diff options
Diffstat (limited to 'arch/sh/kernel/entry-common.S')
| -rw-r--r-- | arch/sh/kernel/entry-common.S | 400 |
1 files changed, 400 insertions, 0 deletions
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S new file mode 100644 index 0000000000..91ab2607a1 --- /dev/null +++ b/arch/sh/kernel/entry-common.S @@ -0,0 +1,400 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * Copyright (C) 1999, 2000, 2002 Niibe Yutaka + * Copyright (C) 2003 - 2008 Paul Mundt + */ + +! 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 # + * + */ +#include <asm/dwarf.h> + +#if defined(CONFIG_PREEMPTION) +# define preempt_stop() cli ; TRACE_IRQS_OFF +#else +# define preempt_stop() +# define resume_kernel __restore_all +#endif + + + .align 2 +ENTRY(exception_error) + ! + TRACE_IRQS_ON + sti + mov.l 1f, r0 + jmp @r0 + nop + + .align 2 +1: .long do_exception_error + + .align 2 +ret_from_exception: + CFI_STARTPROC simple + CFI_DEF_CFA r14, 0 + CFI_REL_OFFSET 17, 64 + CFI_REL_OFFSET 15, 60 + CFI_REL_OFFSET 14, 56 + CFI_REL_OFFSET 13, 52 + CFI_REL_OFFSET 12, 48 + CFI_REL_OFFSET 11, 44 + CFI_REL_OFFSET 10, 40 + CFI_REL_OFFSET 9, 36 + CFI_REL_OFFSET 8, 32 + 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_PREEMPTION + bra resume_userspace + nop +ENTRY(resume_kernel) + cli + TRACE_IRQS_OFF + 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 + shlr r0 + and #(0xf0>>1), r0 ! interrupts off (exception path)? + cmp/eq #(0xf0>>1), r0 + bt noresched + mov.l 1f, r0 + jsr @r0 ! call preempt_schedule_irq + nop + bra need_resched + nop + +noresched: + bra __restore_all + nop + + .align 2 +1: .long preempt_schedule_irq +#endif + +ENTRY(resume_userspace) + ! r8: current_thread_info + cli + TRACE_IRQS_OFF + mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags + tst #(_TIF_WORK_MASK & 0xff), 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_NOTIFY_RESUME), r0 +work_notifysig: + bt/s __restore_all + mov r15, r4 + mov r12, r5 ! set arg1(save_r0) + mov r0, r6 + sti + mov.l 2f, r1 + mov.l 3f, r0 + jmp @r1 + lds r0, pr +work_resched: + mov.l 1f, r1 + jsr @r1 ! schedule + nop + cli + TRACE_IRQS_OFF + ! + mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags + tst #(_TIF_WORK_MASK & 0xff), r0 + bt __restore_all + bra work_pending + tst #_TIF_NEED_RESCHED, r0 + + .align 2 +1: .long schedule +2: .long do_notify_resume +3: .long resume_userspace + + .align 2 +syscall_exit_work: + ! r0: current_thread_info->flags + ! r8: current_thread_info + tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0 + bt/s work_pending + tst #_TIF_NEED_RESCHED, r0 + TRACE_IRQS_ON + sti + mov r15, r4 + mov.l 8f, r0 ! do_syscall_trace_leave + jsr @r0 + nop + bra resume_userspace + nop + +__restore_all: + mov #OFF_SR, r0 + mov.l @(r0,r15), r0 ! get status register + + shlr2 r0 + and #0x3c, r0 + cmp/eq #0x3c, r0 + bt 1f + TRACE_IRQS_ON + bra 2f + nop +1: + TRACE_IRQS_OFF +2: + mov.l 3f, r0 + jmp @r0 + nop + + .align 2 +3: .long restore_all + + .align 2 +syscall_badsys: ! Bad syscall number + get_current_thread_info r8, r0 + mov #-ENOSYS, r0 + bra resume_userspace + mov.l r0, @(OFF_R0,r15) ! Return value + +/* + * The main debug trap handler. + * + * r8=TRA (not the trap number!) + * + * Note: This assumes that the trapa value is left in its original + * form (without the shlr2 shift) so the calculation for the jump + * call table offset remains a simple in place mask. + */ +debug_trap: + mov r8, r0 + and #(0xf << 2), r0 + mov.l 1f, r8 + add r0, r8 + mov.l @r8, r8 + jsr @r8 + nop + bra ret_from_exception + nop + CFI_ENDPROC + + .align 2 +1: .long debug_trap_table + +/* + * Syscall interface: + * + * Syscall #: R3 + * Arguments #0 to #3: R4--R7 + * Arguments #4 to #6: R0, R1, R2 + * TRA: See following table. + * + * (TRA>>2) Purpose + * -------- ------- + * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). + * 0x10-0x1f general SH-3/4 syscall ABI. + * 0x1f unified SH-2/3/4 syscall ABI (preferred). + * 0x20-0x2f original SH-2 syscall ABI. + * 0x30-0x3f debug traps used by the kernel. + * 0x40-0xff Not supported by all parts, so left unhandled. + * + * For making system calls, any trap number in the range for the + * given cpu model may be used, but the unified trap number 0x1f is + * preferred for compatibility with all models. + * + * The low bits of the trap number were once documented as matching + * the number of arguments, but they were never actually used as such + * by the kernel. SH-2 originally used its own separate trap range + * because several hardware exceptions fell in the range used for the + * SH-3/4 syscall ABI. + * + * This code also handles delegating other traps to the 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 + .globl ret_from_kernel_thread +ret_from_kernel_thread: + mov.l 1f, r8 + jsr @r8 + mov r0, r4 + mov.l @(OFF_R5,r15), r5 ! fn + jsr @r5 + mov.l @(OFF_R4,r15), r4 ! arg + bra syscall_exit + nop + + .align 2 +1: .long schedule_tail + +/* + * The poorly named main trapa decode and dispatch routine, for + * system calls and debug traps through their respective jump tables. + */ +ENTRY(system_call) + setup_frame_reg +#if !defined(CONFIG_CPU_SH2) + mov.l 1f, r9 + mov.l @r9, r8 ! Read from TRA (Trap Address) Register +#endif + + mov #OFF_TRA, r10 + add r15, r10 + mov.l r8, @r10 ! set TRA value to tra + + /* + * Check the trap type + */ + mov #((0x20 << 2) - 1), r9 + cmp/hi r9, r8 + bt/s debug_trap ! it's a debug trap.. + nop + + TRACE_IRQS_ON + sti + + ! + get_current_thread_info r8, r10 + mov.l @(TI_FLAGS,r8), r8 + mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 + mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 + tst r10, r8 + shll8 r9 + bf syscall_trace_entry + tst r9, r8 + bf syscall_trace_entry + ! + mov.l 6f, r8 ! Number of syscalls + cmp/hs r8, r3 + bt syscall_badsys + ! +syscall_call: + shll2 r3 ! x4 + mov.l 3f, r8 ! Load the address of sys_call_table + add r8, r3 + mov.l @r3, r8 + mov.l @(OFF_R2,r15), r2 + mov.l @(OFF_R1,r15), r1 + mov.l @(OFF_R0,r15), r0 + mov.l r2, @-r15 + mov.l r1, @-r15 + mov.l r0, @-r15 + jsr @r8 ! jump to specific syscall handler + nop + add #12, r15 + mov.l @(OFF_R0,r15), r12 ! save r0 + mov.l r0, @(OFF_R0,r15) ! save the return value + ! +syscall_exit: + cli + TRACE_IRQS_OFF + ! + get_current_thread_info r8, r0 + mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags + tst #(_TIF_ALLWORK_MASK & 0xff), r0 + mov #(_TIF_ALLWORK_MASK >> 8), r1 + bf syscall_exit_work + shlr8 r0 + tst r0, r1 + bf syscall_exit_work + bra __restore_all + nop + + .align 2 +syscall_trace_entry: + ! Yes it is traced. + mov r15, r4 + mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies + jsr @r11 ! superior (will chomp R[0-7]) + nop + cmp/eq #-1, r0 + bt syscall_exit + ! Reload R0-R4 from kernel stack, where the + ! parent may have modified them using + ! ptrace(POKEUSR). (Note that R0-R2 are + ! reloaded from the kernel stack by syscall_call + ! below, 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 + ! + mov.l 6f, 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 + + .align 2 +#if !defined(CONFIG_CPU_SH2) +1: .long TRA +#endif +6: .long NR_syscalls +3: .long sys_call_table +7: .long do_syscall_trace_enter +8: .long do_syscall_trace_leave |