On 18/8/26 21:47, Brian Cain wrote:
On 8/14/2026 12:29 PM, Philippe Mathieu-Daudé wrote:
Hi Brian, Taylor,
(now committed as acd2b7a2f19ac04bd313e816e5f9e7f87adc9858)
On 29/5/26 23:57, Brian Cain wrote:
From: Brian Cain <[email protected]>
Reviewed-by: Taylor Simpson <[email protected]>
Signed-off-by: Brian Cain <[email protected]>
---
target/hexagon/gen_tcg_sys.h | 2 +-
target/hexagon/op_helper.c | 60 ++++++++++++++++++++++++++++++++++--
2 files changed, 59 insertions(+), 3 deletions(-)
diff --git a/target/hexagon/gen_tcg_sys.h b/target/hexagon/gen_tcg_sys.h
index 000fc415c74..98cf6216780 100644
--- a/target/hexagon/gen_tcg_sys.h
+++ b/target/hexagon/gen_tcg_sys.h
@@ -80,7 +80,7 @@
#define fGEN_TCG_Y2_wait(SHORTCODE) \
do { \
RsV = RsV; \
- gen_helper_wait(tcg_env, tcg_constant_tl(ctx->pkt->pc)); \
+ gen_helper_wait(tcg_env, tcg_constant_tl(ctx->pkt.pc)); \
} while (0)
#define fGEN_TCG_Y2_resume(SHORTCODE) \
diff --git a/target/hexagon/op_helper.c b/target/hexagon/op_helper.c
index 235c70f7370..d40061de06e 100644
--- a/target/hexagon/op_helper.c
+++ b/target/hexagon/op_helper.c
@@ -1486,9 +1486,65 @@ void HELPER(stop)(CPUHexagonState *env)
hexagon_stop_thread(env);
}
-void HELPER(wait)(CPUHexagonState *env, target_ulong PC)
+static void set_wait_mode(CPUHexagonState *env)
{
- g_assert_not_reached();
+ HexagonCPU *cpu;
+ uint32_t modectl;
+ uint32_t thread_wait_mask;
+
+ g_assert(bql_locked());
+
+ cpu = env_archcpu(env);
+ if (!cpu->globalregs) {
+ return;
+ }
+ modectl =
+ hexagon_globalreg_read(cpu->globalregs, HEX_SREG_MODECTL,
+ env->threadId);
+ thread_wait_mask = GET_FIELD(MODECTL_W, modectl);
+ thread_wait_mask |= 0x1 << env->threadId;
+ SET_SYSTEM_FIELD(env, HEX_SREG_MODECTL, MODECTL_W,
thread_wait_mask);
+}
+
+static void hexagon_wait_thread(CPUHexagonState *env, uint32_t PC)
+{
+ CPUState *cs;
+
+ g_assert(bql_locked());
+
+ if (qemu_loglevel_mask(LOG_GUEST_ERROR) &&
+ (env->k0_lock_state != HEX_LOCK_UNLOCKED ||
+ env->tlb_lock_state != HEX_LOCK_UNLOCKED)) {
+ qemu_log("WARNING: executing wait() with acquired lock"
+ "may lead to deadlock\n");
+ }
+ g_assert(get_exe_mode(env) != HEX_EXE_MODE_WAIT);
+
+ cs = env_cpu(env);
+ /*
+ * The addtion of cpu_has_work is borrowed from arm's wfi helper
+ * and is critical for our stability
Could you explain this comment?
It's a note that was added to our downstream fork when fixing a bug
attributed to hexagon_wait_thread() that was a bit challenging to
uncover because none of our existing regression suite detected it. It
was only uncovered in a "virtual platform" environment modeling the
various cores among the SoC.
We can follow up with a reword/clarification or deletion if you prefer.
But you recall the bug? Why isn't this an issue with RISCV?
No urgent need for cleanup, I'll likely rework this area in my
generic CPU scheduling work.
+ */
+ if ((cs->exception_index != HEX_EVENT_NONE) ||
+ (cpu_has_work(cs))) {
+ qemu_log_mask(CPU_LOG_INT,
+ "%s: thread %" PRIu32 " skipping WAIT mode, have some
work\n",
+ __func__, env->threadId);
+ return;
+ }
+ set_wait_mode(env);
+ env->wait_next_pc = PC + 4;
+
+ cpu_interrupt(cs, CPU_INTERRUPT_HALT);
+}
+
+void HELPER(wait)(CPUHexagonState *env, uint32_t PC)
+{
+ BQL_LOCK_GUARD();
+
+ if (!fIN_DEBUG_MODE(env->threadId)) {
+ hexagon_wait_thread(env, PC);
+ }
}
void HELPER(resume)(CPUHexagonState *env, uint32_t mask)
