Commit 814b9a47 authored by ths's avatar ths
Browse files

MIPS TLB performance improvements, by Daniel Jacobowitz.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2220 c046a42c-6fe2-441c-8c8c-71466251a162
parent ec230928
......@@ -94,7 +94,8 @@ struct CPUMIPSState {
#endif
#if defined(MIPS_USES_R4K_TLB)
tlb_t tlb[MIPS_TLB_NB];
tlb_t tlb[MIPS_TLB_MAX];
uint32_t tlb_in_use;
#endif
uint32_t CP0_index;
uint32_t CP0_random;
......
......@@ -115,5 +115,6 @@ uint32_t cpu_mips_get_count (CPUState *env);
void cpu_mips_store_count (CPUState *env, uint32_t value);
void cpu_mips_store_compare (CPUState *env, uint32_t value);
void cpu_mips_clock_init (CPUState *env);
void cpu_mips_tlb_flush (CPUState *env, int flush_global);
#endif /* !defined(__QEMU_MIPS_EXEC_H__) */
......@@ -46,7 +46,7 @@ static int map_address (CPUState *env, target_ulong *physical, int *prot,
tlb_t *tlb;
int i, n;
for (i = 0; i < MIPS_TLB_NB; i++) {
for (i = 0; i < env->tlb_in_use; i++) {
tlb = &env->tlb[i];
/* Check ASID, virtual page number & size */
if ((tlb->G == 1 || tlb->ASID == ASID) &&
......
......@@ -22,6 +22,7 @@
/* Uses MIPS R4Kc TLB model */
#define MIPS_USES_R4K_TLB
#define MIPS_TLB_NB 16
#define MIPS_TLB_MAX 128
/* basic FPU register support */
#define MIPS_USES_FPU 1
/* Define a implementation number of 1.
......
......@@ -367,7 +367,7 @@ void do_mtc0 (int reg, int sel)
env->CP0_EntryHi = val;
/* If the ASID changes, flush qemu's TLB. */
if ((old & 0xFF) != (val & 0xFF))
tlb_flush (env, 1);
cpu_mips_tlb_flush (env, 1);
rn = "EntryHi";
break;
case 11:
......@@ -568,7 +568,14 @@ void fpu_handle_exception(void)
/* TLB management */
#if defined(MIPS_USES_R4K_TLB)
static void invalidate_tlb (int idx)
void cpu_mips_tlb_flush (CPUState *env, int flush_global)
{
/* Flush qemu's TLB and discard all shadowed entries. */
tlb_flush (env, flush_global);
env->tlb_in_use = MIPS_TLB_NB;
}
static void invalidate_tlb (int idx, int use_extra)
{
tlb_t *tlb;
target_ulong addr;
......@@ -583,6 +590,15 @@ static void invalidate_tlb (int idx)
return;
}
if (use_extra && env->tlb_in_use < MIPS_TLB_MAX) {
/* For tlbwr, we can shadow the discarded entry into
a new (fake) TLB entry, as long as the guest can not
tell that it's there. */
env->tlb[env->tlb_in_use] = *tlb;
env->tlb_in_use++;
return;
}
if (tlb->V0) {
tb_invalidate_page_range(tlb->PFN[0], tlb->end - tlb->VPN);
addr = tlb->VPN;
......@@ -601,6 +617,14 @@ static void invalidate_tlb (int idx)
}
}
static void mips_tlb_flush_extra (CPUState *env, int first)
{
/* Discard entries from env->tlb[first] onwards. */
while (env->tlb_in_use > first) {
invalidate_tlb(--env->tlb_in_use, 0);
}
}
static void fill_tlb (int idx)
{
tlb_t *tlb;
......@@ -627,9 +651,14 @@ static void fill_tlb (int idx)
void do_tlbwi (void)
{
/* Discard cached TLB entries. We could avoid doing this if the
tlbwi is just upgrading access permissions on the current entry;
that might be a further win. */
mips_tlb_flush_extra (env, MIPS_TLB_NB);
/* Wildly undefined effects for CP0_index containing a too high value and
MIPS_TLB_NB not being a power of two. But so does real silicon. */
invalidate_tlb(env->CP0_index & (MIPS_TLB_NB - 1));
invalidate_tlb(env->CP0_index & (MIPS_TLB_NB - 1), 0);
fill_tlb(env->CP0_index & (MIPS_TLB_NB - 1));
}
......@@ -637,7 +666,7 @@ void do_tlbwr (void)
{
int r = cpu_mips_get_random(env);
invalidate_tlb(r);
invalidate_tlb(r, 1);
fill_tlb(r);
}
......@@ -660,6 +689,17 @@ void do_tlbp (void)
}
}
if (i == MIPS_TLB_NB) {
/* No match. Discard any shadow entries, if any of them match. */
for (i = MIPS_TLB_NB; i < env->tlb_in_use; i++) {
tlb = &env->tlb[i];
/* Check ASID, virtual page number & size */
if ((tlb->G == 1 || tlb->ASID == ASID) && tlb->VPN == tag) {
mips_tlb_flush_extra (env, i);
break;
}
}
env->CP0_index |= 0x80000000;
}
}
......@@ -674,8 +714,10 @@ void do_tlbr (void)
tlb = &env->tlb[env->CP0_index & (MIPS_TLB_NB - 1)];
/* If this will change the current ASID, flush qemu's TLB. */
if (ASID != tlb->ASID && tlb->G != 1)
tlb_flush (env, 1);
if (ASID != tlb->ASID)
cpu_mips_tlb_flush (env, 1);
mips_tlb_flush_extra(env, MIPS_TLB_NB);
env->CP0_EntryHi = tlb->VPN | tlb->ASID;
size = (tlb->end - tlb->VPN) >> 12;
......
......@@ -2430,6 +2430,7 @@ CPUMIPSState *cpu_mips_init (void)
env->PC = 0xBFC00000;
#if defined (MIPS_USES_R4K_TLB)
env->CP0_random = MIPS_TLB_NB - 1;
env->tlb_in_use = MIPS_TLB_NB;
#endif
env->CP0_Wired = 0;
env->CP0_Config0 = MIPS_CONFIG0;
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment