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https://github.com/jart/cosmopolitan.git
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e9a756e78b
Sometimes we need to interact with code that wasn't compiled using `-fno-omit-frame-pointer`. For example, if a function pointer gets passed and called by a foreign function, linked by cosmo_dlopen(). Function call tracing will now detect backtrace pointer corruption and simply reduce the indentation level back to zero, as a result.
118 lines
4.6 KiB
C
118 lines
4.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/errno.h"
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#include "libc/fmt/itoa.h"
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#include "libc/intrin/cmpxchg.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/macros.internal.h"
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#include "libc/nexgen32e/stackframe.h"
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#include "libc/runtime/internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/stack.h"
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#include "libc/thread/posixthread.internal.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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#include "libc/thread/tls2.internal.h"
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/**
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* @fileoverview Plain-text function call logging.
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*
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* Able to log ~2 million function calls per second, which is mostly
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* bottlenecked by system call overhead. Log size is reasonable if piped
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* into gzip.
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*/
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#define MAX_NESTING 512
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#ifdef __x86_64__
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#define DETOUR_SKEW 2
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#elif defined(__aarch64__)
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#define DETOUR_SKEW 8
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#endif
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static struct CosmoFtrace g_ftrace;
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__funline int GetNestingLevelImpl(struct StackFrame *frame) {
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int nesting = -2;
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while (frame && !kisdangerous(frame)) {
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++nesting;
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frame = frame->next;
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}
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return MAX(0, nesting);
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}
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__funline int GetNestingLevel(struct CosmoFtrace *ft, struct StackFrame *sf) {
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int nesting;
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nesting = GetNestingLevelImpl(sf);
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if (nesting < ft->ft_skew) ft->ft_skew = nesting;
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nesting -= ft->ft_skew;
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return MIN(MAX_NESTING, nesting);
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}
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/**
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* Prints name of function being called.
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*
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* Whenever a function is called, ftrace_hook() will be called from the
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* function prologue which saves the parameter registers and calls this
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* function, which is responsible for logging the function call.
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*
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* @see ftrace_install()
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*/
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privileged void ftracer(void) {
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long stackuse;
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uintptr_t fn, st;
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struct CosmoTib *tib;
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struct StackFrame *sf;
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struct CosmoFtrace *ft;
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struct PosixThread *pt;
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sf = __builtin_frame_address(0);
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st = (uintptr_t)__argv - sizeof(uintptr_t);
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if (__ftrace <= 0) return;
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if (__tls_enabled) {
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tib = __get_tls_privileged();
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if (tib->tib_ftrace <= 0) return;
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ft = &tib->tib_ftracer;
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if ((char *)sf >= tib->tib_sigstack_addr &&
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(char *)sf <= tib->tib_sigstack_addr + tib->tib_sigstack_size) {
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st = (uintptr_t)tib->tib_sigstack_addr + tib->tib_sigstack_size;
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} else if ((pt = (struct PosixThread *)tib->tib_pthread) &&
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pt->pt_attr.__stacksize) {
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st = (uintptr_t)pt->pt_attr.__stackaddr + pt->pt_attr.__stacksize;
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}
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} else {
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ft = &g_ftrace;
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}
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stackuse = st - (intptr_t)sf;
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if (_cmpxchg(&ft->ft_once, false, true)) {
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ft->ft_lastaddr = -1;
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ft->ft_skew = GetNestingLevelImpl(sf);
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}
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if (_cmpxchg(&ft->ft_noreentry, false, true)) {
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sf = sf->next;
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fn = sf->addr + DETOUR_SKEW;
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if (fn != ft->ft_lastaddr) {
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kprintf("%rFUN %6P %6H %'18T %'*ld %*s%t\n", ftrace_stackdigs, stackuse,
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GetNestingLevel(ft, sf) * 2, "", fn);
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ft->ft_lastaddr = fn;
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}
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ft->ft_noreentry = false;
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}
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}
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