target-sh4: improve TLB
SH4 is using 16-bit instructions which means most of the constants are loaded through a constant pool at the end of the subroutine. The same memory page is therefore accessed in exec and read mode. With the current implementation, a QEMU TLB entry is set to read or read/write mode after an UTLB search and to exec mode after an ITLB search, which causes a lot of TLB exceptions to switch from read or read/write to exec and vice versa. This patch optimizes that by already setting the QEMU TLB entry in read or read/write mode when an UTLB entry is copied into ITLB (during an ITLB miss). This improve the emulation speed by about 14%. Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
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@ -280,35 +280,40 @@ static void increment_urc(CPUState * env)
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env->mmucr = (env->mmucr & 0xffff03ff) | (urc << 10);
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}
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/* Find itlb entry - update itlb from utlb if necessary and asked for
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/* Copy and utlb entry into itlb
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Return entry
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*/
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static int copy_utlb_entry_itlb(CPUState *env, int utlb)
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{
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int itlb;
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tlb_t * ientry;
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itlb = itlb_replacement(env);
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ientry = &env->itlb[itlb];
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if (ientry->v) {
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tlb_flush_page(env, ientry->vpn << 10);
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}
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*ientry = env->utlb[utlb];
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update_itlb_use(env, itlb);
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return itlb;
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}
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/* Find itlb entry
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Return entry, MMU_ITLB_MISS, MMU_ITLB_MULTIPLE or MMU_DTLB_MULTIPLE
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Update the itlb from utlb if update is not 0
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*/
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static int find_itlb_entry(CPUState * env, target_ulong address,
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int use_asid, int update)
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int use_asid)
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{
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int e, n;
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int e;
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e = find_tlb_entry(env, address, env->itlb, ITLB_SIZE, use_asid);
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if (e == MMU_DTLB_MULTIPLE)
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if (e == MMU_DTLB_MULTIPLE) {
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e = MMU_ITLB_MULTIPLE;
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else if (e == MMU_DTLB_MISS && update) {
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e = find_tlb_entry(env, address, env->utlb, UTLB_SIZE, use_asid);
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if (e >= 0) {
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tlb_t * ientry;
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n = itlb_replacement(env);
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ientry = &env->itlb[n];
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if (ientry->v) {
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tlb_flush_page(env, ientry->vpn << 10);
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}
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*ientry = env->utlb[e];
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e = n;
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} else if (e == MMU_DTLB_MISS)
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e = MMU_ITLB_MISS;
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} else if (e == MMU_DTLB_MISS)
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} else if (e == MMU_DTLB_MISS) {
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e = MMU_ITLB_MISS;
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if (e >= 0)
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} else if (e >= 0) {
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update_itlb_use(env, e);
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}
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return e;
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}
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@ -340,13 +345,31 @@ static int get_mmu_address(CPUState * env, target_ulong * physical,
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use_asid = (env->mmucr & MMUCR_SV) == 0 || (env->sr & SR_MD) == 0;
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if (rw == 2) {
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n = find_itlb_entry(env, address, use_asid, 1);
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n = find_itlb_entry(env, address, use_asid);
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if (n >= 0) {
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matching = &env->itlb[n];
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if (!(env->sr & SR_MD) && !(matching->pr & 2))
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n = MMU_ITLB_VIOLATION;
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else
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*prot = PAGE_EXEC;
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} else {
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n = find_utlb_entry(env, address, use_asid);
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if (n >= 0) {
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n = copy_utlb_entry_itlb(env, n);
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matching = &env->itlb[n];
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if (!(env->sr & SR_MD) && !(matching->pr & 2)) {
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n = MMU_ITLB_VIOLATION;
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} else {
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*prot = PAGE_READ | PAGE_EXEC;
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if ((matching->pr & 1) && matching->d) {
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*prot |= PAGE_WRITE;
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}
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}
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} else if (n == MMU_DTLB_MULTIPLE) {
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n = MMU_ITLB_MULTIPLE;
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} else if (n == MMU_DTLB_MISS) {
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n = MMU_ITLB_MISS;
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}
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}
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} else {
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n = find_utlb_entry(env, address, use_asid);
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