214 lines
8.4 KiB
C
214 lines
8.4 KiB
C
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net 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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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/alg/bisectcarleft.h"
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#include "libc/bits/bits.h"
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#include "libc/bits/safemacros.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/struct/sigset.h"
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#include "libc/dce.h"
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#include "libc/macros.h"
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#include "libc/nt/files.h"
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#include "libc/nt/runtime.h"
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#include "libc/nt/thunk/msabi.h"
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#include "libc/runtime/internal.h"
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#include "libc/runtime/missioncritical.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/symbols.h"
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#include "libc/sysv/consts/fileno.h"
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#include "libc/sysv/consts/nr.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/sysv/consts/sig.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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static char g_buf[512];
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static const char *g_lastsymbol;
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static struct SymbolTable *g_symbols;
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forceinline int getnestinglevel(struct StackFrame *frame) {
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int nesting = -2;
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while (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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/**
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* Prints name of function being called.
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*
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* We insert CALL instructions that point to this function, in the
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* prologues of other functions. We assume those functions behave
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* according to the System Five NexGen32e ABI.
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*/
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privileged interruptfn void ftrace_hook(void) {
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size_t i, j, nesting;
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const char *symbol;
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struct StackFrame *frame;
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LOAD_DEFAULT_RBX();
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if (g_symbols && !(g_runstate & RUNSTATE_BROKEN)) {
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frame = __builtin_frame_address(0);
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symbol =
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&g_symbols->name_base[g_symbols
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->symbols[bisectcarleft(
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(const int32_t(*)[2])g_symbols->symbols,
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g_symbols->count,
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frame->addr - g_symbols->addr_base)]
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.name_rva];
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if (symbol != g_lastsymbol &&
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(nesting = getnestinglevel(frame)) * 2 < ARRAYLEN(g_buf) - 3) {
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i = 2;
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j = 0;
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while (nesting--) {
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g_buf[i++] = ' ';
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g_buf[i++] = ' ';
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}
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while (i < ARRAYLEN(g_buf) - 2 && symbol[j]) {
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g_buf[i++] = symbol[j++];
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}
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g_buf[i++] = '\n';
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__print(g_buf, i);
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}
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g_lastsymbol = symbol;
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}
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RESTORE_RBX();
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}
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/**
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* Rewrites code in memory to log function calls.
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*
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* We do this by searching each function for the nop instruction
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* inserted by GCC when we use the -pg -mnop-mcount flags. There's no
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* risk of corrupting data since the linker scripts won't mix code and
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* data.
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*
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* Modules built with -O3 and without the profiling flags might have
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* these same nop instructions, but that shouldn't be problematic since
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* they're only there for the puposes of aligning jumps, and therefore
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* aren't actually executed. However codebases that use huge function
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* alignments with wide-nop slides could pose minor issues. Further note
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* that Cosmopolitan sources are almost never intentionally written to
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* use code alignment, since we've only seen a few cases where it helps.
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*
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* @see ape/ape.lds
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*/
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privileged void ftrace_install(void) {
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/* TODO(jart): Is -fschedule-insns2 so aggro that we need XED here? */
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size_t i;
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intptr_t addr;
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sigset_t oldmask;
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uint64_t code, mcode;
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unsigned char *p, *pe;
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const intptr_t kMcount = (intptr_t)&mcount;
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const intptr_t kFtraceHook = (intptr_t)&ftrace_hook;
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const intptr_t kProgramCodeStart = (intptr_t)&_ereal;
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const intptr_t kPrivilegedStart = (intptr_t)&__privileged_start;
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const bool kIsBinaryAligned = !(kPrivilegedStart & (PAGESIZE - 1));
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g_buf[0] = '+';
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g_buf[1] = ' ';
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sigprocmask(SIG_BLOCK, &kSigsetFull, &oldmask);
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if (__mprotect((void *)g_symbols->addr_base,
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kPrivilegedStart - g_symbols->addr_base,
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kIsBinaryAligned ? PROT_READ | PROT_WRITE
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: PROT_READ | PROT_WRITE | PROT_EXEC) != -1) {
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for (i = 0; i < g_symbols->count - 1; ++i) {
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if (g_symbols->addr_base + g_symbols->symbols[i].addr_rva <
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kProgramCodeStart) {
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continue; /* skip over real mode symbols */
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}
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if (g_symbols->addr_base + g_symbols->symbols[i].addr_rva >=
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kPrivilegedStart) {
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break; /* stop before privileged symbols */
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}
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for (p = (unsigned char *)(g_symbols->addr_base +
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g_symbols->symbols[i].addr_rva),
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pe = (unsigned char *)(g_symbols->addr_base +
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g_symbols->symbols[i + 1].addr_rva);
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p < pe - 8; ++p) {
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code = read64le(p);
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/*
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* Test for -mrecord-mcount (w/ -fpie or -fpic)
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*
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* nopw 0x00(%rax,%rax,1) ← morphed by package.com
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* call *mcount(%rip) ← linked w/o -static
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* addr32 call mcount ← relaxed w/ -static
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* addr32 call mcount ← relaxed w/ -static
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*
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* Note that gcc refuses to insert the six byte nop.
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*/
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if ((code & 0x0000FFFFFFFFFFFF) == 0x0000441F0F66 ||
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(code & 0x0000FFFFFFFFFFFF) ==
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((((kMcount - ((intptr_t)&p[2] + 4)) << 16) | 0xE867) &
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0x0000FFFFFFFFFFFF) ||
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(code & 0x0000FFFFFFFFFFFF) ==
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((((kMcount - ((intptr_t)&p[2] + 4)) << 16) | 0xFF15) &
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0x0000FFFFFFFFFFFF)) {
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p[0] = 0x67;
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p[1] = 0xE8;
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addr = kFtraceHook - ((intptr_t)&p[2] + 4);
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p[2] = addr >> 000;
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p[3] = addr >> 010;
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p[4] = addr >> 020;
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p[5] = addr >> 030;
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break;
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}
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/*
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* Test for -mnop-mcount (w/ -fno-pie)
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*/
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mcode = code & 0x000000FFFFFFFFFF;
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if ((mcode == 0x00441F0F /* nopl 0x00(%eax,%eax,1) [canonical] */) ||
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(mcode == 0x00041F0F67 /* nopl (%eax,%eax,1) [older gcc] */)) {
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if (p[-1] != 0x66 /* nopw 0x0(%rax,%rax,1) [donotwant] */) {
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p[0] = 0xE8 /* call Jvds */;
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addr = kFtraceHook - ((intptr_t)&p[1] + 4);
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p[1] = addr >> 000;
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p[2] = addr >> 010;
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p[3] = addr >> 020;
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p[4] = addr >> 030;
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}
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break;
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}
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}
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}
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__mprotect((void *)g_symbols->addr_base,
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kPrivilegedStart - g_symbols->addr_base, PROT_READ | PROT_EXEC);
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}
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sigprocmask(SIG_SETMASK, &oldmask, NULL);
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}
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/**
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* Installs plaintext function tracer. Do not call.
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* @see libc/runtime/_init.S for documentation
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*/
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textstartup void ftrace_init(void) {
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if ((g_symbols = opensymboltable(finddebugbinary()))) {
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ftrace_install();
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}
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}
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