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