gnulib/tests/jit/test-cache.c

/* Test clear_cache.

   Copyright 2020-2025 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include <jit/cache.h>

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#if HAVE_SYS_MMAN_H
# include <sys/mman.h>
#endif

#if defined __APPLE__ && defined __MACH__ /* only needed on macOS */
# define KEEP_TEMP_FILE_VISIBLE
/* Support for temporary files that are cleaned up automatically. */
# include "clean-temp-simple.h"
#endif

#include "xalloc.h"
#include "macros.h"

/* With clang ≥ 17, when the undefined-behaviour sanitizer is in use, 8 bytes of
   meta-information precede each function: a magic number 0xC105CAFE and a word
   that encodes the function's signature.  See
   <https://reviews.llvm.org/D148665>
   <https://github.com/llvm/llvm-project/issues/65253>
   <https://www.reddit.com/r/C_Programming/comments/1dj9gg8/>  */
#if defined __clang__ && __clang_major__ >= 17 && defined __ELF__
# include <dlfcn.h>
#endif
static int clang_ubsan_workaround = 0;

/* On most platforms, function pointers are just a pointer to the
   code, i.e. to the first instruction to be executed.  This,
   however, is not universally true, see:
   https://git.savannah.gnu.org/gitweb/?p=libffcall.git;a=blob;f=porting-tools/abis/function-pointer.txt.  */

#if ((defined __powerpc__ || defined __powerpc64__) && defined _AIX) || (defined __powerpc64__ && !defined __powerpc64_elfv2__ && defined __linux__)
struct func
{
  void *code_address;
  void *toc_pointer;
  void *static_chain;
};
#elif defined __ia64__
# if defined __ia64_ilp32__
struct func
{
  void *code_address;
  void *unused1;
  void *global_pointer;
  void *unused2;
};
# else
struct func
{
  void *code_address;
  void *global_pointer;
};
# endif
#elif defined __hppa__
# if defined __hppa64__
struct func
{
  void *some_other_code_address;
  void *some_other_pic_base;
  void *code_address;
  void *pic_base;
};
# else
struct func
{
  void *code_address;
  void *pic_base;
};
#  define FUNCPTR_BIAS 2
# endif
#else
# define FUNCPTR_POINTS_TO_CODE
#endif
#ifdef FUNCPTR_POINTS_TO_CODE
/* A function pointer points directly to the code.  */
# define COPY_FUNCPTR(funcptr) funcptr
/* On arm, bit 0 of a function pointer tells which instruction set the function
   uses.  */
# if defined __arm__ || defined __armhf__
#  define CODE(funcptr) ((void *) ((uintptr_t) (funcptr) & ~(intptr_t)1))
#  define SET_CODE(funcptr,code_addr) \
     ((void) ((funcptr) =                                     \
              (void *) (((uintptr_t) (funcptr) & (intptr_t)1) \
                        | (uintptr_t) (code_addr))))
#  define IS(funcptr)  ((uintptr_t) (funcptr) & 1)
#  define SET_IS(funcptr,is)  \
     ((void) ((funcptr) = \
              (void *) (((uintptr_t) (funcptr) & ~(intptr_t)1) | (is))))
# else
#  define CODE(funcptr) ((char *) (funcptr) - clang_ubsan_workaround)
#  define SET_CODE(funcptr,code_addr) \
     ((void) ((funcptr) = (void *) ((char *) (code_addr) + clang_ubsan_workaround)))
#  define IS(funcptr) ((void) (funcptr), 0)
#  define SET_IS(funcptr,is) ((void) (funcptr), (void) (is))
# endif
#else
/* A function pointer points to a 'struct func'.  */
# if FUNCPTR_BIAS
static inline void *
structptr_to_funcptr (struct func *p)
{
  return (char *) p + FUNCPTR_BIAS;
}
static inline struct func *
funcptr_to_structptr (void * volatile funcptr)
{
  return (struct func *) ((char *) funcptr - FUNCPTR_BIAS);
}
# else
#  define structptr_to_funcptr(p) ((void *) (p))
static inline struct func *
funcptr_to_structptr (void * volatile funcptr)
{
  return (struct func *) funcptr;
}
# endif
static inline struct func *
xcopy_structptr (struct func *structptr)
{
  struct func *copy = (struct func *) xmalloc (sizeof (struct func));
  *copy = *structptr;
  return copy;
}
# define COPY_FUNCPTR(funcptr) \
    structptr_to_funcptr (xcopy_structptr (funcptr_to_structptr (funcptr)))
# define CODE(funcptr) \
    ((funcptr_to_structptr (funcptr))->code_address)
# define SET_CODE(funcptr,code_addr) \
    ((void) (CODE (funcptr) = (code_addr)))
# define IS(funcptr) ((void) (funcptr), 0)
# define SET_IS(funcptr,is) ((void) (funcptr), (void) (is))
#endif

/* This test assumes that the code generated by the compiler for the
   procedures `return1' and `return2' is position independent.  It
   also assumes that data pointers are bit-compatible to integers.  */

static int
return1 (void)
{
  return 1;
}

static int
return2 (void)
{
  return 2;
}

/* For those platforms which map code with PROT_EXEC (as opposed to
   PROT_READ | PROT_EXEC), not allowing us to read from the code area at
   run time, here is a copy of the code of the functions 'return1' and
   'return2'.  Produced with a cross-compiler like this:
     $ <cpu>-linux-gnu-gcc -O2 -fomit-frame-pointer -c foo.c
     $ <cpu>-linux-gnu-objdump -d -r foo.o
 */

#if defined __x86_64__ || defined __x86_64_x32__ || defined __i386__
unsigned char const return1_code[] = { 0xb8,0x01,0x00,0x00,0x00, 0xc3 };
unsigned char const return2_code[] = { 0xb8,0x02,0x00,0x00,0x00, 0xc3 };
#endif
#if defined __alpha__
unsigned int const return1_code[] = { 0x201f0001, 0x6bfa8001 };
unsigned int const return2_code[] = { 0x201f0002, 0x6bfa8001 };
#endif
#if defined __arm64__ || defined __arm64_ilp32__
unsigned int const return1_code[] = { 0x52800020, 0xd65f03c0 };
unsigned int const return2_code[] = { 0x52800040, 0xd65f03c0 };
#elif defined __arm__ || defined __armhf__
unsigned int const return1_code[] = { 0xe3a00001, 0xe1a0f00e };
unsigned int const return2_code[] = { 0xe3a00002, 0xe1a0f00e };
#endif
#if defined __hppa64__
unsigned int const return1_code[] = { 0xe840d000, 0x341c0002 };
unsigned int const return2_code[] = { 0xe840d000, 0x341c0004 };
#elif defined __hppa__
unsigned int const return1_code[] = { 0xe840c000, 0x341c0002 };
unsigned int const return2_code[] = { 0xe840c000, 0x341c0004 };
#endif
#if defined __ia64__ || defined __ia64_ilp32__
unsigned char const return1_code[] =
  { 0x11,0x00,0x00,0x00,0x01,0x00,0x80,0x08,0x00,0x00,0x48,0x80,0x08,0x00,0x84,0x00 };
unsigned char const return2_code[] =
  { 0x11,0x00,0x00,0x00,0x01,0x00,0x80,0x10,0x00,0x00,0x48,0x80,0x08,0x00,0x84,0x00 };
#endif
#if defined __loongarch64__
unsigned int const return1_code[] = { 0x02800404, 0x4c000020 };
unsigned int const return2_code[] = { 0x02800804, 0x4c000020 };
#endif
#if defined __m68k__
unsigned short const return1_code[] = { 0x7001, 0x4e75 };
unsigned short const return2_code[] = { 0x7002, 0x4e75 };
#endif
#if defined __mips64__ || defined __mipsn32__ || defined __mips__
unsigned int const return1_code[] = { 0x03e00008, 0x24020001 };
unsigned int const return2_code[] = { 0x03e00008, 0x24020002};
#endif
#if defined __powerpc64__ || defined __powerpc64_elfv2__ || defined __powerpc__
unsigned int const return1_code[] = { 0x38600001, 0x4e800020 };
unsigned int const return2_code[] = { 0x38600002, 0x4e800020 };
#endif
#if defined __riscv64__ || defined __riscv32__
unsigned short const return1_code[] = { 0x4505, 0x8082 };
unsigned short const return2_code[] = { 0x4509, 0x8082 };
#endif
#if defined __s390x__
unsigned short const return1_code[] = { 0xa729,0x0001, 0x07fe, 0x0707 };
unsigned short const return2_code[] = { 0xa729,0x0002, 0x07fe, 0x0707 };
#elif defined __s390__
unsigned short const return1_code[] = { 0xa728,0x0001, 0x07fe, 0x0707 };
unsigned short const return2_code[] = { 0xa728,0x0002, 0x07fe, 0x0707 };
#endif
#if defined __sparc64__ || defined __sparc__
unsigned int const return1_code[] = { 0x81c3e008, 0x90102001 };
unsigned int const return2_code[] = { 0x81c3e008, 0x90102002 };
#endif

int
main ()
{
#if defined __clang__ && __clang_major__ >= 17 && defined __ELF__
  if (dlsym (RTLD_DEFAULT, "__ubsan_handle_function_type_mismatch") != NULL)
    /* This program is built with clang ≥ 17 and its UBSAN.  */
    clang_ubsan_workaround = 8;
#endif

  void const *code_of_return1;
  void const *code_of_return2;
  size_t size_of_return1;
  size_t size_of_return2;
  int is_of_return1;
  int is_of_return2;
#if defined __OpenBSD__ || defined _RET_PROTECTOR
  /* OpenBSD maps code with PROT_EXEC (as opposed to PROT_READ | PROT_EXEC).
     We need to use predetermined code for 'return1' and 'return2'.  */
  /* The OpenBSD "retguard" stack protector produces code for 'return1' and
     'return2' that is not position independent, and there is no clang
     attribute for turning this instrumentation off for specific functions.
     If this stack protector has not been disabled through a configure test,
     we need to use predetermined code for 'return1' and 'return2'.  */
  code_of_return1 = return1_code;
  code_of_return2 = return2_code;
  size_of_return1 = sizeof (return1_code);
  size_of_return2 = sizeof (return2_code);
  /* On arm, return1_code and return2_code use the "ARM" instruction set.  */
  is_of_return1 = 0;
  is_of_return2 = 0;
#else
  code_of_return1 = CODE (return1);
  code_of_return2 = CODE (return2);
  /* We assume that the code is not longer than 64 bytes.  */
  size_of_return1 = 64;
  size_of_return2 = 64;
  is_of_return1 = IS (return1);
  is_of_return2 = IS (return2);
#endif

  int const pagesize = getpagesize ();
  int const mapping_size = 1 * pagesize;
  /* Bounds of an executable memory region.  */
  char *start;
  char *end;
  /* Start of a writable memory region.  */
  char *start_rw;

  /* Initialization.  */
  {
#if defined _WIN32 && !defined __CYGWIN__
    /* VirtualAlloc
       <https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualalloc>
       <https://learn.microsoft.com/en-us/windows/win32/memory/memory-protection-constants> */
    start = VirtualAlloc (NULL, mapping_size, MEM_COMMIT,
                          PAGE_EXECUTE_READWRITE);
    if (start == NULL)
      return 1;
    start_rw = start;
#else
    start = mmap (NULL, mapping_size, PROT_READ | PROT_WRITE | PROT_EXEC,
                  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
    if (start != (char *) (-1))
      {
        /* A platform that allows a mmap'ed memory region to be simultaneously
           writable and executable.  */
        start_rw = start;
      }
    else
      {
        /* A platform which requires the writable mapping and the executable
           mapping to be separate: macOS, FreeBSD, NetBSD, OpenBSD.  */
        fprintf (stderr, "simple mmap failed, using separate mappings\n");
        char filename[100];
        sprintf (filename,
                 "%s/gnulib-test-cache-%u-%d-%ld",
                 "/tmp", (unsigned int) getuid (), (int) getpid (), random ());
# ifdef KEEP_TEMP_FILE_VISIBLE
        if (register_temporary_file (filename) < 0)
          return 2;
# endif
        int fd = open (filename, O_CREAT | O_RDWR | O_TRUNC, 0700);
        if (fd < 0)
          return 3;
# ifndef KEEP_TEMP_FILE_VISIBLE
        /* Remove the file from the file system as soon as possible, to make
           sure there is no leftover after this process terminates or crashes.
           On macOS 11.2, this does not work: It would make the mmap call below,
           with arguments PROT_READ|PROT_EXEC and MAP_SHARED, fail. */
        unlink (filename);
# endif
        if (ftruncate (fd, mapping_size) < 0)
          return 4;
        start = mmap (NULL, mapping_size, PROT_READ | PROT_EXEC, MAP_SHARED,
                      fd, 0);
        start_rw = mmap (NULL, mapping_size, PROT_READ | PROT_WRITE, MAP_SHARED,
                         fd, 0);
        if (start == (char *) (-1) || start_rw == (char *) (-1))
          return 5;
      }
#endif
    end = start + mapping_size;
  }

  int (*f) (void) = COPY_FUNCPTR (return1);
  SET_CODE (f, start);

  memcpy (start_rw, code_of_return1, size_of_return1);
  SET_IS (f, is_of_return1);
  clear_cache (start, end);
  ASSERT (f () == 1);

  memcpy (start_rw, code_of_return2, size_of_return2);
  SET_IS (f, is_of_return2);
  clear_cache (start, end);
  ASSERT (f () == 2);

  return test_exit_status;
}