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target/ppc: Improve helper_dcbz for user-only 

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 no longer
spend nearly 25% of runtime within page_get_flags.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2024-07-09 16:56:48 -07:00
parent c6d84fd7cf
commit f6bcc5b8f9
1 changed files with 11 additions and 4 deletions
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15
target/ppc/mem_helper.c
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@ -280,20 +280,27 @@ 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);
}
return;
}
#endif
set_helper_retaddr(retaddr);
memset(haddr, 0, dcbz_size);
clear_helper_retaddr();
}
void helper_dcbz(CPUPPCState *env, target_ulong addr, int mmu_idx)