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RISC-V: Add support for vectored interrupts 

If vectored interrupts are enabled (bits[1:0]
of mtvec/stvec == 1) then use the following
logic for trap entry address calculation:

 pc = mtvec + cause * 4

In addition to adding support for vectored interrupts
this patch simplifies the interrupt delivery logic
by making sync/async cause decoding and encoding
steps distinct.

The cause code and the sign bit indicating sync/async
is split at the beginning of the function and fixed
cause is renamed to cause. The MSB setting for async
traps is delayed until setting mcause/scause to allow
redundant variables to be eliminated. Some variables
are renamed for conciseness and moved so that decls
are at the start of the block.

Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This commit is contained in:
Michael Clark 2019-03-16 01:21:03 +00:00 committed by Palmer Dabbelt
parent d26f5a4234
commit acbbb94e57
No known key found for this signature in database
GPG Key ID: EF4CA1502CCBAB41
2 changed files with 63 additions and 100 deletions
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151
target/riscv/cpu_helper.c
View File

@ -454,118 +454,81 @@ void riscv_cpu_do_interrupt(CPUState *cs)
RISCVCPU *cpu = RISCV_CPU(cs);
CPURISCVState *env = &cpu->env;
/* cs->exception is 32-bits wide unlike mcause which is XLEN-bits wide
* so we mask off the MSB and separate into trap type and cause.
*/
bool async = !!(cs->exception_index & RISCV_EXCP_INT_FLAG);
target_ulong cause = cs->exception_index & RISCV_EXCP_INT_MASK;
target_ulong deleg = async ? env->mideleg : env->medeleg;
target_ulong tval = 0;
static const int ecall_cause_map[] = {
[PRV_U] = RISCV_EXCP_U_ECALL,
[PRV_S] = RISCV_EXCP_S_ECALL,
[PRV_H] = RISCV_EXCP_H_ECALL,
[PRV_M] = RISCV_EXCP_M_ECALL
};
if (!async) {
/* set tval to badaddr for traps with address information */
switch (cause) {
case RISCV_EXCP_INST_ADDR_MIS:
case RISCV_EXCP_INST_ACCESS_FAULT:
case RISCV_EXCP_LOAD_ADDR_MIS:
case RISCV_EXCP_STORE_AMO_ADDR_MIS:
case RISCV_EXCP_LOAD_ACCESS_FAULT:
case RISCV_EXCP_STORE_AMO_ACCESS_FAULT:
case RISCV_EXCP_INST_PAGE_FAULT:
case RISCV_EXCP_LOAD_PAGE_FAULT:
case RISCV_EXCP_STORE_PAGE_FAULT:
tval = env->badaddr;
break;
default:
break;
}
/* ecall is dispatched as one cause so translate based on mode */
if (cause == RISCV_EXCP_U_ECALL) {
assert(env->priv <= 3);
cause = ecall_cause_map[env->priv];
}
}
if (RISCV_DEBUG_INTERRUPT) {
int log_cause = cs->exception_index & RISCV_EXCP_INT_MASK;
if (cs->exception_index & RISCV_EXCP_INT_FLAG) {
qemu_log_mask(LOG_TRACE, "core "
TARGET_FMT_ld ": trap %s, epc 0x" TARGET_FMT_lx "\n",
env->mhartid, riscv_intr_names[log_cause], env->pc);
} else {
qemu_log_mask(LOG_TRACE, "core "
TARGET_FMT_ld ": intr %s, epc 0x" TARGET_FMT_lx "\n",
env->mhartid, riscv_excp_names[log_cause], env->pc);
}
qemu_log_mask(LOG_TRACE, "core " TARGET_FMT_ld ": %s %s, "
"epc 0x" TARGET_FMT_lx ": tval 0x" TARGET_FMT_lx "\n",
env->mhartid, async ? "intr" : "trap",
(async ? riscv_intr_names : riscv_excp_names)[cause],
env->pc, tval);
}
target_ulong fixed_cause = 0;
if (cs->exception_index & (RISCV_EXCP_INT_FLAG)) {
/* hacky for now. the MSB (bit 63) indicates interrupt but cs->exception
index is only 32 bits wide */
fixed_cause = cs->exception_index & RISCV_EXCP_INT_MASK;
fixed_cause |= ((target_ulong)1) << (TARGET_LONG_BITS - 1);
} else {
/* fixup User ECALL -> correct priv ECALL */
if (cs->exception_index == RISCV_EXCP_U_ECALL) {
switch (env->priv) {
case PRV_U:
fixed_cause = RISCV_EXCP_U_ECALL;
break;
case PRV_S:
fixed_cause = RISCV_EXCP_S_ECALL;
break;
case PRV_H:
fixed_cause = RISCV_EXCP_H_ECALL;
break;
case PRV_M:
fixed_cause = RISCV_EXCP_M_ECALL;
break;
}
} else {
fixed_cause = cs->exception_index;
}
}
target_ulong backup_epc = env->pc;
target_ulong bit = fixed_cause;
target_ulong deleg = env->medeleg;
int hasbadaddr =
(fixed_cause == RISCV_EXCP_INST_ADDR_MIS) ||
(fixed_cause == RISCV_EXCP_INST_ACCESS_FAULT) ||
(fixed_cause == RISCV_EXCP_LOAD_ADDR_MIS) ||
(fixed_cause == RISCV_EXCP_STORE_AMO_ADDR_MIS) ||
(fixed_cause == RISCV_EXCP_LOAD_ACCESS_FAULT) ||
(fixed_cause == RISCV_EXCP_STORE_AMO_ACCESS_FAULT) ||
(fixed_cause == RISCV_EXCP_INST_PAGE_FAULT) ||
(fixed_cause == RISCV_EXCP_LOAD_PAGE_FAULT) ||
(fixed_cause == RISCV_EXCP_STORE_PAGE_FAULT);
if (bit & ((target_ulong)1 << (TARGET_LONG_BITS - 1))) {
deleg = env->mideleg;
bit &= ~((target_ulong)1 << (TARGET_LONG_BITS - 1));
}
if (env->priv <= PRV_S && bit < 64 && ((deleg >> bit) & 1)) {
if (env->priv <= PRV_S &&
cause < TARGET_LONG_BITS && ((deleg >> cause) & 1)) {
/* handle the trap in S-mode */
/* No need to check STVEC for misaligned - lower 2 bits cannot be set */
env->pc = env->stvec;
env->scause = fixed_cause;
env->sepc = backup_epc;
if (hasbadaddr) {
if (RISCV_DEBUG_INTERRUPT) {
qemu_log_mask(LOG_TRACE, "core " TARGET_FMT_ld ": badaddr 0x"
TARGET_FMT_lx "\n", env->mhartid, env->badaddr);
}
env->sbadaddr = env->badaddr;
} else {
/* otherwise we must clear sbadaddr/stval
* todo: support populating stval on illegal instructions */
env->sbadaddr = 0;
}
target_ulong s = env->mstatus;
s = set_field(s, MSTATUS_SPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
get_field(s, MSTATUS_SIE) : get_field(s, MSTATUS_UIE << env->priv));
s = set_field(s, MSTATUS_SPP, env->priv);
s = set_field(s, MSTATUS_SIE, 0);
env->mstatus = s;
env->scause = cause | ~(((target_ulong)-1) >> async);
env->sepc = env->pc;
env->sbadaddr = tval;
env->pc = (env->stvec >> 2 << 2) +
((async && (env->stvec & 3) == 1) ? cause * 4 : 0);
riscv_cpu_set_mode(env, PRV_S);
} else {
/* No need to check MTVEC for misaligned - lower 2 bits cannot be set */
env->pc = env->mtvec;
env->mepc = backup_epc;
env->mcause = fixed_cause;
if (hasbadaddr) {
if (RISCV_DEBUG_INTERRUPT) {
qemu_log_mask(LOG_TRACE, "core " TARGET_FMT_ld ": badaddr 0x"
TARGET_FMT_lx "\n", env->mhartid, env->badaddr);
}
env->mbadaddr = env->badaddr;
} else {
/* otherwise we must clear mbadaddr/mtval
* todo: support populating mtval on illegal instructions */
env->mbadaddr = 0;
}
/* handle the trap in M-mode */
target_ulong s = env->mstatus;
s = set_field(s, MSTATUS_MPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
get_field(s, MSTATUS_MIE) : get_field(s, MSTATUS_UIE << env->priv));
s = set_field(s, MSTATUS_MPP, env->priv);
s = set_field(s, MSTATUS_MIE, 0);
env->mstatus = s;
env->mcause = cause | ~(((target_ulong)-1) >> async);
env->mepc = env->pc;
env->mbadaddr = tval;
env->pc = (env->mtvec >> 2 << 2) +
((async && (env->mtvec & 3) == 1) ? cause * 4 : 0);
riscv_cpu_set_mode(env, PRV_M);
}
/* TODO yield load reservation */

12
target/riscv/csr.c
View File

@ -435,10 +435,10 @@ static int read_mtvec(CPURISCVState *env, int csrno, target_ulong *val)
static int write_mtvec(CPURISCVState *env, int csrno, target_ulong val)
{
/* bits [1:0] encode mode; 0 = direct, 1 = vectored, 2 >= reserved */
if ((val & 3) == 0) {
env->mtvec = val >> 2 << 2;
if ((val & 3) < 2) {
env->mtvec = val;
} else {
qemu_log_mask(LOG_UNIMP, "CSR_MTVEC: vectored traps not supported");
qemu_log_mask(LOG_UNIMP, "CSR_MTVEC: reserved mode not supported\n");
}
return 0;
}
@ -607,10 +607,10 @@ static int read_stvec(CPURISCVState *env, int csrno, target_ulong *val)
static int write_stvec(CPURISCVState *env, int csrno, target_ulong val)
{
/* bits [1:0] encode mode; 0 = direct, 1 = vectored, 2 >= reserved */
if ((val & 3) == 0) {
env->stvec = val >> 2 << 2;
if ((val & 3) < 2) {
env->stvec = val;
} else {
qemu_log_mask(LOG_UNIMP, "CSR_STVEC: vectored traps not supported");
qemu_log_mask(LOG_UNIMP, "CSR_STVEC: reserved mode not supported\n");
}
return 0;
}