Add tests for rseq(2)

Add a decent set of syscall tests for rseq(2). These are a bit awkward because
of issues with library integration. libc may register rseq on thread start
(including before main on the initial thread), precluding much testing. Thus we
run tests in a libc-free subprocess.

Support for rseq(2) in gVisor will come in a later commit.

PiperOrigin-RevId: 284595994

1 files changed, 45 insertions, 0 deletions

diff --git a/test/syscalls/linux/rseq/start.S b/test/syscalls/linux/rseq/start.S
new file mode 100644
index 000000000..b9611b276
--- /dev/null
+++ b/test/syscalls/linux/rseq/start.S
@@ -0,0 +1,45 @@
+// Copyright 2019 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.
+
+
+  .text
+  .align 4
+  .type  _start,@function
+  .globl  _start
+
+_start:
+  movq  %rsp,%rdi
+  call  __init
+  hlt
+
+  .size  _start,.-_start
+  .section  .note.GNU-stack,"",@progbits
+
+  .text
+  .globl  raw_syscall
+  .type   raw_syscall, @function
+
+raw_syscall:
+  mov  %rdi,%rax      // syscall #
+  mov  %rsi,%rdi      // arg0
+  mov  %rdx,%rsi      // arg1
+  mov  %rcx,%rdx      // arg2
+  mov  %r8,%r10       // arg3 (goes in r10 instead of rcx for system calls)
+  mov  %r9,%r8        // arg4
+  mov  0x8(%rsp),%r9  // arg5
+  syscall
+  ret
+
+  .size  raw_syscall,.-raw_syscall
+  .section  .note.GNU-stack,"",@progbits