond.
375 mov r0, #0 @ trace entry [IP = 0]
378 adr lr, BSYM(__sys_trace_return) @ return address
379 mov scno, r0 @ syscall number (possibly new)
380 add r1, sp, #S_R0 + S_OFF @ pointer to regs
381 cmp scno, #NR_syscalls @ check upper syscall limit
382 ldmccia r1, {r0 - r3} @ have to reload r0 - r3
383 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
387 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
390 mov r0, #1 @ trace exit [IP = 1]
395 #ifdef CONFIG_ALIGNMENT_TRAP
396 .type __cr_alignment, #object
403 * This is the syscall table declaration for native ABI syscalls.
404 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
406 #define ABI(native, compat) native
408 #define OBSOLETE(syscall) sys_ni_syscall
410 #define OBSOLETE(syscall) syscall
413 .type sys_call_table, #object
414 ENTRY(sys_call_table)
419 /*============================================================================
420 * Special system call wrappers
422 @ r0 = syscall number
425 bic scno, r0, #__NR_OABI_SYSCALL_BASE
426 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
427 cmpne scno, #NR_syscalls @ check range
428 stmloia sp, {r5, r6} @ shuffle args
433 ldrlo pc, [tbl, scno, lsl #2]
440 ENDPROC(sys_fork_wrapper)
445 ENDPROC(sys_vfork_wrapper)
450 ENDPROC(sys_execve_wrapper)
456 ENDPROC(sys_clone_wrapper)
458 sys_sigreturn_wrapper:
461 ENDPROC(sys_sigreturn_wrapper)
463 sys_rt_sigreturn_wrapper:
466 ENDPROC(sys_rt_sigreturn_wrapper)
468 sys_sigaltstack_wrapper:
469 ldr r2, [sp, #S_OFF + S_SP]
471 ENDPROC(sys_sigaltstack_wrapper)
473 sys_statfs64_wrapper:
477 ENDPROC(sys_statfs64_wrapper)
479 sys_fstatfs64_wrapper:
483 ENDPROC(sys_fstatfs64_wrapper)
486 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
487 * offset, we return EINVAL.
492 moveq r5, r5, lsr #PAGE_SHIFT - 12
503 #ifdef CONFIG_OABI_COMPAT
506 * These are syscalls with argument register differences
512 ENDPROC(sys_oabi_pread64)
517 ENDPROC(sys_oabi_pwrite64)
523 ENDPROC(sys_oabi_truncate64)
525 sys_oabi_ftruncate64:
529 ENDPROC(sys_oabi_ftruncate64)
536 ENDPROC(sys_oabi_readahead)
539 * Let's declare a second syscall table for old ABI binaries
540 * using the compatibility syscall entries.
542 #define ABI(native, compat) compat
543 #define OBSOLETE(syscall) syscall
545 .type sys_oabi_call_table, #object
546 ENTRY(sys_oabi_call_table)