cosmopolitan/libc/runtime/ftrace.c
2021-04-24 13:58:50 -07:00

117 lines
4.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or 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 "libc/alg/bisectcarleft.internal.h"
#include "libc/bits/bits.h"
#include "libc/bits/safemacros.internal.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/sigset.h"
#include "libc/dce.h"
#include "libc/intrin/repmovsb.h"
#include "libc/macros.internal.h"
#include "libc/nexgen32e/stackframe.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/symbols.internal.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/fileno.h"
#include "libc/sysv/consts/nr.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/consts/sig.h"
/**
* @fileoverview Plain-text function call logging.
*
* Able to log ~2 million function calls per second, which is mostly
* bottlenecked by system call overhead. Log size is reasonable if piped
* into gzip.
*/
void ftrace_hook(void);
static int noreentry;
static char g_buf[512];
static const char *g_lastsymbol;
static struct SymbolTable *g_symbols;
static noasan int GetNestingLevel(struct StackFrame *frame) {
int nesting = -2;
while (frame) {
++nesting;
frame = frame->next;
}
return max(0, nesting);
}
/**
* Prints name of function being called.
*
* We insert CALL instructions that point to this function, in the
* prologues of other functions. We assume those functions behave
* according to the System Five NexGen32e ABI.
*/
privileged noasan void ftrace(void) {
size_t i, j, nesting;
const char *symbol;
struct StackFrame *frame;
if (!cmpxchg(&noreentry, 0, 1)) return;
if (g_symbols) {
frame = __builtin_frame_address(0);
frame = frame->next;
symbol =
&g_symbols->name_base[g_symbols
->symbols[bisectcarleft(
(const int32_t(*)[2])g_symbols->symbols,
g_symbols->count,
frame->addr - g_symbols->addr_base)]
.name_rva];
if (symbol != g_lastsymbol &&
(nesting = GetNestingLevel(frame)) * 2 < ARRAYLEN(g_buf) - 4) {
i = 2;
j = 0;
while (nesting--) {
asm volatile("" : : : "memory");
g_buf[i++] = ' ';
g_buf[i++] = ' ';
}
while (i < ARRAYLEN(g_buf) - 2 && symbol[j]) {
asm volatile("" : : : "memory");
g_buf[i++] = symbol[j++];
}
g_buf[i++] = '\r';
g_buf[i++] = '\n';
write(2, g_buf, i);
}
g_lastsymbol = symbol;
}
noreentry = 0;
}
textstartup void ftrace_install(void) {
g_buf[0] = '+';
g_buf[1] = ' ';
if ((g_symbols = OpenSymbolTable(FindDebugBinary()))) {
__hook(ftrace_hook, g_symbols);
} else {
write(2, "error: --ftrace needs the concomitant .com.dbg binary\n", 54);
}
}