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Diffstat (limited to 'arch/arc/kernel/entry.S')
| -rw-r--r-- | arch/arc/kernel/entry.S | 347 |
1 files changed, 347 insertions, 0 deletions
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S new file mode 100644 index 0000000000..089f668051 --- /dev/null +++ b/arch/arc/kernel/entry.S @@ -0,0 +1,347 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Common Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC + * (included from entry-<isa>.S + * + * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +/*------------------------------------------------------------------ + * Function ABI + *------------------------------------------------------------------ + * + * Arguments r0 - r7 + * Caller Saved Registers r0 - r12 + * Callee Saved Registers r13- r25 + * Global Pointer (gp) r26 + * Frame Pointer (fp) r27 + * Stack Pointer (sp) r28 + * Branch link register (blink) r31 + *------------------------------------------------------------------ + */ + +;################### Special Sys Call Wrappers ########################## + +ENTRY(sys_clone_wrapper) + SAVE_CALLEE_SAVED_USER + bl @sys_clone + DISCARD_CALLEE_SAVED_USER + + GET_CURR_THR_INFO_FLAGS r10 + and.f 0, r10, _TIF_SYSCALL_WORK + bnz tracesys_exit + + b .Lret_from_system_call +END(sys_clone_wrapper) + +ENTRY(sys_clone3_wrapper) + SAVE_CALLEE_SAVED_USER + bl @sys_clone3 + DISCARD_CALLEE_SAVED_USER + + GET_CURR_THR_INFO_FLAGS r10 + and.f 0, r10, _TIF_SYSCALL_WORK + bnz tracesys_exit + + b .Lret_from_system_call +END(sys_clone3_wrapper) + +ENTRY(ret_from_fork) + ; when the forked child comes here from the __switch_to function + ; r0 has the last task pointer. + ; put last task in scheduler queue + jl @schedule_tail + + ld r9, [sp, PT_status32] + brne r9, 0, 1f + + jl.d [r14] ; kernel thread entry point + mov r0, r13 ; (see PF_KTHREAD block in copy_thread) + +1: + ; Return to user space + ; 1. Any forked task (Reach here via BRne above) + ; 2. First ever init task (Reach here via return from JL above) + ; This is the historic "kernel_execve" use-case, to return to init + ; user mode, in a round about way since that is always done from + ; a kernel thread which is executed via JL above but always returns + ; out whenever kernel_execve (now inline do_fork()) is involved + b ret_from_exception +END(ret_from_fork) + +;################### Non TLB Exception Handling ############################# + +; --------------------------------------------- +; Instruction Error Exception Handler +; --------------------------------------------- + +ENTRY(instr_service) + + EXCEPTION_PROLOGUE + + bl do_insterror_or_kprobe + b ret_from_exception +END(instr_service) + +; --------------------------------------------- +; Machine Check Exception Handler +; --------------------------------------------- + +ENTRY(EV_MachineCheck) + + EXCEPTION_PROLOGUE_KEEP_AE ; ECR returned in r10 + + lr r0, [efa] + mov r1, sp + + ; MC excpetions disable MMU + ARC_MMU_REENABLE r3 + + lsr r3, r10, 8 + bmsk r3, r3, 7 + brne r3, ECR_C_MCHK_DUP_TLB, 1f + + bl do_tlb_overlap_fault + b ret_from_exception + +1: + ; DEAD END: can't do much, display Regs and HALT + SAVE_CALLEE_SAVED_USER + + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 + st sp, [r10, THREAD_CALLEE_REG] + + j do_machine_check_fault + +END(EV_MachineCheck) + +; --------------------------------------------- +; Privilege Violation Exception Handler +; --------------------------------------------- +ENTRY(EV_PrivilegeV) + + EXCEPTION_PROLOGUE + + bl do_privilege_fault + b ret_from_exception +END(EV_PrivilegeV) + +; --------------------------------------------- +; Extension Instruction Exception Handler +; --------------------------------------------- +ENTRY(EV_Extension) + + EXCEPTION_PROLOGUE + + bl do_extension_fault + b ret_from_exception +END(EV_Extension) + +;################ Trap Handling (Syscall, Breakpoint) ################## + +; --------------------------------------------- +; syscall Tracing +; --------------------------------------------- +tracesys: + ; safekeep EFA (r12) if syscall tracer wanted PC + ; for traps, ERET is pre-commit so points to next-PC + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11 + st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address + + ; PRE syscall trace hook + mov r0, sp ; pt_regs + bl @syscall_trace_enter + + ; Tracing code now returns the syscall num (orig or modif) + mov r8, r0 + + ; Do the Sys Call as we normally would. + cmp r8, NR_syscalls - 1 + mov.hi r0, -ENOSYS + bhi tracesys_exit + + ; Restore the sys-call args. Mere invocation of the hook abv could have + ; clobbered them (since they are in scratch regs). The tracer could also + ; have deliberately changed the syscall args: r0-r7 + ld r0, [sp, PT_r0] + ld r1, [sp, PT_r1] + ld r2, [sp, PT_r2] + ld r3, [sp, PT_r3] + ld r4, [sp, PT_r4] + ld r5, [sp, PT_r5] + ld r6, [sp, PT_r6] + ld r7, [sp, PT_r7] + ld.as r9, [sys_call_table, r8] + jl [r9] + +tracesys_exit: + st r0, [sp, PT_r0] + + ; POST syscall trace hook + mov r0, sp ; pt_regs needed + bl @syscall_trace_exit + + ; don't call ret_from_system_call as it saves r0, already done above + b ret_from_exception + +; --------------------------------------------- +; Breakpoint TRAP +; --------------------------------------------- +trap_with_param: + mov r0, r12 ; EFA in case ptracer/gdb wants stop_pc + mov r1, sp ; pt_regs + + ; save callee regs in case tracer/gdb wants to peek + SAVE_CALLEE_SAVED_USER + + ; safekeep ref to callee regs + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 + st sp, [r10, THREAD_CALLEE_REG] + + ; call the non syscall trap handler + bl do_non_swi_trap + + ; unwind stack to discard callee regs + DISCARD_CALLEE_SAVED_USER + + b ret_from_exception + +; --------------------------------------------- +; syscall TRAP +; ABI: (r0-r7) upto 8 args, (r8) syscall number +; --------------------------------------------- + +ENTRY(EV_Trap) + + EXCEPTION_PROLOGUE_KEEP_AE + + lr r12, [efa] + + FAKE_RET_FROM_EXCPN + + ;============ TRAP N : breakpoints, kprobes etc + bmsk.f 0, r10, 7 + bnz trap_with_param + + ;============ TRAP 0 (no param): syscall + + ; syscall tracing ongoing, invoke pre-post-hooks around syscall + GET_CURR_THR_INFO_FLAGS r10 + and.f 0, r10, _TIF_SYSCALL_WORK + bnz tracesys ; this never comes back + + ;============ Normal syscall case + + cmp r8, NR_syscalls - 1 + mov.hi r0, -ENOSYS + bhi .Lret_from_system_call + + ld.as r9,[sys_call_table, r8] + jl [r9] + +.Lret_from_system_call: + st r0, [sp, PT_r0] ; sys call return value in pt_regs + + ; fall through to ret_from_exception +END(EV_Trap) + +;############# Return from Intr/Excp/Trap (Linux Specifics) ############## +; +; If ret to user mode do we need to handle signals, schedule() et al. + +ENTRY(ret_from_exception) + + ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 + ld r8, [sp, PT_status32] ; returning to User/Kernel Mode + + bbit0 r8, STATUS_U_BIT, resume_kernel_mode + + ; Before returning to User mode check-for-and-complete any pending work + ; such as rescheduling/signal-delivery etc. +resume_user_mode_begin: + + ; Disable IRQs to ensures that chk for pending work itself is atomic + ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an + ; interim IRQ). + IRQ_DISABLE r10 + + ; Fast Path return to user mode if no pending work + GET_CURR_THR_INFO_FLAGS r9 + and.f 0, r9, _TIF_WORK_MASK + bz .Lrestore_regs + + ; --- (Slow Path #1) task preemption --- + bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals + mov blink, resume_user_mode_begin ; tail-call to U mode ret chks + j @schedule ; BTST+Bnz causes relo error in link + +.Lchk_pend_signals: + IRQ_ENABLE r10 + + ; --- (Slow Path #2) pending signal --- + mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() + + GET_CURR_THR_INFO_FLAGS r9 + and.f 0, r9, _TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL + bz .Lchk_notify_resume + + ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs + ; in pt_reg since the "C" ABI (kernel code) will automatically + ; save/restore callee-saved regs. + ; + ; However, here we need to explicitly save callee regs because + ; (i) If this signal causes coredump - full regfile needed + ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus + ; tracer might call PEEKUSR(CALLEE reg) + ; + ; NOTE: SP will grow up by size of CALLEE Reg-File + SAVE_CALLEE_SAVED_USER + + ; save location of saved Callee Regs @ thread_struct->callee + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 + st sp, [r10, THREAD_CALLEE_REG] + + bl @do_signal + + ; Ideally we want to discard the Callee reg above, however if this was + ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) + RESTORE_CALLEE_SAVED_USER + + b resume_user_mode_begin ; loop back to start of U mode ret + + ; --- (Slow Path #3) notify_resume --- +.Lchk_notify_resume: + btst r9, TIF_NOTIFY_RESUME + blnz @do_notify_resume + b resume_user_mode_begin ; unconditionally back to U mode ret chks + ; for single exit point from this block + +resume_kernel_mode: + + ; Disable Interrupts from this point on + ; CONFIG_PREEMPTION: This is a must for preempt_schedule_irq() + ; !CONFIG_PREEMPTION: To ensure restore_regs is intr safe + IRQ_DISABLE r9 + +#ifdef CONFIG_PREEMPTION + + ; Can't preempt if preemption disabled + GET_CURR_THR_INFO_FROM_SP r10 + ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] + brne r8, 0, .Lrestore_regs + + ; check if this task's NEED_RESCHED flag set + ld r9, [r10, THREAD_INFO_FLAGS] + bbit0 r9, TIF_NEED_RESCHED, .Lrestore_regs + + ; Invoke PREEMPTION + jl preempt_schedule_irq + + ; preempt_schedule_irq() always returns with IRQ disabled +#endif + + b .Lrestore_regs + +##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S + |