/* $NetBSD: exception.S,v 1.13 2003/10/31 16:30:15 scw Exp $ */
/*-
* Copyright (c) 1994-1997 Mark Brinicombe.
* Copyright (c) 1994 Brini.
* All rights reserved.
*
* This code is derived from software written for Brini by Mark Brinicombe
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Brini.
* 4. The name of the company nor the name of the author may be used to
* endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* RiscBSD kernel project
*
* exception.S
*
* Low level handlers for exception vectors
*
* Created : 24/09/94
*
* Based on kate/display/abort.s
*
*/
#include "assym.s"
#include <machine/asm.h>
#include <machine/armreg.h>
#include <machine/asmacros.h>
#include <machine/trap.h>
__FBSDID("$FreeBSD$");
#ifdef KDTRACE_HOOKS
.bss
.align 4
.global _C_LABEL(dtrace_invop_jump_addr)
_C_LABEL(dtrace_invop_jump_addr):
.word 0
.word 0
#endif
.text
.align 2
/*
* ASM macros for pushing and pulling trapframes from the stack
*
* These macros are used to handle the irqframe and trapframe structures
* defined above.
*/
/*
* PUSHFRAME - macro to push a trap frame on the stack in the current mode
* Since the current mode is used, the SVC lr field is not defined.
*
* NOTE: r13 and r14 are stored separately as a work around for the
* SA110 rev 2 STM^ bug
*/
#if __ARM_ARCH < 6
#define PUSHFRAME \
sub sp, sp, #4; /* Align the stack */ \
str lr, [sp, #-4]!; /* Push the return address */ \
sub sp, sp, #(4*17); /* Adjust the stack pointer */ \
stmia sp, {r0-r12}; /* Push the user mode registers */ \
add r0, sp, #(4*13); /* Adjust the stack pointer */ \
stmia r0, {r13-r14}^; /* Push the user mode registers */ \
mov r0, r0; /* NOP for previous instruction */ \
mrs r0, spsr; /* Put the SPSR on the stack */ \
str r0, [sp, #-4]!; \
ldr r0, =ARM_RAS_START; \
mov r1, #0; \
str r1, [r0]; \
mov r1, #0xffffffff; \
str r1, [r0, #4];
#else
#define PUSHFRAME \
sub sp, sp, #4; /* Align the stack */ \
str lr, [sp, #-4]!; /* Push the return address */ \
sub sp, sp, #(4*17); /* Adjust the stack pointer */ \
stmia sp, {r0-r12}; /* Push the user mode registers */ \
add r0, sp, #(4*13); /* Adjust the stack pointer */ \
stmia r0, {r13-r14}^; /* Push the user mode registers */ \
mov r0, r0; /* NOP for previous instruction */ \
mrs r0, spsr; /* Put the SPSR on the stack */ \
str r0, [sp, #-4]!;
#endif
/*
* PULLFRAME - macro to pull a trap frame from the stack in the current mode
* Since the current mode is used, the SVC lr field is ignored.
*/
#if __ARM_ARCH < 6
#define PULLFRAME \
ldr r0, [sp], #4; /* Get the SPSR from stack */ \
msr spsr_fsxc, r0; \
ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
mov r0, r0; /* NOP for previous instruction */ \
add sp, sp, #(4*17); /* Adjust the stack pointer */ \
ldr lr, [sp], #4; /* Pull the return address */ \
add sp, sp, #4 /* Align the stack */
#else
#define PULLFRAME \
ldr r0, [sp], #4 ; /* Get the SPSR from stack */ \
msr spsr_fsxc, r0; \
clrex; \
ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
mov r0, r0; /* NOP for previous instruction */ \
add sp, sp, #(4*17); /* Adjust the stack pointer */ \
ldr lr, [sp], #4; /* Pull the return address */ \
add sp, sp, #4 /* Align the stack */
#endif
/*
* PUSHFRAMEINSVC - macro to push a trap frame on the stack in SVC32 mode
* This should only be used if the processor is not currently in SVC32
* mode. The processor mode is switched to SVC mode and the trap frame is
* stored. The SVC lr field is used to store the previous value of
* lr in SVC mode.
*
* NOTE: r13 and r14 are stored separately as a work around for the
* SA110 rev 2 STM^ bug
*/
#if __ARM_ARCH < 6
#define PUSHFRAMEINSVC \
stmdb sp, {r0-r3}; /* Save 4 registers */ \
mov r0, lr; /* Save xxx32 r14 */ \
mov r1, sp; /* Save xxx32 sp */ \
mrs r3, spsr; /* Save xxx32 spsr */ \
mrs r2, cpsr; /* Get the CPSR */ \
bic r2, r2, #(PSR_MODE); /* Fix for SVC mode */ \
orr r2, r2, #(PSR_SVC32_MODE); \
msr cpsr_c, r2; /* Punch into SVC mode */ \
mov r2, sp; /* Save SVC sp */ \
bic sp, sp, #7; /* Align sp to an 8-byte addrress */ \
sub sp, sp, #(4 * 17); /* Pad trapframe to keep alignment */ \
/* and for dtrace to emulate push/pop */ \
str r0, [sp, #-4]!; /* Push return address */ \
str lr, [sp, #-4]!; /* Push SVC lr */ \
str r2, [sp, #-4]!; /* Push SVC sp */ \
msr spsr_fsxc, r3; /* Restore correct spsr */ \
ldmdb r1, {r0-r3}; /* Restore 4 regs from xxx mode */ \
sub sp, sp, #(4*15); /* Adjust the stack pointer */ \
stmia sp, {r0-r12}; /* Push the user mode registers */ \
add r0, sp, #(4*13); /* Adjust the stack pointer */ \
stmia r0, {r13-r14}^; /* Push the user mode registers */ \
mov r0, r0; /* NOP for previous instruction */ \
ldr r5, =ARM_RAS_START; /* Check if there's any RAS */ \
ldr r4, [r5, #4]; /* reset it to point at the */ \
cmp r4, #0xffffffff; /* end of memory if necessary; */ \
movne r1, #0xffffffff; /* leave value in r4 for later */ \
strne r1, [r5, #4]; /* comparison against PC. */ \
ldr r3, [r5]; /* Retrieve global RAS_START */ \
cmp r3, #0; /* and reset it if non-zero. */ \
movne r1, #0; /* If non-zero RAS_START and */ \
strne r1, [r5]; /* PC was lower than RAS_END, */ \
ldrne r1, [r0, #16]; /* adjust the saved PC so that */ \
cmpne r4, r1; /* execution later resumes at */ \
strhi r3, [r0, #16]; /* the RAS_START location. */ \
mrs r0, spsr; \
str r0, [sp, #-4]!
#else
#define PUSHFRAMEINSVC \
stmdb sp, {r0-r3}; /* Save 4 registers */ \
mov r0, lr; /* Save xxx32 r14 */ \
mov r1, sp; /* Save xxx32 sp */ \
mrs r3, spsr; /* Save xxx32 spsr */ \
mrs r2, cpsr; /* Get the CPSR */ \
bic r2, r2, #(PSR_MODE); /* Fix for SVC mode */ \
orr r2, r2, #(PSR_SVC32_MODE); \
msr cpsr_c, r2; /* Punch into SVC mode */ \
mov r2, sp; /* Save SVC sp */ \
bic sp, sp, #7; /* Align sp to an 8-byte addrress */ \
sub sp, sp, #(4 * 17); /* Pad trapframe to keep alignment */ \
/* and for dtrace to emulate push/pop */ \
str r0, [sp, #-4]!; /* Push return address */ \
str lr, [sp, #-4]!; /* Push SVC lr */ \
str r2, [sp, #-4]!; /* Push SVC sp */ \
msr spsr_fsxc, r3; /* Restore correct spsr */ \
ldmdb r1, {r0-r3}; /* Restore 4 regs from xxx mode */ \
sub sp, sp, #(4*15); /* Adjust the stack pointer */ \
stmia sp, {r0-r12}; /* Push the user mode registers */ \
add r0, sp, #(4*13); /* Adjust the stack pointer */ \
stmia r0, {r13-r14}^; /* Push the user mode registers */ \
mov r0, r0; /* NOP for previous instruction */ \
mrs r0, spsr; /* Put the SPSR on the stack */ \
str r0, [sp, #-4]!
#endif
/*
* PULLFRAMEFROMSVCANDEXIT - macro to pull a trap frame from the stack
* in SVC32 mode and restore the saved processor mode and PC.
* This should be used when the SVC lr register needs to be restored on
* exit.
*/
#if __ARM_ARCH < 6
#define PULLFRAMEFROMSVCANDEXIT \
ldr r0, [sp], #4; /* Get the SPSR from stack */ \
msr spsr_fsxc, r0; /* restore SPSR */ \
ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
mov r0, r0; /* NOP for previous instruction */ \
add sp, sp, #(4*15); /* Adjust the stack pointer */ \
ldmia sp, {sp, lr, pc}^ /* Restore lr and exit */
#else
#define PULLFRAMEFROMSVCANDEXIT \
ldr r0, [sp], #4; /* Get the SPSR from stack */ \
msr spsr_fsxc, r0; /* restore SPSR */ \
clrex; \
ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
mov r0, r0; /* NOP for previous instruction */ \
add sp, sp, #(4*15); /* Adjust the stack pointer */ \
ldmia sp, {sp, lr, pc}^ /* Restore lr and exit */
#endif
/*
* Unwind hints so we can unwind past functions that use
* PULLFRAMEFROMSVCANDEXIT. They are run in reverse order.
* As the last thing we do is restore the stack pointer
* we can ignore the padding at the end of struct trapframe.
*/
#define UNWINDSVCFRAME \
.save {r13-r15}; /* Restore sp, lr, pc */ \
.pad #(2*4); /* Skip user sp and lr */ \
.save {r0-r12}; /* Restore r0-r12 */ \
.pad #(4) /* Skip spsr */
#define DO_AST \
ldr r0, [sp]; /* Get the SPSR from stack */ \
mrs r4, cpsr; /* save CPSR */ \
orr r1, r4, #(PSR_I|PSR_F); \
msr cpsr_c, r1; /* Disable interrupts */ \
and r0, r0, #(PSR_MODE); /* Returning to USR mode? */ \
teq r0, #(PSR_USR32_MODE); \
bne 2f; /* Nope, get out now */ \
bic r4, r4, #(PSR_I|PSR_F); \
1: GET_CURTHREAD_PTR(r5); \
ldr r1, [r5, #(TD_FLAGS)]; \
and r1, r1, #(TDF_ASTPENDING|TDF_NEEDRESCHED); \
teq r1, #0; \
beq 2f; /* Nope. Just bail */ \
msr cpsr_c, r4; /* Restore interrupts */ \
mov r0, sp; \
bl _C_LABEL(ast); /* ast(frame) */ \
orr r0, r4, #(PSR_I|PSR_F); \
msr cpsr_c, r0; \
b 1b; \
2:
/*
* Entry point for a Software Interrupt (SWI).
*
* The hardware switches to svc32 mode on a swi, so we're already on the
* right stack; just build a trapframe and call the handler.
*/
ASENTRY_NP(swi_entry)
PUSHFRAME /* Build the trapframe on the */
mov r0, sp /* scv32 stack, pass it to the */
bl _C_LABEL(swi_handler) /* swi handler. */
/*
* The fork_trampoline() code in swtch.S aranges for the MI fork_exit()
* to return to swi_exit here, to return to userland. The net effect is
* that a newly created thread appears to return from a SWI just like
* the parent thread that created it.
*/
ASEENTRY_NP(swi_exit)
DO_AST /* Handle pending signals. */
PULLFRAME /* Deallocate trapframe. */
movs pc, lr /* Return to userland. */
STOP_UNWINDING /* Don't unwind into user mode. */
EEND(swi_exit)
END(swi_entry)
/*
* Standard exception exit handler.
*
* This is used to return from all exceptions except SWI. It uses DO_AST and
* PULLFRAMEFROMSVCANDEXIT and can only be called if the exception entry code
* used PUSHFRAMEINSVC.
*
* If the return is to user mode, this uses DO_AST to deliver any pending
* signals and/or handle TDF_NEEDRESCHED first.
*/
ASENTRY_NP(exception_exit)
DO_AST /* Handle pending signals. */
PULLFRAMEFROMSVCANDEXIT /* Return. */
UNWINDSVCFRAME /* Special unwinding for exceptions. */
END(exception_exit)
/*
* Entry point for a Prefetch Abort exception.
*
* The hardware switches to the abort mode stack; we switch to svc32 before
* calling the handler, then return directly to the original mode/stack
* on exit (without transitioning back through the abort mode stack).
*/
ASENTRY_NP(prefetch_abort_entry)
#ifdef __XSCALE__
nop /* Make absolutely sure any pending */
nop /* imprecise aborts have occurred. */
#endif
sub lr, lr, #4 /* Adjust the lr. Transition to scv32 */
PUSHFRAMEINSVC /* mode stack, build trapframe there. */
adr lr, exception_exit /* Return from handler via standard */
mov r0, sp /* exception exit routine. Pass the */
mov r1, #1 /* Type flag */
b _C_LABEL(abort_handler)
END(prefetch_abort_entry)
/*
* Entry point for a Data Abort exception.
*
* The hardware switches to the abort mode stack; we switch to svc32 before
* calling the handler, then return directly to the original mode/stack
* on exit (without transitioning back through the abort mode stack).
*/
ASENTRY_NP(data_abort_entry)
#ifdef __XSCALE__
nop /* Make absolutely sure any pending */
nop /* imprecise aborts have occurred. */
#endif
sub lr, lr, #8 /* Adjust the lr. Transition to scv32 */
PUSHFRAMEINSVC /* mode stack, build trapframe there. */
adr lr, exception_exit /* Exception exit routine */
mov r0, sp /* Trapframe to the handler */
mov r1, #0 /* Type flag */
b _C_LABEL(abort_handler)
END(data_abort_entry)
/*
* Entry point for an Undefined Instruction exception.
*
* The hardware switches to the undefined mode stack; we switch to svc32 before
* calling the handler, then return directly to the original mode/stack
* on exit (without transitioning back through the undefined mode stack).
*/
ASENTRY_NP(undefined_entry)
PUSHFRAMEINSVC /* mode stack, build trapframe there. */
mov r4, r0 /* R0 contains SPSR */
adr lr, exception_exit /* Return from handler via standard */
mov r0, sp /* exception exit routine. pass frame */
ldr r2, [sp, #(TF_PC)] /* load pc */
#if __ARM_ARCH >= 7
tst r4, #(PSR_T) /* test if PSR_T */
subne r2, r2, #(THUMB_INSN_SIZE)
subeq r2, r2, #(INSN_SIZE)
#else
sub r2, r2, #(INSN_SIZE) /* fix pc */
#endif
str r2, [sp, #TF_PC] /* store pc */
#ifdef KDTRACE_HOOKS
/* Check if dtrace is enabled */
ldr r1, =_C_LABEL(dtrace_invop_jump_addr)
ldr r3, [r1]
cmp r3, #0
beq undefinedinstruction
and r4, r4, #(PSR_MODE) /* Mask out unneeded bits */
cmp r4, #(PSR_USR32_MODE) /* Check if we came from usermode */
beq undefinedinstruction
ldr r4, [r2] /* load instrution */
ldr r1, =FBT_BREAKPOINT /* load fbt inv op */
cmp r1, r4
bne undefinedinstruction
bx r3 /* call invop_jump_addr */
#endif
b undefinedinstruction /* call stadnard handler */
END(undefined_entry)
/*
* Entry point for a normal IRQ.
*
* The hardware switches to the IRQ mode stack; we switch to svc32 before
* calling the handler, then return directly to the original mode/stack
* on exit (without transitioning back through the IRQ mode stack).
*/
ASENTRY_NP(irq_entry)
sub lr, lr, #4 /* Adjust the lr. Transition to scv32 */
PUSHFRAMEINSVC /* mode stack, build trapframe there. */
adr lr, exception_exit /* Return from handler via standard */
mov r0, sp /* exception exit routine. Pass the */
b _C_LABEL(intr_irq_handler)/* trapframe to the handler. */
END(irq_entry)
/*
* Entry point for an FIQ interrupt.
*
* We don't currently support FIQ handlers very much. Something can
* install itself in the FIQ vector using code (that may or may not work
* these days) in fiq.c. If nobody does that and an FIQ happens, this
* default handler just disables FIQs and otherwise ignores it.
*/
ASENTRY_NP(fiq_entry)
mrs r8, cpsr /* FIQ handling isn't supported, */
bic r8, #(PSR_F) /* just disable FIQ and return. */
msr cpsr_c, r8 /* The r8 we trash here is the */
subs pc, lr, #4 /* banked FIQ-mode r8. */
END(fiq_entry)
/*
* Entry point for an Address Exception exception.
* This is an arm26 exception that should never happen.
*/
ASENTRY_NP(addr_exception_entry)
mov r3, lr
mrs r2, spsr
mrs r1, cpsr
adr r0, Laddr_exception_msg
b _C_LABEL(panic)
Laddr_exception_msg:
.asciz "Address Exception CPSR=0x%08x SPSR=0x%08x LR=0x%08x\n"
.balign 4
END(addr_exception_entry)
/*
* Entry point for the system Reset vector.
* This should never happen, so panic.
*/
ASENTRY_NP(reset_entry)
mov r1, lr
adr r0, Lreset_panicmsg
b _C_LABEL(panic)
/* NOTREACHED */
Lreset_panicmsg:
.asciz "Reset vector called, LR = 0x%08x"
.balign 4
END(reset_entry)
/*
* page0 and page0_data -- An image of the ARM vectors which is copied to
* the ARM vectors page (high or low) as part of CPU initialization. The
* code that does the copy assumes that page0_data holds one 32-bit word
* of data for each of the predefined ARM vectors. It also assumes that
* page0_data follows the vectors in page0, but other stuff can appear
* between the two. We currently leave room between the two for some fiq
* handler code to be copied in.
*/
.global _C_LABEL(page0), _C_LABEL(page0_data)
_C_LABEL(page0):
ldr pc, .Lreset_entry
ldr pc, .Lundefined_entry
ldr pc, .Lswi_entry
ldr pc, .Lprefetch_abort_entry
ldr pc, .Ldata_abort_entry
ldr pc, .Laddr_exception_entry
ldr pc, .Lirq_entry
.fiqv: ldr pc, .Lfiq_entry
.space 256 /* room for some fiq handler code */
_C_LABEL(page0_data):
.Lreset_entry: .word reset_entry
.Lundefined_entry: .word undefined_entry
.Lswi_entry: .word swi_entry
.Lprefetch_abort_entry: .word prefetch_abort_entry
.Ldata_abort_entry: .word data_abort_entry
.Laddr_exception_entry: .word addr_exception_entry
.Lirq_entry: .word irq_entry
.Lfiq_entry: .word fiq_entry
/*
* These items are used by the code in fiq.c to install what it calls the
* "null" handler. It's actually our default vector entry that just jumps
* to the default handler which just disables FIQs and returns.
*/
.global _C_LABEL(fiq_nullhandler_code), _C_LABEL(fiq_nullhandler_size)
_C_LABEL(fiq_nullhandler_code):
.word .fiqv
_C_LABEL(fiq_nullhandler_size):
.word 4