Currently, when we minit on a thread that already has an alternate
signal stack (e.g., because the M was an extram being used for a cgo
callback, or to handle a signal on a C thread, or because the
platform's libc always allocates a signal stack like on Android), we
simply drop the Go-allocated gsignal stack on the floor.
This is a problem for Ms on the extram list because those Ms may later
be reused for a different thread that may not have its own alternate
signal stack. On tip, this manifests as a crash in sigaltstack because
we clear the gsignal stack bounds in unminit and later try to use
those cleared bounds when we re-minit that M. On 1.9 and earlier, we
didn't clear the bounds, so this manifests as running more than one
signal handler on the same signal stack, which could lead to arbitrary
memory corruption.
This CL fixes this problem by saving the Go-allocated gsignal stack in
a new field in the m struct when overwriting it with a system-provided
signal stack, and then restoring the original gsignal stack in
unminit.
This CL is designed to be easy to back-port to 1.9. It won't quite
cherry-pick cleanly, but it should be sufficient to simply ignore the
change in mexit (which didn't exist in 1.9).
Now that we always have a place to stash the original signal stack in
the m struct, there are some simplifications we can make to the signal
stack handling. We'll do those in a later CL.
Fixes#22930.
Change-Id: I55c5a6dd9d97532f131146afdef0b216e1433054
Reviewed-on: https://go-review.googlesource.com/81476
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Currently mmap returns an unsafe.Pointer that encodes OS errors as
values less than 4096. In practice this is okay, but it borders on
being really unsafe: for example, the value has to be checked
immediately after return and if stack copying were ever to observe
such a value, it would panic. It's also not remotely idiomatic.
Fix this by making mmap return a separate pointer value and error,
like a normal Go function.
Updates #22218.
Change-Id: Iefd965095ffc82cc91118872753a5d39d785c3a6
Reviewed-on: https://go-review.googlesource.com/71270
Run-TryBot: Austin Clements <austin@google.com>
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>
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 ensures that SIGPROF is handled correctly when using
runtime/pprof in a c-archive or c-shared library.
Separate profiler handling into pre-process changes and per-thread
changes. Simplify the Windows code slightly accordingly.
Fixes#18220.
Change-Id: I5060f7084c91ef0bbe797848978bdc527c312777
Reviewed-on: https://go-review.googlesource.com/34018
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
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>
The cgocallback function picked up a ctxt parameter in CL 22508.
That CL updated the assembler implementation, but there are a few
mentions in Go code that were not updated. This CL fixes that.
Fixes#16326
Change-Id: I5f68e23565c6a0b11057aff476d13990bff54a66
Reviewed-on: https://go-review.googlesource.com/24848
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@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>
The tree's pretty inconsistent about single space vs double space
after a period in documentation. Make it consistently a single space,
per earlier decisions. This means contributors won't be confused by
misleading precedence.
This CL doesn't use go/doc to parse. It only addresses // comments.
It was generated with:
$ perl -i -npe 's,^(\s*// .+[a-z]\.) +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.) +([A-Z])')
$ go test go/doc -update
Change-Id: Iccdb99c37c797ef1f804a94b22ba5ee4b500c4f7
Reviewed-on: https://go-review.googlesource.com/20022
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Dave Day <djd@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@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>
Previously, when a program died because of a SIGHUP, SIGINT, or SIGTERM
signal it would exit with status 2. This CL fixes the runtime to exit
with a status indicating that the program was killed by a signal.
Change-Id: Ic2982a2562857edfdccaf68856e0e4df532af136
Reviewed-on: https://go-review.googlesource.com/18156
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Ian Lance Taylor <iant@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>
This change splits signal_unix.go into signal_unix.go and
signal2_unix.go and removes the fake symbol sigfwd from signal
forwarding unsupported platforms for clarification purpose.
Change-Id: I205eab5cf1930fda8a68659b35cfa9f3a0e67ca6
Reviewed-on: https://go-review.googlesource.com/12062
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Follows the linux signal forwarding semantics from
http://golang.org/cl/8712, sharing the implementation of sigfwdgo.
Forwarding for 386, arm, and arm64 will follow.
Change-Id: I6bf30d563d19da39b6aec6900c7fe12d82ed4f62
Reviewed-on: https://go-review.googlesource.com/9302
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>
Error detection code copied from syscall, where presumably
we actually do it right.
Note that we throw the errno away. The runtime doesn't use it.
Fixes#10052
Change-Id: I8de77dda6bf287276b137646c26b84fa61554ec8
Reviewed-on: https://go-review.googlesource.com/6571
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Normally, a panic/throw only shows the thread stack for the current thread
and all paused goroutines. Goroutines running on other threads, or other threads
running on their system stacks, are opaque. Change that when GODEBUG=crash,
by passing a SIGQUIT around to all the threads when GODEBUG=crash.
If this works out reasonably well, we might make the SIGQUIT relay part of
the standard panic/throw death, perhaps eliding idle m's.
Change-Id: If7dd354f7f3a6e326d17c254afcf4f7681af2f8b
Reviewed-on: https://go-review.googlesource.com/2811
Reviewed-by: Rick Hudson <rlh@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>
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
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
