compiler-rt/test/profile/ContinuousSyncMode/darwin-proof-of-concept.c

   1 // Test whether mmap'ing profile counters onto an open file is feasible. As
   2 // this involves some platform-specific logic, this test is designed to be a
   3 // minimum viable proof-of-concept: it may be useful when porting the mmap()
   4 // mode to a new platform, but is not in and of itself a test of the profiling
   5 // runtime.
   6
   7 // REQUIRES: darwin
   8
   9 // Align counters and data to the maximum expected page size (16K).
  10 // RUN: %clang -g -o %t %s \
  11 // RUN:   -Wl,-sectalign,__DATA,__pcnts,0x4000 \
  12 // RUN:   -Wl,-sectalign,__DATA,__pdata,0x4000
  13
  14 // Create a 'profile' using mmap() and validate it.
  15 // RUN: %run %t create %t.tmpfile
  16 // RUN: %run %t validate %t.tmpfile
  17
  18 #include <fcntl.h>
  19 #include <unistd.h>
  20 #include <sys/mman.h>
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24
  25 __attribute__((section("__DATA,__pcnts"))) int counters[] = {0xbad};
  26 extern int cnts_start __asm("section$start$__DATA$__pcnts");
  27 const size_t cnts_len = 0x4000;
  28
  29 __attribute__((section("__DATA,__pdata"))) int data[] = {1, 2, 3};
  30 extern int data_start __asm("section$start$__DATA$__pdata");
  31 const size_t data_len = sizeof(int) * 3;
  32
  33 int create_tmpfile(char *path) {
  34   // Create a temp file.
  35   int fd = open(path, O_RDWR | O_TRUNC | O_CREAT, 0666);
  36   if (fd == -1) {
  37     perror("open");
  38     return EXIT_FAILURE;
  39   }
  40
  41   // Grow the file to hold data and counters.
  42   if (0 != ftruncate(fd, cnts_len + data_len)) {
  43     perror("ftruncate");
  44     return EXIT_FAILURE;
  45   }
  46
  47   // Write the data first (at offset 0x4000, after the counters).
  48   if (data_len != pwrite(fd, &data, data_len, 0x4000)) {
  49     perror("write");
  50     return EXIT_FAILURE;
  51   }
  52
  53   // Map the counters into the file, before the data.
  54   //
  55   // Requirements (on Darwin):
  56   // - &cnts_start must be page-aligned.
  57   // - The length and offset-into-fd must be page-aligned.
  58   int *counter_map = (int *)mmap(&cnts_start, 0x4000, PROT_READ | PROT_WRITE,
  59       MAP_FIXED | MAP_SHARED, fd, 0);
  60   if (counter_map != &cnts_start) {
  61     perror("mmap");
  62     return EXIT_FAILURE;
  63   }
  64
  65   // Update counters 1..9. These updates should be visible in the file.
  66   // Expect counter 0 (0xbad), which is not updated, to be zero in the file.
  67   for (int i = 1; i < 10; ++i)
  68     counter_map[i] = i;
  69
  70   // Intentionally do not msync(), munmap(), or close().
  71   return EXIT_SUCCESS;
  72 }
  73
  74 int validate_tmpfile(char *path) {
  75   int fd = open(path, O_RDONLY);
  76   if (fd == -1) {
  77     perror("open");
  78     return EXIT_FAILURE;
  79   }
  80
  81   // Verify that the file length is: sizeof(counters) + sizeof(data).
  82   const size_t num_bytes = cnts_len + data_len;
  83   int buf[num_bytes];
  84   if (num_bytes != read(fd, &buf, num_bytes)) {
  85     perror("read");
  86     return EXIT_FAILURE;
  87   }
  88
  89   // Verify the values of counters 1..9 (i.e. that the mmap() worked).
  90   for (int i = 0; i < 10; ++i) {
  91     if (buf[i] != i) {
  92       fprintf(stderr,
  93           "validate_tmpfile: Expected '%d' at pos=%d, but got '%d' instead.\n",
  94           i, i, buf[i]);
  95       return EXIT_FAILURE;
  96     }
  97   }
  98
  99   // Verify that the rest of the counters (after counter 9) are 0.
 100   const int num_cnts = 0x4000 / sizeof(int);
 101   for (int i = 10; i < num_cnts; ++i) {
 102     if (buf[i] != 0) {
 103       fprintf(stderr,
 104           "validate_tmpfile: Expected '%d' at pos=%d, but got '%d' instead.\n",
 105           0, i, buf[i]);
 106       return EXIT_FAILURE;
 107     }
 108   }
 109
 110   // Verify that the data written after the counters is equal to the "data[]"
 111   // array (i.e. {1, 2, 3}).
 112   for (int i = num_cnts; i < num_cnts + 3; ++i) {
 113     if (buf[i] != (i - num_cnts + 1)) {
 114       fprintf(stderr,
 115           "validate_tmpfile: Expected '%d' at pos=%d, but got '%d' instead.\n",
 116           i - num_cnts + 1, i, buf[i]);
 117       return EXIT_FAILURE;
 118     }
 119   }
 120
 121   // Intentionally do not close().
 122   return EXIT_SUCCESS;
 123 }
 124
 125 int main(int argc, char **argv) {
 126   intptr_t cnts_start_int = (intptr_t)&cnts_start;
 127   intptr_t data_start_int = (intptr_t)&data_start;
 128   int pagesz = getpagesize();
 129
 130   if (cnts_start_int % pagesz != 0) {
 131     fprintf(stderr, "__pcnts is not page-aligned: 0x%lx.\n", cnts_start_int);
 132     return EXIT_FAILURE;
 133   }
 134   if (data_start_int % pagesz != 0) {
 135     fprintf(stderr, "__pdata is not page-aligned: 0x%lx.\n", data_start_int);
 136     return EXIT_FAILURE;
 137   }
 138   if (cnts_start_int + 0x4000 != data_start_int) {
 139     fprintf(stderr, "__pdata not ordered after __pcnts.\n");
 140     return EXIT_FAILURE;
 141   }
 142
 143   char *action = argv[1];
 144   char *path = argv[2];
 145   if (0 == strcmp(action, "create"))
 146     return create_tmpfile(path);
 147   else if (0 == strcmp(action, "validate"))
 148     return validate_tmpfile(path);
 149   else
 150     return EXIT_FAILURE;
 151 }