/* * 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 #ifdef CONFIG_NEED_RET_TO_USER #include #else .macro arch_ret_to_user, tmp1, tmp2 .endm #endif #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 asm_trace_hardirqs_on /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr ct_user_enter 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: mov r0, sp @ 'regs' mov r2, why @ 'syscall' bl do_work_pending cmp r0, #0 beq no_work_pending movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) ldmia sp, {r0 - r6} @ have to reload r0 - r6 b local_restart @ ... and off we go /* * "slow" syscall return path. "why" tells us if this was a real syscall. */ ENTRY(ret_to_user) ret_slow_syscall: disable_irq @ disable interrupts ENTRY(ret_to_user_from_irq) ldr r1, [tsk, #TI_FLAGS] tst r1, #_TIF_WORK_MASK bne work_pending no_work_pending: asm_trace_hardirqs_on /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr ct_user_enter save = 0 restore_user_regs fast = 0, offset = 0 ENDPROC(ret_to_user_from_irq) ENDPROC(ret_to_user) /* * This is how we return from a fork. */ ENTRY(ret_from_fork) bl schedule_tail cmp r5, #0 movne r0, r4 adrne lr, BSYM(1f) retne r5 1: get_thread_info tsk b ret_slow_syscall ENDPROC(ret_from_fork) .equ NR_syscalls,0 #define CALL(x) .equ NR_syscalls,NR_syscalls+1 #include "calls.S" /* * Ensure that the system call table is equal to __NR_syscalls, * which is the value the rest of the system sees */ .ifne NR_syscalls - __NR_syscalls .error "__NR_syscalls is not equal to the size of the syscall table" .endif #undef CALL #define CALL(x) .long x /*============================================================================= * SWI handler *----------------------------------------------------------------------------- */ .align 5 ENTRY(vector_swi) #ifdef CONFIG_CPU_V7M v7m_exception_entry #else 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 #endif zero_fp alignment_trap r10, ip, __cr_alignment enable_irq ct_user_exit get_thread_info tsk /* * 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 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction #else USER( ldr r10, [lr, #-4] ) @ get SWI instruction #endif ARM_BE8(rev r10, r10) @ little endian instruction #elif defined(CONFIG_AEABI) /* * Pure EABI user space always put syscall number into scno (r7). */ #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 USER( ldreq scno, [lr, #-4] ) #else /* Legacy ABI only. */ USER( ldr scno, [lr, #-4] ) @ get SWI instruction #endif 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 local_restart: ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing stmdb sp!, {r4, r5} @ push fifth and sixth args tst r10, #_TIF_SYSCALL_WORK @ 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: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back bcs arm_syscall mov why, #0 @ no longer a real syscall b sys_ni_syscall @ not private func #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) /* * We failed to handle a fault trying to access the page * containing the swi instruction, but we're not really in a * position to return -EFAULT. Instead, return back to the * instruction and re-enter the user fault handling path trying * to page it in. This will likely result in sending SEGV to the * current task. */ 9001: sub lr, lr, #4 str lr, [sp, #S_PC] b ret_fast_syscall #endif 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 r1, scno add r0, sp, #S_OFF bl syscall_trace_enter 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 - r6} @ have to reload r0 - r6 stmccia sp, {r4, r5} @ and update the stack args ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine cmp scno, #-1 @ skip the syscall? bne 2b add sp, sp, #S_OFF @ restore stack b ret_slow_syscall __sys_trace_return: str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 mov r0, sp bl syscall_trace_exit 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_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_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 ret 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