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bca17d16ca
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>
76 lines
1.8 KiB
ArmAsm
76 lines
1.8 KiB
ArmAsm
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "textflag.h"
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#include "funcdata.h"
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//
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// System calls for arm, Linux
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//
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#define SYS__LLSEEK 140 /* from zsysnum_linux_arm.go */
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// func seek(fd int, offset int64, whence int) (newoffset int64, errno int)
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// Implemented in assembly to avoid allocation when
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// taking the address of the return value newoffset.
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// Underlying system call is
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// llseek(int fd, int offhi, int offlo, int64 *result, int whence)
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TEXT ·seek(SB),NOSPLIT,$0-28
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BL runtime·entersyscall(SB)
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MOVW $SYS__LLSEEK, R7 // syscall entry
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MOVW fd+0(FP), R0
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MOVW offset_hi+8(FP), R1
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MOVW offset_lo+4(FP), R2
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MOVW $newoffset_lo+16(FP), R3
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MOVW whence+12(FP), R4
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SWI $0
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MOVW $0xfffff001, R6
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CMP R6, R0
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BLS okseek
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MOVW $0, R1
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MOVW R1, newoffset_lo+16(FP)
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MOVW R1, newoffset_hi+20(FP)
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RSB $0, R0, R0
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MOVW R0, err+24(FP)
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BL runtime·exitsyscall(SB)
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RET
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okseek:
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// system call filled in newoffset already
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MOVW $0, R0
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MOVW R0, err+24(FP)
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BL runtime·exitsyscall(SB)
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RET
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// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
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TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-20
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MOVW trap+0(FP), R7 // syscall entry
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MOVW a1+4(FP), R0
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MOVW a2+8(FP), R1
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MOVW $0, R2
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SWI $0
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MOVW $0xfffff001, R1
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CMP R1, R0
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BLS ok
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MOVW $-1, R1
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MOVW R1, r1+12(FP)
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RSB $0, R0, R0
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MOVW R0, err+16(FP)
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RET
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ok:
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MOVW R0, r1+12(FP)
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MOVW $0, R0
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MOVW R0, err+16(FP)
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RET
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// func rawSyscallNoError(trap uintptr, a1, a2, a3 uintptr) (r1, r2 uintptr);
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TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-24
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MOVW trap+0(FP), R7 // syscall entry
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MOVW a1+4(FP), R0
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MOVW a2+8(FP), R1
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MOVW a3+12(FP), R2
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SWI $0
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MOVW R0, r1+16(FP)
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MOVW $0, R0
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MOVW R0, r2+20(FP)
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RET
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