/* * 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) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ /*------------------------------------------------------------------ *    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	btst r10, TIF_SYSCALL_TRACE	bnz  tracesys_exit 	b ret_from_system_callEND(sys_clone_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	bl   @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_exceptionEND(ret_from_fork) #ifdef CONFIG_ARC_DW2_UNWIND; Workaround for bug 94179 (STAR ):; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder; section (.debug_frame) as loadable. So we force it here.; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag); would not work after a clean build due to kernel build system dependencies..section .debug_frame, "wa",@progbits ; Reset to .text as this file is included in entry-<isa>.S.section .text, "ax",@progbits#endif ;################### Non TLB Exception Handling ############################# ; ---------------------------------------------; Instruction Error Exception Handler; --------------------------------------------- ENTRY(instr_service) 	EXCEPTION_PROLOGUE 	lr  r0, [efa]	mov r1, sp 	FAKE_RET_FROM_EXCPN 	bl  do_insterror_or_kprobe	b   ret_from_exceptionEND(instr_service) ; ---------------------------------------------; Memory Error Exception Handler; --------------------------------------------- ENTRY(mem_service) 	EXCEPTION_PROLOGUE 	lr  r0, [efa]	mov r1, sp 	FAKE_RET_FROM_EXCPN 	bl  do_memory_error	b   ret_from_exceptionEND(mem_service) ; ---------------------------------------------; Machine Check Exception Handler; --------------------------------------------- ENTRY(EV_MachineCheck) 	EXCEPTION_PROLOGUE 	lr  r2, [ecr]	lr  r0, [efa]	mov r1, sp 	lsr  	r3, r2, 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 	lr  r0, [efa]	mov r1, sp 	FAKE_RET_FROM_EXCPN 	bl  do_privilege_fault	b   ret_from_exceptionEND(EV_PrivilegeV) ; ---------------------------------------------; Extension Instruction Exception Handler; ---------------------------------------------ENTRY(EV_Extension) 	EXCEPTION_PROLOGUE 	lr  r0, [efa]	mov r1, sp 	FAKE_RET_FROM_EXCPN 	bl  do_extension_fault	b   ret_from_exceptionEND(EV_Extension) ;################ Trap Handling (Syscall, Breakpoint) ################## ; ---------------------------------------------; syscall Tracing; ---------------------------------------------tracesys:	; save EFA in case tracer wants the PC of traced task	; using ERET won't work since next-PC has already committed	lr  r12, [efa]	GET_CURR_TASK_FIELD_PTR   TASK_THREAD, r11	st  r12, [r11, THREAD_FAULT_ADDR]	; thread.fault_address 	; PRE Sys Call Ptrace hook	mov r0, sp			; pt_regs needed	bl  @syscall_trace_entry 	; Tracing code now returns the syscall num (orig or modif)	mov r8, r0 	; Do the Sys Call as we normally would.	; Validate the Sys Call number	cmp     r8,  NR_syscalls	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]        ; Entry into Sys Call Handler tracesys_exit:	st  r0, [sp, PT_r0]     ; sys call return value in pt_regs 	;POST Sys Call Ptrace Hook	bl  @syscall_trace_exit	b   ret_from_exception ; NOT ret_from_system_call at is saves r0 which	; we'd done before calling post hook above ; ---------------------------------------------; Breakpoint TRAP; ---------------------------------------------trap_with_param: 	; stop_pc info by gdb needs this info	lr  r0, [efa]	mov r1, sp 	; Now that we have read EFA, it is safe to do "fake" rtie	;   and get out of CPU exception mode	FAKE_RET_FROM_EXCPN 	; Save callee regs in case gdb wants to have a look	; SP will grow up by size of CALLEE Reg-File	; NOTE: clobbers r12	SAVE_CALLEE_SAVED_USER 	; save location of saved Callee Regs @ thread_struct->pc	GET_CURR_TASK_FIELD_PTR   TASK_THREAD, r10	st  sp, [r10, THREAD_CALLEE_REG] 	; Call the trap handler	bl  do_non_swi_trap 	; unwind stack to discard Callee saved 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 	;============ TRAP 1   :breakpoints	; Check ECR for trap with arg (PROLOGUE ensures r9 has ECR)	bmsk.f 0, r9, 7	bnz    trap_with_param 	;============ TRAP  (no param): syscall top level 	; First return from Exception to pure K mode (Exception/IRQs renabled)	FAKE_RET_FROM_EXCPN 	; If syscall tracing ongoing, invoke pre-post-hooks	GET_CURR_THR_INFO_FLAGS   r10	btst r10, TIF_SYSCALL_TRACE	bnz tracesys  ; this never comes back 	;============ Normal syscall case 	; syscall num shd not exceed the total system calls avail	cmp     r8,  NR_syscalls	mov.hi  r0, -ENOSYS	bhi     ret_from_system_call 	; Offset into the syscall_table and call handler	ld.as   r9,[sys_call_table, r8]	jl      [r9]        ; Entry into Sys Call Handler 	; fall through to ret_from_system_callEND(EV_Trap) ENTRY(ret_from_system_call) 	st  r0, [sp, PT_r0]     ; sys call return value in pt_regs 	; fall through yet again to ret_from_exception ;############# 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	b      @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	bbit0  r9, TIF_SIGPENDING, .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		; clobbers r12 	; 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_PREEMPT: This is a must for preempt_schedule_irq()	; !CONFIG_PREEMPT: To ensure restore_regs is intr safe	IRQ_DISABLE	r9 #ifdef CONFIG_PREEMPT 	; 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	bl      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