ref: 75a8003a8afb22e8557da98ad5dae63efa365d5e
dir: /sys/src/9/kw/lexception.s/
/*
* arm exception handlers
*/
#include "arm.s"
#undef B /* B is for 'botch' */
/*
* exception vectors, copied by trapinit() to somewhere useful
*/
TEXT vectors(SB), 1, $-4
MOVW 0x18(R15), R15 /* reset */
MOVW 0x18(R15), R15 /* undefined instr. */
MOVW 0x18(R15), R15 /* SWI & SMC */
MOVW 0x18(R15), R15 /* prefetch abort */
MOVW 0x18(R15), R15 /* data abort */
MOVW 0x18(R15), R15 /* reserved */
MOVW 0x18(R15), R15 /* IRQ */
MOVW 0x18(R15), R15 /* FIQ */
TEXT vtable(SB), 1, $-4
WORD $_vsvc(SB) /* reset, in svc mode already */
WORD $_vund(SB) /* undefined, switch to svc mode */
WORD $_vsvc(SB) /* swi, in svc mode already */
WORD $_vpabt(SB) /* prefetch abort, switch to svc mode */
WORD $_vdabt(SB) /* data abort, switch to svc mode */
WORD $_vsvc(SB) /* reserved */
WORD $_virq(SB) /* IRQ, switch to svc mode */
// WORD $_vfiq(SB) /* FIQ, switch to svc mode */
WORD $_virq(SB) /* FIQ, switch to svc mode */
TEXT _vrst(SB), 1, $-4
BL _reset(SB)
TEXT _vsvc(SB), 1, $-4 /* SWI */
MOVW.W R14, -4(R13) /* ureg->pc = interrupted PC */
MOVW SPSR, R14 /* ureg->psr = SPSR */
MOVW.W R14, -4(R13) /* ... */
MOVW $PsrMsvc, R14 /* ureg->type = PsrMsvc */
MOVW.W R14, -4(R13) /* ... */
/* avoid the ambiguity described in notes/movm.w. */
// MOVM.DB.W.S [R0-R14], (R13) /* save user level registers, at end r13 points to ureg */
MOVM.DB.S [R0-R14], (R13) /* save user level registers */
SUB $(15*4), R13 /* r13 now points to ureg */
MOVW $setR12(SB), R12 /* Make sure we've got the kernel's SB loaded */
// MOVW $(KSEG0+16*KiB-MACHSIZE), R10 /* m */
MOVW $(L1-MACHSIZE), R10 /* m */
MOVW 8(R10), R9 /* up */
MOVW R13, R0 /* first arg is pointer to ureg */
SUB $8, R13 /* space for argument+link */
BL syscall(SB)
ADD $(8+4*15), R13 /* make r13 point to ureg->type */
MOVW 8(R13), R14 /* restore link */
MOVW 4(R13), R0 /* restore SPSR */
MOVW R0, SPSR /* ... */
MOVM.DB.S (R13), [R0-R14] /* restore registers */
ADD $8, R13 /* pop past ureg->{type+psr} */
RFE /* MOVM.IA.S.W (R13), [R15] */
TEXT _vund(SB), 1, $-4 /* undefined */
MOVM.IA [R0-R4], (R13) /* free some working space */
MOVW $PsrMund, R0
B _vswitch
TEXT _vpabt(SB), 1, $-4 /* prefetch abort */
MOVM.IA [R0-R4], (R13) /* free some working space */
MOVW $PsrMabt, R0 /* r0 = type */
B _vswitch
TEXT _vdabt(SB), 1, $-4 /* data abort */
MOVM.IA [R0-R4], (R13) /* free some working space */
MOVW $(PsrMabt+1), R0 /* r0 = type */
B _vswitch
TEXT _virq(SB), 1, $-4 /* IRQ */
MOVM.IA [R0-R4], (R13) /* free some working space */
MOVW $PsrMirq, R0 /* r0 = type */
B _vswitch
/*
* come here with type in R0 and R13 pointing above saved [r0-r4].
* we'll switch to SVC mode and then call trap.
*/
_vswitch:
MOVW SPSR, R1 /* save SPSR for ureg */
MOVW R14, R2 /* save interrupted pc for ureg */
MOVW R13, R3 /* save pointer to where the original [R0-R4] are */
/*
* switch processor to svc mode. this switches the banked registers
* (r13 [sp] and r14 [link]) to those of svc mode.
*/
MOVW CPSR, R14
BIC $PsrMask, R14
ORR $(PsrDirq|PsrDfiq|PsrMsvc), R14
MOVW R14, CPSR /* switch! */
AND.S $0xf, R1, R4 /* interrupted code kernel or user? */
BEQ _userexcep
/* here for trap from SVC mode */
MOVM.DB.W [R0-R2], (R13) /* set ureg->{type, psr, pc}; r13 points to ureg->type */
MOVM.IA (R3), [R0-R4] /* restore [R0-R4] from previous mode's stack */
/*
* avoid the ambiguity described in notes/movm.w.
* In order to get a predictable value in R13 after the stores,
* separate the store-multiple from the stack-pointer adjustment.
* We'll assume that the old value of R13 should be stored on the stack.
*/
/* save kernel level registers, at end r13 points to ureg */
// MOVM.DB.W [R0-R14], (R13)
MOVM.DB [R0-R14], (R13)
SUB $(15*4), R13 /* SP now points to saved R0 */
MOVW $setR12(SB), R12 /* Make sure we've got the kernel's SB loaded */
MOVW R13, R0 /* first arg is pointer to ureg */
SUB $(4*2), R13 /* space for argument+link (for debugger) */
MOVW $0xdeaddead, R11 /* marker */
BL trap(SB)
ADD $(4*2+4*15), R13 /* make r13 point to ureg->type */
MOVW 8(R13), R14 /* restore link */
MOVW 4(R13), R0 /* restore SPSR */
MOVW R0, SPSR /* ... */
MOVM.DB (R13), [R0-R14] /* restore registers */
ADD $(4*2), R13 /* pop past ureg->{type+psr} to pc */
RFE /* MOVM.IA.S.W (R13), [R15] */
/* here for trap from USER mode */
_userexcep:
MOVM.DB.W [R0-R2], (R13) /* set ureg->{type, psr, pc}; r13 points to ureg->type */
MOVM.IA (R3), [R0-R4] /* restore [R0-R4] from previous mode's stack */
/* avoid the ambiguity described in notes/movm.w. */
// MOVM.DB.W.S [R0-R14], (R13) /* save kernel level registers, at end r13 points to ureg */
MOVM.DB.S [R0-R14], (R13) /* save kernel level registers */
SUB $(15*4), R13 /* r13 now points to ureg */
MOVW $setR12(SB), R12 /* Make sure we've got the kernel's SB loaded */
// MOVW $(KSEG0+16*KiB-MACHSIZE), R10 /* m */
MOVW $(L1-MACHSIZE), R10 /* m */
MOVW 8(R10), R9 /* up */
MOVW R13, R0 /* first arg is pointer to ureg */
SUB $(4*2), R13 /* space for argument+link (for debugger) */
BL trap(SB)
ADD $(4*2+4*15), R13 /* make r13 point to ureg->type */
MOVW 8(R13), R14 /* restore link */
MOVW 4(R13), R0 /* restore SPSR */
MOVW R0, SPSR /* ... */
MOVM.DB.S (R13), [R0-R14] /* restore registers */
ADD $(4*2), R13 /* pop past ureg->{type+psr} */
RFE /* MOVM.IA.S.W (R13), [R15] */
TEXT _vfiq(SB), 1, $-4 /* FIQ */
RFE /* FIQ is special, ignore it for now */
/*
* set the stack value for the mode passed in R0
*/
TEXT setr13(SB), 1, $-4
MOVW 4(FP), R1
MOVW CPSR, R2
BIC $PsrMask, R2, R3
ORR R0, R3
MOVW R3, CPSR /* switch to new mode */
MOVW R13, R0 /* return old sp */
MOVW R1, R13 /* install new one */
MOVW R2, CPSR /* switch back to old mode */
RET