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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <signal.h>
#include <sys/types.h>
#include <sys/ucontext.h>
#include <unistd.h>
#include "gtest/gtest.h"
#include "test/util/logging.h"
#include "test/util/signal_util.h"
#include "test/util/test_util.h"
#include "test/util/timer_util.h"
namespace gvisor {
namespace testing {
namespace {
constexpr uint64_t kOrigRcx = 0xdeadbeeffacefeed;
constexpr uint64_t kOrigR11 = 0xfacefeedbaad1dea;
volatile int gotvtalrm, ready;
void sigvtalrm(int sig, siginfo_t* siginfo, void* _uc) {
ucontext_t* uc = reinterpret_cast<ucontext_t*>(_uc);
// Verify that:
// - test is in the busy-wait loop waiting for signal.
// - %rcx and %r11 values in mcontext_t match kOrigRcx and kOrigR11.
if (ready &&
static_cast<uint64_t>(uc->uc_mcontext.gregs[REG_RCX]) == kOrigRcx &&
static_cast<uint64_t>(uc->uc_mcontext.gregs[REG_R11]) == kOrigR11) {
// Modify the values %rcx and %r11 in the ucontext. These are the
// values seen by the application after the signal handler returns.
uc->uc_mcontext.gregs[REG_RCX] = ~kOrigRcx;
uc->uc_mcontext.gregs[REG_R11] = ~kOrigR11;
gotvtalrm = 1;
}
}
TEST(SigIretTest, CheckRcxR11) {
// Setup signal handler for SIGVTALRM.
struct sigaction sa = {};
sigfillset(&sa.sa_mask);
sa.sa_sigaction = sigvtalrm;
sa.sa_flags = SA_SIGINFO;
auto const action_cleanup =
ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(SIGVTALRM, sa));
auto const mask_cleanup =
ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_UNBLOCK, SIGVTALRM));
// Setup itimer to fire after 500 msecs.
struct itimerval itimer = {};
itimer.it_value.tv_usec = 500 * 1000; // 500 msecs.
auto const timer_cleanup =
ASSERT_NO_ERRNO_AND_VALUE(ScopedItimer(ITIMER_VIRTUAL, itimer));
// Initialize %rcx and %r11 and spin until the signal handler returns.
uint64_t rcx = kOrigRcx;
uint64_t r11 = kOrigR11;
asm volatile(
"movq %[rcx], %%rcx;" // %rcx = rcx
"movq %[r11], %%r11;" // %r11 = r11
"movl $1, %[ready];" // ready = 1
"1: pause; cmpl $0, %[gotvtalrm]; je 1b;" // while (!gotvtalrm);
"movq %%rcx, %[rcx];" // rcx = %rcx
"movq %%r11, %[r11];" // r11 = %r11
: [ready] "=m"(ready), [rcx] "+m"(rcx), [r11] "+m"(r11)
: [gotvtalrm] "m"(gotvtalrm)
: "cc", "memory", "rcx", "r11");
// If sigreturn(2) returns via 'sysret' then %rcx and %r11 will be
// clobbered and set to 'ptregs->rip' and 'ptregs->rflags' respectively.
//
// The following check verifies that %rcx and %r11 were not clobbered
// when returning from the signal handler (via sigreturn(2)).
EXPECT_EQ(rcx, ~kOrigRcx);
EXPECT_EQ(r11, ~kOrigR11);
}
constexpr uint64_t kNonCanonicalRip = 0xCCCC000000000000;
// Test that a non-canonical signal handler faults as expected.
TEST(SigIretTest, BadHandler) {
struct sigaction sa = {};
sa.sa_sigaction =
reinterpret_cast<void (*)(int, siginfo_t*, void*)>(kNonCanonicalRip);
auto const cleanup = ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(SIGUSR1, sa));
pid_t pid = fork();
if (pid == 0) {
// Child, wait for signal.
while (1) {
pause();
}
}
ASSERT_THAT(pid, SyscallSucceeds());
EXPECT_THAT(kill(pid, SIGUSR1), SyscallSucceeds());
int status;
EXPECT_THAT(waitpid(pid, &status, 0), SyscallSucceedsWithValue(pid));
EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGSEGV)
<< "status = " << status;
}
} // namespace
} // namespace testing
} // namespace gvisor
int main(int argc, char** argv) {
// SigIretTest.CheckRcxR11 depends on delivering SIGVTALRM to the main thread.
// Block SIGVTALRM so that any other threads created by TestInit will also
// have SIGVTALRM blocked.
sigset_t set;
sigemptyset(&set);
sigaddset(&set, SIGVTALRM);
TEST_PCHECK(sigprocmask(SIG_BLOCK, &set, nullptr) == 0);
gvisor::testing::TestInit(&argc, &argv);
return RUN_ALL_TESTS();
}
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