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cputlb: Introduce TLB_BSWAP
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Handle bswap on ram directly in load/store_helper.  This fixes a
bug with the previous implementation in that one cannot use the
I/O path for RAM.

Fixes: a26fc6f
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@rth7680
rth7680 committed Sep 25, 2019
1 parent 80d9d1c commit 5b87b3e
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Showing 2 changed files with 46 additions and 30 deletions.
72 changes: 43 additions & 29 deletions accel/tcg/cputlb.c
View file
Expand Up @@ -737,8 +737,7 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
address |= TLB_INVALID_MASK;
}
if (attrs.byte_swap) {
/* Force the access through the I/O slow path. */
address |= TLB_MMIO;
address |= TLB_BSWAP;
}
if (!memory_region_is_ram(section->mr) &&
!memory_region_is_romd(section->mr)) {
Expand Down Expand Up @@ -901,10 +900,6 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
bool locked = false;
MemTxResult r;

if (iotlbentry->attrs.byte_swap) {
op ^= MO_BSWAP;
}

section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
mr = section->mr;
mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
Expand Down Expand Up @@ -947,10 +942,6 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
bool locked = false;
MemTxResult r;

if (iotlbentry->attrs.byte_swap) {
op ^= MO_BSWAP;
}

section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
mr = section->mr;
mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
Expand Down Expand Up @@ -1133,8 +1124,8 @@ void *probe_access(CPUArchState *env, target_ulong addr, int size,
wp_access, retaddr);
}

if (tlb_addr & (TLB_NOTDIRTY | TLB_MMIO)) {
/* I/O access */
/* Reject I/O access, or other required slow-path. */
if (tlb_addr & (TLB_NOTDIRTY | TLB_MMIO | TLB_BSWAP)) {
return NULL;
}

Expand Down Expand Up @@ -1344,6 +1335,7 @@ load_helper(CPUArchState *env, target_ulong addr, TCGMemOpIdx oi,
/* Handle anything that isn't just a straight memory access. */
if (unlikely(tlb_addr & ~TARGET_PAGE_MASK)) {
CPUIOTLBEntry *iotlbentry;
bool need_swap;

/* For anything that is unaligned, recurse through full_load. */
if ((addr & (size - 1)) != 0) {
Expand All @@ -1357,17 +1349,27 @@ load_helper(CPUArchState *env, target_ulong addr, TCGMemOpIdx oi,
/* On watchpoint hit, this will longjmp out. */
cpu_check_watchpoint(env_cpu(env), addr, size,
iotlbentry->attrs, BP_MEM_READ, retaddr);

/* The backing page may or may not require I/O. */
tlb_addr &= ~TLB_WATCHPOINT;
if ((tlb_addr & ~TARGET_PAGE_MASK) == 0) {
goto do_aligned_access;
}
}

need_swap = size > 1 && (tlb_addr & TLB_BSWAP);

/* Handle I/O access. */
return io_readx(env, iotlbentry, mmu_idx, addr,
retaddr, access_type, op);
if (likely(tlb_addr & TLB_MMIO)) {
return io_readx(env, iotlbentry, mmu_idx, addr, retaddr,
access_type, op ^ (need_swap * MO_BSWAP));
}

haddr = (void *)((uintptr_t)addr + entry->addend);

/*
* Keep these two load_memop separate to ensure that the compiler
* is able to fold the entire function to a single instruction.
* There is a build-time assert inside to remind you of this. ;-)
*/
if (unlikely(need_swap)) {
return load_memop(haddr, op ^ MO_BSWAP);
}
return load_memop(haddr, op);
}

/* Handle slow unaligned access (it spans two pages or IO). */
Expand All @@ -1394,7 +1396,6 @@ 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);
return load_memop(haddr, op);
}
Expand Down Expand Up @@ -1591,6 +1592,7 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
/* Handle anything that isn't just a straight memory access. */
if (unlikely(tlb_addr & ~TARGET_PAGE_MASK)) {
CPUIOTLBEntry *iotlbentry;
bool need_swap;

/* For anything that is unaligned, recurse through byte stores. */
if ((addr & (size - 1)) != 0) {
Expand All @@ -1604,16 +1606,29 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
/* On watchpoint hit, this will longjmp out. */
cpu_check_watchpoint(env_cpu(env), addr, size,
iotlbentry->attrs, BP_MEM_WRITE, retaddr);

/* The backing page may or may not require I/O. */
tlb_addr &= ~TLB_WATCHPOINT;
if ((tlb_addr & ~TARGET_PAGE_MASK) == 0) {
goto do_aligned_access;
}
}

need_swap = size > 1 && (tlb_addr & TLB_BSWAP);

/* Handle I/O access. */
io_writex(env, iotlbentry, mmu_idx, val, addr, retaddr, op);
if (likely(tlb_addr & (TLB_MMIO | TLB_NOTDIRTY))) {
io_writex(env, iotlbentry, mmu_idx, val, addr, retaddr,
op ^ (need_swap * MO_BSWAP));
return;
}

haddr = (void *)((uintptr_t)addr + entry->addend);

/*
* Keep these two store_memop separate to ensure that the compiler
* is able to fold the entire function to a single instruction.
* There is a build-time assert inside to remind you of this. ;-)
*/
if (unlikely(need_swap)) {
store_memop(haddr, val, op ^ MO_BSWAP);
} else {
store_memop(haddr, val, op);
}
return;
}

Expand Down Expand Up @@ -1682,7 +1697,6 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
return;
}

do_aligned_access:
haddr = (void *)((uintptr_t)addr + entry->addend);
store_memop(haddr, val, op);
}
Expand Down
4 changes: 3 additions & 1 deletion include/exec/cpu-all.h
View file
Expand Up @@ -335,12 +335,14 @@ CPUArchState *cpu_copy(CPUArchState *env);
#define TLB_MMIO (1 << (TARGET_PAGE_BITS_MIN - 3))
/* Set if TLB entry contains a watchpoint. */
#define TLB_WATCHPOINT (1 << (TARGET_PAGE_BITS_MIN - 4))
/* Set if TLB entry requires byte swap. */
#define TLB_BSWAP (1 << (TARGET_PAGE_BITS_MIN - 5))

/* 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_WATCHPOINT)
(TLB_INVALID_MASK | TLB_NOTDIRTY | TLB_MMIO | TLB_WATCHPOINT | TLB_BSWAP)

/**
* tlb_hit_page: return true if page aligned @addr is a hit against the
Expand Down

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