--- /dev/null
+/*
+ * 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
+
+ /*
+ * r0 : PGD/PT/PTE
+ * r1 : Offending address
+ * r2 : Scratch register
+ * r3 : Cause (5, 12 or 13)
+ */
+#define tlbmiss_save pushm r0-r3
+#define tlbmiss_restore popm r0-r3
+
+ .section .tlbx.ex.text,"ax",@progbits
+ .global itlb_miss
+itlb_miss:
+ tlbmiss_save
+ rjmp tlb_miss_common
+
+ .section .tlbr.ex.text,"ax",@progbits
+dtlb_miss_read:
+ tlbmiss_save
+ rjmp tlb_miss_common
+
+ .section .tlbw.ex.text,"ax",@progbits
+dtlb_miss_write:
+ tlbmiss_save
+
+ .global tlb_miss_common
+tlb_miss_common:
+ mfsr r0, SYSREG_PTBR
+ mfsr r1, SYSREG_TLBEAR
+
+ /* Is it the vmalloc space? */
+ bld r1, 31
+ brcs handle_vmalloc_miss
+
+ /* First level lookup */
+pgtbl_lookup:
+ lsr r2, r1, PGDIR_SHIFT
+ ld.w r0, r0[r2 << 2]
+ bld r0, _PAGE_BIT_PRESENT
+ brcc page_table_not_present
+
+ /* TODO: Check access rights on page table if necessary */
+
+ /* Translate to virtual address in P1. */
+ andl r0, 0xf000
+ sbr r0, 31
+
+ /* Second level lookup */
+ lsl r1, (32 - PGDIR_SHIFT)
+ lsr r1, (32 - PGDIR_SHIFT) + PAGE_SHIFT
+ add r2, r0, r1 << 2
+ ld.w r1, r2[0]
+ bld r1, _PAGE_BIT_PRESENT
+ brcc page_not_present
+
+ /* Mark the page as accessed */
+ sbr r1, _PAGE_BIT_ACCESSED
+ st.w r2[0], r1
+
+ /* Drop software flags */
+ andl r1, _PAGE_FLAGS_HARDWARE_MASK & 0xffff
+ mtsr SYSREG_TLBELO, r1
+
+ /* Figure out which entry we want to replace */
+ mfsr r0, SYSREG_TLBARLO
+ clz r2, r0
+ brcc 1f
+ mov r1, -1 /* All entries have been accessed, */
+ mtsr SYSREG_TLBARLO, r1 /* so reset TLBAR */
+ mov r2, 0 /* and start at 0 */
+1: mfsr r1, SYSREG_MMUCR
+ lsl r2, 14
+ andl r1, 0x3fff, COH
+ or r1, r2
+ mtsr SYSREG_MMUCR, r1
+
+ tlbw
+
+ tlbmiss_restore
+ rete
+
+handle_vmalloc_miss:
+ /* Simply do the lookup in init's page table */
+ mov r0, lo(swapper_pg_dir)
+ orh r0, hi(swapper_pg_dir)
+ rjmp pgtbl_lookup
+
+
+ /* --- System Call --- */
+
+ .section .scall.text,"ax",@progbits
+system_call:
+ pushm r12 /* r12_orig */
+ stmts --sp, r0-lr
+ zero_fp
+ mfsr r0, SYSREG_RAR_SUP
+ mfsr r1, SYSREG_RSR_SUP
+ 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:
+ rcall schedule_tail
+
+ /* check for syscall tracing */
+ get_thread_info r0
+ ld.w r1, r0[TI_flags]
+ andl r1, _TIF_ALLWORK_MASK, COH
+ brne syscall_exit_work
+ rjmp syscall_exit_cont
+
+syscall_trace_enter:
+ pushm r8-r12
+ rcall syscall_trace
+ popm r8-r12
+ rjmp syscall_trace_cont
+
+syscall_exit_work:
+ bld r1, TIF_SYSCALL_TRACE
+ brcc 1f
+ unmask_interrupts
+ rcall syscall_trace
+ mask_interrupts
+ ld.w r1, r0[TI_flags]
+
+1: bld r1, TIF_NEED_RESCHED
+ brcc 2f
+ unmask_interrupts
+ rcall schedule
+ mask_interrupts
+ ld.w r1, r0[TI_flags]
+ rjmp 1b
+
+2: mov r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
+ tst r1, r2
+ breq 3f
+ unmask_interrupts
+ mov r12, sp
+ mov r11, r0
+ rcall do_notify_resume
+ mask_interrupts
+ ld.w r1, r0[TI_flags]
+ rjmp 1b
+
+3: bld r1, TIF_BREAKPOINT
+ brcc syscall_exit_cont
+ mfsr r3, SYSREG_TLBEHI
+ lddsp r2, sp[REG_PC]
+ andl r3, 0xff, COH
+ lsl r3, 1
+ sbr r3, 30
+ sbr r3, 0
+ mtdr DBGREG_BWA2A, r2
+ mtdr DBGREG_BWC2A, r3
+ rjmp syscall_exit_cont
+
+
+ /* The slow path of the TLB miss handler */
+page_table_not_present:
+page_not_present:
+ tlbmiss_restore
+ sub sp, 4
+ stmts --sp, r0-lr
+ rcall save_full_context_ex
+ mfsr r12, SYSREG_ECR
+ mov r11, sp
+ rcall do_page_fault
+ rjmp ret_from_exception
+
+ /* This function expects to find offending PC in SYSREG_RAR_EX */
+save_full_context_ex:
+ mfsr r8, SYSREG_RSR_EX
+ mov r12, r8
+ andh r8, (MODE_MASK >> 16), COH
+ mfsr r11, SYSREG_RAR_EX
+ 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
+
+ /* Low-level exception handlers */
+handle_critical:
+ pushm r12
+ pushm r0-r12
+ rcall save_full_context_ex
+ mfsr r12, SYSREG_ECR
+ mov r11, sp
+ rcall do_critical_exception
+
+ /* We should never get here... */
+bad_return:
+ sub r12, pc, (. - 1f)
+ bral panic
+ .align 2
+1: .asciz "Return from critical exception!"
+
+ .align 1
+do_bus_error_write:
+ sub sp, 4
+ stmts --sp, r0-lr
+ rcall save_full_context_ex
+ mov r11, 1
+ rjmp 1f
+
+do_bus_error_read:
+ sub sp, 4
+ stmts --sp, r0-lr
+ rcall save_full_context_ex
+ mov r11, 0
+1: mfsr r12, SYSREG_BEAR
+ mov r10, sp
+ rcall do_bus_error
+ rjmp ret_from_exception
+
+ .align 1
+do_nmi_ll:
+ sub sp, 4
+ stmts --sp, r0-lr
+ /* FIXME: Make sure RAR_NMI and RSR_NMI are pushed instead of *_EX */
+ rcall save_full_context_ex
+ mfsr r12, SYSREG_ECR
+ mov r11, sp
+ rcall do_nmi
+ rjmp bad_return
+
+handle_address_fault:
+ sub sp, 4
+ stmts --sp, r0-lr
+ rcall save_full_context_ex
+ mfsr r12, SYSREG_ECR
+ mov r11, sp
+ rcall do_address_exception
+ rjmp ret_from_exception
+
+handle_protection_fault:
+ sub sp, 4
+ stmts --sp, r0-lr
+ rcall save_full_context_ex
+ mfsr r12, SYSREG_ECR
+ mov r11, sp
+ rcall do_page_fault
+ rjmp ret_from_exception
+
+ .align 1
+do_illegal_opcode_ll:
+ sub sp, 4
+ stmts --sp, r0-lr
+ rcall save_full_context_ex
+ mfsr r12, SYSREG_ECR
+ mov r11, sp
+ rcall 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
+ rcall save_full_context_ex
+ unmask_interrupts
+ mov r12, 26
+ mov r11, sp
+ rcall 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
+ rcall 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
+ rcall schedule
+ mask_interrupts
+ ld.w r1, r0[TI_flags]
+ rjmp fault_exit_work
+
+1: mov r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
+ tst r1, r2
+ breq 2f
+ unmask_interrupts
+ mov r12, sp
+ mov r11, r0
+ rcall do_notify_resume
+ mask_interrupts
+ ld.w r1, r0[TI_flags]
+ rjmp fault_exit_work
+
+2: bld r1, TIF_BREAKPOINT
+ brcc fault_resume_user
+ mfsr r3, SYSREG_TLBEHI
+ lddsp r2, sp[REG_PC]
+ andl r3, 0xff, COH
+ lsl r3, 1
+ sbr r3, 30
+ sbr r3, 0
+ mtdr DBGREG_BWA2A, r2
+ mtdr DBGREG_BWC2A, r3
+ rjmp fault_resume_user
+
+ /* If we get a debug trap from privileged context we end up here */
+handle_debug_priv:
+ /* Fix up LR and SP in regs. r11 contains the mode we came from */
+ mfsr r8, SYSREG_SR
+ mov r9, r8
+ andh r8, hi(~MODE_MASK)
+ or r8, r11
+ mtsr SYSREG_SR, r8
+ sub pc, -2
+ stdsp sp[REG_LR], lr
+ mtsr SYSREG_SR, r9
+ sub pc, -2
+ sub r10, sp, -FRAME_SIZE_FULL
+ stdsp sp[REG_SP], r10
+ mov r12, sp
+ rcall do_debug_priv
+
+ /* Now, put everything back */
+ ssrf SR_EM_BIT
+ popm r10, r11
+ mtsr SYSREG_RAR_DBG, r10
+ mtsr SYSREG_RSR_DBG, r11
+ mfsr r8, SYSREG_SR
+ mov r9, r8
+ andh r8, hi(~MODE_MASK)
+ andh r11, hi(MODE_MASK)
+ or r8, r11
+ mtsr SYSREG_SR, r8
+ sub pc, -2
+ popm lr
+ mtsr SYSREG_SR, r9
+ sub pc, -2
+ sub sp, -4 /* skip SP */
+ popm r0-r12
+ sub sp, -4
+ retd
+
+ /*
+ * At this point, everything is masked, that is, interrupts,
+ * exceptions and debugging traps. We might get called from
+ * interrupt or exception context in some rare cases, but this
+ * will be taken care of by do_debug(), so we're not going to
+ * do a 100% correct context save here.
+ */
+handle_debug:
+ sub sp, 4 /* r12_orig */
+ stmts --sp, r0-lr
+ mfsr r10, SYSREG_RAR_DBG
+ mfsr r11, SYSREG_RSR_DBG
+ unmask_exceptions
+ pushm r10,r11
+ andh r11, (MODE_MASK >> 16), COH
+ brne handle_debug_priv
+
+ mov r12, sp
+ rcall do_debug
+
+ lddsp r10, sp[REG_SR]
+ andh r10, (MODE_MASK >> 16), COH
+ breq debug_resume_user
+
+debug_restore_all:
+ popm r10,r11
+ mask_exceptions
+ mtsr SYSREG_RSR_DBG, r11
+ mtsr SYSREG_RAR_DBG, r10
+ ldmts sp++, r0-lr
+ sub sp, -4
+ retd
+
+debug_resume_user:
+ get_thread_info r0
+ mask_interrupts
+
+ ld.w r1, r0[TI_flags]
+ andl r1, _TIF_DBGWORK_MASK, COH
+ breq debug_restore_all
+
+1: bld r1, TIF_NEED_RESCHED
+ brcc 2f
+ unmask_interrupts
+ rcall schedule
+ mask_interrupts
+ ld.w r1, r0[TI_flags]
+ rjmp 1b
+
+2: mov r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
+ tst r1, r2
+ breq 3f
+ unmask_interrupts
+ mov r12, sp
+ mov r11, r0
+ rcall do_notify_resume
+ mask_interrupts
+ ld.w r1, r0[TI_flags]
+ rjmp 1b
+
+3: bld r1, TIF_SINGLE_STEP
+ brcc debug_restore_all
+ mfdr r2, DBGREG_DC
+ sbr r2, DC_SS_BIT
+ mtdr DBGREG_DC, r2
+ rjmp debug_restore_all
+
+ .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
+ pushm r8-r9
+
+ mov r11, sp
+ mov r12, \level
+
+ rcall do_IRQ
+
+ lddsp r4, sp[REG_SR]
+ andh r4, (MODE_MASK >> 16), COH
+#ifdef CONFIG_PREEMPT
+ brne 2f
+#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: 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
+2:
+ 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
+ rcall preempt_schedule_irq
+ rjmp 1b
+#endif
+ .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
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