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cputlb: Handle watchpoints via TLB_WATCHPOINT 

The raising of exceptions from check_watchpoint, buried inside
of the I/O subsystem, is fundamentally broken.  We do not have
the helper return address with which we can unwind guest state.

Replace PHYS_SECTION_WATCH and io_mem_watch with TLB_WATCHPOINT.
Move the call to cpu_check_watchpoint into the cputlb helpers
where we do have the helper return address.

This allows watchpoints on RAM to bypass the full i/o access path.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-08-24 09:51:09 -07:00
parent 5787585d04
commit 50b107c5d6
3 changed files with 90 additions and 118 deletions
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89
accel/tcg/cputlb.c
View File

@ -710,6 +710,7 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
hwaddr iotlb, xlat, sz, paddr_page;
target_ulong vaddr_page;
int asidx = cpu_asidx_from_attrs(cpu, attrs);
int wp_flags;
assert_cpu_is_self(cpu);
@ -752,6 +753,8 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
code_address = address;
iotlb = memory_region_section_get_iotlb(cpu, section, vaddr_page,
paddr_page, xlat, prot, &address);
wp_flags = cpu_watchpoint_address_matches(cpu, vaddr_page,
TARGET_PAGE_SIZE);
index = tlb_index(env, mmu_idx, vaddr_page);
te = tlb_entry(env, mmu_idx, vaddr_page);
@ -805,6 +808,9 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
tn.addend = addend - vaddr_page;
if (prot & PAGE_READ) {
tn.addr_read = address;
if (wp_flags & BP_MEM_READ) {
tn.addr_read |= TLB_WATCHPOINT;
}
} else {
tn.addr_read = -1;
}
@ -831,6 +837,9 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
if (prot & PAGE_WRITE_INV) {
tn.addr_write |= TLB_INVALID_MASK;
}
if (wp_flags & BP_MEM_WRITE) {
tn.addr_write |= TLB_WATCHPOINT;
}
}
copy_tlb_helper_locked(te, &tn);
@ -1264,13 +1273,33 @@ load_helper(CPUArchState *env, target_ulong addr, TCGMemOpIdx oi,
tlb_addr &= ~TLB_INVALID_MASK;
}
/* Handle an IO access. */
/* Handle anything that isn't just a straight memory access. */
if (unlikely(tlb_addr & ~TARGET_PAGE_MASK)) {
CPUIOTLBEntry *iotlbentry;
/* For anything that is unaligned, recurse through full_load. */
if ((addr & (size - 1)) != 0) {
goto do_unaligned_access;
}
return io_readx(env, &env_tlb(env)->d[mmu_idx].iotlb[index],
mmu_idx, addr, retaddr, access_type, op);
iotlbentry = &env_tlb(env)->d[mmu_idx].iotlb[index];
/* Handle watchpoints. */
if (unlikely(tlb_addr & TLB_WATCHPOINT)) {
/* 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;
}
}
/* Handle I/O access. */
return io_readx(env, iotlbentry, mmu_idx, addr,
retaddr, access_type, op);
}
/* Handle slow unaligned access (it spans two pages or IO). */
@ -1297,6 +1326,7 @@ 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:
@ -1486,13 +1516,32 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
tlb_addr = tlb_addr_write(entry) & ~TLB_INVALID_MASK;
}
/* Handle an IO access. */
/* Handle anything that isn't just a straight memory access. */
if (unlikely(tlb_addr & ~TARGET_PAGE_MASK)) {
CPUIOTLBEntry *iotlbentry;
/* For anything that is unaligned, recurse through byte stores. */
if ((addr & (size - 1)) != 0) {
goto do_unaligned_access;
}
io_writex(env, &env_tlb(env)->d[mmu_idx].iotlb[index], mmu_idx,
val, addr, retaddr, op);
iotlbentry = &env_tlb(env)->d[mmu_idx].iotlb[index];
/* Handle watchpoints. */
if (unlikely(tlb_addr & TLB_WATCHPOINT)) {
/* 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;
}
}
/* Handle I/O access. */
io_writex(env, iotlbentry, mmu_idx, val, addr, retaddr, op);
return;
}
@ -1517,10 +1566,29 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
index2 = tlb_index(env, mmu_idx, page2);
entry2 = tlb_entry(env, mmu_idx, page2);
tlb_addr2 = tlb_addr_write(entry2);
if (!tlb_hit_page(tlb_addr2, page2)
&& !victim_tlb_hit(env, mmu_idx, index2, tlb_off, page2)) {
tlb_fill(env_cpu(env), page2, size2, MMU_DATA_STORE,
mmu_idx, retaddr);
if (!tlb_hit_page(tlb_addr2, page2)) {
if (!victim_tlb_hit(env, mmu_idx, index2, tlb_off, page2)) {
tlb_fill(env_cpu(env), page2, size2, MMU_DATA_STORE,
mmu_idx, retaddr);
index2 = tlb_index(env, mmu_idx, page2);
entry2 = tlb_entry(env, mmu_idx, page2);
}
tlb_addr2 = tlb_addr_write(entry2);
}
/*
* Handle watchpoints. Since this may trap, all checks
* must happen before any store.
*/
if (unlikely(tlb_addr & TLB_WATCHPOINT)) {
cpu_check_watchpoint(env_cpu(env), addr, size - size2,
env_tlb(env)->d[mmu_idx].iotlb[index].attrs,
BP_MEM_WRITE, retaddr);
}
if (unlikely(tlb_addr2 & TLB_WATCHPOINT)) {
cpu_check_watchpoint(env_cpu(env), page2, size2,
env_tlb(env)->d[mmu_idx].iotlb[index2].attrs,
BP_MEM_WRITE, retaddr);
}
/*
@ -1542,6 +1610,7 @@ 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:

114
exec.c
View File

@ -193,15 +193,12 @@ typedef struct subpage_t {
#define PHYS_SECTION_UNASSIGNED 0
#define PHYS_SECTION_NOTDIRTY 1
#define PHYS_SECTION_ROM 2
#define PHYS_SECTION_WATCH 3
static void io_mem_init(void);
static void memory_map_init(void);
static void tcg_log_global_after_sync(MemoryListener *listener);
static void tcg_commit(MemoryListener *listener);
static MemoryRegion io_mem_watch;
/**
* CPUAddressSpace: all the information a CPU needs about an AddressSpace
* @cpu: the CPU whose AddressSpace this is
@ -1472,7 +1469,6 @@ hwaddr memory_region_section_get_iotlb(CPUState *cpu,
target_ulong *address)
{
hwaddr iotlb;
int flags, match;
if (memory_region_is_ram(section->mr)) {
/* Normal RAM. */
@ -1490,19 +1486,6 @@ hwaddr memory_region_section_get_iotlb(CPUState *cpu,
iotlb += xlat;
}
/* Avoid trapping reads of pages with a write breakpoint. */
match = (prot & PAGE_READ ? BP_MEM_READ : 0)
| (prot & PAGE_WRITE ? BP_MEM_WRITE : 0);
flags = cpu_watchpoint_address_matches(cpu, vaddr, TARGET_PAGE_SIZE);
if (flags & match) {
/*
* Make accesses to pages with watchpoints go via the
* watchpoint trap routines.
*/
iotlb = PHYS_SECTION_WATCH + paddr;
*address |= TLB_MMIO;
}
return iotlb;
}
#endif /* defined(CONFIG_USER_ONLY) */
@ -2810,10 +2793,14 @@ void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
assert(tcg_enabled());
if (cpu->watchpoint_hit) {
/* We re-entered the check after replacing the TB. Now raise
* the debug interrupt so that is will trigger after the
* current instruction. */
/*
* We re-entered the check after replacing the TB.
* Now raise the debug interrupt so that it will
* trigger after the current instruction.
*/
qemu_mutex_lock_iothread();
cpu_interrupt(cpu, CPU_INTERRUPT_DEBUG);
qemu_mutex_unlock_iothread();
return;
}
@ -2858,88 +2845,6 @@ void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
}
}
static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags)
{
CPUState *cpu = current_cpu;
vaddr addr = (cpu->mem_io_vaddr & TARGET_PAGE_MASK) + offset;
cpu_check_watchpoint(cpu, addr, len, attrs, flags, 0);
}
/* Watchpoint access routines. Watchpoints are inserted using TLB tricks,
so these check for a hit then pass through to the normal out-of-line
phys routines. */
static MemTxResult watch_mem_read(void *opaque, hwaddr addr, uint64_t *pdata,
unsigned size, MemTxAttrs attrs)
{
MemTxResult res;
uint64_t data;
int asidx = cpu_asidx_from_attrs(current_cpu, attrs);
AddressSpace *as = current_cpu->cpu_ases[asidx].as;
check_watchpoint(addr & ~TARGET_PAGE_MASK, size, attrs, BP_MEM_READ);
switch (size) {
case 1:
data = address_space_ldub(as, addr, attrs, &res);
break;
case 2:
data = address_space_lduw(as, addr, attrs, &res);
break;
case 4:
data = address_space_ldl(as, addr, attrs, &res);
break;
case 8:
data = address_space_ldq(as, addr, attrs, &res);
break;
default: abort();
}
*pdata = data;
return res;
}
static MemTxResult watch_mem_write(void *opaque, hwaddr addr,
uint64_t val, unsigned size,
MemTxAttrs attrs)
{
MemTxResult res;
int asidx = cpu_asidx_from_attrs(current_cpu, attrs);
AddressSpace *as = current_cpu->cpu_ases[asidx].as;
check_watchpoint(addr & ~TARGET_PAGE_MASK, size, attrs, BP_MEM_WRITE);
switch (size) {
case 1:
address_space_stb(as, addr, val, attrs, &res);
break;
case 2:
address_space_stw(as, addr, val, attrs, &res);
break;
case 4:
address_space_stl(as, addr, val, attrs, &res);
break;
case 8:
address_space_stq(as, addr, val, attrs, &res);
break;
default: abort();
}
return res;
}
static const MemoryRegionOps watch_mem_ops = {
.read_with_attrs = watch_mem_read,
.write_with_attrs = watch_mem_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.valid = {
.min_access_size = 1,
.max_access_size = 8,
.unaligned = false,
},
.impl = {
.min_access_size = 1,
.max_access_size = 8,
.unaligned = false,
},
};
static MemTxResult flatview_read(FlatView *fv, hwaddr addr,
MemTxAttrs attrs, uint8_t *buf, hwaddr len);
static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
@ -3115,9 +3020,6 @@ static void io_mem_init(void)
memory_region_init_io(&io_mem_notdirty, NULL, &notdirty_mem_ops, NULL,
NULL, UINT64_MAX);
memory_region_clear_global_locking(&io_mem_notdirty);
memory_region_init_io(&io_mem_watch, NULL, &watch_mem_ops, NULL,
NULL, UINT64_MAX);
}
AddressSpaceDispatch *address_space_dispatch_new(FlatView *fv)
@ -3131,8 +3033,6 @@ AddressSpaceDispatch *address_space_dispatch_new(FlatView *fv)
assert(n == PHYS_SECTION_NOTDIRTY);
n = dummy_section(&d->map, fv, &io_mem_rom);
assert(n == PHYS_SECTION_ROM);
n = dummy_section(&d->map, fv, &io_mem_watch);
assert(n == PHYS_SECTION_WATCH);
d->phys_map = (PhysPageEntry) { .ptr = PHYS_MAP_NODE_NIL, .skip = 1 };

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

@ -329,11 +329,14 @@ 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 contains a watchpoint. */
#define TLB_WATCHPOINT (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)
#define TLB_FLAGS_MASK \
(TLB_INVALID_MASK | TLB_NOTDIRTY | TLB_MMIO | TLB_WATCHPOINT)
/**
* tlb_hit_page: return true if page aligned @addr is a hit against the