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[nfc][lsan] Extract significant part of the loop into a function #112610

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Merged
merged 4 commits into from
Oct 17, 2024
Merged

[nfc][lsan] Extract significant part of the loop into a function #112610

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3a24624
[𝘀𝗽𝗿] changes to main this commit is based on
vitalybuka Oct 16, 2024
8bbcf00
[𝘀𝗽𝗿] initial version
vitalybuka Oct 16, 2024
22bded5
[𝘀𝗽𝗿] changes introduced through rebase
thetruestblue Oct 17, 2024
7b17437
rebase
vitalybuka Oct 17, 2024
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209 changes: 108 additions & 101 deletions compiler-rt/lib/lsan/lsan_common.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -399,6 +399,112 @@ static void ProcessThreadRegistry(Frontier *frontier) {
}

// Scans thread data (stacks and TLS) for heap pointers.
static void ProcessThread(tid_t os_id, uptr sp,
const InternalMmapVector<uptr> &registers,
InternalMmapVector<Range> &extra_ranges,
Frontier *frontier) {
// `extra_ranges` is outside of the function and the loop to reused mapped
// memory.
CHECK(extra_ranges.empty());
LOG_THREADS("Processing thread %llu.\n", os_id);
uptr stack_begin, stack_end, tls_begin, tls_end, cache_begin, cache_end;
DTLS *dtls;
bool thread_found =
GetThreadRangesLocked(os_id, &stack_begin, &stack_end, &tls_begin,
&tls_end, &cache_begin, &cache_end, &dtls);
if (!thread_found) {
// If a thread can't be found in the thread registry, it's probably in the
// process of destruction. Log this event and move on.
LOG_THREADS("Thread %llu not found in registry.\n", os_id);
return;
}

if (!sp)
sp = stack_begin;

if (flags()->use_registers) {
uptr registers_begin = reinterpret_cast<uptr>(registers.data());
uptr registers_end =
reinterpret_cast<uptr>(registers.data() + registers.size());
ScanRangeForPointers(registers_begin, registers_end, frontier, "REGISTERS",
kReachable);
}

if (flags()->use_stacks) {
LOG_THREADS("Stack at %p-%p (SP = %p).\n", (void *)stack_begin,
(void *)stack_end, (void *)sp);
if (sp < stack_begin || sp >= stack_end) {
// SP is outside the recorded stack range (e.g. the thread is running a
// signal handler on alternate stack, or swapcontext was used).
// Again, consider the entire stack range to be reachable.
LOG_THREADS("WARNING: stack pointer not in stack range.\n");
uptr page_size = GetPageSizeCached();
int skipped = 0;
while (stack_begin < stack_end &&
!IsAccessibleMemoryRange(stack_begin, 1)) {
skipped++;
stack_begin += page_size;
}
LOG_THREADS("Skipped %d guard page(s) to obtain stack %p-%p.\n", skipped,
(void *)stack_begin, (void *)stack_end);
} else {
// Shrink the stack range to ignore out-of-scope values.
stack_begin = sp;
}
ScanRangeForPointers(stack_begin, stack_end, frontier, "STACK", kReachable);
GetThreadExtraStackRangesLocked(os_id, &extra_ranges);
ScanExtraStackRanges(extra_ranges, frontier);
}

if (flags()->use_tls) {
if (tls_begin) {
LOG_THREADS("TLS at %p-%p.\n", (void *)tls_begin, (void *)tls_end);
// If the tls and cache ranges don't overlap, scan full tls range,
// otherwise, only scan the non-overlapping portions
if (cache_begin == cache_end || tls_end < cache_begin ||
tls_begin > cache_end) {
ScanRangeForPointers(tls_begin, tls_end, frontier, "TLS", kReachable);
} else {
if (tls_begin < cache_begin)
ScanRangeForPointers(tls_begin, cache_begin, frontier, "TLS",
kReachable);
if (tls_end > cache_end)
ScanRangeForPointers(cache_end, tls_end, frontier, "TLS", kReachable);
}
}
# if SANITIZER_ANDROID
auto *cb = +[](void *dtls_begin, void *dtls_end, uptr /*dso_idd*/,
void *arg) -> void {
ScanRangeForPointers(
reinterpret_cast<uptr>(dtls_begin), reinterpret_cast<uptr>(dtls_end),
reinterpret_cast<Frontier *>(arg), "DTLS", kReachable);
};

// FIXME: There might be a race-condition here (and in Bionic) if the
// thread is suspended in the middle of updating its DTLS. IOWs, we
// could scan already freed memory. (probably fine for now)
__libc_iterate_dynamic_tls(os_id, cb, frontier);
# else
if (dtls && !DTLSInDestruction(dtls)) {
ForEachDVT(dtls, [&](const DTLS::DTV &dtv, int id) {
uptr dtls_beg = dtv.beg;
uptr dtls_end = dtls_beg + dtv.size;
if (dtls_beg < dtls_end) {
LOG_THREADS("DTLS %d at %p-%p.\n", id, (void *)dtls_beg,
(void *)dtls_end);
ScanRangeForPointers(dtls_beg, dtls_end, frontier, "DTLS",
kReachable);
}
});
} else {
// We are handling a thread with DTLS under destruction. Log about
// this and continue.
LOG_THREADS("Thread %llu has DTLS under destruction.\n", os_id);
}
# endif
}
}

static void ProcessThreads(SuspendedThreadsList const &suspended_threads,
Frontier *frontier, tid_t caller_tid,
uptr caller_sp) {
Expand All @@ -408,7 +514,7 @@ static void ProcessThreads(SuspendedThreadsList const &suspended_threads,
registers.clear();
extra_ranges.clear();

const tid_t os_id = static_cast<tid_t>(suspended_threads.GetThreadID(i));
const tid_t os_id = suspended_threads.GetThreadID(i);
uptr sp = 0;
PtraceRegistersStatus have_registers =
suspended_threads.GetRegistersAndSP(i, &registers, &sp);
Expand All @@ -421,109 +527,10 @@ static void ProcessThreads(SuspendedThreadsList const &suspended_threads,
sp = 0;
}

LOG_THREADS("Processing thread %llu.\n", os_id);
uptr stack_begin, stack_end, tls_begin, tls_end, cache_begin, cache_end;
DTLS *dtls;
bool thread_found =
GetThreadRangesLocked(os_id, &stack_begin, &stack_end, &tls_begin,
&tls_end, &cache_begin, &cache_end, &dtls);
if (!thread_found) {
// If a thread can't be found in the thread registry, it's probably in the
// process of destruction. Log this event and move on.
LOG_THREADS("Thread %llu not found in registry.\n", os_id);
continue;
}

if (os_id == caller_tid)
sp = caller_sp;

if (!sp)
sp = stack_begin;

if (flags()->use_registers && have_registers) {
uptr registers_begin = reinterpret_cast<uptr>(registers.data());
uptr registers_end =
reinterpret_cast<uptr>(registers.data() + registers.size());
ScanRangeForPointers(registers_begin, registers_end, frontier,
"REGISTERS", kReachable);
}

if (flags()->use_stacks) {
LOG_THREADS("Stack at %p-%p (SP = %p).\n", (void *)stack_begin,
(void *)stack_end, (void *)sp);
if (sp < stack_begin || sp >= stack_end) {
// SP is outside the recorded stack range (e.g. the thread is running a
// signal handler on alternate stack, or swapcontext was used).
// Again, consider the entire stack range to be reachable.
LOG_THREADS("WARNING: stack pointer not in stack range.\n");
uptr page_size = GetPageSizeCached();
int skipped = 0;
while (stack_begin < stack_end &&
!IsAccessibleMemoryRange(stack_begin, 1)) {
skipped++;
stack_begin += page_size;
}
LOG_THREADS("Skipped %d guard page(s) to obtain stack %p-%p.\n",
skipped, (void *)stack_begin, (void *)stack_end);
} else {
// Shrink the stack range to ignore out-of-scope values.
stack_begin = sp;
}
ScanRangeForPointers(stack_begin, stack_end, frontier, "STACK",
kReachable);
GetThreadExtraStackRangesLocked(os_id, &extra_ranges);
ScanExtraStackRanges(extra_ranges, frontier);
}

if (flags()->use_tls) {
if (tls_begin) {
LOG_THREADS("TLS at %p-%p.\n", (void *)tls_begin, (void *)tls_end);
// If the tls and cache ranges don't overlap, scan full tls range,
// otherwise, only scan the non-overlapping portions
if (cache_begin == cache_end || tls_end < cache_begin ||
tls_begin > cache_end) {
ScanRangeForPointers(tls_begin, tls_end, frontier, "TLS", kReachable);
} else {
if (tls_begin < cache_begin)
ScanRangeForPointers(tls_begin, cache_begin, frontier, "TLS",
kReachable);
if (tls_end > cache_end)
ScanRangeForPointers(cache_end, tls_end, frontier, "TLS",
kReachable);
}
}
# if SANITIZER_ANDROID
auto *cb = +[](void *dtls_begin, void *dtls_end, uptr /*dso_idd*/,
void *arg) -> void {
ScanRangeForPointers(reinterpret_cast<uptr>(dtls_begin),
reinterpret_cast<uptr>(dtls_end),
reinterpret_cast<Frontier *>(arg), "DTLS",
kReachable);
};

// FIXME: There might be a race-condition here (and in Bionic) if the
// thread is suspended in the middle of updating its DTLS. IOWs, we
// could scan already freed memory. (probably fine for now)
__libc_iterate_dynamic_tls(os_id, cb, frontier);
# else
if (dtls && !DTLSInDestruction(dtls)) {
ForEachDVT(dtls, [&](const DTLS::DTV &dtv, int id) {
uptr dtls_beg = dtv.beg;
uptr dtls_end = dtls_beg + dtv.size;
if (dtls_beg < dtls_end) {
LOG_THREADS("DTLS %d at %p-%p.\n", id, (void *)dtls_beg,
(void *)dtls_end);
ScanRangeForPointers(dtls_beg, dtls_end, frontier, "DTLS",
kReachable);
}
});
} else {
// We are handling a thread with DTLS under destruction. Log about
// this and continue.
LOG_THREADS("Thread %llu has DTLS under destruction.\n", os_id);
}
# endif
}
ProcessThread(os_id, sp, registers, extra_ranges, frontier);
}

// Add pointers reachable from ThreadContexts
Expand Down
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