In os.Getenv and os.Setenv, instead of directly reading and writing the
Plan 9 environment device (which may be shared with other processes),
use a local copy of environment variables cached at the start of
execution. This gives the same semantics for Getenv and Setenv as on
other operating systems which don't share the environment, making it
more likely that Go programs (for example the build tests) will be
portable to Plan 9.
This doesn't preclude writing non-portable Plan 9 Go programs which make
use of the shared environment semantics (for example to have a command
which exports variable definitions to the parent shell). To do this, use
ioutil.ReadFile("/env/"+key) and
ioutil.WriteFile("/env/"+key, value, 0666)
in place of os.Getenv(key) and os.Setenv(key, value) respectively.
Note that CL 5599054 previously added env cacheing, citing efficiency
as the reason. However it made the cache write-through, with Setenv
changing the shared environment as well as the cache (so not consistent
with Posix semantics), and Clearenv breaking the sharing of the
environment between the calling thread and other threads (leading to
unpredictable behaviour). Because of these inconsistencies (#8849),
CL 158970045 removed the cacheing again.
This CL restores cacheing but without write-through. The local cache is
initialised at start of execution, manipulated by the standard functions
in syscall/env_unix.go to ensure the same semantics, and exported only
when exec'ing a new program.
Fixes#34971Fixes#25234Fixes#19388
Updates #38772
Change-Id: I2dd15516d27414afaf99ea382f0e00be37a570c3
Reviewed-on: https://go-review.googlesource.com/c/go/+/236520
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Fazlul Shahriar <fshahriar@gmail.com>
Reviewed-by: David du Colombier <0intro@gmail.com>
The Plan 9 runtime startup was enabling notes (like Unix signals)
before the gsignal stack was allocated. This left a small window
of time where an interrupt (eg by the parent killing a subprocess
quickly after exec) would cause a null pointer dereference in
sigtramp. This would leave the interrupted process suspended in
'broken' state instead of exiting. We've observed this on the
builders, where it can make a test time out waiting for the broken
process to terminate.
Updates #38772
Change-Id: I54584069fd3109595f06c78724c1f6419e028aab
Reviewed-on: https://go-review.googlesource.com/c/go/+/234397
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David du Colombier <0intro@gmail.com>
This adds support for pausing a running G by sending a signal to its
M.
The main complication is that we want to target a G, but can only send
a signal to an M. Hence, the protocol we use is to simply mark the G
for preemption (which we already do) and send the M a "wake up and
look around" signal. The signal checks if it's running a G with a
preemption request and stops it if so in the same way that stack check
preemptions stop Gs. Since the preemption may fail (the G could be
moved or the signal could arrive at an unsafe point), we keep a count
of the number of received preemption signals. This lets stopG detect
if its request failed and should be retried without an explicit
channel back to suspendG.
For #10958, #24543.
Change-Id: I3e1538d5ea5200aeb434374abb5d5fdc56107e53
Reviewed-on: https://go-review.googlesource.com/c/go/+/201760
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
In preparation for general faketime support, this renames the existing
nanotime, walltime, and write functions to nanotime1, walltime1, and
write1 and wraps them with trivial Go functions. This will let us
inject different implementations on all platforms when faketime is
enabled.
Updates #30439.
Change-Id: Ice5ccc513a32a6d89ea051638676d3ee05b00418
Reviewed-on: https://go-review.googlesource.com/c/go/+/192738
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
A few examples (for accessing a slice of length 3):
s[-1] runtime error: index out of range [-1]
s[3] runtime error: index out of range [3] with length 3
s[-1:0] runtime error: slice bounds out of range [-1:]
s[3:0] runtime error: slice bounds out of range [3:0]
s[3:-1] runtime error: slice bounds out of range [:-1]
s[3:4] runtime error: slice bounds out of range [:4] with capacity 3
s[0:3:4] runtime error: slice bounds out of range [::4] with capacity 3
Note that in cases where there are multiple things wrong with the
indexes (e.g. s[3:-1]), we report one of those errors kind of
arbitrarily, currently the rightmost one.
An exhaustive set of examples is in issue30116[u].out in the CL.
The message text has the same prefix as the old message text. That
leads to slightly awkward phrasing but hopefully minimizes the chance
that code depending on the error text will break.
Increases the size of the go binary by 0.5% (amd64). The panic functions
take arguments in registers in order to keep the size of the compiled code
as small as possible.
Fixes#30116
Change-Id: Idb99a827b7888822ca34c240eca87b7e44a04fdd
Reviewed-on: https://go-review.googlesource.com/c/go/+/161477
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
The hasprefix function is redundant and can be removed since it has
the same implementation as hasPrefix modulo variable names.
Fixes#25688
Change-Id: I499cc24a2b5c38d1301718a4e66f555fd138386f
Reviewed-on: https://go-review.googlesource.com/115835
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
CL 93658 moved stack trace printing inside a systemstack call to
sidestep complexity in case the runtime is in a inconsistent state.
Unfortunately, debuggers generating backtraces for a Go panic
will be confused and come up with a technical correct but useless
stack. This CL moves just the crash performing - typically a SIGABRT
signal - outside the systemstack call to improve backtraces.
Unfortunately, the crash function now needs to be marked nosplit and
that triggers the no split stackoverflow check. To work around that,
split fatalpanic in two: fatalthrow for runtime.throw and fatalpanic for
runtime.gopanic. Only Go panics really needs crashes on the right stack
and there is enough stack for gopanic.
Example program:
package main
import "runtime/debug"
func main() {
debug.SetTraceback("crash")
crash()
}
func crash() {
panic("panic!")
}
Before:
(lldb) bt
* thread #1, name = 'simple', stop reason = signal SIGABRT
* frame #0: 0x000000000044ffe4 simple`runtime.raise at <autogenerated>:1
frame #1: 0x0000000000438cfb simple`runtime.dieFromSignal(sig=<unavailable>) at signal_unix.go:424
frame #2: 0x0000000000438ec9 simple`runtime.crash at signal_unix.go:525
frame #3: 0x00000000004268f5 simple`runtime.dopanic_m(gp=<unavailable>, pc=<unavailable>, sp=<unavailable>) at panic.go:758
frame #4: 0x000000000044bead simple`runtime.fatalpanic.func1 at panic.go:657
frame #5: 0x000000000044d066 simple`runtime.systemstack at <autogenerated>:1
frame #6: 0x000000000042a980 simple at proc.go:1094
frame #7: 0x0000000000438ec9 simple`runtime.crash at signal_unix.go:525
frame #8: 0x00000000004268f5 simple`runtime.dopanic_m(gp=<unavailable>, pc=<unavailable>, sp=<unavailable>) at panic.go:758
frame #9: 0x000000000044bead simple`runtime.fatalpanic.func1 at panic.go:657
frame #10: 0x000000000044d066 simple`runtime.systemstack at <autogenerated>:1
frame #11: 0x000000000042a980 simple at proc.go:1094
frame #12: 0x00000000004268f5 simple`runtime.dopanic_m(gp=<unavailable>, pc=<unavailable>, sp=<unavailable>) at panic.go:758
frame #13: 0x000000000044bead simple`runtime.fatalpanic.func1 at panic.go:657
frame #14: 0x000000000044d066 simple`runtime.systemstack at <autogenerated>:1
frame #15: 0x000000000042a980 simple at proc.go:1094
frame #16: 0x000000000044bead simple`runtime.fatalpanic.func1 at panic.go:657
frame #17: 0x000000000044d066 simple`runtime.systemstack at <autogenerated>:1
After:
(lldb) bt
* thread #7, stop reason = signal SIGABRT
* frame #0: 0x0000000000450024 simple`runtime.raise at <autogenerated>:1
frame #1: 0x0000000000438d1b simple`runtime.dieFromSignal(sig=<unavailable>) at signal_unix.go:424
frame #2: 0x0000000000438ee9 simple`runtime.crash at signal_unix.go:525
frame #3: 0x00000000004264e3 simple`runtime.fatalpanic(msgs=<unavailable>) at panic.go:664
frame #4: 0x0000000000425f1b simple`runtime.gopanic(e=<unavailable>) at panic.go:537
frame #5: 0x0000000000470c62 simple`main.crash at simple.go:11
frame #6: 0x0000000000470c00 simple`main.main at simple.go:6
frame #7: 0x0000000000427be7 simple`runtime.main at proc.go:198
frame #8: 0x000000000044ef91 simple`runtime.goexit at <autogenerated>:1
Updates #22716
Change-Id: Ib5fa35c13662c1dac2f1eac8b59c4a5824b98d92
Reviewed-on: https://go-review.googlesource.com/110065
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Replace thread creation with calls to the pthread
library in libc.
Update #17490
Change-Id: I1e19965c45255deb849b059231252fc6a7861d6c
Reviewed-on: https://go-review.googlesource.com/108679
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Currently, threads created by the runtime exist until the whole
program exits. For #14592 and #20395, we want to be able to exit and
clean up threads created by the runtime. This commit implements that
mechanism.
The main difficulty is how to clean up the g0 stack. In cgo mode and
on Solaris and Windows where the OS manages thread stacks, we simply
arrange to return from mstart and let the system clean up the thread.
If the runtime allocated the g0 stack, then we use a new exitThread
syscall wrapper that arranges to clear a flag in the M once the stack
can safely be reaped and call the thread termination syscall.
exitThread is based on the existing exit1 wrapper, which was always
meant to terminate the calling thread. However, exit1 has never been
used since it was introduced 9 years ago, so it was broken on several
platforms. exitThread also has the additional complication of having
to flag that the stack is unused, which requires some tricks on
platforms that use the stack for syscalls.
This still leaves the problem of how to reap the unused g0 stacks. For
this, we move the M from allm to a new freem list as part of the M
exiting. Later, allocm scans the freem list, finds Ms that are marked
as done with their stack, removes these from the list and frees their
g0 stacks. This also allows these Ms to be garbage collected.
This CL does not yet use any of this functionality. Follow-up CLs
will. Likewise, there are no new tests in this CL because we'll need
follow-up functionality to test it.
Change-Id: Ic851ee74227b6d39c6fc1219fc71b45d3004bc63
Reviewed-on: https://go-review.googlesource.com/46037
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
syscall.Exit and runtime.exit do the same thing.
Why duplicate code?
CL 45115 fixed bug where windows runtime.exit was correct,
but syscall.Exit was broken. So CL 45115 fixed windows
syscall.Exit by calling runtime.exit.
Austin suggested that all OSes should do the same, and
this CL implements his idea.
While making changes, I discovered that nacl syscall.Exit
returned error
func Exit(code int) (err error)
and I changed it into
func Exit(code int)
like all other OSes. I assumed it was a mistake and it
is OK to do because cmd/api does not complain about it.
Also I changed plan9 runtime.exit to accept int32 just
like all other OSes do.
Change-Id: I12f6022ad81406566cf9befcc6edc382eebd413b
Reviewed-on: https://go-review.googlesource.com/66170
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: David du Colombier <0intro@gmail.com>
Block all signals during a fork. In the parent process, after the
fork, restore the signal mask. In the child process, reset all
currently handled signals to the default handler, and then restore the
signal mask.
The effect of this is that the child will be operating using the same
signal regime as the program it is about to exec, as exec resets all
non-ignored signals to the default, and preserves the signal mask.
We do this so that in the case of a signal sent to the process group,
the child process will not try to run a signal handler while in the
precarious state after a fork.
Fixes#18600.
Change-Id: I9f39aaa3884035908d687ee323c975f349d5faaa
Reviewed-on: https://go-review.googlesource.com/45471
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change is an experimental implementation of asynchronous
cancelable I/O operations on Plan 9, which are required to
implement deadlines.
There are no asynchronous syscalls on Plan 9. I/O operations
are performed with blocking pread and pwrite syscalls.
Implementing deadlines in Go requires a way to interrupt
I/O operations.
It is possible to interrupt reads and writes on a TCP connection
by forcing the closure of the TCP connection. This approach
has been used successfully in CL 31390.
However, we can't implement deadlines with this method, since
we require to be able to reuse the connection after the timeout.
On Plan 9, I/O operations are interrupted when the process
receives a note. We can rely on this behavior to implement
a more generic approach.
When doing an I/O operation (read or write), we start the I/O in
its own process, then wait for the result asynchronously. The
process is able to handle the "hangup" note. When receiving the
"hangup" note, the currently running I/O operation is canceled
and the process returns.
This way, deadlines can be implemented by sending an "hangup"
note to the process running the blocking I/O operation, after
the expiration of a timer.
Fixes#11932.
Fixes#17498.
Change-Id: I414f72c7a9a4f9b8f9c09ed3b6c269f899d9b430
Reviewed-on: https://go-review.googlesource.com/31521
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Change setsig, setsigstack, getsig, raise, raiseproc to take uint32 for
signal number parameter, as that is the type mostly used for signal
numbers. Same for dieFromSignal, sigInstallGoHandler, raisebadsignal.
Remove setsig restart parameter, as it is always either true or
irrelevant.
Don't check the handler in setsigstack, as the only caller does that
anyhow.
Don't bother to convert the handler from sigtramp to sighandler in
getsig, as it will never be called when the handler is sigtramp or
sighandler.
Don't check the return value from rt_sigaction in the GNU/Linux version
of setsigstack; no other setsigstack checks it, and it never fails.
Change-Id: I6bbd677e048a77eddf974dd3d017bc3c560fbd48
Reviewed-on: https://go-review.googlesource.com/29953
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Currently the physical page size assumed by the runtime is hard-coded.
On Linux the runtime at least fetches the OS page size during init and
sanity checks against the hard-coded value, but they may still differ.
On other OSes we wouldn't even notice.
Add support on all OSes to fetch the actual OS physical page size
during runtime init and lift the sanity check of PhysPageSize from the
Linux init code to general malloc init. Currently this is the only use
of the retrieved page size, but we'll add more shortly.
Updates #12480 and #10180.
Change-Id: I065f2834bc97c71d3208edc17fd990ec9058b6da
Reviewed-on: https://go-review.googlesource.com/25050
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Change-Id: Ice9c234960adc7857c8370b777a0b18e29d59281
Reviewed-on: https://go-review.googlesource.com/22853
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
I meant to delete these in CL 22850, actually.
Change-Id: I0c286efd2b9f1caf0221aa88e3bcc03649c89517
Reviewed-on: https://go-review.googlesource.com/22851
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Plan 9 trap/signal handling differs on ARM from other architectures
because ARM has a link register. Also trap message syntax varies
between different architectures (historical accident?).
Revised 7 March to clarify a comment.
Change-Id: Ib6485f82857a2f9a0d6b2c375cf0aaa230b83656
Reviewed-on: https://go-review.googlesource.com/18969
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This is a subset of https://golang.org/cl/20022 with only the copyright
header lines, so the next CL will be smaller and more reviewable.
Go policy has been single space after periods in comments for some time.
The copyright header template at:
https://golang.org/doc/contribute.html#copyright
also uses a single space.
Make them all consistent.
Change-Id: Icc26c6b8495c3820da6b171ca96a74701b4a01b0
Reviewed-on: https://go-review.googlesource.com/20111
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Allows removing fields that aren't relevant to a particular OS or
changing their types to match the underlying OS system calls they'll
be used for.
Change-Id: I5cea89ee77b4e7b985bff41337e561887c3272ff
Reviewed-on: https://go-review.googlesource.com/16176
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reduces the size of m by ~8% on linux/amd64 (1040 bytes -> 960 bytes).
There are also windows-specific fields, but they're currently
referenced in OS-independent source files (but only when
GOOS=="windows").
Change-Id: I13e1471ff585ccced1271f74209f8ed6df14c202
Reviewed-on: https://go-review.googlesource.com/16173
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Avoids shadowing the builtin channel close function.
Change-Id: I7a729b0937c8248fe27222be61318a88db995eee
Reviewed-on: https://go-review.googlesource.com/8898
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
Rename "gothrow" to "throw" now that the C version of "throw"
is no longer needed.
This change is purely mechanical except in panic.go where the
old version of "throw" has been deleted.
sed -i "" 's/[[:<:]]gothrow[[:>:]]/throw/g' runtime/*.go
Change-Id: Icf0752299c35958b92870a97111c67bcd9159dc3
Reviewed-on: https://go-review.googlesource.com/2150
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Replace with uses of //go:linkname in Go files, direct use of name in .s files.
The only one that really truly needs a jump is reflect.call; the jump is now
next to the runtime.reflectcall assembly implementations.
Change-Id: Ie7ff3020a8f60a8e4c8645fe236e7883a3f23f46
Reviewed-on: https://go-review.googlesource.com/1962
Reviewed-by: Austin Clements <austin@google.com>
with uintptr, the check for < 0 will never succeed in mem_plan9.go's
sbrk() because the brk_ syscall returns -1 on failure. fixes the plan9/amd64 build.
this failed on plan9/amd64 because of the attempt to allocate 136GB in mallocinit(),
which failed. it was just by chance that on plan9/386 allocations never failed.
Change-Id: Ia3059cf5eb752e20d9e60c9619e591b80e8fb03c
Reviewed-on: https://go-review.googlesource.com/1590
Reviewed-by: Anthony Martin <ality@pbrane.org>
Reviewed-by: David du Colombier <0intro@gmail.com>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Thanks to Aram Hăvărneanu, Nick Owens
and Russ Cox for the early reviews.
LGTM=aram, rsc
R=rsc, lucio.dere, aram, ality
CC=golang-codereviews, mischief
https://golang.org/cl/175370043
The C header files are the single point of truth:
every C enum constant Foo is available to Go as _Foo.
Remove or redirect duplicate Go declarations so they
cannot be out of sync.
Eventually we will need to put constants in Go, but for now having
them be out of sync with C is too risky. These predate the build
support for auto-generating Go constants from the C definitions.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/141510043
A race exists between the parent and child processes after a fork.
The child needs to access the new M pointer passed as an argument
but the parent may have already returned and clobbered it.
Previously, we avoided this by saving the necessary data into
registers before the rfork system call but this isn't guaranteed
to work because Plan 9 makes no promises about the register state
after a system call. Only the 386 kernel seems to save them.
For amd64 and arm, this method won't work.
We eliminate the race by allocating stack space for the scheduler
goroutines (g0) in the per-process copy-on-write stack segment and
by only calling rfork on the scheduler stack.
LGTM=aram, 0intro, rsc
R=aram, 0intro, mischief, rsc
CC=golang-codereviews
https://golang.org/cl/110680044
This CL contains compiler+runtime changes that detect C code
running on Go (not g0, not gsignal) stacks, and it contains
corrections for what it detected.
The detection works by changing the C prologue to use a different
stack guard word in the G than Go prologue does. On the g0 and
gsignal stacks, that stack guard word is set to the usual
stack guard value. But on ordinary Go stacks, that stack
guard word is set to ^0, which will make any stack split
check fail. The C prologue then calls morestackc instead
of morestack, and morestackc aborts the program with
a message about running C code on a Go stack.
This check catches all C code running on the Go stack
except NOSPLIT code. The NOSPLIT code is allowed,
so the check is complete. Since it is a dynamic check,
the code must execute to be caught. But unlike the static
checks we've been using in cmd/ld, the dynamic check
works with function pointers and other indirect calls.
For example it caught sigpanic being pushed onto Go
stacks in the signal handlers.
Fixes#8667.
LGTM=khr, iant
R=golang-codereviews, khr, iant
CC=golang-codereviews, r
https://golang.org/cl/133700043
