cosmopolitan/libc/runtime/ftrace.greg.c

142 lines
5.4 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 │
│ │
│ 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; version 2 of the License. │
│ │
│ 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, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#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.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.
*/
static char g_buf[512];
static const char *g_lastsymbol;
static struct SymbolTable *g_symbols;
forceinline 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 interruptfn void ftrace_hook(void) {
size_t i, j, nesting;
const char *symbol;
struct StackFrame *frame;
if (g_symbols) {
frame = __builtin_frame_address(0);
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--) {
g_buf[i++] = ' ';
g_buf[i++] = ' ';
}
while (i < ARRAYLEN(g_buf) - 2 && symbol[j]) {
g_buf[i++] = symbol[j++];
}
g_buf[i++] = '\r';
g_buf[i++] = '\n';
__print(g_buf, i);
}
g_lastsymbol = symbol;
}
}
/**
* Enables plaintext function tracing if --ftrace flag passed.
*
* The --ftrace CLI arg is removed before main() is called. This
* code is intended for diagnostic purposes and assumes binaries
* are trustworthy and stack isn't corrupted. Logging plain text
* allows program structure to easily be visualized and hotspots
* identified w/ sed | sort | uniq -c | sort. A compressed trace
* can be made by appending --ftrace 2>&1 | gzip -4 >trace.gz to
* the CLI arguments. Have fun.
*
* @see libc/runtime/_init.S for documentation
*/
textstartup int ftrace_init(int argc, char *argv[]) {
int i;
bool foundflag;
foundflag = false;
for (i = 1; i <= argc; ++i) {
if (!foundflag) {
if (argv[i]) {
if (strcmp(argv[i], "--ftrace") == 0) {
foundflag = true;
} else if (strcmp(argv[i], "----ftrace") == 0) {
strcpy(argv[i], "--ftrace");
}
}
} else {
argv[i - 1] = argv[i];
}
}
if (foundflag) {
--argc;
g_buf[0] = '+';
g_buf[1] = ' ';
if ((g_symbols = OpenSymbolTable(FindDebugBinary()))) {
__hook(ftrace_hook, g_symbols);
}
}
return argc;
}