target/riscv: Add itrigger support when icount is enabled

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>

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index c32e484c0b688018d34b38ef11e0e43d2e90558a..b0b4048de9bda0152dc52f4b105c2d4981121b89 100644 (file)
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -329,6 +329,8 @@ struct CPUArchState {
     target_ulong tdata3[RV_MAX_TRIGGERS];
     struct CPUBreakpoint *cpu_breakpoint[RV_MAX_TRIGGERS];
     struct CPUWatchpoint *cpu_watchpoint[RV_MAX_TRIGGERS];
+    QEMUTimer *itrigger_timer[RV_MAX_TRIGGERS];
+    int64_t last_icount;
 
     /* machine specific rdtime callback */
     uint64_t (*rdtime_fn)(void *);

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 9d1d1bf9f1ec7c28d8d7e164cd37dd9886ee93f7..6230f65f706d749051749874f6d8c5592d5c5c5d 100644 (file)
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -676,6 +676,9 @@ void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv)
     if (newpriv == PRV_H) {
         newpriv = PRV_U;
     }
+    if (icount_enabled() && newpriv != env->priv) {
+        riscv_itrigger_update_priv(env);
+    }
     /* tlb_flush is unnecessary as mode is contained in mmu_idx */
     env->priv = newpriv;
     env->xl = cpu_recompute_xl(env);

diff --git a/target/riscv/debug.c b/target/riscv/debug.c
index 036161649f4d1804db1b85508c330d5ee6bd08d6..371862cf3879f9019c0a4cfcdf6a0ac596491d62 100644 (file)
--- a/target/riscv/debug.c
+++ b/target/riscv/debug.c
@@ -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);
     }
 }

diff --git a/target/riscv/debug.h b/target/riscv/debug.h
index cc3358e69bb11b7a6959fc8cd9616c099e6d9b39..c471748d5a9024a80db9721ee7835f959440b947 100644 (file)
--- a/target/riscv/debug.h
+++ b/target/riscv/debug.h
@@ -146,4 +146,5 @@ bool riscv_cpu_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp);
 void riscv_trigger_init(CPURISCVState *env);
 
 bool riscv_itrigger_enabled(CPURISCVState *env);
+void riscv_itrigger_update_priv(CPURISCVState *env);
 #endif /* RISCV_DEBUG_H */