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cputlb: Fold TLB_RECHECK into TLB_INVALID_MASK 

We had two different mechanisms to force a recheck of the tlb.

Before TLB_RECHECK was introduced, we had a PAGE_WRITE_INV bit
that would immediate set TLB_INVALID_MASK, which automatically
means that a second check of the tlb entry fails.

We can use the same mechanism to handle small pages.
Conserve TLB_* bits by removing TLB_RECHECK.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-08-23 15:12:32 -07:00
parent 0026348b48
commit 30d7e098d5
2 changed files with 24 additions and 67 deletions
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86
accel/tcg/cputlb.c
View File

@ -732,11 +732,8 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
address = vaddr_page;
if (size < TARGET_PAGE_SIZE) {
/*
* Slow-path the TLB entries; we will repeat the MMU check and TLB
* fill on every access.
*/
address |= TLB_RECHECK;
/* Repeat the MMU check and TLB fill on every access. */
address |= TLB_INVALID_MASK;
}
if (attrs.byte_swap) {
/* Force the access through the I/O slow path. */
@ -1026,10 +1023,15 @@ static bool victim_tlb_hit(CPUArchState *env, size_t mmu_idx, size_t index,
victim_tlb_hit(env, mmu_idx, index, offsetof(CPUTLBEntry, TY), \
(ADDR) & TARGET_PAGE_MASK)
/* NOTE: this function can trigger an exception */
/* NOTE2: the returned address is not exactly the physical address: it
* is actually a ram_addr_t (in system mode; the user mode emulation
* version of this function returns a guest virtual address).
/*
* Return a ram_addr_t for the virtual address for execution.
*
* Return -1 if we can't translate and execute from an entire page
* of RAM. This will force us to execute by loading and translating
* one insn at a time, without caching.
*
* NOTE: This function will trigger an exception if the page is
* not executable.
*/
tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
{
@ -1043,19 +1045,20 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
tlb_fill(env_cpu(env), addr, 0, MMU_INST_FETCH, mmu_idx, 0);
index = tlb_index(env, mmu_idx, addr);
entry = tlb_entry(env, mmu_idx, addr);
if (unlikely(entry->addr_code & TLB_INVALID_MASK)) {
/*
* The MMU protection covers a smaller range than a target
* page, so we must redo the MMU check for every insn.
*/
return -1;
}
}
assert(tlb_hit(entry->addr_code, addr));
}
if (unlikely(entry->addr_code & (TLB_RECHECK | TLB_MMIO))) {
/*
* Return -1 if we can't translate and execute from an entire
* page of RAM here, which will cause us to execute by loading
* and translating one insn at a time, without caching:
* - TLB_RECHECK: means the MMU protection covers a smaller range
* than a target page, so we must redo the MMU check every insn
* - TLB_MMIO: region is not backed by RAM
*/
if (unlikely(entry->addr_code & TLB_MMIO)) {
/* The region is not backed by RAM. */
return -1;
}
@ -1180,7 +1183,7 @@ static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
}
/* Notice an IO access or a needs-MMU-lookup access */
if (unlikely(tlb_addr & (TLB_MMIO | TLB_RECHECK))) {
if (unlikely(tlb_addr & TLB_MMIO)) {
/* There's really nothing that can be done to
support this apart from stop-the-world. */
goto stop_the_world;
@ -1258,6 +1261,7 @@ load_helper(CPUArchState *env, target_ulong addr, TCGMemOpIdx oi,
entry = tlb_entry(env, mmu_idx, addr);
}
tlb_addr = code_read ? entry->addr_code : entry->addr_read;
tlb_addr &= ~TLB_INVALID_MASK;
}
/* Handle an IO access. */
@ -1265,27 +1269,6 @@ load_helper(CPUArchState *env, target_ulong addr, TCGMemOpIdx oi,
if ((addr & (size - 1)) != 0) {
goto do_unaligned_access;
}
if (tlb_addr & TLB_RECHECK) {
/*
* This is a TLB_RECHECK access, where the MMU protection
* covers a smaller range than a target page, and we must
* repeat the MMU check here. This tlb_fill() call might
* longjump out if this access should cause a guest exception.
*/
tlb_fill(env_cpu(env), addr, size,
access_type, mmu_idx, retaddr);
index = tlb_index(env, mmu_idx, addr);
entry = tlb_entry(env, mmu_idx, addr);
tlb_addr = code_read ? entry->addr_code : entry->addr_read;
tlb_addr &= ~TLB_RECHECK;
if (!(tlb_addr & ~TARGET_PAGE_MASK)) {
/* RAM access */
goto do_aligned_access;
}
}
return io_readx(env, &env_tlb(env)->d[mmu_idx].iotlb[index],
mmu_idx, addr, retaddr, access_type, op);
}
@ -1314,7 +1297,6 @@ load_helper(CPUArchState *env, target_ulong addr, TCGMemOpIdx oi,
return res & MAKE_64BIT_MASK(0, size * 8);
}
do_aligned_access:
haddr = (void *)((uintptr_t)addr + entry->addend);
switch (op) {
case MO_UB:
@ -1509,27 +1491,6 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
if ((addr & (size - 1)) != 0) {
goto do_unaligned_access;
}
if (tlb_addr & TLB_RECHECK) {
/*
* This is a TLB_RECHECK access, where the MMU protection
* covers a smaller range than a target page, and we must
* repeat the MMU check here. This tlb_fill() call might
* longjump out if this access should cause a guest exception.
*/
tlb_fill(env_cpu(env), addr, size, MMU_DATA_STORE,
mmu_idx, retaddr);
index = tlb_index(env, mmu_idx, addr);
entry = tlb_entry(env, mmu_idx, addr);
tlb_addr = tlb_addr_write(entry);
tlb_addr &= ~TLB_RECHECK;
if (!(tlb_addr & ~TARGET_PAGE_MASK)) {
/* RAM access */
goto do_aligned_access;
}
}
io_writex(env, &env_tlb(env)->d[mmu_idx].iotlb[index], mmu_idx,
val, addr, retaddr, op);
return;
@ -1579,7 +1540,6 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
return;
}
do_aligned_access:
haddr = (void *)((uintptr_t)addr + entry->addend);
switch (op) {
case MO_UB:

5
include/exec/cpu-all.h
View File

@ -329,14 +329,11 @@ CPUArchState *cpu_copy(CPUArchState *env);
#define TLB_NOTDIRTY (1 << (TARGET_PAGE_BITS - 2))
/* Set if TLB entry is an IO callback. */
#define TLB_MMIO (1 << (TARGET_PAGE_BITS - 3))
/* Set if TLB entry must have MMU lookup repeated for every access */
#define TLB_RECHECK (1 << (TARGET_PAGE_BITS - 4))
/* Use this mask to check interception with an alignment mask
* in a TCG backend.
*/
#define TLB_FLAGS_MASK (TLB_INVALID_MASK | TLB_NOTDIRTY | TLB_MMIO \
| TLB_RECHECK)
#define TLB_FLAGS_MASK (TLB_INVALID_MASK | TLB_NOTDIRTY | TLB_MMIO)
/**
* tlb_hit_page: return true if page aligned @addr is a hit against the