On 7/10/24 05:25, BALATON Zoltan wrote:
On Tue, 9 Jul 2024, Richard Henderson wrote:
Mark the reserve_addr check unlikely. Use tlb_vaddr_to_host
instead of probe_write, relying on the memset itself to test
for page writability. Use set/clear_helper_retaddr so that
we can properly unwind on segfault.
With this, a trivial loop around guest memset will spend
nearly 50% of runtime within helper_dcbz and host memset.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
target/ppc/mem_helper.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/target/ppc/mem_helper.c b/target/ppc/mem_helper.c
index 24bae3b80c..fa4c4f9fa9 100644
--- a/target/ppc/mem_helper.c
+++ b/target/ppc/mem_helper.c
@@ -280,20 +280,26 @@ static void dcbz_common(CPUPPCState *env, target_ulong
addr,
addr &= mask;
/* Check reservation */
- if ((env->reserve_addr & mask) == addr) {
+ if (unlikely((env->reserve_addr & mask) == addr)) {
env->reserve_addr = (target_ulong)-1ULL;
}
/* Try fast path translate */
+#ifdef CONFIG_USER_ONLY
+ haddr = tlb_vaddr_to_host(env, addr, MMU_DATA_STORE, mmu_idx);
+#else
haddr = probe_write(env, addr, dcbz_size, mmu_idx, retaddr);
- if (haddr) {
- memset(haddr, 0, dcbz_size);
- } else {
+ if (unlikely(!haddr)) {
/* Slow path */
for (int i = 0; i < dcbz_size; i += 8) {
cpu_stq_mmuidx_ra(env, addr + i, 0, mmu_idx, retaddr);
}
Is a return needed here to only get to memset below when haddr != NULL?
Oops, yes.
r~
