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heap: Map DOS area as readable

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Resolves #74
This commit is contained in:
Luke Street
2025-11-18 21:53:34 -07:00
parent 64511becf2
commit 11deab36e4
1 changed files with 49 additions and 40 deletions
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89
src/heap.cpp
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@@ -75,9 +75,9 @@ struct VirtualAllocation {
std::map<uintptr_t, VirtualAllocation> g_virtualAllocations;
#ifndef __APPLE__
const uintptr_t kDefaultMmapMinAddr = 0x10000u;
#ifdef __linux__
uintptr_t readMmapMinAddr() {
char buf[64];
int fd = open("/proc/sys/vm/mmap_min_addr", O_RDONLY | O_CLOEXEC, 0);
@@ -100,19 +100,31 @@ uintptr_t readMmapMinAddr() {
}
return value;
}
uintptr_t mmapMinAddr() {
static uintptr_t minAddr = readMmapMinAddr();
return minAddr;
}
#endif
uintptr_t alignDown(uintptr_t value, std::size_t alignment) {
inline uintptr_t mmapMinAddr() {
#ifdef __linux__
static uintptr_t minAddr = readMmapMinAddr();
return minAddr;
#else
return kDefaultMmapMinAddr;
#endif
}
inline void setVirtualAllocationName(void *ptr, std::size_t len, const char *name) {
#ifdef __linux__
if (name) {
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, len, name);
}
#endif
}
constexpr uintptr_t alignDown(uintptr_t value, std::size_t alignment) {
const uintptr_t mask = static_cast<uintptr_t>(alignment) - 1;
return value & ~mask;
}
uintptr_t alignUp(uintptr_t value, std::size_t alignment) {
constexpr uintptr_t alignUp(uintptr_t value, std::size_t alignment) {
const uintptr_t mask = static_cast<uintptr_t>(alignment) - 1;
if (mask == std::numeric_limits<uintptr_t>::max()) {
return value;
@@ -123,11 +135,11 @@ uintptr_t alignUp(uintptr_t value, std::size_t alignment) {
return (value + mask) & ~mask;
}
bool addOverflows(uintptr_t base, std::size_t amount) {
constexpr bool addOverflows(uintptr_t base, std::size_t amount) {
return base > std::numeric_limits<uintptr_t>::max() - static_cast<uintptr_t>(amount);
}
uintptr_t regionEnd(const VirtualAllocation &region) { return region.base + region.size; }
constexpr uintptr_t regionEnd(const VirtualAllocation &region) { return region.base + region.size; }
std::map<uintptr_t, VirtualAllocation>::iterator findRegionIterator(uintptr_t address) {
auto it = g_virtualAllocations.upper_bound(address);
@@ -149,7 +161,7 @@ VirtualAllocation *lookupRegion(uintptr_t address) {
return &it->second;
}
bool rangeWithinRegion(const VirtualAllocation &region, uintptr_t start, std::size_t length) {
constexpr bool rangeWithinRegion(const VirtualAllocation &region, uintptr_t start, std::size_t length) {
if (length == 0) {
return start >= region.base && start <= regionEnd(region);
}
@@ -316,14 +328,9 @@ bool mapAtAddrLocked(uintptr_t addr, std::size_t size, const char *name, void **
if (p == MAP_FAILED) {
return false;
}
#ifdef __linux__
if (name) {
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, addr, size, name);
}
#else
(void)name;
#endif
recordGuestMappingLocked(addr, size, PAGE_READWRITE, MEM_RESERVE, PAGE_READWRITE, MEM_PRIVATE);
setVirtualAllocationName(p, size, name);
recordGuestMappingLocked(reinterpret_cast<uintptr_t>(p), size, PAGE_READWRITE, MEM_RESERVE, PAGE_READWRITE,
MEM_PRIVATE);
if (outPtr) {
*outPtr = p;
}
@@ -677,13 +684,11 @@ VmStatus virtualAlloc(void **baseAddress, std::size_t *regionSize, DWORD allocat
if (mapped == MAP_FAILED) {
return vmStatusFromErrno(errno);
}
#ifdef __linux__
if (type == MEM_IMAGE) {
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, base, length, "wibo guest image");
setVirtualAllocationName(mapped, length, "wibo guest image");
} else {
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, base, length, "wibo guest allocated");
setVirtualAllocationName(mapped, length, "wibo guest allocated");
}
#endif
uintptr_t actualBase = reinterpret_cast<uintptr_t>(mapped);
VirtualAllocation allocation{};
allocation.base = actualBase;
@@ -750,9 +755,7 @@ VmStatus virtualAlloc(void **baseAddress, std::size_t *regionSize, DWORD allocat
if (res == MAP_FAILED) {
return vmStatusFromErrno(errno);
}
#ifdef __linux__
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, run.first, run.second, "wibo guest committed");
#endif
setVirtualAllocationName(res, run.second, "wibo guest committed");
markCommitted(*region, run.first, run.second, protect);
}
@@ -803,9 +806,7 @@ VmStatus virtualFree(void *baseAddress, std::size_t regionSize, DWORD freeType)
if (res == MAP_FAILED) {
return vmStatusFromErrno(errno);
}
#ifdef __linux__
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, base, length, "wibo reserved");
#endif
setVirtualAllocationName(res, length, "wibo reserved");
eraseGuestMappingLocked(base);
return VmStatus::Success;
}
@@ -842,9 +843,7 @@ VmStatus virtualFree(void *baseAddress, std::size_t regionSize, DWORD freeType)
if (res == MAP_FAILED) {
return vmStatusFromErrno(errno);
}
#ifdef __linux__
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, res, length, "wibo reserved");
#endif
setVirtualAllocationName(res, length, "wibo reserved");
markDecommitted(region, start, length);
refreshGuestMappingLocked(region);
return VmStatus::Success;
@@ -1065,7 +1064,7 @@ bool reserveGuestStack(std::size_t stackSizeBytes, void **outStackLimit, void **
} // namespace wibo::heap
#ifndef __APPLE__
#ifdef __linux__
static void debugPrintMaps() {
char buf[1024];
int fd = open("/proc/self/maps", O_RDONLY);
@@ -1225,9 +1224,7 @@ static size_t blockLower2GB(MEMORY_BASIC_INFORMATION mappings[MAX_NUM_MAPPINGS])
perror("heap: failed reserve memory");
exit(1);
}
#ifdef __linux__
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, len, "wibo reserved");
#endif
setVirtualAllocationName(ptr, len, "wibo reserved");
}
lastMapEnd = mapEnd;
@@ -1243,27 +1240,39 @@ __attribute__((constructor(101)))
__attribute__((constructor))
#endif
__attribute__((used)) static void wibo_heap_constructor() {
#ifndef __APPLE__
#ifdef __linux__
MEMORY_BASIC_INFORMATION mappings[MAX_NUM_MAPPINGS];
memset(mappings, 0, sizeof(mappings));
#endif
bool debug = getenv("WIBO_DEBUG_HEAP") != nullptr;
if (debug) {
LOG_OUT("heap: initializing...\n");
#ifndef __APPLE__
#ifdef __linux__
debugPrintMaps();
#endif
}
#ifndef __APPLE__
#ifdef __linux__
size_t numMappings = blockLower2GB(mappings);
#endif
// Mark DOS area as read-only
const uintptr_t minAddr = mmapMinAddr();
if (minAddr < kLowMemoryStart) {
size_t len = static_cast<size_t>(kLowMemoryStart - minAddr);
void *ptr = mmap(reinterpret_cast<void *>(minAddr), len, PROT_READ,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE | MAP_FIXED, -1, 0);
if (ptr == MAP_FAILED) {
LOG_ERR("heap: failed to allocate DOS area\n");
} else {
setVirtualAllocationName(ptr, len, "wibo DOS area");
}
}
// Now we can allocate memory
if (debug) {
mi_option_enable(mi_option_show_stats);
mi_option_enable(mi_option_verbose);
}
g_mappings = new std::map<uintptr_t, MEMORY_BASIC_INFORMATION>;
#ifndef __APPLE__
#ifdef __linux__
for (size_t i = 0; i < numMappings; ++i) {
if (debug) {
fprintf(stderr, "Existing %zu: BaseAddress=%x, RegionSize=%u\n", i, mappings[i].BaseAddress,