fae1cc06e6
Reviewers: fmayer, vitalybuka Reviewed By: vitalybuka, fmayer Pull Request: https://github.com/llvm/llvm-project/pull/179011
101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
//===-- ubsan_loop_detect.cpp ---------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Runtime support for -fsanitize-trap-loop.
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//
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//===----------------------------------------------------------------------===//
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#include <sanitizer/ubsan_interface.h>
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#if defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
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#include <asm/processor-flags.h>
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#include <signal.h>
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#include <stdint.h>
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#include <sys/time.h>
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#include <sys/ucontext.h>
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int __ubsan_is_trap_loop(void *c) {
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auto *uc = reinterpret_cast<ucontext_t *>(c);
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#if defined(__x86_64__)
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auto *ip = reinterpret_cast<const uint8_t *>(uc->uc_mcontext.gregs[REG_RIP]);
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#else
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auto *ip = reinterpret_cast<const uint8_t *>(uc->uc_mcontext.gregs[REG_EIP]);
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#endif
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// Test whether IP is at a conditional branch to self instruction.
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if ((ip[0] & 0xf0) != 0x70 || ip[1] != 0xfe)
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return false;
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// If so, test whether the condition is satisfied, in case we happened to
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// receive the signal at a not-taken branch to self.
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uint64_t eflags = uc->uc_mcontext.gregs[REG_EFL];
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switch (ip[0]) {
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case 0x70: // JO
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return eflags & X86_EFLAGS_OF;
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case 0x71: // JNO
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return !(eflags & X86_EFLAGS_OF);
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case 0x72: // JB
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return eflags & X86_EFLAGS_CF;
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case 0x73: // JAE
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return !(eflags & X86_EFLAGS_CF);
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case 0x74: // JE
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return eflags & X86_EFLAGS_ZF;
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case 0x75: // JNE
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return !(eflags & X86_EFLAGS_ZF);
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case 0x76: // JBE
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return (eflags & X86_EFLAGS_CF) || (eflags & X86_EFLAGS_ZF);
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case 0x77: // JA
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return !(eflags & X86_EFLAGS_CF) && !(eflags & X86_EFLAGS_ZF);
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case 0x78: // JS
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return eflags & X86_EFLAGS_SF;
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case 0x79: // JNS
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return !(eflags & X86_EFLAGS_SF);
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case 0x7A: // JP
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return eflags & X86_EFLAGS_PF;
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case 0x7B: // JNP
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return !(eflags & X86_EFLAGS_PF);
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case 0x7C: // JL
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return !!(eflags & X86_EFLAGS_SF) != !!(eflags & X86_EFLAGS_OF);
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case 0x7D: // JGE
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return !!(eflags & X86_EFLAGS_SF) == !!(eflags & X86_EFLAGS_OF);
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case 0x7E: // JLE
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return (eflags & X86_EFLAGS_ZF) ||
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!!(eflags & X86_EFLAGS_SF) != !!(eflags & X86_EFLAGS_OF);
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case 0x7F: // JG
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return !(eflags & X86_EFLAGS_ZF) &&
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!!(eflags & X86_EFLAGS_SF) == !!(eflags & X86_EFLAGS_OF);
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default:
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return false;
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}
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}
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static void SigprofHandler(int signo, siginfo_t *si, void *c) {
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if (__ubsan_is_trap_loop(c)) {
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__builtin_trap();
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}
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}
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void __ubsan_install_trap_loop_detection(void) {
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struct sigaction sa;
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sa.sa_sigaction = SigprofHandler;
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sigaction(SIGPROF, &sa, nullptr);
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struct itimerval timer;
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timer.it_value.tv_sec = 0;
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timer.it_value.tv_usec = 100000;
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timer.it_interval = timer.it_value;
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setitimer(ITIMER_PROF, &timer, NULL);
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}
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#else
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int __ubsan_is_trap_loop(void *c) { return false; }
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void __ubsan_install_trap_loop_detection(void) {}
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#endif
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