delta/go-git.git/src/syscall/syscall_linux_arm.go, branch dev.go2go

syscall: implement rawVforkSyscall for remaining linux platforms

2021-03-03T05:33:21+00:00

This allows the use of CLONE_VFORK and CLONE_VM for fork/exec, preventing
'fork/exec ...: cannot allocate memory' failures from occuring when attempting
to execute commands from a Go process that has a large memory footprint.
Additionally, this should reduce the latency of fork/exec on these platforms.

Fixes #31936

Change-Id: I4e28cf0763173145cacaa5340680dca9ff449305
Reviewed-on: https://go-review.googlesource.com/c/go/+/295849
Trust: Joel Sing 
Run-TryBot: Joel Sing 
Reviewed-by: Cherry Zhang

syscall: handle undefined r2 value on linux-ppc64x

2020-10-29T17:53:57+00:00

This change fixes two failng tests on linux-ppc64x:

- TestAllThreadsSyscall() exposed a real bug in the ppc64x support:
  - It turns out that the r2 syscall return value is not defined
    on all architectures. Notably linux-ppc64x so address that by
    introducing a private architectural constant in the syscall
    package, archHonorsR2: true if r2 has a determanistic value.

- TestSetuidEtc() was sensitive to /proc//status content:
  - The amount of padding space has changed with kernel vintage.
  - Stress testing revealed a race with /proc files disappearing.

Fixes #42178

Change-Id: Ie6fc0b8f2f94a409ac0e5756e73bfce113274709
Reviewed-on: https://go-review.googlesource.com/c/go/+/266202
Run-TryBot: Ian Lance Taylor 
Reviewed-by: Emmanuel Odeke 
Reviewed-by: Ian Lance Taylor 
TryBot-Result: Go Bot

syscall: support POSIX semantics for Linux syscalls

2020-10-23T20:53:14+00:00

This change adds two new methods for invoking system calls
under Linux: syscall.AllThreadsSyscall() and
syscall.AllThreadsSyscall6().

These system call wrappers ensure that all OSThreads mirror
a common system call. The wrappers serialize execution of the
runtime to ensure no race conditions where any Go code observes
a non-atomic OS state change. As such, the syscalls have
higher runtime overhead than regular system calls, and only
need to be used where such thread (or 'm' in the parlance
of the runtime sources) consistency is required.

The new support is used to enable these functions under Linux:

  syscall.Setegid(), syscall.Seteuid(), syscall.Setgroups(),
  syscall.Setgid(), syscall.Setregid(), syscall.Setreuid(),
  syscall.Setresgid(), syscall.Setresuid() and syscall.Setuid().

They work identically to their glibc counterparts.

Extensive discussion of the background issue addressed in this
patch can be found here:

   https://github.com/golang/go/issues/1435

In the case where cgo is used, the C runtime can launch pthreads that
are not managed by the Go runtime. As such, the added
syscall.AllThreadsSyscall*() return ENOTSUP when cgo is enabled.
However, for the 9 syscall.Set*() functions listed above, when cgo is
active, these functions redirect to invoke their C.set*() equivalents
in glibc, which wraps the raw system calls with a nptl:setxid fixup
mechanism. This achieves POSIX semantics for these functions in the
combined Go and C runtime.

As a side note, the glibc/nptl:setxid support (2019-11-30) does not
extend to all security related system calls under Linux so using
native Go (CGO_ENABLED=0) and these AllThreadsSyscall*()s, where
needed, will yield more well defined/consistent behavior over all
threads of a Go program. That is, using the
syscall.AllThreadsSyscall*() wrappers for things like setting state
through SYS_PRCTL and SYS_CAPSET etc.

Fixes #1435

Change-Id: Ib1a3e16b9180f64223196a32fc0f9dce14d9105c
Reviewed-on: https://go-review.googlesource.com/c/go/+/210639
Trust: Emmanuel Odeke 
Trust: Ian Lance Taylor 
Trust: Michael Pratt 
Run-TryBot: Emmanuel Odeke 
Reviewed-by: Michael Pratt 
Reviewed-by: Austin Clements

syscall: avoid dup2 in forkAndExecInChild1 on Android

2020-05-28T19:51:59+00:00

Android O and newer blocks the dup2 syscall.

Change-Id: Ibca01fc72ef114deeef6c0450a8b81a556ed0530
Reviewed-on: https://go-review.googlesource.com/c/go/+/235537
Run-TryBot: Elias Naur 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

syscall: don't use deprecated syscalls on linux/arm64

2019-10-08T10:45:48+00:00

Reimplement syscall wrappers for linux/arm64 in terms of supported
syscalls (or in case of Ustat make it return ENOSYS) and remove the
manually added SYS_* consts for the deprecated syscalls. Adapted from
golang.org/x/sys/unix where this is already done since CL 119655.

Change-Id: I94ab48a4645924df3822497d0575f1a1573d509f
Reviewed-on: https://go-review.googlesource.com/c/go/+/199140
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

syscall: move Renameat to syscall_linux_$GOARCH.go

2019-08-28T15:44:01+00:00

On linux/riscv64, the renameat syscall no longer exists and has been
superseded by renameat2. Thus we'll have to use Renameat2 to implement
Renameat on linux/riscv64 for #27532. Prepare for this by moving the
Renameat definition to the GOARCH specific files.

Follow CL 157899 which did the same for golang.org/x/sys/unix

Change-Id: I9670213cc3987df48fee962ddee36915a7785560
Reviewed-on: https://go-review.googlesource.com/c/go/+/192077
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

syscall: on ARM GNU/Linux let Pipe fall back to pipe

2019-03-05T02:49:10+00:00

Android O seems to require Pipe to call the pipe2 system call.
But kernel version 2.6.23 only supports pipe, not pipe2.
So try pipe2 first, then fall back to pipe.

Fixes #30549

Change-Id: I3c5d86e8e945a5ec8a0ecea7853302952c0476c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/165217
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

syscall: replace lstat, lchown, stat to please Android O

2018-09-24T17:08:51+00:00

Implement Lstat with fstatat and Lchown with Fchownat on
linux/amd64, linux/arm and linux/386. Furthermore, implement Stat
with fstatat on linux/arm and linux/386. Linux/arm64 already had
similar replacements.

The fstatat and fchownat system calls were added in kernel 2.6.16,
which is before the Go minimum, 2.6.23.

The three syscalls then match the android bionic implementation
and avoids the Android O seccomp filter.

Fixes #27797

Change-Id: I07fd5506955d454a1a660fef5af0e1ac1ecb0959
Reviewed-on: https://go-review.googlesource.com/136795
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

syscall: support Faccessat flags argument

2018-07-27T21:13:43+00:00

The Linux kernel faccessat system call does not take a flags parameter.
The flag parameter to the C library faccessat function is implemented in C.
The syscall.Faccessat function takes a flags parameter. In older releases
we have passed the flags parameter to the kernel, which ignored it.
In CL 120015 we started returning an error if any flags were set.
That seems clearly better than ignoring them, but it turns out that some
code was using the flags. The code was previously subtly broken.
Now it is obviously broken. That is better, but we can do better still:
we can implement the flags as the C library does. That is what this CL does.

Change-Id: I259bd6f240c3951e939b81c3032dead3d9c567b4
Reviewed-on: https://go-review.googlesource.com/126415
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

syscall: fix EpollWait for arm64

2018-06-04T15:13:16+00:00

The SYS_EPOLL_WAIT syscall doesn't exist on arm64. This CL implements EpollWait
with SYS_EPOLL_PWAIT syscall.

Change-Id: Ica9107a58d7da45351fe2e900f59bec5b7b18f39
Reviewed-on: https://go-review.googlesource.com/115735
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Tobias Klauser 
Reviewed-by: Brad Fitzpatrick