instrument.cc

/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
#include "instrument.h"
 
extern "C" {
void __cyg_profile_func_enter(void* func_address, void* call_site)
    __attribute__((no_instrument_function)) __attribute__((hot));
 
#define COM1 0x3F8
#define COM2 0x2F8
#define COM3 0x3E8
#define COM4 0x2E8
 
#ifdef INSTRUMENTATION
static volatile int g_WrittenFirst = 0;
#endif
 
void __cyg_profile_func_enter(void* func_address, void* call_site) {
#ifdef INSTRUMENTATION
// NOTE: you cannot call anything in this function, as doing so would
// re-enter. That means hand-crafted serial writes are necessary.
#if X64
  if (UNLIKELY(g_WrittenFirst == 0)) {
    if (__sync_bool_compare_and_swap(&g_WrittenFirst, 0, 1)) {
      uint8_t flag = 0;
      flag |= INSTRUMENT_GLOBAL_LITE;
      asm volatile("outb %%al, %%dx" ::"d"(COM2), "a"(flag));
    }
  }
 
  LiteInstrumentationRecord record;
  record.data.function = reinterpret_cast<uintptr_t>(func_address);
 
  // Semi-unrolled, all-in-one assembly serial-port write.
  uintptr_t x = 0;
  size_t y = 0;
  asm volatile(
      "pushf; cli;"
      ".1:\n"
      "movq (%0), %%rax;"
      "outb %%al, %%dx;"
      "shr $8, %%rax;"
      "outb %%al, %%dx;"
      "shr $8, %%rax;"
      "outb %%al, %%dx;"
      "shr $8, %%rax;"
      "outb %%al, %%dx;"
      "add $4, %0;"
      "sub $4, %1;"
      "jnz .1; popf"
      : "=&r"(x), "=&r"(y)
      : "d"(COM2), "0"(record.buffer), "1"(sizeof record.buffer)
      : "rax", "memory");
#endif
#endif
}
 
}  // extern "C"