sandbox: Add Arm64 support for seccomp-BPF

sandbox/linux/seccomp-bpf/syscall.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sandbox/linux/seccomp-bpf/syscall.h"
 
 #include <asm/unistd.h>
 #include <errno.h>
 
 #include "base/basictypes.h"
@@ skipping 207 matching lines @@
     // Enter the kernel
     "syscall\n"
     // This is our "magic" return address that the BPF filter sees.
     // Restore the return address from the stack.
     "2:lw     $ra, 36($sp)\n"
     "jr     $ra\n"
     " addiu  $sp, $sp, 40\n"
     ".set    pop\n"
     ".end    SyscallAsm\n"
     ".size   SyscallAsm,.-SyscallAsm\n"
+#elif defined(__aarch64__)

[jln (very slow on Chromium), 2014/08/21 19:04:53]

I did not review this yet.

+    ".text\n"
+    ".align 2\n"
+    ".type SyscallAsm, %function\n"
+    "SyscallAsm:\n"
+    ".cfi_startproc\n"
+    "cmp x0, #0\n"
+    "b.ge 1f\n"
+    "adr x0,2f\n"
+    "b 2f\n"
+    "1:ldr x5, [x6, #40]\n"
+    "ldr x4, [x6, #32]\n"
+    "ldr x3, [x6, #24]\n"
+    "ldr x2, [x6, #16]\n"
+    "ldr x1, [x6, #8]\n"
+    "mov x8, x0\n"
+    "ldr x0, [x6, #0]\n"
+    // Enter the kernel
+    "svc 0\n"
+    "2:ret\n"
+    ".cfi_endproc\n"
+    ".size SyscallAsm, .-SyscallAsm\n"
 #endif
     );  // asm
 
 }  // namespace
 
 intptr_t Syscall::InvalidCall() {
   // Explicitly pass eight zero arguments just in case.
   return Call(kInvalidSyscallNumber, 0, 0, 0, 0, 0, 0, 0, 0);
 }
 
@@ skipping 96 matching lines @@
 #elif defined(__mips__)
   int err_status;
   intptr_t ret = Syscall::SandboxSyscallRaw(nr, args, &err_status);
 
   if (err_status) {
     // On error, MIPS returns errno from syscall instead of -errno.
     // The purpose of this negation is for SandboxSyscall() to behave
     // more like it would on other architectures.
     ret = -ret;
   }
+#elif defined(__aarch64__)
+  intptr_t ret;
+  {
+    register intptr_t inout __asm__("x0") = nr;
+    register const intptr_t* data __asm__("x6") = args;
+    asm volatile("bl SyscallAsm\n"
+                 : "=r"(inout)
+                 : "0"(inout), "r"(data)
+                 : "memory", "x1", "x2", "x3", "x4", "x5", "x8", "x30");
+    ret = inout;
+  }
+
 #else
 #error "Unimplemented architecture"
 #endif
   return ret;
 }
 
 void Syscall::PutValueInUcontext(intptr_t ret_val, ucontext_t* ctx) {
 #if defined(__mips__)
   // Mips ABI states that on error a3 CPU register has non zero value and if
   // there is no error, it should be zero.
@@ skipping 31 matching lines @@
   }
 
   // Set an error status so it can be used outside of this function
   *err_ret = err_stat;
 
   return ret;
 }
 #endif  // defined(__mips__)
 
 }  // namespace sandbox