--- /dev/null
+/*
+ * arch/sh/kernel/entry.S
+ *
+ * Copyright (C) 1999, 2000, 2002 Niibe Yutaka
+ * Copyright (C) 2003 - 2006 Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/sys.h>
+#include <linux/errno.h>
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+#include <asm/unistd.h>
+#include <asm/cpu/mmu_context.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+
+! NOTE:
+! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
+! to be jumped is too far, but it causes illegal slot exception.
+
+/*
+ * entry.S contains the system-call and fault low-level handling routines.
+ * This also contains the timer-interrupt handler, as well as all interrupts
+ * and faults that can result in a task-switch.
+ *
+ * NOTE: This code handles signal-recognition, which happens every time
+ * after a timer-interrupt and after each system call.
+ *
+ * NOTE: This code uses a convention that instructions in the delay slot
+ * of a transfer-control instruction are indented by an extra space, thus:
+ *
+ * jmp @k0 ! control-transfer instruction
+ * ldc k1, ssr ! delay slot
+ *
+ * Stack layout in 'ret_from_syscall':
+ * ptrace needs to have all regs on the stack.
+ * if the order here is changed, it needs to be
+ * updated in ptrace.c and ptrace.h
+ *
+ * r0
+ * ...
+ * r15 = stack pointer
+ * spc
+ * pr
+ * ssr
+ * gbr
+ * mach
+ * macl
+ * syscall #
+ *
+ */
+#if defined(CONFIG_KGDB_NMI)
+NMI_VEC = 0x1c0 ! Must catch early for debounce
+#endif
+
+/* Offsets to the stack */
+OFF_R0 = 0 /* Return value. New ABI also arg4 */
+OFF_R1 = 4 /* New ABI: arg5 */
+OFF_R2 = 8 /* New ABI: arg6 */
+OFF_R3 = 12 /* New ABI: syscall_nr */
+OFF_R4 = 16 /* New ABI: arg0 */
+OFF_R5 = 20 /* New ABI: arg1 */
+OFF_R6 = 24 /* New ABI: arg2 */
+OFF_R7 = 28 /* New ABI: arg3 */
+OFF_SP = (15*4)
+OFF_PC = (16*4)
+OFF_SR = (16*4+8)
+OFF_TRA = (16*4+6*4)
+
+
+#define k0 r0
+#define k1 r1
+#define k2 r2
+#define k3 r3
+#define k4 r4
+
+#define g_imask r6 /* r6_bank1 */
+#define k_g_imask r6_bank /* r6_bank1 */
+#define current r7 /* r7_bank1 */
+
+#include <asm/entry-macros.S>
+
+/*
+ * Kernel mode register usage:
+ * k0 scratch
+ * k1 scratch
+ * k2 scratch (Exception code)
+ * k3 scratch (Return address)
+ * k4 scratch
+ * k5 reserved
+ * k6 Global Interrupt Mask (0--15 << 4)
+ * k7 CURRENT_THREAD_INFO (pointer to current thread info)
+ */
+
+!
+! TLB Miss / Initial Page write exception handling
+! _and_
+! TLB hits, but the access violate the protection.
+! It can be valid access, such as stack grow and/or C-O-W.
+!
+!
+! Find the pmd/pte entry and loadtlb
+! If it's not found, cause address error (SEGV)
+!
+! Although this could be written in assembly language (and it'd be faster),
+! this first version depends *much* on C implementation.
+!
+
+#if defined(CONFIG_MMU)
+ .align 2
+ENTRY(tlb_miss_load)
+ bra call_dpf
+ mov #0, r5
+
+ .align 2
+ENTRY(tlb_miss_store)
+ bra call_dpf
+ mov #1, r5
+
+ .align 2
+ENTRY(initial_page_write)
+ bra call_dpf
+ mov #1, r5
+
+ .align 2
+ENTRY(tlb_protection_violation_load)
+ bra call_dpf
+ mov #0, r5
+
+ .align 2
+ENTRY(tlb_protection_violation_store)
+ bra call_dpf
+ mov #1, r5
+
+call_dpf:
+ mov.l 1f, r0
+ mov.l @r0, r6 ! address
+ mov.l 3f, r0
+
+ jmp @r0
+ mov r15, r4 ! regs
+
+ .align 2
+1: .long MMU_TEA
+3: .long do_page_fault
+
+ .align 2
+ENTRY(address_error_load)
+ bra call_dae
+ mov #0,r5 ! writeaccess = 0
+
+ .align 2
+ENTRY(address_error_store)
+ bra call_dae
+ mov #1,r5 ! writeaccess = 1
+
+ .align 2
+call_dae:
+ mov.l 1f, r0
+ mov.l @r0, r6 ! address
+ mov.l 2f, r0
+ jmp @r0
+ mov r15, r4 ! regs
+
+ .align 2
+1: .long MMU_TEA
+2: .long do_address_error
+#endif /* CONFIG_MMU */
+
+#if defined(CONFIG_SH_STANDARD_BIOS)
+ /* Unwind the stack and jmp to the debug entry */
+debug_kernel_fw:
+ mov.l @r15+, r0
+ mov.l @r15+, r1
+ mov.l @r15+, r2
+ mov.l @r15+, r3
+ mov.l @r15+, r4
+ mov.l @r15+, r5
+ mov.l @r15+, r6
+ mov.l @r15+, r7
+ stc sr, r8
+ mov.l 1f, r9 ! BL =1, RB=1, IMASK=0x0F
+ or r9, r8
+ ldc r8, sr ! here, change the register bank
+ mov.l @r15+, r8
+ mov.l @r15+, r9
+ mov.l @r15+, r10
+ mov.l @r15+, r11
+ mov.l @r15+, r12
+ mov.l @r15+, r13
+ mov.l @r15+, r14
+ mov.l @r15+, k0
+ ldc.l @r15+, spc
+ lds.l @r15+, pr
+ mov.l @r15+, k1
+ ldc.l @r15+, gbr
+ lds.l @r15+, mach
+ lds.l @r15+, macl
+ mov k0, r15
+ !
+ mov.l 2f, k0
+ mov.l @k0, k0
+ jmp @k0
+ ldc k1, ssr
+ .align 2
+1: .long 0x300000f0
+2: .long gdb_vbr_vector
+#endif /* CONFIG_SH_STANDARD_BIOS */
+
+restore_all:
+ mov.l @r15+, r0
+ mov.l @r15+, r1
+ mov.l @r15+, r2
+ mov.l @r15+, r3
+ mov.l @r15+, r4
+ mov.l @r15+, r5
+ mov.l @r15+, r6
+ mov.l @r15+, r7
+ !
+ stc sr, r8
+ mov.l 7f, r9
+ or r9, r8 ! BL =1, RB=1
+ ldc r8, sr ! here, change the register bank
+ !
+ mov.l @r15+, r8
+ mov.l @r15+, r9
+ mov.l @r15+, r10
+ mov.l @r15+, r11
+ mov.l @r15+, r12
+ mov.l @r15+, r13
+ mov.l @r15+, r14
+ mov.l @r15+, k4 ! original stack pointer
+ ldc.l @r15+, spc
+ lds.l @r15+, pr
+ mov.l @r15+, k3 ! original SR
+ ldc.l @r15+, gbr
+ lds.l @r15+, mach
+ lds.l @r15+, macl
+ add #4, r15 ! Skip syscall number
+ !
+#ifdef CONFIG_SH_DSP
+ mov.l @r15+, k0 ! DSP mode marker
+ mov.l 5f, k1
+ cmp/eq k0, k1 ! Do we have a DSP stack frame?
+ bf skip_restore
+
+ stc sr, k0 ! Enable CPU DSP mode
+ or k1, k0 ! (within kernel it may be disabled)
+ ldc k0, sr
+ mov r2, k0 ! Backup r2
+
+ ! Restore DSP registers from stack
+ mov r15, r2
+ movs.l @r2+, a1
+ movs.l @r2+, a0g
+ movs.l @r2+, a1g
+ movs.l @r2+, m0
+ movs.l @r2+, m1
+ mov r2, r15
+
+ lds.l @r15+, a0
+ lds.l @r15+, x0
+ lds.l @r15+, x1
+ lds.l @r15+, y0
+ lds.l @r15+, y1
+ lds.l @r15+, dsr
+ ldc.l @r15+, rs
+ ldc.l @r15+, re
+ ldc.l @r15+, mod
+
+ mov k0, r2 ! Restore r2
+skip_restore:
+#endif
+ !
+ ! Calculate new SR value
+ mov k3, k2 ! original SR value
+ mov #0xf0, k1
+ extu.b k1, k1
+ not k1, k1
+ and k1, k2 ! Mask orignal SR value
+ !
+ mov k3, k0 ! Calculate IMASK-bits
+ shlr2 k0
+ and #0x3c, k0
+ cmp/eq #0x3c, k0
+ bt/s 6f
+ shll2 k0
+ mov g_imask, k0
+ !
+6: or k0, k2 ! Set the IMASK-bits
+ ldc k2, ssr
+ !
+#if defined(CONFIG_KGDB_NMI)
+ ! Clear in_nmi
+ mov.l 6f, k0
+ mov #0, k1
+ mov.b k1, @k0
+#endif
+ mov.l @r15+, k2 ! restore EXPEVT
+ mov k4, r15
+ rte
+ nop
+
+ .align 2
+5: .long 0x00001000 ! DSP
+7: .long 0x30000000
+
+! common exception handler
+#include "../../entry-common.S"
+
+! Exception Vector Base
+!
+! Should be aligned page boundary.
+!
+ .balign 4096,0,4096
+ENTRY(vbr_base)
+ .long 0
+!
+ .balign 256,0,256
+general_exception:
+ mov.l 1f, k2
+ mov.l 2f, k3
+ bra handle_exception
+ mov.l @k2, k2
+ .align 2
+1: .long EXPEVT
+2: .long ret_from_exception
+!
+!
+
+/* This code makes some assumptions to improve performance.
+ * Make sure they are stil true. */
+#if PTRS_PER_PGD != PTRS_PER_PTE
+#error PGD and PTE sizes don't match
+#endif
+
+/* gas doesn't flag impossible values for mov #immediate as an error */
+#if (_PAGE_PRESENT >> 2) > 0x7f
+#error cannot load PAGE_PRESENT as an immediate
+#endif
+#if _PAGE_DIRTY > 0x7f
+#error cannot load PAGE_DIRTY as an immediate
+#endif
+#if (_PAGE_PRESENT << 2) != _PAGE_ACCESSED
+#error cannot derive PAGE_ACCESSED from PAGE_PRESENT
+#endif
+
+#if defined(CONFIG_CPU_SH4)
+#define ldmmupteh(r) mov.l 8f, r
+#else
+#define ldmmupteh(r) mov #MMU_PTEH, r
+#endif
+
+ .balign 1024,0,1024
+tlb_miss:
+#ifdef COUNT_EXCEPTIONS
+ ! Increment the counts
+ mov.l 9f, k1
+ mov.l @k1, k2
+ add #1, k2
+ mov.l k2, @k1
+#endif
+
+ ! k0 scratch
+ ! k1 pgd and pte pointers
+ ! k2 faulting address
+ ! k3 pgd and pte index masks
+ ! k4 shift
+
+ ! Load up the pgd entry (k1)
+
+ ldmmupteh(k0) ! 9 LS (latency=2) MMU_PTEH
+
+ mov.w 4f, k3 ! 8 LS (latency=2) (PTRS_PER_PGD-1) << 2
+ mov #-(PGDIR_SHIFT-2), k4 ! 6 EX
+
+ mov.l @(MMU_TEA-MMU_PTEH,k0), k2 ! 18 LS (latency=2)
+
+ mov.l @(MMU_TTB-MMU_PTEH,k0), k1 ! 18 LS (latency=2)
+
+ mov k2, k0 ! 5 MT (latency=0)
+ shld k4, k0 ! 99 EX
+
+ and k3, k0 ! 78 EX
+
+ mov.l @(k0, k1), k1 ! 21 LS (latency=2)
+ mov #-(PAGE_SHIFT-2), k4 ! 6 EX
+
+ ! Load up the pte entry (k2)
+
+ mov k2, k0 ! 5 MT (latency=0)
+ shld k4, k0 ! 99 EX
+
+ tst k1, k1 ! 86 MT
+
+ bt 20f ! 110 BR
+
+ and k3, k0 ! 78 EX
+ mov.w 5f, k4 ! 8 LS (latency=2) _PAGE_PRESENT
+
+ mov.l @(k0, k1), k2 ! 21 LS (latency=2)
+ add k0, k1 ! 49 EX
+
+#ifdef CONFIG_CPU_HAS_PTEA
+ ! Test the entry for present and _PAGE_ACCESSED
+
+ mov #-28, k3 ! 6 EX
+ mov k2, k0 ! 5 MT (latency=0)
+
+ tst k4, k2 ! 68 MT
+ shld k3, k0 ! 99 EX
+
+ bt 20f ! 110 BR
+
+ ! Set PTEA register
+ ! MMU_PTEA = ((pteval >> 28) & 0xe) | (pteval & 0x1)
+ !
+ ! k0=pte>>28, k1=pte*, k2=pte, k3=<unused>, k4=_PAGE_PRESENT
+
+ and #0xe, k0 ! 79 EX
+
+ mov k0, k3 ! 5 MT (latency=0)
+ mov k2, k0 ! 5 MT (latency=0)
+
+ and #1, k0 ! 79 EX
+
+ or k0, k3 ! 82 EX
+
+ ldmmupteh(k0) ! 9 LS (latency=2)
+ shll2 k4 ! 101 EX _PAGE_ACCESSED
+
+ tst k4, k2 ! 68 MT
+
+ mov.l k3, @(MMU_PTEA-MMU_PTEH,k0) ! 27 LS
+
+ mov.l 7f, k3 ! 9 LS (latency=2) _PAGE_FLAGS_HARDWARE_MASK
+
+ ! k0=MMU_PTEH, k1=pte*, k2=pte, k3=_PAGE_FLAGS_HARDWARE, k4=_PAGE_ACCESSED
+#else
+
+ ! Test the entry for present and _PAGE_ACCESSED
+
+ mov.l 7f, k3 ! 9 LS (latency=2) _PAGE_FLAGS_HARDWARE_MASK
+ tst k4, k2 ! 68 MT
+
+ shll2 k4 ! 101 EX _PAGE_ACCESSED
+ ldmmupteh(k0) ! 9 LS (latency=2)
+
+ bt 20f ! 110 BR
+ tst k4, k2 ! 68 MT
+
+ ! k0=MMU_PTEH, k1=pte*, k2=pte, k3=_PAGE_FLAGS_HARDWARE, k4=_PAGE_ACCESSED
+
+#endif
+
+ ! Set up the entry
+
+ and k2, k3 ! 78 EX
+ bt/s 10f ! 108 BR
+
+ mov.l k3, @(MMU_PTEL-MMU_PTEH,k0) ! 27 LS
+
+ ldtlb ! 128 CO
+
+ ! At least one instruction between ldtlb and rte
+ nop ! 119 NOP
+
+ rte ! 126 CO
+
+ nop ! 119 NOP
+
+
+10: or k4, k2 ! 82 EX
+
+ ldtlb ! 128 CO
+
+ ! At least one instruction between ldtlb and rte
+ mov.l k2, @k1 ! 27 LS
+
+ rte ! 126 CO
+
+ ! Note we cannot execute mov here, because it is executed after
+ ! restoring SSR, so would be executed in user space.
+ nop ! 119 NOP
+
+
+ .align 5
+ ! Once cache line if possible...
+1: .long swapper_pg_dir
+4: .short (PTRS_PER_PGD-1) << 2
+5: .short _PAGE_PRESENT
+7: .long _PAGE_FLAGS_HARDWARE_MASK
+8: .long MMU_PTEH
+#ifdef COUNT_EXCEPTIONS
+9: .long exception_count_miss
+#endif
+
+ ! Either pgd or pte not present
+20: mov.l 1f, k2
+ mov.l 4f, k3
+ bra handle_exception
+ mov.l @k2, k2
+!
+ .balign 512,0,512
+interrupt:
+ mov.l 2f, k2
+ mov.l 3f, k3
+#if defined(CONFIG_KGDB_NMI)
+ ! Debounce (filter nested NMI)
+ mov.l @k2, k0
+ mov.l 5f, k1
+ cmp/eq k1, k0
+ bf 0f
+ mov.l 6f, k1
+ tas.b @k1
+ bt 0f
+ rte
+ nop
+ .align 2
+5: .long NMI_VEC
+6: .long in_nmi
+0:
+#endif /* defined(CONFIG_KGDB_NMI) */
+ bra handle_exception
+ mov #-1, k2 ! interrupt exception marker
+
+ .align 2
+1: .long EXPEVT
+2: .long INTEVT
+3: .long ret_from_irq
+4: .long ret_from_exception
+
+!
+!
+ .align 2
+ENTRY(handle_exception)
+ ! Using k0, k1 for scratch registers (r0_bank1, r1_bank),
+ ! save all registers onto stack.
+ !
+ stc ssr, k0 ! Is it from kernel space?
+ shll k0 ! Check MD bit (bit30) by shifting it into...
+ shll k0 ! ...the T bit
+ bt/s 1f ! It's a kernel to kernel transition.
+ mov r15, k0 ! save original stack to k0
+ /* User space to kernel */
+ mov #(THREAD_SIZE >> 10), k1
+ shll8 k1 ! k1 := THREAD_SIZE
+ shll2 k1
+ add current, k1
+ mov k1, r15 ! change to kernel stack
+ !
+1: mov.l 2f, k1
+ !
+#ifdef CONFIG_SH_DSP
+ mov.l r2, @-r15 ! Save r2, we need another reg
+ stc sr, k4
+ mov.l 1f, r2
+ tst r2, k4 ! Check if in DSP mode
+ mov.l @r15+, r2 ! Restore r2 now
+ bt/s skip_save
+ mov #0, k4 ! Set marker for no stack frame
+
+ mov r2, k4 ! Backup r2 (in k4) for later
+
+ ! Save DSP registers on stack
+ stc.l mod, @-r15
+ stc.l re, @-r15
+ stc.l rs, @-r15
+ sts.l dsr, @-r15
+ sts.l y1, @-r15
+ sts.l y0, @-r15
+ sts.l x1, @-r15
+ sts.l x0, @-r15
+ sts.l a0, @-r15
+
+ ! GAS is broken, does not generate correct "movs.l Ds,@-As" instr.
+
+ ! FIXME: Make sure that this is still the case with newer toolchains,
+ ! as we're not at all interested in supporting ancient toolchains at
+ ! this point. -- PFM.
+
+ mov r15, r2
+ .word 0xf653 ! movs.l a1, @-r2
+ .word 0xf6f3 ! movs.l a0g, @-r2
+ .word 0xf6d3 ! movs.l a1g, @-r2
+ .word 0xf6c3 ! movs.l m0, @-r2
+ .word 0xf6e3 ! movs.l m1, @-r2
+ mov r2, r15
+
+ mov k4, r2 ! Restore r2
+ mov.l 1f, k4 ! Force DSP stack frame
+skip_save:
+ mov.l k4, @-r15 ! Push DSP mode marker onto stack
+#endif
+ ! Save the user registers on the stack.
+ mov.l k2, @-r15 ! EXPEVT
+
+ mov #-1, k4
+ mov.l k4, @-r15 ! set TRA (default: -1)
+ !
+ sts.l macl, @-r15
+ sts.l mach, @-r15
+ stc.l gbr, @-r15
+ stc.l ssr, @-r15
+ sts.l pr, @-r15
+ stc.l spc, @-r15
+ !
+ lds k3, pr ! Set the return address to pr
+ !
+ mov.l k0, @-r15 ! save orignal stack
+ mov.l r14, @-r15
+ mov.l r13, @-r15
+ mov.l r12, @-r15
+ mov.l r11, @-r15
+ mov.l r10, @-r15
+ mov.l r9, @-r15
+ mov.l r8, @-r15
+ !
+ stc sr, r8 ! Back to normal register bank, and
+ or k1, r8 ! Block all interrupts
+ mov.l 3f, k1
+ and k1, r8 ! ...
+ ldc r8, sr ! ...changed here.
+ !
+ mov.l r7, @-r15
+ mov.l r6, @-r15
+ mov.l r5, @-r15
+ mov.l r4, @-r15
+ mov.l r3, @-r15
+ mov.l r2, @-r15
+ mov.l r1, @-r15
+ mov.l r0, @-r15
+
+ /*
+ * This gets a bit tricky.. in the INTEVT case we don't want to use
+ * the VBR offset as a destination in the jump call table, since all
+ * of the destinations are the same. In this case, (interrupt) sets
+ * a marker in r2 (now r2_bank since SR.RB changed), which we check
+ * to determine the exception type. For all other exceptions, we
+ * forcibly read EXPEVT from memory and fix up the jump address, in
+ * the interrupt exception case we jump to do_IRQ() and defer the
+ * INTEVT read until there. As a bonus, we can also clean up the SR.RB
+ * checks that do_IRQ() was doing..
+ */
+ stc r2_bank, r8
+ cmp/pz r8
+ bf interrupt_exception
+ shlr2 r8
+ shlr r8
+
+#ifdef COUNT_EXCEPTIONS
+ mov.l 5f, r9
+ add r8, r9
+ mov.l @r9, r10
+ add #1, r10
+ mov.l r10, @r9
+#endif
+
+ mov.l 4f, r9
+ add r8, r9
+ mov.l @r9, r9
+ jmp @r9
+ nop
+ rts
+ nop
+
+ .align 2
+1: .long 0x00001000 ! DSP=1
+2: .long 0x000080f0 ! FD=1, IMASK=15
+3: .long 0xcfffffff ! RB=0, BL=0
+4: .long exception_handling_table
+#ifdef COUNT_EXCEPTIONS
+5: .long exception_count_table
+#endif
+
+interrupt_exception:
+ mov.l 1f, r9
+ jmp @r9
+ nop
+ rts
+ nop
+
+ .align 2
+1: .long do_IRQ
+
+ .align 2
+ENTRY(exception_none)
+ rts
+ nop
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