1 files changed, 136 insertions, 0 deletions
diff --git a/test/syscalls/linux/sigiret.cc b/test/syscalls/linux/sigiret.cc
new file mode 100644
index 000000000..6227774a4
--- /dev/null
+++ b/test/syscalls/linux/sigiret.cc
@@ -0,0 +1,136 @@
+// Copyright 2018 The gVisor Authors.
+//
+// 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 gvisor::testing::RunAllTests();
+}