github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/arch/syscalls_amd64.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // +build amd64
    16  
    17  package arch
    18  
    19  const restartSyscallNr = uintptr(219)
    20  
    21  // SyscallSaveOrig save the value of the register which is clobbered in
    22  // syscall handler(doSyscall()).
    23  //
    24  // Noop on x86.
    25  func (c *context64) SyscallSaveOrig() {
    26  }
    27  
    28  // SyscallNo returns the syscall number according to the 64-bit convention.
    29  func (c *context64) SyscallNo() uintptr {
    30  	return uintptr(c.Regs.Orig_rax)
    31  }
    32  
    33  // SyscallArgs provides syscall arguments according to the 64-bit convention.
    34  //
    35  // Due to the way addresses are mapped for the sentry this binary *must* be
    36  // built in 64-bit mode. So we can just assume the syscall numbers that come
    37  // back match the expected host system call numbers.
    38  func (c *context64) SyscallArgs() SyscallArguments {
    39  	return SyscallArguments{
    40  		SyscallArgument{Value: uintptr(c.Regs.Rdi)},
    41  		SyscallArgument{Value: uintptr(c.Regs.Rsi)},
    42  		SyscallArgument{Value: uintptr(c.Regs.Rdx)},
    43  		SyscallArgument{Value: uintptr(c.Regs.R10)},
    44  		SyscallArgument{Value: uintptr(c.Regs.R8)},
    45  		SyscallArgument{Value: uintptr(c.Regs.R9)},
    46  	}
    47  }
    48  
    49  // RestartSyscall implements Context.RestartSyscall.
    50  func (c *context64) RestartSyscall() {
    51  	c.Regs.Rip -= SyscallWidth
    52  	c.Regs.Rax = c.Regs.Orig_rax
    53  }
    54  
    55  // RestartSyscallWithRestartBlock implements Context.RestartSyscallWithRestartBlock.
    56  func (c *context64) RestartSyscallWithRestartBlock() {
    57  	c.Regs.Rip -= SyscallWidth
    58  	c.Regs.Rax = uint64(restartSyscallNr)
    59  }