On 2023/9/10 1:43, Richard Henderson wrote:
On 9/7/23 20:23, LIU Zhiwei wrote:
From: LIU Zhiwei <lzw194...@alibaba-inc.com>
Signed-off-by: LIU Zhiwei <zhiwei_...@linux.alibaba.com>
---
include/qemu/timer.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 9a91cb1248..ce0b66d122 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -979,6 +979,25 @@ static inline int64_t cpu_get_host_ticks(void)
return cur - ofs;
}
+#elif defined(__riscv) && defined(__riscv_xlen) && __riscv_xlen == 32
+static inline int64_t cpu_get_host_ticks(void)
+{
+ uint32_t lo, hi;
+ asm volatile("RDCYCLE %0\n\t"
+ "RDCYCLEH %1"
+ : "=r"(lo), "=r"(hi));
+ return lo | (uint64_t)hi << 32;
+}
+
+#elif defined(__riscv) && defined(__riscv_xlen) && __riscv_xlen > 32
+static inline int64_t cpu_get_host_ticks(void)
+{
+ int64_t val;
+
+ asm volatile("RDCYCLE %0" : "=r"(cc));
+ return val;
+}
__riscv_xlen should never be undefined.
OK
Don't you need a loop for RDCYCLEH to avoid time going backward?
do {
asm("rdcycleh %0\n\t"
"rdcycle %1\n\t"
"rdcycleh %2\n\t"
: "=r"(hi), "=r"(lo), "=r"(tmph));
} while (unlikely(tmph != hi));
Yes, I think we should do this for XLEN == 32bits.
Thanks,
Zhiwei
r~
