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"

#define USE_LITE_RECORD 1

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.
#ifdef X64
    if (UNLIKELY(g_WrittenFirst == 0))
    {
        if (__sync_bool_compare_and_swap(&g_WrittenFirst, 0, 1))
        {
            uint8_t flag = 0;
#if USE_LITE_RECORD
            flag |= INSTRUMENT_GLOBAL_LITE;
#endif
            asm volatile("outb %%al, %%dx" ::"d"(COM2), "a"(flag));
        }
    }

#if USE_LITE_RECORD
    LiteInstrumentationRecord record;
#else
    InstrumentationRecord record;
    record.data.flags = INSTRUMENT_RECORD_ENTRY;
    record.data.caller = reinterpret_cast<uintptr_t>(call_site);
    record.data.magic = INSTRUMENT_MAGIC;
#endif
    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"