/*
* 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_TLBEAR
mfsr r1, SYSREG_PTBR
/* Is it the vmalloc space? */
bld r0, 31
brcs handle_vmalloc_miss
/* First level lookup */
pgtbl_lookup:
lsr r2, r0, PGDIR_SHIFT
ld.w r3, r1[r2 << 2]
bfextu r1, r0, PAGE_SHIFT, PGDIR_SHIFT - PAGE_SHIFT
bld r3, _PAGE_BIT_PRESENT
brcc page_table_not_present
/* Translate to virtual address in P1. */
andl r3, 0xf000
sbr r3, 31
/* 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
handle_vmalloc_miss:
/* Simply do the lookup in init's page table */
mov r1, lo(swapper_pg_dir)
orh r1, 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
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
rcall 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
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]
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: popm r8-r9
mtsr rar_int\level, r8
mtsr rsr_int\level, r9
ldmts sp++,r0-lr
sub sp, -4 /* ignore r12_orig */
rete
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
rcall preempt_schedule_irq
#endif
rjmp 1b
.endm
.section .irq.text,"ax",@progbits
.global cpu_idle_sleep
cpu_idle_sleep:
mask_interrupts
get_thread_info r8
ld.w r9, r8[TI_flags]
bld r9, TIF_NEED_RESCHED
brcs cpu_idle_enable_int_and_exit
sbr r9, TIF_CPU_GOING_TO_SLEEP
st.w r8[TI_flags], r9
unmask_interrupts
sleep 0
cpu_idle_skip_sleep:
mask_interrupts
ld.w r9, r8[TI_flags]
cbr r9, TIF_CPU_GOING_TO_SLEEP
st.w r8[TI_flags], r9
cpu_idle_enable_int_and_exit:
unmask_interrupts
retal r12
.global irq_level0
.global irq_level1
.global irq_level2
.global irq_level3
IRQ_LEVEL 0
IRQ_LEVEL 1
IRQ_LEVEL 2
IRQ_LEVEL 3
