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trap.c
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trap.c
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/*
* Trap
*/
#include "trap.h"
#include "device.h"
uint64_t
trap_enter(uint64_t pc, uint32_t next_priv, uint64_t cause, uint64_t tval)
{
uint64_t ret;
bool has_except = false;
if (next_priv == S_MODE) {
/* Handle trap in S_MODE */
uint64_t mode_bit = (priv() == U_MODE) ? 0UL : 1UL;
uint64_t sstatus = csr_read(SSTATUS, &has_except);
SET_BIT(sstatus, BIT_SPP_POS, mode_bit);
switch_to(S_MODE);
csr_update(SCAUSE, cause, CSR_OP_WRITE, &has_except);
csr_update(STVAL, tval, CSR_OP_WRITE, &has_except);
SET_BIT(sstatus, BIT_SPIE_POS, BIT(sstatus, BIT_SIE_POS));
SET_BIT(sstatus, BIT_SIE_POS, 0UL);
csr_update(SSTATUS, sstatus, CSR_OP_WRITE, &has_except);
csr_update(SEPC, pc, CSR_OP_WRITE, &has_except);
ret = csr_read(STVEC, &has_except);
} else {
/* Handle trap in M_MODE. MS_MPP at [12,11]. */
uint64_t mstatus = csr_read(MSTATUS, &has_except);
SET_BITS(mstatus, 12, 11, priv());
switch_to(M_MODE);
csr_update(MCAUSE, cause, CSR_OP_WRITE, &has_except);
csr_update(MTVAL, tval, CSR_OP_WRITE, &has_except);
SET_BIT(mstatus, BIT_MPIE_POS, BIT(mstatus, BIT_MIE_POS));
SET_BIT(mstatus, BIT_MIE_POS, 0UL);
csr_update(MSTATUS, mstatus, CSR_OP_WRITE, &has_except);
csr_update(MEPC, pc, CSR_OP_WRITE, &has_except);
ret = csr_read(MTVEC, &has_except);
}
return ret;
}
uint64_t
trap_exit(op_t op)
{
uint64_t ret;
uint64_t sstatus;
uint64_t mstatus;
bool has_except = false;
switch (op)
{
case SRET:
sstatus = csr_read(SSTATUS, &has_except);
switch_to(BIT(sstatus, BIT_SPP_POS) ? S_MODE : U_MODE);
SET_BIT(sstatus, BIT_SIE_POS, BIT(sstatus, BIT_SPIE_POS));
csr_update(SSTATUS, sstatus, CSR_OP_WRITE, &has_except);
ret = csr_read(SEPC, &has_except);
break;
case MRET:
mstatus = csr_read(MSTATUS, &has_except);
switch_to(BITS(mstatus, 12, 11));
SET_BIT(mstatus, BIT_MIE_POS, BIT(mstatus, BIT_MPIE_POS));
csr_update(MSTATUS, mstatus, CSR_OP_WRITE, &has_except);
ret = csr_read(MEPC, &has_except);
break;
default:
panic("%s: bad op(0x%x)\n", __func__, op);
}
return ret;
}
uint64_t
handle_interrupt(uint64_t pc)
{
uint32_t next_priv;
uint64_t ret_pc = 0;
bool has_except = false;
uint32_t eid = 0;
intr_type_t type = INTR_TYPE_NONE;
/* Source */
eid = plic_interrupt();
if (eid)
type = EXTERNAL_INTR_TYPE;
else
type = clint_interrupt();
if (!type)
return 0;
/* Target */
next_priv = intr_next_priv(type, priv());
if (next_priv == S_MODE) {
uint64_t sstatus = csr_read(SSTATUS, &has_except);
if (sstatus & BIT_SIE) {
uint64_t sie = csr_read(SIE, &has_except);
uint32_t irq_bit = intr_bit_flag(type, S_MODE);
if (sie & irq_bit) {
csr_update(SIP, irq_bit, CSR_OP_SET, &has_except);
ret_pc = trap_enter(pc, next_priv,
intr_cause(type, next_priv), 0);
}
}
} else {
uint64_t mstatus = csr_read(MSTATUS, &has_except);
if (mstatus & BIT_MIE) {
uint64_t mie = csr_read(MIE, &has_except);
uint32_t irq_bit = intr_bit_flag(type, M_MODE);
if (mie & irq_bit) {
csr_update(MIP, irq_bit, CSR_OP_SET, &has_except);
ret_pc = trap_enter(pc, next_priv,
intr_cause(type, next_priv), 0);
}
}
}
return ret_pc;
}