text: //===-- sanitizer_linux_s390.cpp ------------------------------------------===//
  //
  // 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
  //
  //===----------------------------------------------------------------------===//
  //
  // This file is shared between AddressSanitizer and ThreadSanitizer
  // run-time libraries and implements s390-linux-specific functions from
  // sanitizer_libc.h.
  //===----------------------------------------------------------------------===//
  
  #include "sanitizer_platform.h"
  
  #if SANITIZER_LINUX && SANITIZER_S390
  
  #include <dlfcn.h>
  #include <errno.h>
  #include <sys/syscall.h>
  #include <sys/utsname.h>
  #include <unistd.h>
  
  #include "sanitizer_libc.h"
  #include "sanitizer_linux.h"
  
  namespace __sanitizer {
  
  // --------------- sanitizer_libc.h
  uptr internal_mmap(void *addr, usize length, int prot, int flags, int fd,
                     u64 offset) {
    struct s390_mmap_params {
      unsigned long addr;
      unsigned long length;
      unsigned long prot;
      unsigned long flags;
      unsigned long fd;
      unsigned long offset;
    } params = {
      (unsigned long)addr,
      (unsigned long)length,
      (unsigned long)prot,
      (unsigned long)flags,
      (unsigned long)fd,
  # ifdef __s390x__
      (unsigned long)offset,
  # else
      (unsigned long)(offset / 4096),
  # endif
    };
  # ifdef __s390x__
    return syscall(__NR_mmap, &params);
  # else
    return syscall(__NR_mmap2, &params);
  # endif
  }
  
  uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
                      int *parent_tidptr, void *newtls, int *child_tidptr) {
    if (!fn || !child_stack)
      return -EINVAL;
    CHECK_EQ(0, (uptr)child_stack % 16);
    // Minimum frame size.
  #ifdef __s390x__
    child_stack = (char *)child_stack - 160;
  #else
    child_stack = (char *)child_stack - 96;
  #endif
    // Terminate unwind chain.
    ((unsigned long *)child_stack)[0] = 0;
    // And pass parameters.
    ((unsigned long *)child_stack)[1] = (uptr)fn;
    ((unsigned long *)child_stack)[2] = (uptr)arg;
    register long res __asm__("r2");
    register void *__cstack      __asm__("r2") = child_stack;
    register int __flags         __asm__("r3") = flags;
    register int * __ptidptr     __asm__("r4") = parent_tidptr;
    register int * __ctidptr     __asm__("r5") = child_tidptr;
    register void * __newtls     __asm__("r6") = newtls;
  
    __asm__ __volatile__(
                         /* Clone. */
                         "svc    %1\n"
  
                         /* if (%r2 != 0)
                          *   return;
                          */
  #ifdef __s390x__
                         "cghi   %%r2, 0\n"
  #else
                         "chi    %%r2, 0\n"
  #endif
                         "jne    1f\n"
  
                         /* Call "fn(arg)". */
  #ifdef __s390x__
                         "lmg    %%r1, %%r2, 8(%%r15)\n"
  #else
                         "lm     %%r1, %%r2, 4(%%r15)\n"
  #endif
                         "basr   %%r14, %%r1\n"
  
                         /* Call _exit(%r2). */
                         "svc %2\n"
  
                         /* Return to parent. */
                       "1:\n"
                         : "=r" (res)
                         : "i"(__NR_clone), "i"(__NR_exit),
                           "r"(__cstack),
                           "r"(__flags),
                           "r"(__ptidptr),
                           "r"(__ctidptr),
                           "r"(__newtls)
                         : "memory", "cc");
    return res;
  }
  
  #if SANITIZER_S390_64
  static bool FixedCVE_2016_2143() {
    // Try to determine if the running kernel has a fix for CVE-2016-2143,
    // return false if in doubt (better safe than sorry).  Distros may want to
    // adjust this for their own kernels.
    struct utsname buf;
    unsigned int major, minor, patch = 0;
    // This should never fail, but just in case...
    if (internal_uname(&buf))
      return false;
    const char *ptr = buf.release;
    major = internal_simple_strtoll(ptr, &ptr, 10);
    // At least first 2 should be matched.
    if (ptr[0] != '.')
      return false;
    minor = internal_simple_strtoll(ptr+1, &ptr, 10);
    // Third is optional.
    if (ptr[0] == '.')
      patch = internal_simple_strtoll(ptr+1, &ptr, 10);
    if (major < 3) {
      if (major == 2 && minor == 6 && patch == 32 && ptr[0] == '-' &&
          internal_strstr(ptr, ".el6")) {
        // Check RHEL6
        int r1 = internal_simple_strtoll(ptr+1, &ptr, 10);
        if (r1 >= 657) // 2.6.32-657.el6 or later
          return true;
        if (r1 == 642 && ptr[0] == '.') {
          int r2 = internal_simple_strtoll(ptr+1, &ptr, 10);
          if (r2 >= 9) // 2.6.32-642.9.1.el6 or later
            return true;
        }
      }
      // <3.0 is bad.
      return false;
    } else if (major == 3) {
      // 3.2.79+ is OK.
      if (minor == 2 && patch >= 79)
        return true;
      // 3.12.58+ is OK.
      if (minor == 12 && patch >= 58)
        return true;
      if (minor == 10 && patch == 0 && ptr[0] == '-' &&
          internal_strstr(ptr, ".el7")) {
        // Check RHEL7
        int r1 = internal_simple_strtoll(ptr+1, &ptr, 10);
        if (r1 >= 426) // 3.10.0-426.el7 or later
          return true;
        if (r1 == 327 && ptr[0] == '.') {
          int r2 = internal_simple_strtoll(ptr+1, &ptr, 10);
          if (r2 >= 27) // 3.10.0-327.27.1.el7 or later
            return true;
        }
      }
      // Otherwise, bad.
      return false;
    } else if (major == 4) {
      // 4.1.21+ is OK.
      if (minor == 1 && patch >= 21)
        return true;
      // 4.4.6+ is OK.
      if (minor == 4 && patch >= 6)
        return true;
      if (minor == 4 && patch == 0 && ptr[0] == '-' &&
          internal_strstr(buf.version, "Ubuntu")) {
        // Check Ubuntu 16.04
        int r1 = internal_simple_strtoll(ptr+1, &ptr, 10);
        if (r1 >= 13) // 4.4.0-13 or later
          return true;
      }
      // Otherwise, OK if 4.5+.
      return minor >= 5;
    } else {
      // Linux 5 and up are fine.
      return true;
    }
  }
  
  void AvoidCVE_2016_2143() {
    // Older kernels are affected by CVE-2016-2143 - they will crash hard
    // if someone uses 4-level page tables (ie. virtual addresses >= 4TB)
    // and fork() in the same process.  Unfortunately, sanitizers tend to
    // require such addresses.  Since this is very likely to crash the whole
    // machine (sanitizers themselves use fork() for llvm-symbolizer, for one),
    // abort the process at initialization instead.
    if (FixedCVE_2016_2143())
      return;
    if (GetEnv("SANITIZER_IGNORE_CVE_2016_2143"))
      return;
    Report(
      "ERROR: Your kernel seems to be vulnerable to CVE-2016-2143.  Using ASan,\n"
      "MSan, TSan, DFSan or LSan with such kernel can and will crash your\n"
      "machine, or worse.\n"
      "\n"
      "If you are certain your kernel is not vulnerable (you have compiled it\n"
      "yourself, or are using an unrecognized distribution kernel), you can\n"
      "override this safety check by exporting SANITIZER_IGNORE_CVE_2016_2143\n"
      "with any value.\n");
    Die();
  }
  #endif
  
  } // namespace __sanitizer
  
  #endif // SANITIZER_LINUX && SANITIZER_S390
  