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target/riscv: Add itrigger support when icount is enabled

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The max count in itrigger can be 0x3FFF, which will cause a no trivial
translation and execution overload.

When icount is enabled, QEMU provides API that can fetch guest
instruction number. Thus, we can set an timer for itrigger with
the count as deadline.

Only when timer expires or priviledge mode changes, do lazy update
to count.

Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221013062946.7530-3-zhiwei_liu@linux.alibaba.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
LIU Zhiwei 2022-10-13 14:29:44 +08:00 • committed by Alistair Francis
parent 2c9d747121
commit 5a4ae64cac
4 changed files with 65 additions and 0 deletions
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59
target/riscv/debug.c
View file

@ -30,6 +30,7 @@
#include "trace.h"
#include "exec/exec-all.h"
#include "exec/helper-proto.h"
#include "sysemu/cpu-timers.h"
/*
* The following M-mode trigger CSRs are implemented:
@ -567,6 +568,62 @@ void helper_itrigger_match(CPURISCVState *env)
}
}
static void riscv_itrigger_update_count(CPURISCVState *env)
{
int count, executed;
/*
* Record last icount, so that we can evaluate the executed instructions
* since last priviledge mode change or timer expire.
*/
int64_t last_icount = env->last_icount, current_icount;
current_icount = env->last_icount = icount_get_raw();
for (int i = 0; i < RV_MAX_TRIGGERS; i++) {
if (get_trigger_type(env, i) != TRIGGER_TYPE_INST_CNT) {
continue;
}
count = itrigger_get_count(env, i);
if (!count) {
continue;
}
/*
* Only when priviledge is changed or itrigger timer expires,
* the count field in itrigger tdata1 register is updated.
* And the count field in itrigger only contains remaining value.
*/
if (check_itrigger_priv(env, i)) {
/*
* If itrigger enabled in this priviledge mode, the number of
* executed instructions since last priviledge change
* should be reduced from current itrigger count.
*/
executed = current_icount - last_icount;
itrigger_set_count(env, i, count - executed);
if (count == executed) {
do_trigger_action(env, i);
}
} else {
/*
* If itrigger is not enabled in this priviledge mode,
* the number of executed instructions will be discard and
* the count field in itrigger will not change.
*/
timer_mod(env->itrigger_timer[i],
current_icount + count);
}
}
}
static void riscv_itrigger_timer_cb(void *opaque)
{
riscv_itrigger_update_count((CPURISCVState *)opaque);
}
void riscv_itrigger_update_priv(CPURISCVState *env)
{
riscv_itrigger_update_count(env);
}
target_ulong tdata_csr_read(CPURISCVState *env, int tdata_index)
{
switch (tdata_index) {
@ -796,5 +853,7 @@ void riscv_trigger_init(CPURISCVState *env)
env->tdata3[i] = 0;
env->cpu_breakpoint[i] = NULL;
env->cpu_watchpoint[i] = NULL;
env->itrigger_timer[i] = timer_new_ns(QEMU_CLOCK_VIRTUAL,
riscv_itrigger_timer_cb, env);
}
}