diff options
Diffstat (limited to 'arch/sh/kernel/entry-common.S')
| -rw-r--r-- | arch/sh/kernel/entry-common.S | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S new file mode 100644 index 0000000..5bc7fa9 --- /dev/null +++ b/arch/sh/kernel/entry-common.S @@ -0,0 +1,372 @@ +/* $Id: entry.S,v 1.37 2004/06/11 13:02:46 doyu Exp $ + * + * linux/arch/sh/entry.S + * + * Copyright (C) 1999, 2000, 2002 Niibe Yutaka + * Copyright (C) 2003 Paul Mundt + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + */ + +! NOTE: +! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address +! to be jumped is too far, but it causes illegal slot exception. + +/* + * entry.S contains the system-call and fault low-level handling routines. + * This also contains the timer-interrupt handler, as well as all interrupts + * and faults that can result in a task-switch. + * + * NOTE: This code handles signal-recognition, which happens every time + * after a timer-interrupt and after each system call. + * + * NOTE: This code uses a convention that instructions in the delay slot + * of a transfer-control instruction are indented by an extra space, thus: + * + * jmp @k0 ! control-transfer instruction + * ldc k1, ssr ! delay slot + * + * Stack layout in 'ret_from_syscall': + * ptrace needs to have all regs on the stack. + * if the order here is changed, it needs to be + * updated in ptrace.c and ptrace.h + * + * r0 + * ... + * r15 = stack pointer + * spc + * pr + * ssr + * gbr + * mach + * macl + * syscall # + * + */ + +#if defined(CONFIG_PREEMPT) +# define preempt_stop() cli +#else +# define preempt_stop() +# define resume_kernel __restore_all +#endif + +#if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB) +! Handle kernel debug if either kgdb (SW) or gdb-stub (FW) is present. +! If both are configured, handle the debug traps (breakpoints) in SW, +! but still allow BIOS traps to FW. + + .align 2 +debug_kernel: +#if defined(CONFIG_SH_STANDARD_BIOS) && defined(CONFIG_SH_KGDB) + /* Force BIOS call to FW (debug_trap put TRA in r8) */ + mov r8,r0 + shlr2 r0 + cmp/eq #0x3f,r0 + bt debug_kernel_fw +#endif /* CONFIG_SH_STANDARD_BIOS && CONFIG_SH_KGDB */ + +debug_enter: +#if defined(CONFIG_SH_KGDB) + /* Jump to kgdb, pass stacked regs as arg */ +debug_kernel_sw: + mov.l 3f, r0 + jmp @r0 + mov r15, r4 + .align 2 +3: .long kgdb_handle_exception +#endif /* CONFIG_SH_KGDB */ + +#endif /* CONFIG_SH_STANDARD_BIOS || CONFIG_SH_KGDB */ + + + .align 2 +debug_trap: +#if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB) + mov #OFF_SR, r0 + mov.l @(r0,r15), r0 ! get status register + shll r0 + shll r0 ! kernel space? + bt/s debug_kernel +#endif + mov.l @r15, r0 ! Restore R0 value + mov.l 1f, r8 + jmp @r8 + nop + + .align 2 +ENTRY(exception_error) + ! + sti + mov.l 2f, r0 + jmp @r0 + nop + +! + .align 2 +1: .long break_point_trap_software +2: .long do_exception_error + + .align 2 +ret_from_exception: + preempt_stop() +ENTRY(ret_from_irq) + ! + mov #OFF_SR, r0 + mov.l @(r0,r15), r0 ! get status register + shll r0 + shll r0 ! kernel space? + get_current_thread_info r8, r0 + bt resume_kernel ! Yes, it's from kernel, go back soon + +#ifdef CONFIG_PREEMPT + bra resume_userspace + nop +ENTRY(resume_kernel) + mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count + tst r0, r0 + bf noresched +need_resched: + mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags + tst #_TIF_NEED_RESCHED, r0 ! need_resched set? + bt noresched + + mov #OFF_SR, r0 + mov.l @(r0,r15), r0 ! get status register + and #0xf0, r0 ! interrupts off (exception path)? + cmp/eq #0xf0, r0 + bt noresched + + mov.l 1f, r0 + mov.l r0, @(TI_PRE_COUNT,r8) + + sti + mov.l 2f, r0 + jsr @r0 + nop + mov #0, r0 + mov.l r0, @(TI_PRE_COUNT,r8) + cli + + bra need_resched + nop +noresched: + bra __restore_all + nop + + .align 2 +1: .long PREEMPT_ACTIVE +2: .long schedule +#endif + +ENTRY(resume_userspace) + ! r8: current_thread_info + cli + mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags + tst #_TIF_WORK_MASK, r0 + bt/s __restore_all + tst #_TIF_NEED_RESCHED, r0 + + .align 2 +work_pending: + ! r0: current_thread_info->flags + ! r8: current_thread_info + ! t: result of "tst #_TIF_NEED_RESCHED, r0" + bf/s work_resched + tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 +work_notifysig: + bt/s __restore_all + mov r15, r4 + mov r12, r5 ! set arg1(save_r0) + mov r0, r6 + mov.l 2f, r1 + mov.l 3f, r0 + jmp @r1 + lds r0, pr +work_resched: +#ifndef CONFIG_PREEMPT + ! gUSA handling + mov.l @(OFF_SP,r15), r0 ! get user space stack pointer + mov r0, r1 + shll r0 + bf/s 1f + shll r0 + bf/s 1f + mov #OFF_PC, r0 + ! SP >= 0xc0000000 : gUSA mark + mov.l @(r0,r15), r2 ! get user space PC (program counter) + mov.l @(OFF_R0,r15), r3 ! end point + cmp/hs r3, r2 ! r2 >= r3? + bt 1f + add r3, r1 ! rewind point #2 + mov.l r1, @(r0,r15) ! reset PC to rewind point #2 + ! +1: +#endif + mov.l 1f, r1 + jsr @r1 ! schedule + nop + cli + ! + mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags + tst #_TIF_WORK_MASK, r0 + bt __restore_all + bra work_pending + tst #_TIF_NEED_RESCHED, r0 + + .align 2 +1: .long schedule +2: .long do_notify_resume +3: .long restore_all + + .align 2 +syscall_exit_work: + ! r0: current_thread_info->flags + ! r8: current_thread_info + tst #_TIF_SYSCALL_TRACE, r0 + bt/s work_pending + tst #_TIF_NEED_RESCHED, r0 + sti + ! XXX setup arguments... + mov.l 4f, r0 ! do_syscall_trace + jsr @r0 + nop + bra resume_userspace + nop + + .align 2 +syscall_trace_entry: + ! Yes it is traced. + ! XXX setup arguments... + mov.l 4f, r11 ! Call do_syscall_trace which notifies + jsr @r11 ! superior (will chomp R[0-7]) + nop + ! Reload R0-R4 from kernel stack, where the + ! parent may have modified them using + ! ptrace(POKEUSR). (Note that R0-R2 are + ! used by the system call handler directly + ! from the kernel stack anyway, so don't need + ! to be reloaded here.) This allows the parent + ! to rewrite system calls and args on the fly. + mov.l @(OFF_R4,r15), r4 ! arg0 + mov.l @(OFF_R5,r15), r5 + mov.l @(OFF_R6,r15), r6 + mov.l @(OFF_R7,r15), r7 ! arg3 + mov.l @(OFF_R3,r15), r3 ! syscall_nr + ! Arrange for do_syscall_trace to be called + ! again as the system call returns. + mov.l 2f, r10 ! Number of syscalls + cmp/hs r10, r3 + bf syscall_call + mov #-ENOSYS, r0 + bra syscall_exit + mov.l r0, @(OFF_R0,r15) ! Return value + +__restore_all: + mov.l 1f,r0 + jmp @r0 + nop + + .align 2 +1: .long restore_all + +/* + * Syscall interface: + * + * Syscall #: R3 + * Arguments #0 to #3: R4--R7 + * Arguments #4 to #6: R0, R1, R2 + * TRA: (number of arguments + 0x10) x 4 + * + * This code also handles delegating other traps to the BIOS/gdb stub + * according to: + * + * Trap number + * (TRA>>2) Purpose + * -------- ------- + * 0x0-0xf old syscall ABI + * 0x10-0x1f new syscall ABI + * 0x20-0xff delegated through debug_trap to BIOS/gdb stub. + * + * Note: When we're first called, the TRA value must be shifted + * right 2 bits in order to get the value that was used as the "trapa" + * argument. + */ + + .align 2 + .globl ret_from_fork +ret_from_fork: + mov.l 1f, r8 + jsr @r8 + mov r0, r4 + bra syscall_exit + nop + .align 2 +1: .long schedule_tail + ! +ENTRY(system_call) +#if !defined(CONFIG_CPU_SH2) + mov.l 1f, r9 + mov.l @r9, r8 ! Read from TRA (Trap Address) Register +#endif + ! + ! Is the trap argument >= 0x20? (TRA will be >= 0x80) + mov #0x7f, r9 + cmp/hi r9, r8 + bt/s 0f + mov #OFF_TRA, r9 + add r15, r9 + ! + mov.l r8, @r9 ! set TRA value to tra + sti + ! Call the system call handler through the table. + ! First check for bad syscall number + mov r3, r9 + mov.l 2f, r8 ! Number of syscalls + cmp/hs r8, r9 + get_current_thread_info r8, r10 + bf good_system_call +syscall_badsys: ! Bad syscall number + mov #-ENOSYS, r0 + bra resume_userspace + mov.l r0, @(OFF_R0,r15) ! Return value + ! +0: + bra debug_trap + nop + ! +good_system_call: ! Good syscall number + mov.l @(TI_FLAGS,r8), r8 + mov #_TIF_SYSCALL_TRACE, r10 + tst r10, r8 + bf syscall_trace_entry + ! +syscall_call: + shll2 r9 ! x4 + mov.l 3f, r8 ! Load the address of sys_call_table + add r8, r9 + mov.l @r9, r8 + jsr @r8 ! jump to specific syscall handler + nop + mov.l @(OFF_R0,r15), r12 ! save r0 + mov.l r0, @(OFF_R0,r15) ! save the return value + ! +syscall_exit: + cli + ! + get_current_thread_info r8, r0 + mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags + tst #_TIF_ALLWORK_MASK, r0 + bf syscall_exit_work + bra __restore_all + nop + .align 2 +#if !defined(CONFIG_CPU_SH2) +1: .long TRA +#endif +2: .long NR_syscalls +3: .long sys_call_table +4: .long do_syscall_trace |
