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142698282c
The address that ret_from_exception and ret_from_irq will return to is found in the stack slot for SPC, not PR. This error was causing the DWARF unwinder to pick up the wrong return address on the stack and then unwind using the unwind tables for the wrong function. While I'm here I might as well add CFI annotations for the other registers since they could be useful when unwinding. Signed-off-by: Matt Fleming <matt@console-pimps.org> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
375 lines
7.9 KiB
ArmAsm
375 lines
7.9 KiB
ArmAsm
/*
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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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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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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_PREEMPT)
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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_PREEMPT
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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 3f, 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_ACTIVE
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2: .long schedule
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3: .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, 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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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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.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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mov.l r0, @(OFF_R0,r15) ! Save return value
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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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! used by the system call handler directly
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! from the kernel stack anyway, so don't need
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! to be reloaded here.) This allows the parent
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! to rewrite system calls 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 2f, 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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__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 __restore_all
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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: (number of arguments + ABI revision) x 4
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*
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* This code also handles delegating other traps to the BIOS/gdb stub
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* according to:
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*
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* Trap number
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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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* 0x20-0x2f syscall ABI for SH-2 parts.
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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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* 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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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 2f, 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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jsr @r8 ! jump to specific syscall handler
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nop
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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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#if !defined(CONFIG_CPU_SH2)
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1: .long TRA
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#endif
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2: .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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