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Add mremap and shmat/shmdt allocation tracking #556

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64 changes: 64 additions & 0 deletions src/lib/symbol_overrides.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,9 @@
#include <ctime>
#include <dlfcn.h>
#include <malloc.h>
#include <sys/ipc.h>
#include <sys/mman.h>
#include <sys/shm.h>

#if defined(__GNUC__) && !defined(__clang__)
# define NOEXCEPT noexcept
Expand All @@ -35,6 +37,14 @@ extern "C" {
// Declaration of reallocarray is only available starting from glibc 2.28
DDPROF_WEAK void *reallocarray(void *ptr, size_t nmemb, size_t nmenb) NOEXCEPT;
DDPROF_WEAK void *pvalloc(size_t size) NOEXCEPT;
DDPROF_WEAK void *mremap(void *old_address, size_t old_size, size_t new_size,
int flags, ...) NOEXCEPT;
DDPROF_WEAK void *shmat(int shmid, const void *shmaddr, int shmflg) NOEXCEPT;
DDPROF_WEAK int shmdt(const void *shmaddr) NOEXCEPT;
// brk()/sbrk() are not instrumented:
// - They grow/shrink the program break, not individual allocations
// - Would double-count if malloc uses them internally
// - Tracking would require maintaining state of what's actually allocated
DDPROF_WEAK int __libc_allocate_rtsig(int high) NOEXCEPT;
// NOLINTEND

Expand Down Expand Up @@ -857,6 +867,57 @@ struct Munmap_Hook : HookBase {
}
};

struct MremapHook : HookBase {
static constexpr auto name = "mremap";
using FuncType = decltype(&::mremap);
static inline FuncType ref{};

static void *hook(void *old_address, size_t old_size, size_t new_size,
int flags) noexcept {
AllocTrackerHelperMmap helper;
if (likely(old_address) && helper) {
ddprof::AllocationTracker::track_deallocation_s(
reinterpret_cast<uintptr_t>(old_address), *helper.tl_state(), true);
}
auto *new_ptr = ref(old_address, old_size, new_size, flags);

@r1viollet r1viollet Jul 2, 2026

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todo: this does not have the guard

if (likely(new_size && new_ptr != MAP_FAILED)) {
helper.track(new_ptr, new_size);
}
return new_ptr;
}
};

struct ShmatHook : HookBase {
static constexpr auto name = "shmat";
using FuncType = decltype(&::shmat);
static inline FuncType ref{};

static void *hook(int shmid, const void *shmaddr, int shmflg) noexcept {
void *ptr = ref(shmid, shmaddr, shmflg);
if (ptr != reinterpret_cast<void *>(-1)) {
AllocTrackerHelperMmap helper;
// Query the segment size via shmctl
struct shmid_ds buf;
if (shmctl(shmid, IPC_STAT, &buf) == 0) {
helper.track(ptr, buf.shm_segsz);
}
}
return ptr;
}
};

struct ShmdtHook : HookBase {
static constexpr auto name = "shmdt";
using FuncType = decltype(&::shmdt);
static inline FuncType ref{};

static int hook(const void *shmaddr) noexcept {
DeallocTrackerHelperMmap helper;
helper.track(const_cast<void *>(shmaddr));
return ref(shmaddr);
}
};

template <typename T> void register_hook() {
g_symbol_overrides->register_override(T::name,
reinterpret_cast<uintptr_t>(&T::hook),
Expand Down Expand Up @@ -922,6 +983,9 @@ void register_hooks() {
register_hook<MunmapHook>();
register_hook<Mmap_Hook>();
register_hook<Munmap_Hook>();
register_hook<MremapHook>();
register_hook<ShmatHook>();
register_hook<ShmdtHook>();

register_hook<MallocxHook>();
register_hook<RallocxHook>();
Expand Down
35 changes: 34 additions & 1 deletion test/allocation_tracker-ut.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,9 @@ DDPROF_WEAK void sdallocx(void *ptr, size_t size, int flags);
}
#endif
#include <malloc.h>
#include <sys/ipc.h>
#include <sys/mman.h>
#include <sys/shm.h>
#include <unistd.h>

#if defined(__GNUC__) && !defined(__clang__)
Expand All @@ -61,6 +63,10 @@ DDPROF_WEAK void *pvalloc(size_t size) NOEXCEPT;
DDPROF_WEAK void *__mmap(void *addr, size_t length, int prot, int flags, int fd,
off_t offset);
DDPROF_WEAK int __munmap(void *addr, size_t length);
DDPROF_WEAK void *mremap(void *old_address, size_t old_size, size_t new_size,
int flags, ...) NOEXCEPT;
DDPROF_WEAK void *shmat(int shmid, const void *shmaddr, int shmflg) NOEXCEPT;
DDPROF_WEAK int shmdt(const void *shmaddr) NOEXCEPT;
}

namespace ddprof {
Expand Down Expand Up @@ -505,7 +511,34 @@ DDPROF_NOINLINE void test_allocation_functions(RingBuffer &ring_buffer) {
SCOPED_TRACE("__mmap/__munmap");
checker.test_alloc(mmap_wrapper(&::__mmap), &::__munmap);
}

if (mremap) {
SCOPED_TRACE("mremap");
checker.test_realloc(
mmap_wrapper(&::mmap),
[](void *ptr, size_t new_sz) {
auto old_sz = alloc_size;
auto *new_ptr = ::mremap(ptr, old_sz, new_sz, MREMAP_MAYMOVE);
return std::make_pair(new_ptr, new_sz);
},
[](void *ptr, size_t sz) { ::munmap(ptr, sz); });
}
if (shmat && shmdt) {
SCOPED_TRACE("shmat/shmdt");
// Create a System V shared memory segment
int shmid = shmget(IPC_PRIVATE, alloc_size, IPC_CREAT | 0600);
if (shmid != -1) {
checker.empty_ring_buffer();
void *ptr = ::shmat(shmid, nullptr, 0);
if (ptr != reinterpret_cast<void *>(-1)) {
checker.check_alloc(ptr, alloc_size);
checker.check_empty();
::shmdt(ptr);
checker.check_dealloc(ptr);
checker.check_empty();
}
shmctl(shmid, IPC_RMID, nullptr);
}
}
static constexpr size_t big_align = alignof(std::max_align_t) * 2;
static constexpr size_t array_size = 16;
static_assert((alloc_size / array_size) % big_align == 0);
Expand Down