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-rw-r--r--arch/arm26/kernel/entry.S961
1 files changed, 961 insertions, 0 deletions
diff --git a/arch/arm26/kernel/entry.S b/arch/arm26/kernel/entry.S
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+++ b/arch/arm26/kernel/entry.S
@@ -0,0 +1,961 @@
+/* arch/arm26/kernel/entry.S
+ *
+ * Assembled from chunks of code in arch/arm
+ *
+ * Copyright (C) 2003 Ian Molton
+ * Based on the work of RMK.
+ *
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+#include <asm/asm_offsets.h>
+#include <asm/errno.h>
+#include <asm/hardware.h>
+#include <asm/sysirq.h>
+#include <asm/thread_info.h>
+#include <asm/page.h>
+#include <asm/ptrace.h>
+
+ .macro zero_fp
+#ifndef CONFIG_NO_FRAME_POINTER
+ mov fp, #0
+#endif
+ .endm
+
+ .text
+
+@ Bad Abort numbers
+@ -----------------
+@
+#define BAD_PREFETCH 0
+#define BAD_DATA 1
+#define BAD_ADDREXCPTN 2
+#define BAD_IRQ 3
+#define BAD_UNDEFINSTR 4
+
+@ OS version number used in SWIs
+@ RISC OS is 0
+@ RISC iX is 8
+@
+#define OS_NUMBER 9
+#define ARMSWI_OFFSET 0x000f0000
+
+@
+@ Stack format (ensured by USER_* and SVC_*)
+@ PSR and PC are comined on arm26
+@
+
+#define S_OFF 8
+
+#define S_OLD_R0 64
+#define S_PC 60
+#define S_LR 56
+#define S_SP 52
+#define S_IP 48
+#define S_FP 44
+#define S_R10 40
+#define S_R9 36
+#define S_R8 32
+#define S_R7 28
+#define S_R6 24
+#define S_R5 20
+#define S_R4 16
+#define S_R3 12
+#define S_R2 8
+#define S_R1 4
+#define S_R0 0
+
+ .macro save_user_regs
+ str r0, [sp, #-4]! @ Store SVC r0
+ str lr, [sp, #-4]! @ Store user mode PC
+ sub sp, sp, #15*4
+ stmia sp, {r0 - lr}^ @ Store the other user-mode regs
+ mov r0, r0
+ .endm
+
+ .macro slow_restore_user_regs
+ ldmia sp, {r0 - lr}^ @ restore the user regs not including PC
+ mov r0, r0
+ ldr lr, [sp, #15*4] @ get user PC
+ add sp, sp, #15*4+8 @ free stack
+ movs pc, lr @ return
+ .endm
+
+ .macro fast_restore_user_regs
+ add sp, sp, #S_OFF
+ ldmib sp, {r1 - lr}^
+ mov r0, r0
+ ldr lr, [sp, #15*4]
+ add sp, sp, #15*4+8
+ movs pc, lr
+ .endm
+
+ .macro save_svc_regs
+ str sp, [sp, #-16]!
+ str lr, [sp, #8]
+ str lr, [sp, #4]
+ stmfd sp!, {r0 - r12}
+ mov r0, #-1
+ str r0, [sp, #S_OLD_R0]
+ zero_fp
+ .endm
+
+ .macro save_svc_regs_irq
+ str sp, [sp, #-16]!
+ str lr, [sp, #4]
+ ldr lr, .LCirq
+ ldr lr, [lr]
+ str lr, [sp, #8]
+ stmfd sp!, {r0 - r12}
+ mov r0, #-1
+ str r0, [sp, #S_OLD_R0]
+ zero_fp
+ .endm
+
+ .macro restore_svc_regs
+ ldmfd sp, {r0 - pc}^
+ .endm
+
+ .macro mask_pc, rd, rm
+ bic \rd, \rm, #PCMASK
+ .endm
+
+ .macro disable_irqs, temp
+ mov \temp, pc
+ orr \temp, \temp, #PSR_I_BIT
+ teqp \temp, #0
+ .endm
+
+ .macro enable_irqs, temp
+ mov \temp, pc
+ and \temp, \temp, #~PSR_I_BIT
+ teqp \temp, #0
+ .endm
+
+ .macro initialise_traps_extra
+ .endm
+
+ .macro get_thread_info, rd
+ mov \rd, sp, lsr #13
+ mov \rd, \rd, lsl #13
+ .endm
+
+/*
+ * These are the registers used in the syscall handler, and allow us to
+ * have in theory up to 7 arguments to a function - r0 to r6.
+ *
+ * Note that tbl == why is intentional.
+ *
+ * We must set at least "tsk" and "why" when calling ret_with_reschedule.
+ */
+scno .req r7 @ syscall number
+tbl .req r8 @ syscall table pointer
+why .req r8 @ Linux syscall (!= 0)
+tsk .req r9 @ current thread_info
+
+/*
+ * Get the system call number.
+ */
+ .macro get_scno
+ mask_pc lr, lr
+ ldr scno, [lr, #-4] @ get SWI instruction
+ .endm
+/*
+ * -----------------------------------------------------------------------
+ */
+
+/*
+ * We rely on the fact that R0 is at the bottom of the stack (due to
+ * slow/fast restore user regs).
+ */
+#if S_R0 != 0
+#error "Please fix"
+#endif
+
+/*
+ * This is the fast syscall return path. We do as little as
+ * possible here, and this includes saving r0 back into the SVC
+ * stack.
+ */
+ret_fast_syscall:
+ disable_irqs r1 @ disable interrupts
+ ldr r1, [tsk, #TI_FLAGS]
+ tst r1, #_TIF_WORK_MASK
+ bne fast_work_pending
+ fast_restore_user_regs
+
+/*
+ * Ok, we need to do extra processing, enter the slow path.
+ */
+fast_work_pending:
+ str r0, [sp, #S_R0+S_OFF]! @ returned r0
+work_pending:
+ tst r1, #_TIF_NEED_RESCHED
+ bne work_resched
+ tst r1, #_TIF_NOTIFY_RESUME | _TIF_SIGPENDING
+ beq no_work_pending
+ mov r0, sp @ 'regs'
+ mov r2, why @ 'syscall'
+ bl do_notify_resume
+ disable_irqs r1 @ disable interrupts
+ b no_work_pending
+
+work_resched:
+ bl schedule
+/*
+ * "slow" syscall return path. "why" tells us if this was a real syscall.
+ */
+ENTRY(ret_to_user)
+ret_slow_syscall:
+ disable_irqs r1 @ disable interrupts
+ ldr r1, [tsk, #TI_FLAGS]
+ tst r1, #_TIF_WORK_MASK
+ bne work_pending
+no_work_pending:
+ slow_restore_user_regs
+
+/*
+ * This is how we return from a fork.
+ */
+ENTRY(ret_from_fork)
+ bl schedule_tail
+ get_thread_info tsk
+ ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing
+ mov why, #1
+ tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
+ beq ret_slow_syscall
+ mov r1, sp
+ mov r0, #1 @ trace exit [IP = 1]
+ bl syscall_trace
+ b ret_slow_syscall
+
+// FIXME - is this strictly necessary?
+#include "calls.S"
+
+/*=============================================================================
+ * SWI handler
+ *-----------------------------------------------------------------------------
+ */
+
+ .align 5
+ENTRY(vector_swi)
+ save_user_regs
+ zero_fp
+ get_scno
+
+#ifdef CONFIG_ALIGNMENT_TRAP
+ ldr ip, __cr_alignment
+ ldr ip, [ip]
+ mcr p15, 0, ip, c1, c0 @ update control register
+#endif
+ enable_irqs ip
+
+ str r4, [sp, #-S_OFF]! @ push fifth arg
+
+ get_thread_info tsk
+ ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing
+ bic scno, scno, #0xff000000 @ mask off SWI op-code
+ eor scno, scno, #OS_NUMBER << 20 @ check OS number
+ adr tbl, sys_call_table @ load syscall table pointer
+ tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
+ bne __sys_trace
+
+ adral lr, ret_fast_syscall @ set return address
+ orral lr, lr, #PSR_I_BIT | MODE_SVC26 @ Force SVC mode on return
+ cmp scno, #NR_syscalls @ check upper syscall limit
+ ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
+
+ add r1, sp, #S_OFF
+2: mov why, #0 @ no longer a real syscall
+ cmp scno, #ARMSWI_OFFSET
+ eor r0, scno, #OS_NUMBER << 20 @ put OS number back
+ bcs arm_syscall
+ b sys_ni_syscall @ not private func
+
+ /*
+ * This is the really slow path. We're going to be doing
+ * context switches, and waiting for our parent to respond.
+ */
+__sys_trace:
+ add r1, sp, #S_OFF
+ mov r0, #0 @ trace entry [IP = 0]
+ bl syscall_trace
+
+ adral lr, __sys_trace_return @ set return address
+ orral lr, lr, #PSR_I_BIT | MODE_SVC26 @ Force SVC mode on return
+ add r1, sp, #S_R0 + S_OFF @ pointer to regs
+ cmp scno, #NR_syscalls @ check upper syscall limit
+ ldmccia r1, {r0 - r3} @ have to reload r0 - r3
+ ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
+ b 2b
+
+__sys_trace_return:
+ str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
+ mov r1, sp
+ mov r0, #1 @ trace exit [IP = 1]
+ bl syscall_trace
+ b ret_slow_syscall
+
+ .align 5
+#ifdef CONFIG_ALIGNMENT_TRAP
+ .type __cr_alignment, #object
+__cr_alignment:
+ .word cr_alignment
+#endif
+
+ .type sys_call_table, #object
+ENTRY(sys_call_table)
+#include "calls.S"
+
+/*============================================================================
+ * Special system call wrappers
+ */
+@ r0 = syscall number
+@ r5 = syscall table
+ .type sys_syscall, #function
+sys_syscall:
+ eor scno, r0, #OS_NUMBER << 20
+ cmp scno, #NR_syscalls @ check range
+ stmleia sp, {r5, r6} @ shuffle args
+ movle r0, r1
+ movle r1, r2
+ movle r2, r3
+ movle r3, r4
+ ldrle pc, [tbl, scno, lsl #2]
+ b sys_ni_syscall
+
+sys_fork_wrapper:
+ add r0, sp, #S_OFF
+ b sys_fork
+
+sys_vfork_wrapper:
+ add r0, sp, #S_OFF
+ b sys_vfork
+
+sys_execve_wrapper:
+ add r3, sp, #S_OFF
+ b sys_execve
+
+sys_clone_wapper:
+ add r2, sp, #S_OFF
+ b sys_clone
+
+sys_sigsuspend_wrapper:
+ add r3, sp, #S_OFF
+ b sys_sigsuspend
+
+sys_rt_sigsuspend_wrapper:
+ add r2, sp, #S_OFF
+ b sys_rt_sigsuspend
+
+sys_sigreturn_wrapper:
+ add r0, sp, #S_OFF
+ b sys_sigreturn
+
+sys_rt_sigreturn_wrapper:
+ add r0, sp, #S_OFF
+ b sys_rt_sigreturn
+
+sys_sigaltstack_wrapper:
+ ldr r2, [sp, #S_OFF + S_SP]
+ b do_sigaltstack
+
+/*
+ * Note: off_4k (r5) is always units of 4K. If we can't do the requested
+ * offset, we return EINVAL. FIXME - this lost some stuff from arm32 to
+ * ifdefs. check it out.
+ */
+sys_mmap2:
+ tst r5, #((1 << (PAGE_SHIFT - 12)) - 1)
+ moveq r5, r5, lsr #PAGE_SHIFT - 12
+ streq r5, [sp, #4]
+ beq do_mmap2
+ mov r0, #-EINVAL
+ RETINSTR(mov,pc, lr)
+
+/*
+ * Design issues:
+ * - We have several modes that each vector can be called from,
+ * each with its own set of registers. On entry to any vector,
+ * we *must* save the registers used in *that* mode.
+ *
+ * - This code must be as fast as possible.
+ *
+ * There are a few restrictions on the vectors:
+ * - the SWI vector cannot be called from *any* non-user mode
+ *
+ * - the FP emulator is *never* called from *any* non-user mode undefined
+ * instruction.
+ *
+ */
+
+ .text
+
+ .macro handle_irq
+1: mov r4, #IOC_BASE
+ ldrb r6, [r4, #0x24] @ get high priority first
+ adr r5, irq_prio_h
+ teq r6, #0
+ ldreqb r6, [r4, #0x14] @ get low priority
+ adreq r5, irq_prio_l
+
+ teq r6, #0 @ If an IRQ happened...
+ ldrneb r0, [r5, r6] @ get IRQ number
+ movne r1, sp @ get struct pt_regs
+ adrne lr, 1b @ Set return address to 1b
+ orrne lr, lr, #PSR_I_BIT | MODE_SVC26 @ (and force SVC mode)
+ bne asm_do_IRQ @ process IRQ (if asserted)
+ .endm
+
+
+/*
+ * Interrupt table (incorporates priority)
+ */
+ .macro irq_prio_table
+irq_prio_l: .byte 0, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
+ .byte 4, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
+ .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
+ .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
+ .byte 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3
+ .byte 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3
+ .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
+ .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+ .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+irq_prio_h: .byte 0, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 12, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
+ .endm
+
+#if 1
+/*
+ * Uncomment these if you wish to get more debugging into about data aborts.
+ * FIXME - I bet we can find a way to encode these and keep performance.
+ */
+#define FAULT_CODE_LDRSTRPOST 0x80
+#define FAULT_CODE_LDRSTRPRE 0x40
+#define FAULT_CODE_LDRSTRREG 0x20
+#define FAULT_CODE_LDMSTM 0x10
+#define FAULT_CODE_LDCSTC 0x08
+#endif
+#define FAULT_CODE_PREFETCH 0x04
+#define FAULT_CODE_WRITE 0x02
+#define FAULT_CODE_FORCECOW 0x01
+
+/*=============================================================================
+ * Undefined FIQs
+ *-----------------------------------------------------------------------------
+ */
+_unexp_fiq: ldr sp, .LCfiq
+ mov r12, #IOC_BASE
+ strb r12, [r12, #0x38] @ Disable FIQ register
+ teqp pc, #PSR_I_BIT | PSR_F_BIT | MODE_SVC26
+ mov r0, r0
+ stmfd sp!, {r0 - r3, ip, lr}
+ adr r0, Lfiqmsg
+ bl printk
+ ldmfd sp!, {r0 - r3, ip, lr}
+ teqp pc, #PSR_I_BIT | PSR_F_BIT | MODE_FIQ26
+ mov r0, r0
+ movs pc, lr
+
+Lfiqmsg: .ascii "*** Unexpected FIQ\n\0"
+ .align
+
+.LCfiq: .word __temp_fiq
+.LCirq: .word __temp_irq
+
+/*=============================================================================
+ * Undefined instruction handler
+ *-----------------------------------------------------------------------------
+ * Handles floating point instructions
+ */
+vector_undefinstr:
+ tst lr, #MODE_SVC26 @ did we come from a non-user mode?
+ bne __und_svc @ yes - deal with it.
+/* Otherwise, fall through for the user-space (common) case. */
+ save_user_regs
+ zero_fp @ zero frame pointer
+ teqp pc, #PSR_I_BIT | MODE_SVC26 @ disable IRQs
+.Lbug_undef:
+ ldr r4, .LC2
+ ldr pc, [r4] @ Call FP module entry point
+/* FIXME - should we trap for a null pointer here? */
+
+/* The SVC mode case */
+__und_svc: save_svc_regs @ Non-user mode
+ mask_pc r0, lr
+ and r2, lr, #3
+ sub r0, r0, #4
+ mov r1, sp
+ bl do_undefinstr
+ restore_svc_regs
+
+/* We get here if the FP emulator doesnt handle the undef instr.
+ * If the insn WAS handled, the emulator jumps to ret_from_exception by itself/
+ */
+ .globl fpundefinstr
+fpundefinstr:
+ mov r0, lr
+ mov r1, sp
+ teqp pc, #MODE_SVC26
+ bl do_undefinstr
+ b ret_from_exception @ Normal FP exit
+
+#if defined CONFIG_FPE_NWFPE || defined CONFIG_FPE_FASTFPE
+ /* The FPE is always present */
+ .equ fpe_not_present, 0
+#else
+/* We get here if an undefined instruction happens and the floating
+ * point emulator is not present. If the offending instruction was
+ * a WFS, we just perform a normal return as if we had emulated the
+ * operation. This is a hack to allow some basic userland binaries
+ * to run so that the emulator module proper can be loaded. --philb
+ * FIXME - probably a broken useless hack...
+ */
+fpe_not_present:
+ adr r10, wfs_mask_data
+ ldmia r10, {r4, r5, r6, r7, r8}
+ ldr r10, [sp, #S_PC] @ Load PC
+ sub r10, r10, #4
+ mask_pc r10, r10
+ ldrt r10, [r10] @ get instruction
+ and r5, r10, r5
+ teq r5, r4 @ Is it WFS?
+ beq ret_from_exception
+ and r5, r10, r8
+ teq r5, r6 @ Is it LDF/STF on sp or fp?
+ teqne r5, r7
+ bne fpundefinstr
+ tst r10, #0x00200000 @ Does it have WB
+ beq ret_from_exception
+ and r4, r10, #255 @ get offset
+ and r6, r10, #0x000f0000
+ tst r10, #0x00800000 @ +/-
+ ldr r5, [sp, r6, lsr #14] @ Load reg
+ rsbeq r4, r4, #0
+ add r5, r5, r4, lsl #2
+ str r5, [sp, r6, lsr #14] @ Save reg
+ b ret_from_exception
+
+wfs_mask_data: .word 0x0e200110 @ WFS/RFS
+ .word 0x0fef0fff
+ .word 0x0d0d0100 @ LDF [sp]/STF [sp]
+ .word 0x0d0b0100 @ LDF [fp]/STF [fp]
+ .word 0x0f0f0f00
+#endif
+
+.LC2: .word fp_enter
+
+/*=============================================================================
+ * Prefetch abort handler
+ *-----------------------------------------------------------------------------
+ */
+#define DEBUG_UNDEF
+/* remember: lr = USR pc */
+vector_prefetch:
+ sub lr, lr, #4
+ tst lr, #MODE_SVC26
+ bne __pabt_invalid
+ save_user_regs
+ teqp pc, #MODE_SVC26 @ Enable IRQs...
+ mask_pc r0, lr @ Address of abort
+ mov r1, sp @ Tasks registers
+ bl do_PrefetchAbort
+ teq r0, #0 @ If non-zero, we believe this abort..
+ bne ret_from_exception
+#ifdef DEBUG_UNDEF
+ adr r0, t
+ bl printk
+#endif
+ ldr lr, [sp,#S_PC] @ FIXME program to test this on. I think its
+ b .Lbug_undef @ broken at the moment though!)
+
+__pabt_invalid: save_svc_regs
+ mov r0, sp @ Prefetch aborts are definitely *not*
+ mov r1, #BAD_PREFETCH @ allowed in non-user modes. We cant
+ and r2, lr, #3 @ recover from this problem.
+ b bad_mode
+
+#ifdef DEBUG_UNDEF
+t: .ascii "*** undef ***\r\n\0"
+ .align
+#endif
+
+/*=============================================================================
+ * Address exception handler
+ *-----------------------------------------------------------------------------
+ * These aren't too critical.
+ * (they're not supposed to happen).
+ * In order to debug the reason for address exceptions in non-user modes,
+ * we have to obtain all the registers so that we can see what's going on.
+ */
+
+vector_addrexcptn:
+ sub lr, lr, #8
+ tst lr, #3
+ bne Laddrexcptn_not_user
+ save_user_regs
+ teq pc, #MODE_SVC26
+ mask_pc r0, lr @ Point to instruction
+ mov r1, sp @ Point to registers
+ mov r2, #0x400
+ mov lr, pc
+ bl do_excpt
+ b ret_from_exception
+
+Laddrexcptn_not_user:
+ save_svc_regs
+ and r2, lr, #3
+ teq r2, #3
+ bne Laddrexcptn_illegal_mode
+ teqp pc, #MODE_SVC26
+ mask_pc r0, lr
+ mov r1, sp
+ orr r2, r2, #0x400
+ bl do_excpt
+ ldmia sp, {r0 - lr} @ I cant remember the reason I changed this...
+ add sp, sp, #15*4
+ movs pc, lr
+
+Laddrexcptn_illegal_mode:
+ mov r0, sp
+ str lr, [sp, #-4]!
+ orr r1, r2, #PSR_I_BIT | PSR_F_BIT
+ teqp r1, #0 @ change into mode (wont be user mode)
+ mov r0, r0
+ mov r1, r8 @ Any register from r8 - r14 can be banked
+ mov r2, r9
+ mov r3, r10
+ mov r4, r11
+ mov r5, r12
+ mov r6, r13
+ mov r7, r14
+ teqp pc, #PSR_F_BIT | MODE_SVC26 @ back to svc
+ mov r0, r0
+ stmfd sp!, {r1-r7}
+ ldmia r0, {r0-r7}
+ stmfd sp!, {r0-r7}
+ mov r0, sp
+ mov r1, #BAD_ADDREXCPTN
+ b bad_mode
+
+/*=============================================================================
+ * Interrupt (IRQ) handler
+ *-----------------------------------------------------------------------------
+ * Note: if the IRQ was taken whilst in user mode, then *no* kernel routine
+ * is running, so do not have to save svc lr.
+ *
+ * Entered in IRQ mode.
+ */
+
+vector_IRQ: ldr sp, .LCirq @ Setup some temporary stack
+ sub lr, lr, #4
+ str lr, [sp] @ push return address
+
+ tst lr, #3
+ bne __irq_non_usr
+
+__irq_usr: teqp pc, #PSR_I_BIT | MODE_SVC26 @ Enter SVC mode
+ mov r0, r0
+
+ ldr lr, .LCirq
+ ldr lr, [lr] @ Restore lr for jump back to USR
+
+ save_user_regs
+
+ handle_irq
+
+ mov why, #0
+ get_thread_info tsk
+ b ret_to_user
+
+@ Place the IRQ priority table here so that the handle_irq macros above
+@ and below here can access it.
+
+ irq_prio_table
+
+__irq_non_usr: teqp pc, #PSR_I_BIT | MODE_SVC26 @ Enter SVC mode
+ mov r0, r0
+
+ save_svc_regs_irq
+
+ and r2, lr, #3
+ teq r2, #3
+ bne __irq_invalid @ IRQ not from SVC mode
+
+ handle_irq
+
+ restore_svc_regs
+
+__irq_invalid: mov r0, sp
+ mov r1, #BAD_IRQ
+ b bad_mode
+
+/*=============================================================================
+ * Data abort handler code
+ *-----------------------------------------------------------------------------
+ *
+ * This handles both exceptions from user and SVC modes, computes the address
+ * range of the problem, and does any correction that is required. It then
+ * calls the kernel data abort routine.
+ *
+ * This is where I wish that the ARM would tell you which address aborted.
+ */
+
+vector_data: sub lr, lr, #8 @ Correct lr
+ tst lr, #3
+ bne Ldata_not_user
+ save_user_regs
+ teqp pc, #MODE_SVC26
+ mask_pc r0, lr
+ bl Ldata_do
+ b ret_from_exception
+
+Ldata_not_user:
+ save_svc_regs
+ and r2, lr, #3
+ teq r2, #3
+ bne Ldata_illegal_mode
+ tst lr, #PSR_I_BIT
+ teqeqp pc, #MODE_SVC26
+ mask_pc r0, lr
+ bl Ldata_do
+ restore_svc_regs
+
+Ldata_illegal_mode:
+ mov r0, sp
+ mov r1, #BAD_DATA
+ b bad_mode
+
+Ldata_do: mov r3, sp
+ ldr r4, [r0] @ Get instruction
+ mov r2, #0
+ tst r4, #1 << 20 @ Check to see if it is a write instruction
+ orreq r2, r2, #FAULT_CODE_WRITE @ Indicate write instruction
+ mov r1, r4, lsr #22 @ Now branch to the relevent processing routine
+ and r1, r1, #15 << 2
+ add pc, pc, r1
+ movs pc, lr
+ b Ldata_unknown
+ b Ldata_unknown
+ b Ldata_unknown
+ b Ldata_unknown
+ b Ldata_ldrstr_post @ ldr rd, [rn], #m
+ b Ldata_ldrstr_numindex @ ldr rd, [rn, #m] @ RegVal
+ b Ldata_ldrstr_post @ ldr rd, [rn], rm
+ b Ldata_ldrstr_regindex @ ldr rd, [rn, rm]
+ b Ldata_ldmstm @ ldm*a rn, <rlist>
+ b Ldata_ldmstm @ ldm*b rn, <rlist>
+ b Ldata_unknown
+ b Ldata_unknown
+ b Ldata_ldrstr_post @ ldc rd, [rn], #m @ Same as ldr rd, [rn], #m
+ b Ldata_ldcstc_pre @ ldc rd, [rn, #m]
+ b Ldata_unknown
+Ldata_unknown: @ Part of jumptable
+ mov r0, r1
+ mov r1, r4
+ mov r2, r3
+ b baddataabort
+
+Ldata_ldrstr_post:
+ mov r0, r4, lsr #14 @ Get Rn
+ and r0, r0, #15 << 2 @ Mask out reg.
+ teq r0, #15 << 2
+ ldr r0, [r3, r0] @ Get register
+ biceq r0, r0, #PCMASK
+ mov r1, r0
+#ifdef FAULT_CODE_LDRSTRPOST
+ orr r2, r2, #FAULT_CODE_LDRSTRPOST
+#endif
+ b do_DataAbort
+
+Ldata_ldrstr_numindex:
+ mov r0, r4, lsr #14 @ Get Rn
+ and r0, r0, #15 << 2 @ Mask out reg.
+ teq r0, #15 << 2
+ ldr r0, [r3, r0] @ Get register
+ mov r1, r4, lsl #20
+ biceq r0, r0, #PCMASK
+ tst r4, #1 << 23
+ addne r0, r0, r1, lsr #20
+ subeq r0, r0, r1, lsr #20
+ mov r1, r0
+#ifdef FAULT_CODE_LDRSTRPRE
+ orr r2, r2, #FAULT_CODE_LDRSTRPRE
+#endif
+ b do_DataAbort
+
+Ldata_ldrstr_regindex:
+ mov r0, r4, lsr #14 @ Get Rn
+ and r0, r0, #15 << 2 @ Mask out reg.
+ teq r0, #15 << 2
+ ldr r0, [r3, r0] @ Get register
+ and r7, r4, #15
+ biceq r0, r0, #PCMASK
+ teq r7, #15 @ Check for PC
+ ldr r7, [r3, r7, lsl #2] @ Get Rm
+ and r8, r4, #0x60 @ Get shift types
+ biceq r7, r7, #PCMASK
+ mov r9, r4, lsr #7 @ Get shift amount
+ and r9, r9, #31
+ teq r8, #0
+ moveq r7, r7, lsl r9
+ teq r8, #0x20 @ LSR shift
+ moveq r7, r7, lsr r9
+ teq r8, #0x40 @ ASR shift
+ moveq r7, r7, asr r9
+ teq r8, #0x60 @ ROR shift
+ moveq r7, r7, ror r9
+ tst r4, #1 << 23
+ addne r0, r0, r7
+ subeq r0, r0, r7 @ Apply correction
+ mov r1, r0
+#ifdef FAULT_CODE_LDRSTRREG
+ orr r2, r2, #FAULT_CODE_LDRSTRREG
+#endif
+ b do_DataAbort
+
+Ldata_ldmstm:
+ mov r7, #0x11
+ orr r7, r7, r7, lsl #8
+ and r0, r4, r7
+ and r1, r4, r7, lsl #1
+ add r0, r0, r1, lsr #1
+ and r1, r4, r7, lsl #2
+ add r0, r0, r1, lsr #2
+ and r1, r4, r7, lsl #3
+ add r0, r0, r1, lsr #3
+ add r0, r0, r0, lsr #8
+ add r0, r0, r0, lsr #4
+ and r7, r0, #15 @ r7 = no. of registers to transfer.
+ mov r5, r4, lsr #14 @ Get Rn
+ and r5, r5, #15 << 2
+ ldr r0, [r3, r5] @ Get reg
+ eor r6, r4, r4, lsl #2
+ tst r6, #1 << 23 @ Check inc/dec ^ writeback
+ rsbeq r7, r7, #0
+ add r7, r0, r7, lsl #2 @ Do correction (signed)
+ subne r1, r7, #1
+ subeq r1, r0, #1
+ moveq r0, r7
+ tst r4, #1 << 21 @ Check writeback
+ strne r7, [r3, r5]
+ eor r6, r4, r4, lsl #1
+ tst r6, #1 << 24 @ Check Pre/Post ^ inc/dec
+ addeq r0, r0, #4
+ addeq r1, r1, #4
+ teq r5, #15*4 @ CHECK FOR PC
+ biceq r1, r1, #PCMASK
+ biceq r0, r0, #PCMASK
+#ifdef FAULT_CODE_LDMSTM
+ orr r2, r2, #FAULT_CODE_LDMSTM
+#endif
+ b do_DataAbort
+
+Ldata_ldcstc_pre:
+ mov r0, r4, lsr #14 @ Get Rn
+ and r0, r0, #15 << 2 @ Mask out reg.
+ teq r0, #15 << 2
+ ldr r0, [r3, r0] @ Get register
+ mov r1, r4, lsl #24 @ Get offset
+ biceq r0, r0, #PCMASK
+ tst r4, #1 << 23
+ addne r0, r0, r1, lsr #24
+ subeq r0, r0, r1, lsr #24
+ mov r1, r0
+#ifdef FAULT_CODE_LDCSTC
+ orr r2, r2, #FAULT_CODE_LDCSTC
+#endif
+ b do_DataAbort
+
+
+/*
+ * This is the return code to user mode for abort handlers
+ */
+ENTRY(ret_from_exception)
+ get_thread_info tsk
+ mov why, #0
+ b ret_to_user
+
+ .data
+ENTRY(fp_enter)
+ .word fpe_not_present
+ .text
+/*
+ * Register switch for older 26-bit only ARMs
+ */
+ENTRY(__switch_to)
+ add r0, r0, #TI_CPU_SAVE
+ stmia r0, {r4 - sl, fp, sp, lr}
+ add r1, r1, #TI_CPU_SAVE
+ ldmia r1, {r4 - sl, fp, sp, pc}^
+
+/*
+ *=============================================================================
+ * Low-level interface code
+ *-----------------------------------------------------------------------------
+ * Trap initialisation
+ *-----------------------------------------------------------------------------
+ *
+ * Note - FIQ code has changed. The default is a couple of words in 0x1c, 0x20
+ * that call _unexp_fiq. Nowever, we now copy the FIQ routine to 0x1c (removes
+ * some excess cycles).
+ *
+ * What we need to put into 0-0x1c are branches to branch to the kernel.
+ */
+
+ .section ".init.text",#alloc,#execinstr
+
+.Ljump_addresses:
+ swi SYS_ERROR0
+ .word vector_undefinstr - 12
+ .word vector_swi - 16
+ .word vector_prefetch - 20
+ .word vector_data - 24
+ .word vector_addrexcptn - 28
+ .word vector_IRQ - 32
+ .word _unexp_fiq - 36
+ b . + 8
+/*
+ * initialise the trap system
+ */
+ENTRY(__trap_init)
+ stmfd sp!, {r4 - r7, lr}
+ adr r1, .Ljump_addresses
+ ldmia r1, {r1 - r7, ip, lr}
+ orr r2, lr, r2, lsr #2
+ orr r3, lr, r3, lsr #2
+ orr r4, lr, r4, lsr #2
+ orr r5, lr, r5, lsr #2
+ orr r6, lr, r6, lsr #2
+ orr r7, lr, r7, lsr #2
+ orr ip, lr, ip, lsr #2
+ mov r0, #0
+ stmia r0, {r1 - r7, ip}
+ ldmfd sp!, {r4 - r7, pc}^
+
+ .bss
+__temp_irq: .space 4 @ saved lr_irq
+__temp_fiq: .space 128
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