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400 lines
8.5 KiB
400 lines
8.5 KiB
/* SPDX-License-Identifier: GPL-2.0 |
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* |
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* Copyright (C) 1999, 2000, 2002 Niibe Yutaka |
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* Copyright (C) 2003 - 2008 Paul Mundt |
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*/ |
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! NOTE: |
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! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address |
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! to be jumped is too far, but it causes illegal slot exception. |
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/* |
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* entry.S contains the system-call and fault low-level handling routines. |
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* This also contains the timer-interrupt handler, as well as all interrupts |
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* and faults that can result in a task-switch. |
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* |
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* NOTE: This code handles signal-recognition, which happens every time |
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* after a timer-interrupt and after each system call. |
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* |
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* NOTE: This code uses a convention that instructions in the delay slot |
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* of a transfer-control instruction are indented by an extra space, thus: |
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* |
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* jmp @k0 ! control-transfer instruction |
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* ldc k1, ssr ! delay slot |
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* |
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* Stack layout in 'ret_from_syscall': |
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* ptrace needs to have all regs on the stack. |
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* if the order here is changed, it needs to be |
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* updated in ptrace.c and ptrace.h |
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* |
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* r0 |
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* ... |
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* r15 = stack pointer |
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* spc |
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* pr |
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* ssr |
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* gbr |
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* mach |
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* macl |
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* syscall # |
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* |
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*/ |
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#include <asm/dwarf.h> |
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#if defined(CONFIG_PREEMPTION) |
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# define preempt_stop() cli ; TRACE_IRQS_OFF |
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#else |
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# define preempt_stop() |
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# define resume_kernel __restore_all |
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#endif |
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.align 2 |
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ENTRY(exception_error) |
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! |
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TRACE_IRQS_ON |
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sti |
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mov.l 1f, r0 |
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jmp @r0 |
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nop |
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.align 2 |
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1: .long do_exception_error |
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.align 2 |
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ret_from_exception: |
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CFI_STARTPROC simple |
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CFI_DEF_CFA r14, 0 |
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CFI_REL_OFFSET 17, 64 |
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CFI_REL_OFFSET 15, 60 |
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CFI_REL_OFFSET 14, 56 |
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CFI_REL_OFFSET 13, 52 |
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CFI_REL_OFFSET 12, 48 |
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CFI_REL_OFFSET 11, 44 |
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CFI_REL_OFFSET 10, 40 |
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CFI_REL_OFFSET 9, 36 |
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CFI_REL_OFFSET 8, 32 |
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preempt_stop() |
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ENTRY(ret_from_irq) |
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! |
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mov #OFF_SR, r0 |
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mov.l @(r0,r15), r0 ! get status register |
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shll r0 |
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shll r0 ! kernel space? |
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get_current_thread_info r8, r0 |
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bt resume_kernel ! Yes, it's from kernel, go back soon |
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#ifdef CONFIG_PREEMPTION |
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bra resume_userspace |
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nop |
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ENTRY(resume_kernel) |
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cli |
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TRACE_IRQS_OFF |
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mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count |
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tst r0, r0 |
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bf noresched |
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need_resched: |
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mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
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tst #_TIF_NEED_RESCHED, r0 ! need_resched set? |
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bt noresched |
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mov #OFF_SR, r0 |
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mov.l @(r0,r15), r0 ! get status register |
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shlr r0 |
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and #(0xf0>>1), r0 ! interrupts off (exception path)? |
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cmp/eq #(0xf0>>1), r0 |
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bt noresched |
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mov.l 1f, r0 |
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jsr @r0 ! call preempt_schedule_irq |
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nop |
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bra need_resched |
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nop |
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noresched: |
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bra __restore_all |
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nop |
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.align 2 |
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1: .long preempt_schedule_irq |
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#endif |
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ENTRY(resume_userspace) |
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! r8: current_thread_info |
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cli |
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TRACE_IRQS_OFF |
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mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
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tst #(_TIF_WORK_MASK & 0xff), r0 |
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bt/s __restore_all |
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tst #_TIF_NEED_RESCHED, r0 |
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.align 2 |
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work_pending: |
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! r0: current_thread_info->flags |
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! r8: current_thread_info |
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! t: result of "tst #_TIF_NEED_RESCHED, r0" |
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bf/s work_resched |
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tst #(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME), r0 |
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work_notifysig: |
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bt/s __restore_all |
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mov r15, r4 |
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mov r12, r5 ! set arg1(save_r0) |
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mov r0, r6 |
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sti |
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mov.l 2f, r1 |
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mov.l 3f, r0 |
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jmp @r1 |
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lds r0, pr |
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work_resched: |
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mov.l 1f, r1 |
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jsr @r1 ! schedule |
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nop |
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cli |
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TRACE_IRQS_OFF |
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! |
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mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
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tst #(_TIF_WORK_MASK & 0xff), r0 |
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bt __restore_all |
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bra work_pending |
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tst #_TIF_NEED_RESCHED, r0 |
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.align 2 |
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1: .long schedule |
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2: .long do_notify_resume |
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3: .long resume_userspace |
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.align 2 |
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syscall_exit_work: |
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! r0: current_thread_info->flags |
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! r8: current_thread_info |
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tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0 |
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bt/s work_pending |
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tst #_TIF_NEED_RESCHED, r0 |
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TRACE_IRQS_ON |
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sti |
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mov r15, r4 |
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mov.l 8f, r0 ! do_syscall_trace_leave |
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jsr @r0 |
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nop |
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bra resume_userspace |
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nop |
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__restore_all: |
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mov #OFF_SR, r0 |
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mov.l @(r0,r15), r0 ! get status register |
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shlr2 r0 |
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and #0x3c, r0 |
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cmp/eq #0x3c, r0 |
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bt 1f |
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TRACE_IRQS_ON |
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bra 2f |
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nop |
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1: |
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TRACE_IRQS_OFF |
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2: |
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mov.l 3f, r0 |
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jmp @r0 |
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nop |
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.align 2 |
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3: .long restore_all |
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.align 2 |
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syscall_badsys: ! Bad syscall number |
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get_current_thread_info r8, r0 |
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mov #-ENOSYS, r0 |
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bra resume_userspace |
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mov.l r0, @(OFF_R0,r15) ! Return value |
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/* |
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* The main debug trap handler. |
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* |
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* r8=TRA (not the trap number!) |
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* |
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* Note: This assumes that the trapa value is left in its original |
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* form (without the shlr2 shift) so the calculation for the jump |
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* call table offset remains a simple in place mask. |
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*/ |
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debug_trap: |
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mov r8, r0 |
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and #(0xf << 2), r0 |
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mov.l 1f, r8 |
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add r0, r8 |
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mov.l @r8, r8 |
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jsr @r8 |
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nop |
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bra ret_from_exception |
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nop |
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CFI_ENDPROC |
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.align 2 |
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1: .long debug_trap_table |
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/* |
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* Syscall interface: |
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* |
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* Syscall #: R3 |
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* Arguments #0 to #3: R4--R7 |
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* Arguments #4 to #6: R0, R1, R2 |
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* TRA: See following table. |
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* |
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* (TRA>>2) Purpose |
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* -------- ------- |
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* 0x00-0x0f original SH-3/4 syscall ABI (not in general use). |
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* 0x10-0x1f general SH-3/4 syscall ABI. |
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* 0x1f unified SH-2/3/4 syscall ABI (preferred). |
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* 0x20-0x2f original SH-2 syscall ABI. |
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* 0x30-0x3f debug traps used by the kernel. |
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* 0x40-0xff Not supported by all parts, so left unhandled. |
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* |
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* For making system calls, any trap number in the range for the |
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* given cpu model may be used, but the unified trap number 0x1f is |
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* preferred for compatibility with all models. |
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* |
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* The low bits of the trap number were once documented as matching |
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* the number of arguments, but they were never actually used as such |
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* by the kernel. SH-2 originally used its own separate trap range |
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* because several hardware exceptions fell in the range used for the |
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* SH-3/4 syscall ABI. |
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* |
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* This code also handles delegating other traps to the BIOS/gdb stub. |
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* |
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* Note: When we're first called, the TRA value must be shifted |
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* right 2 bits in order to get the value that was used as the "trapa" |
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* argument. |
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*/ |
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.align 2 |
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.globl ret_from_fork |
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ret_from_fork: |
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mov.l 1f, r8 |
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jsr @r8 |
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mov r0, r4 |
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bra syscall_exit |
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nop |
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.align 2 |
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.globl ret_from_kernel_thread |
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ret_from_kernel_thread: |
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mov.l 1f, r8 |
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jsr @r8 |
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mov r0, r4 |
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mov.l @(OFF_R5,r15), r5 ! fn |
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jsr @r5 |
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mov.l @(OFF_R4,r15), r4 ! arg |
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bra syscall_exit |
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nop |
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.align 2 |
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1: .long schedule_tail |
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/* |
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* The poorly named main trapa decode and dispatch routine, for |
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* system calls and debug traps through their respective jump tables. |
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*/ |
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ENTRY(system_call) |
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setup_frame_reg |
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#if !defined(CONFIG_CPU_SH2) |
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mov.l 1f, r9 |
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mov.l @r9, r8 ! Read from TRA (Trap Address) Register |
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#endif |
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mov #OFF_TRA, r10 |
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add r15, r10 |
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mov.l r8, @r10 ! set TRA value to tra |
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/* |
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* Check the trap type |
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*/ |
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mov #((0x20 << 2) - 1), r9 |
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cmp/hi r9, r8 |
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bt/s debug_trap ! it's a debug trap.. |
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nop |
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TRACE_IRQS_ON |
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sti |
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! |
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get_current_thread_info r8, r10 |
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mov.l @(TI_FLAGS,r8), r8 |
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mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 |
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mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 |
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tst r10, r8 |
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shll8 r9 |
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bf syscall_trace_entry |
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tst r9, r8 |
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bf syscall_trace_entry |
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! |
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mov.l 6f, r8 ! Number of syscalls |
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cmp/hs r8, r3 |
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bt syscall_badsys |
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! |
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syscall_call: |
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shll2 r3 ! x4 |
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mov.l 3f, r8 ! Load the address of sys_call_table |
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add r8, r3 |
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mov.l @r3, r8 |
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mov.l @(OFF_R2,r15), r2 |
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mov.l @(OFF_R1,r15), r1 |
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mov.l @(OFF_R0,r15), r0 |
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mov.l r2, @-r15 |
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mov.l r1, @-r15 |
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mov.l r0, @-r15 |
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jsr @r8 ! jump to specific syscall handler |
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nop |
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add #12, r15 |
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mov.l @(OFF_R0,r15), r12 ! save r0 |
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mov.l r0, @(OFF_R0,r15) ! save the return value |
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! |
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syscall_exit: |
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cli |
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TRACE_IRQS_OFF |
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! |
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get_current_thread_info r8, r0 |
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mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
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tst #(_TIF_ALLWORK_MASK & 0xff), r0 |
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mov #(_TIF_ALLWORK_MASK >> 8), r1 |
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bf syscall_exit_work |
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shlr8 r0 |
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tst r0, r1 |
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bf syscall_exit_work |
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bra __restore_all |
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nop |
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.align 2 |
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syscall_trace_entry: |
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! Yes it is traced. |
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mov r15, r4 |
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mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies |
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jsr @r11 ! superior (will chomp R[0-7]) |
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nop |
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cmp/eq #-1, r0 |
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bt syscall_exit |
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! Reload R0-R4 from kernel stack, where the |
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! parent may have modified them using |
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! ptrace(POKEUSR). (Note that R0-R2 are |
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! reloaded from the kernel stack by syscall_call |
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! below, so don't need to be reloaded here.) |
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! This allows the parent to rewrite system calls |
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! and args on the fly. |
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mov.l @(OFF_R4,r15), r4 ! arg0 |
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mov.l @(OFF_R5,r15), r5 |
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mov.l @(OFF_R6,r15), r6 |
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mov.l @(OFF_R7,r15), r7 ! arg3 |
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mov.l @(OFF_R3,r15), r3 ! syscall_nr |
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! |
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mov.l 6f, r10 ! Number of syscalls |
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cmp/hs r10, r3 |
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bf syscall_call |
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mov #-ENOSYS, r0 |
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bra syscall_exit |
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mov.l r0, @(OFF_R0,r15) ! Return value |
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.align 2 |
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#if !defined(CONFIG_CPU_SH2) |
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1: .long TRA |
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#endif |
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6: .long NR_syscalls |
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3: .long sys_call_table |
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7: .long do_syscall_trace_enter |
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8: .long do_syscall_trace_leave
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