/* * linux/arch/arm/kernel/entry-common.S * * Copyright (C) 2000 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include "entry-header.S" .align 5 /* * This is the fast syscall return path. We do as little as * possible here, and this includes saving r0 back into the SVC * stack. */ ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) disable_irq @ disable interrupts ldr r1, [tsk, #TI_FLAGS] tst r1, #_TIF_WORK_MASK bne fast_work_pending /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr restore_user_regs fast = 1, offset = S_OFF UNWIND(.fnend ) /* * Ok, we need to do extra processing, enter the slow path. */ fast_work_pending: str r0, [sp, #S_R0+S_OFF]! @ returned r0 work_pending: tst r1, #_TIF_NEED_RESCHED bne work_resched tst r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME beq no_work_pending mov r0, sp @ 'regs' mov r2, why @ 'syscall' tst r1, #_TIF_SIGPENDING @ delivering a signal? movne why, #0 @ prevent further restarts bl do_notify_resume b ret_slow_syscall @ Check work again work_resched: bl schedule /* * "slow" syscall return path. "why" tells us if this was a real syscall. */ ENTRY(ret_to_user) ret_slow_syscall: disable_irq @ disable interrupts ldr r1, [tsk, #TI_FLAGS] tst r1, #_TIF_WORK_MASK bne work_pending no_work_pending: /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr restore_user_regs fast = 0, offset = 0 ENDPROC(ret_to_user) /* * This is how we return from a fork. */ ENTRY(ret_from_fork) bl schedule_tail get_thread_info tsk ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing mov why, #1 tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? beq ret_slow_syscall mov r1, sp mov r0, #1 @ trace exit [IP = 1] bl syscall_trace b ret_slow_syscall ENDPROC(ret_from_fork) .equ NR_syscalls,0 #define CALL(x) .equ NR_syscalls,NR_syscalls+1 #include "calls.S" #undef CALL #define CALL(x) .long x #ifdef CONFIG_FUNCTION_TRACER /* * When compiling with -pg, gcc inserts a call to the mcount routine at the * start of every function. In mcount, apart from the function's address (in * lr), we need to get hold of the function's caller's address. * * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: * * bl mcount * * These versions have the limitation that in order for the mcount routine to * be able to determine the function's caller's address, an APCS-style frame * pointer (which is set up with something like the code below) is required. * * mov ip, sp * push {fp, ip, lr, pc} * sub fp, ip, #4 * * With EABI, these frame pointers are not available unless -mapcs-frame is * specified, and if building as Thumb-2, not even then. * * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, * with call sites like: * * push {lr} * bl __gnu_mcount_nc * * With these compilers, frame pointers are not necessary. * * mcount can be thought of as a function called in the middle of a subroutine * call. As such, it needs to be transparent for both the caller and the * callee: the original lr needs to be restored when leaving mcount, and no * registers should be clobbered. (In the __gnu_mcount_nc implementation, we * clobber the ip register. This is OK because the ARM calling convention * allows it to be clobbered in subroutines and doesn't use it to hold * parameters.) * * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see * arch/arm/kernel/ftrace.c). */ #ifndef CONFIG_OLD_MCOUNT #if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) #error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. #endif #endif .macro __mcount suffix mcount_enter ldr r0, =ftrace_trace_function ldr r2, [r0] adr r0, .Lftrace_stub cmp r0, r2 bne 1f mcount_exit 1: mcount_get_lr r1 @ lr of instrumented func mov r0, lr @ instrumented function sub r0, r0, #MCOUNT_INSN_SIZE adr lr, BSYM(2f) mov pc, r2 2: mcount_exit .endm .macro __ftrace_caller suffix mcount_enter mcount_get_lr r1 @ lr of instrumented func mov r0, lr @ instrumented function sub r0, r0, #MCOUNT_INSN_SIZE .globl ftrace_call\suffix ftrace_call\suffix: bl ftrace_stub mcount_exit .endm #ifdef CONFIG_OLD_MCOUNT /* * mcount */ .macro mcount_enter stmdb sp!, {r0-r3, lr} .endm .macro mcount_get_lr reg ldr \reg, [fp, #-4] .endm .macro mcount_exit ldr lr, [fp, #-4] ldmia sp!, {r0-r3, pc} .endm ENTRY(mcount) #ifdef CONFIG_DYNAMIC_FTRACE stmdb sp!, {lr} ldr lr, [fp, #-4] ldmia sp!, {pc} #else __mcount _old #endif ENDPROC(mcount) #ifdef CONFIG_DYNAMIC_FTRACE ENTRY(ftrace_caller_old) __ftrace_caller _old ENDPROC(ftrace_caller_old) #endif .purgem mcount_enter .purgem mcount_get_lr .purgem mcount_exit #endif /* * __gnu_mcount_nc */ .macro mcount_enter stmdb sp!, {r0-r3, lr} .endm .macro mcount_get_lr reg ldr \reg, [sp, #20] .endm .macro mcount_exit ldmia sp!, {r0-r3, ip, lr} mov pc, ip .endm ENTRY(__gnu_mcount_nc) #ifdef CONFIG_DYNAMIC_FTRACE mov ip, lr ldmia sp!, {lr} mov pc, ip #else __mcount #endif ENDPROC(__gnu_mcount_nc) #ifdef CONFIG_DYNAMIC_FTRACE ENTRY(ftrace_caller) __ftrace_caller ENDPROC(ftrace_caller) #endif .purgem mcount_enter .purgem mcount_get_lr .purgem mcount_exit ENTRY(ftrace_stub) .Lftrace_stub: mov pc, lr ENDPROC(ftrace_stub) #endif /* CONFIG_FUNCTION_TRACER */ /*============================================================================= * SWI handler *----------------------------------------------------------------------------- */ /* If we're optimising for StrongARM the resulting code won't run on an ARM7 and we can save a couple of instructions. --pb */ #ifdef CONFIG_CPU_ARM710 #define A710(code...) code .Larm710bug: ldmia sp, {r0 - lr}^ @ Get calling r0 - lr mov r0, r0 add sp, sp, #S_FRAME_SIZE subs pc, lr, #4 #else #define A710(code...) #endif .align 5 ENTRY(vector_swi) sub sp, sp, #S_FRAME_SIZE stmia sp, {r0 - r12} @ Calling r0 - r12 ARM( add r8, sp, #S_PC ) ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr THUMB( mov r8, sp ) THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr mrs r8, spsr @ called from non-FIQ mode, so ok. str lr, [sp, #S_PC] @ Save calling PC str r8, [sp, #S_PSR] @ Save CPSR str r0, [sp, #S_OLD_R0] @ Save OLD_R0 zero_fp /* * Get the system call number. */ #if defined(CONFIG_OABI_COMPAT) /* * If we have CONFIG_OABI_COMPAT then we need to look at the swi * value to determine if it is an EABI or an old ABI call. */ #ifdef CONFIG_ARM_THUMB tst r8, #PSR_T_BIT movne r10, #0 @ no thumb OABI emulation ldreq r10, [lr, #-4] @ get SWI instruction #else ldr r10, [lr, #-4] @ get SWI instruction A710( and ip, r10, #0x0f000000 @ check for SWI ) A710( teq ip, #0x0f000000 ) A710( bne .Larm710bug ) #endif #ifdef CONFIG_CPU_ENDIAN_BE8 rev r10, r10 @ little endian instruction #endif #elif defined(CONFIG_AEABI) /* * Pure EABI user space always put syscall number into scno (r7). */ A710( ldr ip, [lr, #-4] @ get SWI instruction ) A710( and ip, ip, #0x0f000000 @ check for SWI ) A710( teq ip, #0x0f000000 ) A710( bne .Larm710bug ) #elif defined(CONFIG_ARM_THUMB) /* Legacy ABI only, possibly thumb mode. */ tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in ldreq scno, [lr, #-4] #else /* Legacy ABI only. */ ldr scno, [lr, #-4] @ get SWI instruction A710( and ip, scno, #0x0f000000 @ check for SWI ) A710( teq ip, #0x0f000000 ) A710( bne .Larm710bug ) #endif #ifdef CONFIG_ALIGNMENT_TRAP ldr ip, __cr_alignment ldr ip, [ip] mcr p15, 0, ip, c1, c0 @ update control register #endif enable_irq get_thread_info tsk adr tbl, sys_call_table @ load syscall table pointer #if defined(CONFIG_OABI_COMPAT) /* * If the swi argument is zero, this is an EABI call and we do nothing. * * If this is an old ABI call, get the syscall number into scno and * get the old ABI syscall table address. */ bics r10, r10, #0xff000000 eorne scno, r10, #__NR_OABI_SYSCALL_BASE ldrne tbl, =sys_oabi_call_table #elif !defined(CONFIG_AEABI) bic scno, scno, #0xff000000 @ mask off SWI op-code eor scno, scno, #__NR_SYSCALL_BASE @ check OS number #endif ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing stmdb sp!, {r4, r5} @ push fifth and sixth args #ifdef CONFIG_SECCOMP tst r10, #_TIF_SECCOMP beq 1f mov r0, scno bl __secure_computing add r0, sp, #S_R0 + S_OFF @ pointer to regs ldmia r0, {r0 - r3} @ have to reload r0 - r3 1: #endif tst r10, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? bne __sys_trace cmp scno, #NR_syscalls @ check upper syscall limit adr lr, BSYM(ret_fast_syscall) @ return address ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine add r1, sp, #S_OFF 2: mov why, #0 @ no longer a real syscall cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back bcs arm_syscall b sys_ni_syscall @ not private func ENDPROC(vector_swi) /* * This is the really slow path. We're going to be doing * context switches, and waiting for our parent to respond. */ __sys_trace: mov r2, scno add r1, sp, #S_OFF mov r0, #0 @ trace entry [IP = 0] bl syscall_trace adr lr, BSYM(__sys_trace_return) @ return address mov scno, r0 @ syscall number (possibly new) add r1, sp, #S_R0 + S_OFF @ pointer to regs cmp scno, #NR_syscalls @ check upper syscall limit ldmccia r1, {r0 - r3} @ have to reload r0 - r3 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine b 2b __sys_trace_return: str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 mov r2, scno mov r1, sp mov r0, #1 @ trace exit [IP = 1] bl syscall_trace b ret_slow_syscall .align 5 #ifdef CONFIG_ALIGNMENT_TRAP .type __cr_alignment, #object __cr_alignment: .word cr_alignment #endif .ltorg /* * This is the syscall table declaration for native ABI syscalls. * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. */ #define ABI(native, compat) native #ifdef CONFIG_AEABI #define OBSOLETE(syscall) sys_ni_syscall #else #define OBSOLETE(syscall) syscall #endif .type sys_call_table, #object ENTRY(sys_call_table) #include "calls.S" #undef ABI #undef OBSOLETE /*============================================================================ * Special system call wrappers */ @ r0 = syscall number @ r8 = syscall table sys_syscall: bic scno, r0, #__NR_OABI_SYSCALL_BASE cmp scno, #__NR_syscall - __NR_SYSCALL_BASE cmpne scno, #NR_syscalls @ check range stmloia sp, {r5, r6} @ shuffle args movlo r0, r1 movlo r1, r2 movlo r2, r3 movlo r3, r4 ldrlo pc, [tbl, scno, lsl #2] b sys_ni_syscall ENDPROC(sys_syscall) sys_fork_wrapper: add r0, sp, #S_OFF b sys_fork ENDPROC(sys_fork_wrapper) sys_vfork_wrapper: add r0, sp, #S_OFF b sys_vfork ENDPROC(sys_vfork_wrapper) sys_execve_wrapper: add r3, sp, #S_OFF b sys_execve ENDPROC(sys_execve_wrapper) sys_clone_wrapper: add ip, sp, #S_OFF str ip, [sp, #4] b sys_clone ENDPROC(sys_clone_wrapper) sys_sigreturn_wrapper: add r0, sp, #S_OFF mov why, #0 @ prevent syscall restart handling b sys_sigreturn ENDPROC(sys_sigreturn_wrapper) sys_rt_sigreturn_wrapper: add r0, sp, #S_OFF mov why, #0 @ prevent syscall restart handling b sys_rt_sigreturn ENDPROC(sys_rt_sigreturn_wrapper) sys_sigaltstack_wrapper: ldr r2, [sp, #S_OFF + S_SP] b do_sigaltstack ENDPROC(sys_sigaltstack_wrapper) sys_statfs64_wrapper: teq r1, #88 moveq r1, #84 b sys_statfs64 ENDPROC(sys_statfs64_wrapper) sys_fstatfs64_wrapper: teq r1, #88 moveq r1, #84 b sys_fstatfs64 ENDPROC(sys_fstatfs64_wrapper) /* * Note: off_4k (r5) is always units of 4K. If we can't do the requested * offset, we return EINVAL. */ sys_mmap2: #if PAGE_SHIFT > 12 tst r5, #PGOFF_MASK moveq r5, r5, lsr #PAGE_SHIFT - 12 streq r5, [sp, #4] beq sys_mmap_pgoff mov r0, #-EINVAL mov pc, lr #else str r5, [sp, #4] b sys_mmap_pgoff #endif ENDPROC(sys_mmap2) #ifdef CONFIG_OABI_COMPAT /* * These are syscalls with argument register differences */ sys_oabi_pread64: stmia sp, {r3, r4} b sys_pread64 ENDPROC(sys_oabi_pread64) sys_oabi_pwrite64: stmia sp, {r3, r4} b sys_pwrite64 ENDPROC(sys_oabi_pwrite64) sys_oabi_truncate64: mov r3, r2 mov r2, r1 b sys_truncate64 ENDPROC(sys_oabi_truncate64) sys_oabi_ftruncate64: mov r3, r2 mov r2, r1 b sys_ftruncate64 ENDPROC(sys_oabi_ftruncate64) sys_oabi_readahead: str r3, [sp] mov r3, r2 mov r2, r1 b sys_readahead ENDPROC(sys_oabi_readahead) /* * Let's declare a second syscall table for old ABI binaries * using the compatibility syscall entries. */ #define ABI(native, compat) compat #define OBSOLETE(syscall) syscall .type sys_oabi_call_table, #object ENTRY(sys_oabi_call_table) #include "calls.S" #undef ABI #undef OBSOLETE #endif