Commit 03b69480 authored by Benoît Lizé's avatar Benoît Lizé Committed by V8 LUCI CQ

[base/platform] Simplify /proc/self/maps parsing

There are three ways to parse /proc/self/maps in platform-linux.cc,
remove one to use common code. In the process, add a unit test, and fix
some issues in the latest iteration of /proc/self/maps parsing.

Change-Id: I4701ea49fe8cce53aea0179e194dc48fbebb2ff5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3605226
Commit-Queue: Benoit Lize <lizeb@chromium.org>
Reviewed-by: 's avatarIgor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80258}
parent cf6ad387
...@@ -31,6 +31,7 @@ ...@@ -31,6 +31,7 @@
#include <unistd.h> // sysconf #include <unistd.h> // sysconf
#include <cmath> #include <cmath>
#include <cstdio>
#include <memory> #include <memory>
#include "src/base/logging.h" #include "src/base/logging.h"
...@@ -50,83 +51,6 @@ TimezoneCache* OS::CreateTimezoneCache() { ...@@ -50,83 +51,6 @@ TimezoneCache* OS::CreateTimezoneCache() {
return new PosixDefaultTimezoneCache(); return new PosixDefaultTimezoneCache();
} }
std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
std::vector<SharedLibraryAddress> result;
// This function assumes that the layout of the file is as follows:
// hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
// If we encounter an unexpected situation we abort scanning further entries.
FILE* fp = fopen("/proc/self/maps", "r");
if (fp == nullptr) return result;
// Allocate enough room to be able to store a full file name.
const int kLibNameLen = FILENAME_MAX + 1;
char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));
// This loop will terminate once the scanning hits an EOF.
while (true) {
uintptr_t start, end, offset;
char attr_r, attr_w, attr_x, attr_p;
// Parse the addresses and permission bits at the beginning of the line.
if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;
if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;
if (fscanf(fp, "%" V8PRIxPTR, &offset) != 1) break;
int c;
if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
// Found a read-only executable entry. Skip characters until we reach
// the beginning of the filename or the end of the line.
do {
c = getc(fp);
} while ((c != EOF) && (c != '\n') && (c != '/') && (c != '['));
if (c == EOF) break; // EOF: Was unexpected, just exit.
// Process the filename if found.
if ((c == '/') || (c == '[')) {
// Push the '/' or '[' back into the stream to be read below.
ungetc(c, fp);
// Read to the end of the line. Exit if the read fails.
if (fgets(lib_name, kLibNameLen, fp) == nullptr) break;
// Drop the newline character read by fgets. We do not need to check
// for a zero-length string because we know that we at least read the
// '/' or '[' character.
lib_name[strlen(lib_name) - 1] = '\0';
} else {
// No library name found, just record the raw address range.
snprintf(lib_name, kLibNameLen, "%08" V8PRIxPTR "-%08" V8PRIxPTR, start,
end);
}
#ifdef V8_OS_ANDROID
size_t lib_name_length = strlen(lib_name);
if (lib_name_length < 4 ||
strncmp(&lib_name[lib_name_length - 4], ".apk", 4) != 0) {
// Only adjust {start} based on {offset} if the file isn't the APK,
// since we load the library directly from the APK and don't want to
// apply the offset of the .so in the APK as the libraries offset.
start -= offset;
}
#else
// Adjust {start} based on {offset}.
start -= offset;
#endif
result.push_back(SharedLibraryAddress(lib_name, start, end));
} else {
// Entry not describing executable data. Skip to end of line to set up
// reading the next entry.
do {
c = getc(fp);
} while ((c != EOF) && (c != '\n'));
if (c == EOF) break;
}
}
free(lib_name);
fclose(fp);
return result;
}
void OS::SignalCodeMovingGC() { void OS::SignalCodeMovingGC() {
// Support for ll_prof.py. // Support for ll_prof.py.
// //
...@@ -246,10 +170,11 @@ base::Optional<MemoryRegion> MemoryRegion::FromMapsLine(const char* line) { ...@@ -246,10 +170,11 @@ base::Optional<MemoryRegion> MemoryRegion::FromMapsLine(const char* line) {
namespace { namespace {
// Parses /proc/self/maps. // Parses /proc/self/maps.
std::unique_ptr<std::vector<MemoryRegion>> ParseProcSelfMaps( std::unique_ptr<std::vector<MemoryRegion>> ParseProcSelfMaps(
std::function<bool(const MemoryRegion&)> predicate, bool early_stopping) { FILE* fp, std::function<bool(const MemoryRegion&)> predicate,
bool early_stopping) {
auto result = std::make_unique<std::vector<MemoryRegion>>(); auto result = std::make_unique<std::vector<MemoryRegion>>();
FILE* fp = fopen("/proc/self/maps", "r"); if (!fp) fp = fopen("/proc/self/maps", "r");
if (!fp) return nullptr; if (!fp) return nullptr;
// Allocate enough room to be able to store a full file name. // Allocate enough room to be able to store a full file name.
...@@ -263,15 +188,26 @@ std::unique_ptr<std::vector<MemoryRegion>> ParseProcSelfMaps( ...@@ -263,15 +188,26 @@ std::unique_ptr<std::vector<MemoryRegion>> ParseProcSelfMaps(
error = true; error = true;
// Read to the end of the line. Exit if the read fails. // Read to the end of the line. Exit if the read fails.
if (fgets(line.get(), kMaxLineLength, fp) == nullptr) break; if (fgets(line.get(), kMaxLineLength, fp) == nullptr) {
if (feof(fp)) error = false;
break;
}
size_t line_length = strlen(line.get()); size_t line_length = strlen(line.get());
// Empty line at the end.
if (!line_length) {
error = false;
break;
}
// Line was truncated. // Line was truncated.
if (line.get()[line_length - 1] != '\n') break; if (line.get()[line_length - 1] != '\n') break;
line.get()[line_length - 1] = '\0'; line.get()[line_length - 1] = '\0';
base::Optional<MemoryRegion> region = base::Optional<MemoryRegion> region =
MemoryRegion::FromMapsLine(line.get()); MemoryRegion::FromMapsLine(line.get());
if (!region) break; if (!region) {
break;
}
error = false; error = false;
...@@ -289,6 +225,7 @@ std::unique_ptr<std::vector<MemoryRegion>> ParseProcSelfMaps( ...@@ -289,6 +225,7 @@ std::unique_ptr<std::vector<MemoryRegion>> ParseProcSelfMaps(
MemoryRegion FindEnclosingMapping(uintptr_t target_start, size_t size) { MemoryRegion FindEnclosingMapping(uintptr_t target_start, size_t size) {
auto result = ParseProcSelfMaps( auto result = ParseProcSelfMaps(
nullptr,
[=](const MemoryRegion& region) { [=](const MemoryRegion& region) {
return region.start <= target_start && target_start + size < region.end; return region.start <= target_start && target_start + size < region.end;
}, },
...@@ -300,6 +237,45 @@ MemoryRegion FindEnclosingMapping(uintptr_t target_start, size_t size) { ...@@ -300,6 +237,45 @@ MemoryRegion FindEnclosingMapping(uintptr_t target_start, size_t size) {
} }
} // namespace } // namespace
// static
std::vector<OS::SharedLibraryAddress> GetSharedLibraryAddresses(FILE* fp) {
auto regions = ParseProcSelfMaps(
fp,
[](const MemoryRegion& region) {
if (region.permissions[0] == 'r' && region.permissions[1] == '-' &&
region.permissions[2] == 'x') {
return true;
}
return false;
},
false);
if (!regions) return {};
std::vector<OS::SharedLibraryAddress> result;
for (const MemoryRegion& region : *regions) {
uintptr_t start = region.start;
#ifdef V8_OS_ANDROID
if (region.pathname.size() < 4 ||
region.pathname.compare(region.pathname.size() - 4, 4, ".apk") != 0) {
// Only adjust {start} based on {offset} if the file isn't the APK,
// since we load the library directly from the APK and don't want to
// apply the offset of the .so in the APK as the libraries offset.
start -= region.offset;
}
#else
start -= region.offset;
#endif
result.emplace_back(region.pathname, start, region.end);
}
return result;
}
// static
std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
return ::v8::base::GetSharedLibraryAddresses(nullptr);
}
// static // static
bool OS::RemapPages(const void* address, size_t size, void* new_address, bool OS::RemapPages(const void* address, size_t size, void* new_address,
MemoryPermission access) { MemoryPermission access) {
......
...@@ -12,6 +12,7 @@ ...@@ -12,6 +12,7 @@
#include "src/base/base-export.h" #include "src/base/base-export.h"
#include "src/base/optional.h" #include "src/base/optional.h"
#include "src/base/platform/platform.h"
namespace v8 { namespace v8 {
namespace base { namespace base {
...@@ -31,6 +32,10 @@ struct V8_BASE_EXPORT MemoryRegion { ...@@ -31,6 +32,10 @@ struct V8_BASE_EXPORT MemoryRegion {
static base::Optional<MemoryRegion> FromMapsLine(const char* line); static base::Optional<MemoryRegion> FromMapsLine(const char* line);
}; };
// The |fp| parameter is for testing, to pass a fake /proc/self/maps file.
V8_BASE_EXPORT std::vector<OS::SharedLibraryAddress> GetSharedLibraryAddresses(
FILE* fp);
} // namespace base } // namespace base
} // namespace v8 } // namespace v8
......
...@@ -4,6 +4,7 @@ ...@@ -4,6 +4,7 @@
#include "src/base/platform/platform.h" #include "src/base/platform/platform.h"
#include <cstdio>
#include <cstring> #include <cstring>
#include "src/base/build_config.h" #include "src/base/build_config.h"
...@@ -126,6 +127,34 @@ TEST(OS, ParseProcMaps) { ...@@ -126,6 +127,34 @@ TEST(OS, ParseProcMaps) {
EXPECT_EQ(region->pathname, std::string("")); EXPECT_EQ(region->pathname, std::string(""));
#endif // V8_TARGET_ARCH_64_BIT #endif // V8_TARGET_ARCH_64_BIT
} }
TEST(OS, GetSharedLibraryAddresses) {
FILE* fp = tmpfile();
ASSERT_TRUE(fp);
const char* contents =
R"EOF(12340000-12345000 r-xp 00026000 fe:01 12583839 /lib/x86_64-linux-gnu/libc-2.33.so
12365000-12376000 rw-p 00000000 00:00 0 [heap]
12430000-12435000 r-xp 00062000 fe:01 12583839 /path/to/SomeApplication.apk
)EOF";
size_t length = strlen(contents);
ASSERT_EQ(fwrite(contents, 1, length, fp), length);
rewind(fp);
auto shared_library_addresses = GetSharedLibraryAddresses(fp);
EXPECT_EQ(shared_library_addresses.size(), 2u);
EXPECT_EQ(shared_library_addresses[0].library_path,
"/lib/x86_64-linux-gnu/libc-2.33.so");
EXPECT_EQ(shared_library_addresses[0].start, 0x12340000u - 0x26000);
EXPECT_EQ(shared_library_addresses[1].library_path,
"/path/to/SomeApplication.apk");
#if defined(V8_OS_ANDROID)
EXPECT_EQ(shared_library_addresses[1].start, 0x12430000u);
#else
EXPECT_EQ(shared_library_addresses[1].start, 0x12430000u - 0x62000);
#endif
}
#endif // V8_TARGET_OS_LINUX #endif // V8_TARGET_OS_LINUX
namespace { namespace {
......
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