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go/src/syscall/asm_linux_mips64x.s
Kir Kolyshkin bca17d16ca syscall: add CgroupFD support for ForkExec on Linux
Implement CLONE_INTO_CGROUP feature, allowing to put a child in a
specified cgroup in a clean and simple way. Note that the feature only
works for cgroup v2, and requires Linux kernel 5.7 or newer.

Using the feature requires a new syscall, clone3. Currently this is the
only reason to use clone3, but the code is structured in a way so that
other cases may be easily added in the future.

Add a test case.

While at it, try to simplify the syscall calling code in
forkAndExecInChild1, which became complicated over time because:

1. It was using either rawVforkSyscall or RawSyscall6 depending on
   whether CLONE_NEWUSER was set.

2. On Linux/s390, the first two arguments to clone(2) system call are
   swapped (which deserved a mention in Linux ABI hall of shame). It
   was worked around in rawVforkSyscall on s390, but had to be
   implemented via a switch/case when using RawSyscall6, making the code
   less clear.

Let's

 - modify rawVforkSyscall to have two arguments (which is also required
   for clone3);

 - remove the arguments workaround from s390 asm, instead implementing
   arguments swap in the caller (which still looks ugly but at least
   it's done once and is clearly documented now);

 - use rawVforkSyscall for all cases (since it is essentially similar to
   RawSyscall6, except for having less parameters, not returning r2, and
   saving/restoring the return address before/after syscall on 386 and
   amd64).

Updates #51246.

Change-Id: Ifcd418ebead9257177338ffbcccd0bdecb94474e
Reviewed-on: https://go-review.googlesource.com/c/go/+/417695
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Kirill Kolyshkin <kolyshkin@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2022-09-09 15:34:16 +00:00

45 lines
903 B
ArmAsm

// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build linux && (mips64 || mips64le)
#include "textflag.h"
//
// System calls for mips64, Linux
//
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-40
MOVV a1+8(FP), R4
MOVV a2+16(FP), R5
MOVV R0, R6
MOVV R0, R7
MOVV R0, R8
MOVV R0, R9
MOVV trap+0(FP), R2 // syscall entry
SYSCALL
BEQ R7, ok
MOVV $-1, R1
MOVV R1, r1+24(FP) // r1
MOVV R2, err+32(FP) // errno
RET
ok:
MOVV R2, r1+24(FP) // r1
MOVV R0, err+32(FP) // errno
RET
TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48
MOVV a1+8(FP), R4
MOVV a2+16(FP), R5
MOVV a3+24(FP), R6
MOVV R0, R7
MOVV R0, R8
MOVV R0, R9
MOVV trap+0(FP), R2 // syscall entry
SYSCALL
MOVV R2, r1+32(FP)
MOVV R3, r2+40(FP)
RET