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