/*
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* Copyright (C) 2004-2006 Atmel Corporation
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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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* This file contains the low-level entry-points into the kernel, that is,
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* exception handlers, debug trap handlers, interrupt handlers and the
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* system call handler.
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*/
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#include <linux/errno.h>
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#include <asm/asm.h>
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#include <asm/hardirq.h>
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#include <asm/irq.h>
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#include <asm/ocd.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/ptrace.h>
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#include <asm/sysreg.h>
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#include <asm/thread_info.h>
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#include <asm/unistd.h>
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#ifdef CONFIG_PREEMPT
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# define preempt_stop mask_interrupts
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#else
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# define preempt_stop
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# define fault_resume_kernel fault_restore_all
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#endif
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#define __MASK(x) ((1 << (x)) - 1)
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#define IRQ_MASK ((__MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT) | \
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(__MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT))
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.section .ex.text,"ax",@progbits
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.align 2
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exception_vectors:
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bral handle_critical
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.align 2
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bral handle_critical
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.align 2
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bral do_bus_error_write
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.align 2
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bral do_bus_error_read
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.align 2
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bral do_nmi_ll
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.align 2
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bral handle_address_fault
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.align 2
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bral handle_protection_fault
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.align 2
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bral handle_debug
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.align 2
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bral do_illegal_opcode_ll
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.align 2
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bral do_illegal_opcode_ll
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.align 2
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bral do_illegal_opcode_ll
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.align 2
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bral do_fpe_ll
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.align 2
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bral do_illegal_opcode_ll
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.align 2
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bral handle_address_fault
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.align 2
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bral handle_address_fault
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.align 2
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bral handle_protection_fault
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.align 2
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bral handle_protection_fault
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.align 2
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bral do_dtlb_modified
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#define tlbmiss_save pushm r0-r3
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#define tlbmiss_restore popm r0-r3
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.org 0x50
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.global itlb_miss
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itlb_miss:
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tlbmiss_save
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rjmp tlb_miss_common
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.org 0x60
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dtlb_miss_read:
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tlbmiss_save
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rjmp tlb_miss_common
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.org 0x70
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dtlb_miss_write:
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tlbmiss_save
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.global tlb_miss_common
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.align 2
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tlb_miss_common:
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mfsr r0, SYSREG_TLBEAR
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mfsr r1, SYSREG_PTBR
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/*
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* First level lookup: The PGD contains virtual pointers to
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* the second-level page tables, but they may be NULL if not
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* present.
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*/
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pgtbl_lookup:
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lsr r2, r0, PGDIR_SHIFT
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ld.w r3, r1[r2 << 2]
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bfextu r1, r0, PAGE_SHIFT, PGDIR_SHIFT - PAGE_SHIFT
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cp.w r3, 0
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breq page_table_not_present
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/* Second level lookup */
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ld.w r2, r3[r1 << 2]
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mfsr r0, SYSREG_TLBARLO
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bld r2, _PAGE_BIT_PRESENT
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brcc page_not_present
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/* Mark the page as accessed */
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sbr r2, _PAGE_BIT_ACCESSED
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st.w r3[r1 << 2], r2
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/* Drop software flags */
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andl r2, _PAGE_FLAGS_HARDWARE_MASK & 0xffff
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mtsr SYSREG_TLBELO, r2
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/* Figure out which entry we want to replace */
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mfsr r1, SYSREG_MMUCR
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clz r2, r0
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brcc 1f
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mov r3, -1 /* All entries have been accessed, */
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mov r2, 0 /* so start at 0 */
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mtsr SYSREG_TLBARLO, r3 /* and reset TLBAR */
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1: bfins r1, r2, SYSREG_DRP_OFFSET, SYSREG_DRP_SIZE
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mtsr SYSREG_MMUCR, r1
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tlbw
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tlbmiss_restore
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rete
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/* The slow path of the TLB miss handler */
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.align 2
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page_table_not_present:
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/* Do we need to synchronize with swapper_pg_dir? */
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bld r0, 31
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brcs sync_with_swapper_pg_dir
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page_not_present:
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tlbmiss_restore
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sub sp, 4
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stmts --sp, r0-lr
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call save_full_context_ex
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mfsr r12, SYSREG_ECR
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mov r11, sp
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call do_page_fault
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rjmp ret_from_exception
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.align 2
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sync_with_swapper_pg_dir:
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/*
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* If swapper_pg_dir contains a non-NULL second-level page
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* table pointer, copy it into the current PGD. If not, we
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* must handle it as a full-blown page fault.
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*
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* Jumping back to pgtbl_lookup causes an unnecessary lookup,
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* but it is guaranteed to be a cache hit, it won't happen
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* very often, and we absolutely do not want to sacrifice any
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* performance in the fast path in order to improve this.
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*/
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mov r1, lo(swapper_pg_dir)
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orh r1, hi(swapper_pg_dir)
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ld.w r3, r1[r2 << 2]
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cp.w r3, 0
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breq page_not_present
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mfsr r1, SYSREG_PTBR
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st.w r1[r2 << 2], r3
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rjmp pgtbl_lookup
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/*
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* We currently have two bytes left at this point until we
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* crash into the system call handler...
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*
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* Don't worry, the assembler will let us know.
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*/
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/* --- System Call --- */
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.org 0x100
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system_call:
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#ifdef CONFIG_PREEMPT
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mask_interrupts
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#endif
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pushm r12 /* r12_orig */
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stmts --sp, r0-lr
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mfsr r0, SYSREG_RAR_SUP
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mfsr r1, SYSREG_RSR_SUP
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#ifdef CONFIG_PREEMPT
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unmask_interrupts
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#endif
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zero_fp
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stm --sp, r0-r1
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/* check for syscall tracing */
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get_thread_info r0
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ld.w r1, r0[TI_flags]
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bld r1, TIF_SYSCALL_TRACE
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brcs syscall_trace_enter
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syscall_trace_cont:
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cp.w r8, NR_syscalls
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brhs syscall_badsys
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lddpc lr, syscall_table_addr
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ld.w lr, lr[r8 << 2]
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mov r8, r5 /* 5th argument (6th is pushed by stub) */
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icall lr
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.global syscall_return
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syscall_return:
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get_thread_info r0
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mask_interrupts /* make sure we don't miss an interrupt
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setting need_resched or sigpending
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between sampling and the rets */
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/* Store the return value so that the correct value is loaded below */
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stdsp sp[REG_R12], r12
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ld.w r1, r0[TI_flags]
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andl r1, _TIF_ALLWORK_MASK, COH
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brne syscall_exit_work
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syscall_exit_cont:
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popm r8-r9
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mtsr SYSREG_RAR_SUP, r8
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mtsr SYSREG_RSR_SUP, r9
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ldmts sp++, r0-lr
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sub sp, -4 /* r12_orig */
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rets
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.align 2
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syscall_table_addr:
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.long sys_call_table
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syscall_badsys:
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mov r12, -ENOSYS
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rjmp syscall_return
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.global ret_from_fork
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ret_from_fork:
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call schedule_tail
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mov r12, 0
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rjmp syscall_return
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.global ret_from_kernel_thread
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ret_from_kernel_thread:
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call schedule_tail
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mov r12, r0
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mov lr, r2 /* syscall_return */
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mov pc, r1
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syscall_trace_enter:
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pushm r8-r12
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call syscall_trace
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popm r8-r12
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rjmp syscall_trace_cont
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syscall_exit_work:
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bld r1, TIF_SYSCALL_TRACE
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brcc 1f
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unmask_interrupts
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call syscall_trace
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mask_interrupts
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ld.w r1, r0[TI_flags]
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1: bld r1, TIF_NEED_RESCHED
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brcc 2f
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unmask_interrupts
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call schedule
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mask_interrupts
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ld.w r1, r0[TI_flags]
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rjmp 1b
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2: mov r2, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME
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tst r1, r2
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breq 3f
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unmask_interrupts
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mov r12, sp
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mov r11, r0
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call do_notify_resume
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mask_interrupts
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ld.w r1, r0[TI_flags]
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rjmp 1b
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3: bld r1, TIF_BREAKPOINT
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brcc syscall_exit_cont
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rjmp enter_monitor_mode
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/* This function expects to find offending PC in SYSREG_RAR_EX */
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.type save_full_context_ex, @function
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.align 2
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save_full_context_ex:
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mfsr r11, SYSREG_RAR_EX
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sub r9, pc, . - debug_trampoline
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mfsr r8, SYSREG_RSR_EX
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cp.w r9, r11
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breq 3f
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mov r12, r8
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andh r8, (MODE_MASK >> 16), COH
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brne 2f
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1: pushm r11, r12 /* PC and SR */
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unmask_exceptions
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ret r12
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2: sub r10, sp, -(FRAME_SIZE_FULL - REG_LR)
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stdsp sp[4], r10 /* replace saved SP */
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rjmp 1b
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/*
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* The debug handler set up a trampoline to make us
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* automatically enter monitor mode upon return, but since
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* we're saving the full context, we must assume that the
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* exception handler might want to alter the return address
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* and/or status register. So we need to restore the original
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* context and enter monitor mode manually after the exception
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* has been handled.
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*/
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3: get_thread_info r8
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ld.w r11, r8[TI_rar_saved]
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ld.w r12, r8[TI_rsr_saved]
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rjmp 1b
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.size save_full_context_ex, . - save_full_context_ex
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/* Low-level exception handlers */
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handle_critical:
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/*
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* AT32AP700x errata:
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*
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* After a Java stack overflow or underflow trap, any CPU
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* memory access may cause erratic behavior. This will happen
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* when the four least significant bits of the JOSP system
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* register contains any value between 9 and 15 (inclusive).
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*
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* Possible workarounds:
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* - Don't use the Java Extension Module
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* - Ensure that the stack overflow and underflow trap
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* handlers do not do any memory access or trigger any
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* exceptions before the overflow/underflow condition is
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* cleared (by incrementing or decrementing the JOSP)
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* - Make sure that JOSP does not contain any problematic
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* value before doing any exception or interrupt
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* processing.
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* - Set up a critical exception handler which writes a
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* known-to-be-safe value, e.g. 4, to JOSP before doing
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* any further processing.
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*
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* We'll use the last workaround for now since we cannot
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* guarantee that user space processes don't use Java mode.
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* Non-well-behaving userland will be terminated with extreme
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* prejudice.
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*/
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#ifdef CONFIG_CPU_AT32AP700X
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/*
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* There's a chance we can't touch memory, so temporarily
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* borrow PTBR to save the stack pointer while we fix things
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* up...
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*/
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mtsr SYSREG_PTBR, sp
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mov sp, 4
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mtsr SYSREG_JOSP, sp
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mfsr sp, SYSREG_PTBR
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sub pc, -2
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/* Push most of pt_regs on stack. We'll do the rest later */
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sub sp, 4
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pushm r0-r12
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/* PTBR mirrors current_thread_info()->task->active_mm->pgd */
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get_thread_info r0
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ld.w r1, r0[TI_task]
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ld.w r2, r1[TSK_active_mm]
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ld.w r3, r2[MM_pgd]
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mtsr SYSREG_PTBR, r3
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#else
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sub sp, 4
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pushm r0-r12
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#endif
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sub r0, sp, -(14 * 4)
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mov r1, lr
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mfsr r2, SYSREG_RAR_EX
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mfsr r3, SYSREG_RSR_EX
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pushm r0-r3
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mfsr r12, SYSREG_ECR
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mov r11, sp
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call do_critical_exception
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/* We should never get here... */
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bad_return:
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sub r12, pc, (. - 1f)
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lddpc pc, 2f
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.align 2
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1: .asciz "Return from critical exception!"
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2: .long panic
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.align 1
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do_bus_error_write:
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sub sp, 4
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stmts --sp, r0-lr
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call save_full_context_ex
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mov r11, 1
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rjmp 1f
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do_bus_error_read:
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sub sp, 4
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stmts --sp, r0-lr
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call save_full_context_ex
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mov r11, 0
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1: mfsr r12, SYSREG_BEAR
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mov r10, sp
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call do_bus_error
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rjmp ret_from_exception
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.align 1
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do_nmi_ll:
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sub sp, 4
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stmts --sp, r0-lr
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mfsr r9, SYSREG_RSR_NMI
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mfsr r8, SYSREG_RAR_NMI
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bfextu r0, r9, MODE_SHIFT, 3
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brne 2f
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1: pushm r8, r9 /* PC and SR */
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mfsr r12, SYSREG_ECR
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mov r11, sp
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call do_nmi
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popm r8-r9
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mtsr SYSREG_RAR_NMI, r8
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tst r0, r0
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mtsr SYSREG_RSR_NMI, r9
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brne 3f
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ldmts sp++, r0-lr
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sub sp, -4 /* skip r12_orig */
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rete
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2: sub r10, sp, -(FRAME_SIZE_FULL - REG_LR)
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stdsp sp[4], r10 /* replace saved SP */
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rjmp 1b
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3: popm lr
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sub sp, -4 /* skip sp */
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popm r0-r12
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sub sp, -4 /* skip r12_orig */
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rete
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handle_address_fault:
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sub sp, 4
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stmts --sp, r0-lr
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call save_full_context_ex
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mfsr r12, SYSREG_ECR
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mov r11, sp
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call do_address_exception
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rjmp ret_from_exception
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handle_protection_fault:
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sub sp, 4
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stmts --sp, r0-lr
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call save_full_context_ex
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mfsr r12, SYSREG_ECR
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mov r11, sp
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call do_page_fault
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rjmp ret_from_exception
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.align 1
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do_illegal_opcode_ll:
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sub sp, 4
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stmts --sp, r0-lr
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call save_full_context_ex
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mfsr r12, SYSREG_ECR
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mov r11, sp
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call do_illegal_opcode
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rjmp ret_from_exception
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do_dtlb_modified:
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pushm r0-r3
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mfsr r1, SYSREG_TLBEAR
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mfsr r0, SYSREG_PTBR
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lsr r2, r1, PGDIR_SHIFT
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ld.w r0, r0[r2 << 2]
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lsl r1, (32 - PGDIR_SHIFT)
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lsr r1, (32 - PGDIR_SHIFT) + PAGE_SHIFT
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/* Translate to virtual address in P1 */
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andl r0, 0xf000
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sbr r0, 31
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add r2, r0, r1 << 2
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ld.w r3, r2[0]
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sbr r3, _PAGE_BIT_DIRTY
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mov r0, r3
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st.w r2[0], r3
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/* The page table is up-to-date. Update the TLB entry as well */
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andl r0, lo(_PAGE_FLAGS_HARDWARE_MASK)
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mtsr SYSREG_TLBELO, r0
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/* MMUCR[DRP] is updated automatically, so let's go... */
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tlbw
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popm r0-r3
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rete
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do_fpe_ll:
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sub sp, 4
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stmts --sp, r0-lr
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call save_full_context_ex
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unmask_interrupts
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mov r12, 26
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mov r11, sp
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call do_fpe
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rjmp ret_from_exception
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ret_from_exception:
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mask_interrupts
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lddsp r4, sp[REG_SR]
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andh r4, (MODE_MASK >> 16), COH
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brne fault_resume_kernel
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get_thread_info r0
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ld.w r1, r0[TI_flags]
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andl r1, _TIF_WORK_MASK, COH
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brne fault_exit_work
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fault_resume_user:
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popm r8-r9
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mask_exceptions
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mtsr SYSREG_RAR_EX, r8
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mtsr SYSREG_RSR_EX, r9
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ldmts sp++, r0-lr
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sub sp, -4
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rete
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fault_resume_kernel:
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#ifdef CONFIG_PREEMPT
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get_thread_info r0
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ld.w r2, r0[TI_preempt_count]
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cp.w r2, 0
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brne 1f
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ld.w r1, r0[TI_flags]
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bld r1, TIF_NEED_RESCHED
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brcc 1f
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lddsp r4, sp[REG_SR]
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bld r4, SYSREG_GM_OFFSET
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brcs 1f
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call preempt_schedule_irq
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1:
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#endif
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popm r8-r9
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mask_exceptions
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mfsr r1, SYSREG_SR
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mtsr SYSREG_RAR_EX, r8
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mtsr SYSREG_RSR_EX, r9
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popm lr
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sub sp, -4 /* ignore SP */
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popm r0-r12
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sub sp, -4 /* ignore r12_orig */
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rete
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irq_exit_work:
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/* Switch to exception mode so that we can share the same code. */
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mfsr r8, SYSREG_SR
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cbr r8, SYSREG_M0_OFFSET
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orh r8, hi(SYSREG_BIT(M1) | SYSREG_BIT(M2))
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mtsr SYSREG_SR, r8
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sub pc, -2
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get_thread_info r0
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ld.w r1, r0[TI_flags]
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fault_exit_work:
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bld r1, TIF_NEED_RESCHED
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brcc 1f
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unmask_interrupts
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call schedule
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mask_interrupts
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ld.w r1, r0[TI_flags]
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rjmp fault_exit_work
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1: mov r2, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME
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tst r1, r2
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breq 2f
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unmask_interrupts
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mov r12, sp
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mov r11, r0
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call do_notify_resume
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mask_interrupts
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ld.w r1, r0[TI_flags]
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rjmp fault_exit_work
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2: bld r1, TIF_BREAKPOINT
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brcc fault_resume_user
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rjmp enter_monitor_mode
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.section .kprobes.text, "ax", @progbits
|
.type handle_debug, @function
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handle_debug:
|
sub sp, 4 /* r12_orig */
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stmts --sp, r0-lr
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mfsr r8, SYSREG_RAR_DBG
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mfsr r9, SYSREG_RSR_DBG
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unmask_exceptions
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pushm r8-r9
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bfextu r9, r9, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
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brne debug_fixup_regs
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.Ldebug_fixup_cont:
|
#ifdef CONFIG_TRACE_IRQFLAGS
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call trace_hardirqs_off
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#endif
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mov r12, sp
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call do_debug
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mov sp, r12
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lddsp r2, sp[REG_SR]
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bfextu r3, r2, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
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brne debug_resume_kernel
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get_thread_info r0
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ld.w r1, r0[TI_flags]
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mov r2, _TIF_DBGWORK_MASK
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tst r1, r2
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brne debug_exit_work
|
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bld r1, TIF_SINGLE_STEP
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brcc 1f
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mfdr r4, OCD_DC
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sbr r4, OCD_DC_SS_BIT
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mtdr OCD_DC, r4
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1: popm r10,r11
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mask_exceptions
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mtsr SYSREG_RSR_DBG, r11
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mtsr SYSREG_RAR_DBG, r10
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
call trace_hardirqs_on
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1:
|
#endif
|
ldmts sp++, r0-lr
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sub sp, -4
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retd
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.size handle_debug, . - handle_debug
|
|
/* Mode of the trapped context is in r9 */
|
.type debug_fixup_regs, @function
|
debug_fixup_regs:
|
mfsr r8, SYSREG_SR
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mov r10, r8
|
bfins r8, r9, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
|
mtsr SYSREG_SR, r8
|
sub pc, -2
|
stdsp sp[REG_LR], lr
|
mtsr SYSREG_SR, r10
|
sub pc, -2
|
sub r8, sp, -FRAME_SIZE_FULL
|
stdsp sp[REG_SP], r8
|
rjmp .Ldebug_fixup_cont
|
.size debug_fixup_regs, . - debug_fixup_regs
|
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.type debug_resume_kernel, @function
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debug_resume_kernel:
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mask_exceptions
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popm r10, r11
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mtsr SYSREG_RAR_DBG, r10
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mtsr SYSREG_RSR_DBG, r11
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#ifdef CONFIG_TRACE_IRQFLAGS
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bld r11, SYSREG_GM_OFFSET
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brcc 1f
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call trace_hardirqs_on
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1:
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#endif
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mfsr r2, SYSREG_SR
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mov r1, r2
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bfins r2, r3, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
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mtsr SYSREG_SR, r2
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sub pc, -2
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popm lr
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mtsr SYSREG_SR, r1
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sub pc, -2
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sub sp, -4 /* skip SP */
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popm r0-r12
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sub sp, -4
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retd
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.size debug_resume_kernel, . - debug_resume_kernel
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.type debug_exit_work, @function
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debug_exit_work:
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/*
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* We must return from Monitor Mode using a retd, and we must
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* not schedule since that involves the D bit in SR getting
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* cleared by something other than the debug hardware. This
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* may cause undefined behaviour according to the Architecture
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* manual.
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*
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* So we fix up the return address and status and return to a
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* stub below in Exception mode. From there, we can follow the
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* normal exception return path.
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*
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* The real return address and status registers are stored on
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* the stack in the way the exception return path understands,
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* so no need to fix anything up there.
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*/
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sub r8, pc, . - fault_exit_work
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mtsr SYSREG_RAR_DBG, r8
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mov r9, 0
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orh r9, hi(SR_EM | SR_GM | MODE_EXCEPTION)
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mtsr SYSREG_RSR_DBG, r9
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sub pc, -2
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retd
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.size debug_exit_work, . - debug_exit_work
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.set rsr_int0, SYSREG_RSR_INT0
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.set rsr_int1, SYSREG_RSR_INT1
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.set rsr_int2, SYSREG_RSR_INT2
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.set rsr_int3, SYSREG_RSR_INT3
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.set rar_int0, SYSREG_RAR_INT0
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.set rar_int1, SYSREG_RAR_INT1
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.set rar_int2, SYSREG_RAR_INT2
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.set rar_int3, SYSREG_RAR_INT3
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.macro IRQ_LEVEL level
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.type irq_level\level, @function
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irq_level\level:
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sub sp, 4 /* r12_orig */
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stmts --sp,r0-lr
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mfsr r8, rar_int\level
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mfsr r9, rsr_int\level
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#ifdef CONFIG_PREEMPT
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sub r11, pc, (. - system_call)
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cp.w r11, r8
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breq 4f
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#endif
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pushm r8-r9
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mov r11, sp
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mov r12, \level
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call do_IRQ
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lddsp r4, sp[REG_SR]
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bfextu r4, r4, SYSREG_M0_OFFSET, 3
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cp.w r4, MODE_SUPERVISOR >> SYSREG_M0_OFFSET
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breq 2f
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cp.w r4, MODE_USER >> SYSREG_M0_OFFSET
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#ifdef CONFIG_PREEMPT
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brne 3f
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#else
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brne 1f
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#endif
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get_thread_info r0
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ld.w r1, r0[TI_flags]
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andl r1, _TIF_WORK_MASK, COH
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brne irq_exit_work
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1:
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#ifdef CONFIG_TRACE_IRQFLAGS
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call trace_hardirqs_on
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#endif
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popm r8-r9
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mtsr rar_int\level, r8
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mtsr rsr_int\level, r9
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ldmts sp++,r0-lr
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sub sp, -4 /* ignore r12_orig */
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rete
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#ifdef CONFIG_PREEMPT
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4: mask_interrupts
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mfsr r8, rsr_int\level
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sbr r8, 16
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mtsr rsr_int\level, r8
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ldmts sp++, r0-lr
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sub sp, -4 /* ignore r12_orig */
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rete
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#endif
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2: get_thread_info r0
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ld.w r1, r0[TI_flags]
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bld r1, TIF_CPU_GOING_TO_SLEEP
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#ifdef CONFIG_PREEMPT
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brcc 3f
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#else
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brcc 1b
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#endif
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sub r1, pc, . - cpu_idle_skip_sleep
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stdsp sp[REG_PC], r1
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#ifdef CONFIG_PREEMPT
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3: get_thread_info r0
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ld.w r2, r0[TI_preempt_count]
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cp.w r2, 0
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brne 1b
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ld.w r1, r0[TI_flags]
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bld r1, TIF_NEED_RESCHED
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brcc 1b
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lddsp r4, sp[REG_SR]
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bld r4, SYSREG_GM_OFFSET
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brcs 1b
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call preempt_schedule_irq
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#endif
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rjmp 1b
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.endm
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.section .irq.text,"ax",@progbits
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.global irq_level0
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.global irq_level1
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.global irq_level2
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.global irq_level3
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IRQ_LEVEL 0
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IRQ_LEVEL 1
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IRQ_LEVEL 2
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IRQ_LEVEL 3
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.section .kprobes.text, "ax", @progbits
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.type enter_monitor_mode, @function
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enter_monitor_mode:
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/*
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* We need to enter monitor mode to do a single step. The
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* monitor code will alter the return address so that we
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* return directly to the user instead of returning here.
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*/
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breakpoint
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rjmp breakpoint_failed
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.size enter_monitor_mode, . - enter_monitor_mode
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.type debug_trampoline, @function
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.global debug_trampoline
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debug_trampoline:
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/*
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* Save the registers on the stack so that the monitor code
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* can find them easily.
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*/
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sub sp, 4 /* r12_orig */
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stmts --sp, r0-lr
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get_thread_info r0
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ld.w r8, r0[TI_rar_saved]
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ld.w r9, r0[TI_rsr_saved]
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pushm r8-r9
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/*
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* The monitor code will alter the return address so we don't
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* return here.
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*/
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breakpoint
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rjmp breakpoint_failed
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.size debug_trampoline, . - debug_trampoline
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.type breakpoint_failed, @function
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breakpoint_failed:
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/*
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* Something went wrong. Perhaps the debug hardware isn't
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* enabled?
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*/
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lda.w r12, msg_breakpoint_failed
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mov r11, sp
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mov r10, 9 /* SIGKILL */
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call die
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1: rjmp 1b
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msg_breakpoint_failed:
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.asciz "Failed to enter Debug Mode"
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