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//===-- sanitizer_linux.h ---------------------------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Linux-specific syscall wrappers and classes.
#include "sanitizer_platform.h"
#include "sanitizer_common.h"
#include "sanitizer_internal_defs.h"
#include "sanitizer_platform_limits_freebsd.h"
#include "sanitizer_platform_limits_netbsd.h"
#include "sanitizer_platform_limits_posix.h"
#include "sanitizer_platform_limits_solaris.h"
#include "sanitizer_posix.h"
struct link_map; // Opaque type returned by dlopen().
struct utsname;
namespace __sanitizer {
// Dirent structure for getdents(). Note that this structure is different from
// the one in <dirent.h>, which is used by readdir().
struct linux_dirent;
struct ProcSelfMapsBuff {
char *data;
uptr mmaped_size;
uptr len;
struct MemoryMappingLayoutData {
ProcSelfMapsBuff proc_self_maps;
const char *current;
void ReadProcMaps(ProcSelfMapsBuff *proc_maps);
// Syscall wrappers.
uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count);
uptr internal_sigaltstack(const void* ss, void* oss);
uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
__sanitizer_sigset_t *oldset);
uptr internal_clock_gettime(__sanitizer_clockid_t clk_id, void *tp);
// Linux-only syscalls.
uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5);
// Used only by sanitizer_stoptheworld. Signal handlers that are actually used
// (like the process-wide error reporting SEGV handler) must use
// internal_sigaction instead.
int internal_sigaction_norestorer(int signum, const void *act, void *oldact);
void internal_sigdelset(__sanitizer_sigset_t *set, int signum);
#if defined(__x86_64__) || defined(__mips__) || defined(__aarch64__) || \
defined(__powerpc64__) || defined(__s390__) || defined(__i386__) || \
defined(__arm__) || SANITIZER_RISCV64
uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
int *parent_tidptr, void *newtls, int *child_tidptr);
int internal_uname(struct utsname *buf);
void internal_sigdelset(__sanitizer_sigset_t *set, int signum);
void internal_sigdelset(__sanitizer_sigset_t *set, int signum);
uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg);
// This class reads thread IDs from /proc/<pid>/task using only syscalls.
class ThreadLister {
explicit ThreadLister(pid_t pid);
enum Result {
Result ListThreads(InternalMmapVector<tid_t> *threads);
bool IsAlive(int tid);
pid_t pid_;
int descriptor_ = -1;
InternalMmapVector<char> buffer_;
// Exposed for testing.
uptr ThreadDescriptorSize();
uptr ThreadSelf();
// Matches a library's file name against a base name (stripping path and version
// information).
bool LibraryNameIs(const char *full_name, const char *base_name);
// Call cb for each region mapped by map.
void ForEachMappedRegion(link_map *map, void (*cb)(const void *, uptr));
// Releases memory pages entirely within the [beg, end] address range.
// The pages no longer count toward RSS; reads are guaranteed to return 0.
// Requires (but does not verify!) that pages are MAP_PRIVATE.
inline void ReleaseMemoryPagesToOSAndZeroFill(uptr beg, uptr end) {
// man madvise on Linux promises zero-fill for anonymous private pages.
// Testing shows the same behaviour for private (but not anonymous) mappings
// of shm_open() files, as long as the underlying file is untouched.
ReleaseMemoryPagesToOS(beg, end);
#if defined(__aarch64__)
# define __get_tls() \
({ void** __v; __asm__("mrs %0, tpidr_el0" : "=r"(__v)); __v; })
#elif defined(__arm__)
# define __get_tls() \
({ void** __v; __asm__("mrc p15, 0, %0, c13, c0, 3" : "=r"(__v)); __v; })
#elif defined(__mips__)
// On mips32r1, this goes via a kernel illegal instruction trap that's
// optimized for v1.
# define __get_tls() \
({ register void** __v asm("v1"); \
__asm__(".set push\n" \
".set mips32r2\n" \
"rdhwr %0,$29\n" \
".set pop\n" : "=r"(__v)); \
__v; })
#elif defined(__i386__)
# define __get_tls() \
({ void** __v; __asm__("movl %%gs:0, %0" : "=r"(__v)); __v; })
#elif defined(__x86_64__)
# define __get_tls() \
({ void** __v; __asm__("mov %%fs:0, %0" : "=r"(__v)); __v; })
#error "Unsupported architecture."
// The Android Bionic team has allocated a TLS slot for sanitizers starting
// with Q, given that Android currently doesn't support ELF TLS. It is used to
// store sanitizer thread specific data.
static const int TLS_SLOT_SANITIZER = 6;
ALWAYS_INLINE uptr *get_android_tls_ptr() {
return reinterpret_cast<uptr *>(&__get_tls()[TLS_SLOT_SANITIZER]);
} // namespace __sanitizer