//===-- sanitizer_linux.h ---------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Linux-specific syscall wrappers and classes.
//
//===----------------------------------------------------------------------===//
#ifndef SANITIZER_LINUX_H
#define SANITIZER_LINUX_H

#include "sanitizer_platform.h"
#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||                \
    SANITIZER_OPENBSD || SANITIZER_SOLARIS
#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_openbsd.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.
#if SANITIZER_LINUX
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);
#endif
int internal_uname(struct utsname *buf);
#elif SANITIZER_FREEBSD
void internal_sigdelset(__sanitizer_sigset_t *set, int signum);
#elif SANITIZER_NETBSD
void internal_sigdelset(__sanitizer_sigset_t *set, int signum);
uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg);
#endif  // SANITIZER_LINUX

// This class reads thread IDs from /proc/<pid>/task using only syscalls.
class ThreadLister {
 public:
  explicit ThreadLister(pid_t pid);
  ~ThreadLister();
  enum Result {
    Error,
    Incomplete,
    Ok,
  };
  Result ListThreads(InternalMmapVector<tid_t> *threads);

 private:
  bool IsAlive(int tid);

  pid_t pid_;
  int descriptor_ = -1;
  InternalMmapVector<char> buffer_;
};

// Exposed for testing.
uptr ThreadDescriptorSize();
uptr ThreadSelf();
uptr ThreadSelfOffset();

// 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.
  CHECK(SANITIZER_LINUX);
  ReleaseMemoryPagesToOS(beg, end);
}

#if SANITIZER_ANDROID

#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; })
#else
#error "Unsupported architecture."
#endif

// 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]);
}

#endif  // SANITIZER_ANDROID

}  // namespace __sanitizer

#endif
#endif  // SANITIZER_LINUX_H