cosmopolitan/libc/runtime/ftracer.c
2022-09-10 12:03:36 -07:00

107 lines
4.2 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/calls/calls.h"
#include "libc/errno.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/cmpxchg.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/nopl.internal.h"
#include "libc/macros.internal.h"
#include "libc/nexgen32e/stackframe.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/stack.h"
#include "libc/runtime/symbols.internal.h"
#include "libc/thread/tls.h"
#include "libc/thread/tls2.h"
#define MAX_NESTING 512
/**
* @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 g_stackdigs;
static struct CosmoFtrace g_ftrace;
static privileged inline int GetNestingLevelImpl(struct StackFrame *frame) {
int nesting = -2;
while (frame) {
++nesting;
frame = frame->next;
}
return MAX(0, nesting);
}
static privileged inline int GetNestingLevel(struct CosmoFtrace *ft,
struct StackFrame *sf) {
int nesting;
nesting = GetNestingLevelImpl(sf);
if (nesting < ft->ft_skew) ft->ft_skew = nesting;
nesting -= ft->ft_skew;
return MIN(MAX_NESTING, 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 void ftracer(void) {
long stackuse;
struct CosmoFtrace *ft;
struct StackFrame *sf;
if (__tls_enabled) {
ft = &__get_tls_privileged()->tib_ftrace;
} else {
ft = &g_ftrace;
}
if (_cmpxchg(&ft->ft_once, false, true)) {
ft->ft_lastaddr = -1;
ft->ft_skew = GetNestingLevelImpl(__builtin_frame_address(0));
}
if (_cmpxchg(&ft->ft_noreentry, false, true)) {
sf = __builtin_frame_address(0);
sf = sf->next;
if (sf->addr != ft->ft_lastaddr) {
stackuse = GetStackAddr() + GetStackSize() - (intptr_t)sf;
kprintf("%rFUN %6P %'13T %'*ld %*s%t\n", g_stackdigs, stackuse,
GetNestingLevel(ft, sf) * 2, "", sf->addr);
ft->ft_lastaddr = sf->addr;
}
ft->ft_noreentry = false;
}
}
textstartup int ftrace_install(void) {
if (GetSymbolTable()) {
g_stackdigs = LengthInt64Thousands(GetStackSize());
return __hook(ftrace_hook, GetSymbolTable());
} else {
kprintf("error: --ftrace failed to open symbol table\n");
return -1;
}
}