![Vineet Gupta](/assets/img/avatar_default.png)
Bus errors from userspace on ARCompact based cores are handled by core as a high priority L2 interrupt but current code treated it as interrupt Handling an interrupt like exception is certainly not going to go unnoticed. (and it worked so far as we never saw a Bus error from userspace until IPPK guys tested a DDR controller with ECC error detection etc hence needed to explicitly trigger/handle such errors) - So move mem_service exception handler from common code into ARCv2 code. - In ARCompact code, define mem_service as L2 interrupt handler which just drops down to pure kernel mode and goes of to enqueue SIGBUS Reported-by: Nelson Pereira <npereira@synopsys.com> Tested-by: Ana Martins <amartins@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
376 lines
10 KiB
ArmAsm
376 lines
10 KiB
ArmAsm
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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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 ret_from_system_call
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END(sys_clone_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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#ifdef CONFIG_ARC_DW2_UNWIND
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; Workaround for bug 94179 (STAR ):
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; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder
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; section (.debug_frame) as loadable. So we force it here.
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; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag)
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; would not work after a clean build due to kernel build system dependencies.
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.section .debug_frame, "wa",@progbits
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; Reset to .text as this file is included in entry-<isa>.S
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.section .text, "ax",@progbits
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#endif
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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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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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lr r12, [efa]
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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
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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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; stop_pc info by gdb needs this info
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lr r0, [efa]
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mov r1, sp
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; Now that we have read EFA, it is safe to do "fake" rtie
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; and get out of CPU exception mode
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FAKE_RET_FROM_EXCPN
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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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;============ TRAP 1 :breakpoints
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; Check ECR for trap with arg (PROLOGUE ensures r9 has ECR)
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bmsk.f 0, r9, 7
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bnz trap_with_param
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;============ TRAP (no param): syscall top level
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; First return from Exception to pure K mode (Exception/IRQs renabled)
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FAKE_RET_FROM_EXCPN
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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
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mov.hi r0, -ENOSYS
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bhi ret_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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; fall through to ret_from_system_call
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END(EV_Trap)
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ENTRY(ret_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 yet again to ret_from_exception
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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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bbit0 r9, TIF_SIGPENDING, .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_PREEMPT: This is a must for preempt_schedule_irq()
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; !CONFIG_PREEMPT: To ensure restore_regs is intr safe
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IRQ_DISABLE r9
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#ifdef CONFIG_PREEMPT
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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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