In a C thread, it's necessary to acquire an extra M by using needm while invoking a Go function from C. But, needm and dropm are heavy costs due to the signal-related syscalls.
So, we change to not dropm while returning back to C, which means binding the extra M to the C thread until it exits, to avoid needm and dropm on each C to Go call.
Instead, we only dropm while the C thread exits, so the extra M won't leak.
When invoking a Go function from C:
Allocate a pthread variable using pthread_key_create, only once per shared object, and register a thread-exit-time destructor.
And store the g0 of the current m into the thread-specified value of the pthread key, only once per C thread, so that the destructor will put the extra M back onto the extra M list while the C thread exits.
When returning back to C:
Skip dropm in cgocallback, when the pthread variable has been created, so that the extra M will be reused the next time invoke a Go function from C.
This is purely a performance optimization. The old version, in which needm & dropm happen on each cgo call, is still correct too, and we have to keep the old version on systems with cgo but without pthreads, like Windows.
This optimization is significant, and the specific value depends on the OS system and CPU, but in general, it can be considered as 10x faster, for a simple Go function call from a C thread.
For the newly added BenchmarkCGoInCThread, some benchmark results:
1. it's 28x faster, from 3395 ns/op to 121 ns/op, in darwin OS & Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
2. it's 6.5x faster, from 1495 ns/op to 230 ns/op, in Linux OS & Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz
Fixes#51676
Change-Id: I380702fe2f9b6b401b2d6f04b0aba990f4b9ee6c
GitHub-Last-Rev: 93dc64ad98
GitHub-Pull-Request: golang/go#51679
Reviewed-on: https://go-review.googlesource.com/c/go/+/392854
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: thepudds <thepudds1460@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This CL updates the cgo tool to walk the TypeParams fields for
function types and type declarations, so that C.xxx identifiers can
appear within type parameter lists.
Fixes#52542.
Change-Id: Id02a88d529d50fe59b0a834f415c2575204ffd1f
Reviewed-on: https://go-review.googlesource.com/c/go/+/453977
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
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Alpine has a known issue where setgid clobbers the Go stack (#39857).
misc/cgo/test skips other tests that use setgid on Alpine, but not
this one. It's not clear to me why this test *used to* pass, but when
I refactored misc/cgo/test in CL 447355 it started failing.
Disable this test on Alpine, like the other setgid tests.
Change-Id: I2e646ef55e2201a4f0b377319d719a011ec847f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/448355
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
When we were first introducing module mode, CL 163418 moved many of
the tests in misc/cgo/test into their own test binary under testdata
so misc/cgo/test continued to work in both GOPATH mode and module
mode. This introduce a somewhat complicated test driver into
misc/cgo/test. Since the misc/cgo/test test had to invoke "go test" as
a subprocess, this required care to thread any build flags down into
the subprocess. The output from any failures of the sub-process was
also less than ideal.
Now that we don't have to worry about running these in GOPATH mode any
more, this CL moves all of the tests back into misc/cgo/test and drops
the test driver.
There are two slight complications:
- Test41761 was added after this split and has a C type "S" that's
also present in misc/cgo/test itself. We rename that to keep that
test working.
- TestCgo in go/internal/srcimporter now fails to import misc/cgo/test
because misc/cgo/test now contains imports of other "misc" module
packages and the importer it sets up isn't configured to allow that.
We fix this by setting up a build context that's configured for
this.
Preparation for #37486.
Change-Id: I3c4f73540e0482bbd493823cca44b0ce7fac01f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/447355
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Austin Clements <austin@google.com>
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We don't have a good musl detection mechanism, so we detect Alpine (the
most common user of musl) instead.
For #39857.
For #19938.
Change-Id: I2fa39248682aed75884476374fe2212be4427347
Reviewed-on: https://go-review.googlesource.com/c/go/+/425001
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
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These changes are enough to pass all.bash using the
disabled linux-amd64-alpine builder via debugnewvm.
For #19938.
For #39857.
Change-Id: I7d160612259c77764b70d429ad94f0864689cdce
Reviewed-on: https://go-review.googlesource.com/c/go/+/419995
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TestSetgidStress originally spawns 1000 threads for stress testing.
It caused timeout on some builders so CL 415677 reduced to 50 in
short mode. But it still causes flaky timeouts in longtest
builders, so reduce the number of threads in long mode as well.
Should fix#53641.
Change-Id: I02f4ef8a143bb1faafe3d11ad223f36f5cc245c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/419453
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
TestSetgidStress spawns 1000 threads, which can be expensive on
some platforms or slow builders. Run with 50 threads in short
mode instead.
This makes the failure less reproducible even with buggy code. But
one can manually stress test it (e.g. when a flaky failure appear
on the builder).
Fixes#53641.
Change-Id: I33b5ea5ecaa8c7a56f59c16f9171657ee295db47
Reviewed-on: https://go-review.googlesource.com/c/go/+/415677
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
When we create a thread with signals blocked. But glibc's
pthread_sigmask doesn't really allow us to block SIGSETXID. So we
may get a signal early on before the signal stack is set. If we
get a signal on the current stack, it will clobber anything below
the SP. This CL makes it to save LR and decrement SP in a single
MOVD.W instruction for small frames, so we don't write below the
SP.
We used to use a single MOVD.W instruction before CL 379075.
CL 379075 changed to use an STP instruction to save the LR and FP,
then decrementing the SP. This CL changes it back, just this part
(epilogues and large frame prologues are unchanged). For small
frames, it is the same number of instructions either way.
This decreases the size of a "small" frame from 0x1f0 to 0xf0.
For frame sizes in between, it could benefit from using an
STP instruction instead of using the prologue for the "large"
frame case. We don't bother it for now as this is a stop-gap
solution anyway.
This only addresses the issue with small frames. Luckily, all
functions from thread entry to setting up the signal stack have
samll frames.
Other possible ideas:
- Expand the unwind info metadata, separate SP delta and the
location of the return address, so we can express "SP is
decremented but the return address is in the LR register". Then
we can always create the frame first then write the LR, without
writing anything below the SP (except the frame pointer at SP-8,
which is minor because it doesn't really affect program
execution).
- Set up the signal stack immediately in mstart in assembly.
For Go 1.19 we do this simple fix. We plan to do the metadata fix
in Go 1.20 ( #53609 ).
Other LR architectures are addressed in CL 413428.
Fix#53374.
Change-Id: I9d6582ab14ccb06ac61ad43852943d9555e22ae5
Reviewed-on: https://go-review.googlesource.com/c/go/+/412474
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Eric Fang <eric.fang@arm.com>
Fixes#52611
Change-Id: I835df8d6a98a37482446ec00af768c96fd8ee4fe
GitHub-Last-Rev: ea54dd69ee
GitHub-Pull-Request: golang/go#52733
Reviewed-on: https://go-review.googlesource.com/c/go/+/404497
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dexter Ouyang <kkhaike@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Alex Rakoczy <alex@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Contributors to the loong64 port are:
Weining Lu <luweining@loongson.cn>
Lei Wang <wanglei@loongson.cn>
Lingqin Gong <gonglingqin@loongson.cn>
Xiaolin Zhao <zhaoxiaolin@loongson.cn>
Meidan Li <limeidan@loongson.cn>
Xiaojuan Zhai <zhaixiaojuan@loongson.cn>
Qiyuan Pu <puqiyuan@loongson.cn>
Guoqi Chen <chenguoqi@loongson.cn>
This port has been updated to Go 1.15.6:
https://github.com/loongson/go
Updates #46229
Change-Id: I6760b4a7e51646773cd0f48baa1baba01b213b7d
Reviewed-on: https://go-review.googlesource.com/c/go/+/342325
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Rename it TestIssue1560 since it no longer sleeps.
For #1560Fixes#45586
Change-Id: I338eee9de43e871da142143943e9435218438e90
Reviewed-on: https://go-review.googlesource.com/c/go/+/400194
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
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GCC 9 warns about a change in the ABI of passing structs with bitfields,
but we don't care.
Fixes#50987
Change-Id: Ica658d04172a42a7be788f94d31a714bb8c4766f
Reviewed-on: https://go-review.googlesource.com/c/go/+/382956
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
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Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Trust: Benny Siegert <bsiegert@gmail.com>
Fixes for #49680, #49695, #45867, and #49370 all assumed that
SetGCPercent(-1) doesn't block until the GC's mark phase is done, but
it actually does. The cause of 3 of those 4 failures comes from the fact
that at the beginning of the sweep phase, the GC does try to preempt
every P once, and this may run concurrently with test code. In the
fourth case, the issue was likely that only *one* of the debug_test.go
tests was missing a call to SetGCPercent(-1). Just to be safe, leave a
TODO there for now to remove the extraneous runtime.GC calls, but leave
the calls in.
Updates #49680, #49695, #45867, and #49370.
Change-Id: Ibf4e64addfba18312526968bcf40f1f5d54eb3f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/369815
Reviewed-by: Austin Clements <austin@google.com>
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
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As suggested by #49680, a GC could be in-progress when we
disable GC. Force a GC after we pause to ensure we don't
hang in this case.
For #49695
Change-Id: I4fc4c06ef2ac174217c3dcf7d58c7669226e2d24
Reviewed-on: https://go-review.googlesource.com/c/go/+/367874
Run-TryBot: Paul Murphy <murp@ibm.com>
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If a GC triggers while spinning in RewindAndSetgid, it may result in
this test hanging. Avoid it by disabling the collector before entering
the uninterruptable ASM conditional wait.
Fixes#49695
Change-Id: Ie0a03653481fb746f862469361b7840f4bfa8b67
Reviewed-on: https://go-review.googlesource.com/c/go/+/365836
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This test otherwise fails to build on windows/arm64 as of CL 364774
due to a warning (promoted to an error) about a mismatched dllexport
attribute. Fortunately, it seems not to need the forward-declared
function in this file anyway.
Updates #49633
Updates #49721
Change-Id: Ia4698b85077d0718a55d2cc667a7950f1d8e50ab
Reviewed-on: https://go-review.googlesource.com/c/go/+/366075
Trust: Bryan C. Mills <bcmills@google.com>
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Fixes#49633
Change-Id: I12ca350f7dd6bfc8753a4a169f29b89ef219b035
Reviewed-on: https://go-review.googlesource.com/c/go/+/364774
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
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Trust: Bryan C. Mills <bcmills@google.com>
Allows cgo to work with generics.
Updates #47781.
Change-Id: Id1a5d1a0a8193c5b157e3e671b1490d687d10384
Reviewed-on: https://go-review.googlesource.com/c/go/+/353882
Trust: Matthew Dempsky <mdempsky@google.com>
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Applying -Werror compiler option to request warnings is an usual
way to discover potential errors. Go user may put a cgo directive
in preamble: `// #cgo CFLAGS: -Werror=unused-parameter`.
However, the directive also takes effect on the cgo generated files.
I cleaned _cgo_main.c to help Go user only concentrate on warnings
of their own file.
Fixes#43639
Change-Id: I9112f02ae5226f2fc87a8650d19faee59cddd588
GitHub-Last-Rev: f09d172f97
GitHub-Pull-Request: golang/go#46358
Reviewed-on: https://go-review.googlesource.com/c/go/+/322232
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CL 294430 made packages in std and cmd modules use Go 1.17 gofmt format,
adding //go:build lines. This change applies the same formatting to some
more packages that 'go fmt' missed (e.g., syscall/js, runtime/msan), and
everything else that is easy and safe to modify in bulk.
Consider the top-level test directory, testdata, and vendor directories
out of scope, since there are many files that don't follow strict gofmt
formatting, often for intentional and legitimate reasons (testing gofmt
itself, invalid Go programs that shouldn't crash the compiler, etc.).
That makes it easy and safe to gofmt -w the .go files that are found
with gofmt -l with aforementioned directories filtered out:
$ gofmt -l . 2>/dev/null | \
grep -v '^test/' | \
grep -v '/testdata/' | \
grep -v '/vendor/' | wc -l
51
None of the 51 files are generated. After this change, the same command
prints 0.
For #41184.
Change-Id: Ia96ee2a0f998d6a167d4473bcad17ad09bc1d86e
Reviewed-on: https://go-review.googlesource.com/c/go/+/341009
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
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Trust: Dmitri Shuralyov <dmitshur@golang.org>
The test previously had the hardcoded assumption that /proc/self/status
files had "Groups:" lines containing numerical IDs in ascending order.
Because of the possibility of non-monotonic ordering of GIDs in user
namespaces, this assumption was not universally true for all
/proc/self/gid_map setups.
To ensure this test can pass in those setups, sanity check failed
"Groups:" line matches with a string sorted version of the expected
values. (For the test cases here, numerical and string sorted order
are guaranteed to match.)
Fixes#46145
Change-Id: Ia060e80b123604bc394a15c02582fc406f944d36
Reviewed-on: https://go-review.googlesource.com/c/go/+/319591
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Trust: Tobias Klauser <tobias.klauser@gmail.com>
An exported Go function like
//export F
func F() {}
gets declared in _cgo_export.h as something like
extern void F(void);
The exact declaration varies by operating system.
In particular, Windows adds __declspec(dllimport).
Clang on Windows/ARM64 rejects code that contains
conflicting declarations for F, like:
extern void F(void);
extern void __declspec(dllimport) F(void);
This means that F must not be declared separately from _cgo_export.h:
any code that wants to refer to F must use #include "_cgo_export.h".
Unfortunately, the cgo prologue itself (the commented code before import "C")
cannot include "_cgo_export.h", because that file is itself produced from the
cgo Go sources and therefore cannot be a dependency of the cgo Go sources.
This CL rewrites misc/cgo/test to avoid redeclaring exported functions.
Most of the time, this is not a significant problem: just move the code
that needs the header into a .c file, perhaps with a wrapper exposed
to the cgo Go sources.
The one case that is potentially problematic is f7665, which is part of
the test for golang.org/issue/7665. That bug report explicitly identified
a bug in referring to the C name for an exported function in the same
Go source file as it was exported function. That is now impossible,
at least on Windows/ARM64, so the test is modified a bit and possibly
does not test what the original bug was. But the original bug should
be long gone: that part of the compiler has been rewritten.
Change-Id: I0d14d9336632f0e5e3db4273d9d32ef2cca0298d
Reviewed-on: https://go-review.googlesource.com/c/go/+/312029
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
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Reviewed-by: Cherry Zhang <cherryyz@google.com>
This follows the spelling choices that the Go project has made for English words.
https://github.com/golang/go/wiki/Spelling
Change-Id: Ie7c586d2cf23020cb492cfff58c0831d2d8d3a78
GitHub-Last-Rev: e16a32cd22
GitHub-Pull-Request: golang/go#45442
Reviewed-on: https://go-review.googlesource.com/c/go/+/308291
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Trust: Emmanuel Odeke <emmanuel@orijtech.com>
For #42076Fixes#45451
Change-Id: I69646226d3480d5403205412ddd13c0cfc2c8a53
Reviewed-on: https://go-review.googlesource.com/c/go/+/308970
Trust: Ian Lance Taylor <iant@golang.org>
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Reviewed-by: Keith Randall <khr@golang.org>
A non-trivial Cgo program may need to use callbacks and interact with
go objects per goroutine. Because of the rules for passing pointers
between Go and C, such a program needs to store handles to associated
Go values. This often causes much extra effort to figure out a way to
correctly deal with: 1) map collision; 2) identifying leaks and 3)
concurrency.
This CL implements a Handle representation in runtime/cgo package, and
related methods such as Value, Delete, etc. which allows Go users can
use a standard way to handle the above difficulties.
In addition, the CL allows a Go value to have multiple handles, and the
NewHandle always returns a different handle compare to the previously
returned handles. In comparison, CL 294670 implements a different
behavior of NewHandle that returns a unique handle when the Go value is
referring to the same object.
Benchmark:
name time/op
Handle/non-concurrent-16 487ns ± 1%
Handle/concurrent-16 674ns ± 1%
Fixes#37033
Change-Id: I0eadb9d44332fffef8fb567c745246a49dd6d4c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/295369
Run-TryBot: Ian Lance Taylor <iant@golang.org>
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Trust: Cherry Zhang <cherryyz@google.com>
Update references missed in CL 263142.
For #41190
Change-Id: I778760a6a69bd0440fec0848bdef539c9ccb4ee1
GitHub-Last-Rev: dda42b09ff
GitHub-Pull-Request: golang/go#42874
Reviewed-on: https://go-review.googlesource.com/c/go/+/273946
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s/!gccgo/gc/ in files which use gc-syntax assembly.
Change-Id: Ifdadb62edd1210ebc70e7cd415648b752afaf067
Reviewed-on: https://go-review.googlesource.com/c/go/+/269957
Reviewed-by: Than McIntosh <thanm@google.com>
Trust: David Chase <drchase@google.com>
Trust: Matthew Dempsky <mdempsky@google.com>
Both asmcgocall and systemstack need to save the calling Go code's
context for use by traceback, but they do it differently.
Systemstack's appraoch is better, because it doesn't require a
special case in traceback.
So make them both use that.
While we are here, the fake mstart caller in systemstack is
no longer needed and can be removed.
(traceback knows to stop in systemstack because of the writes to SP.)
Also remove the fake mstarts in sys_windows_*.s.
And while we are there, fix the control flow guard code in sys_windows_arm.s.
The current code is using pointers to a stack frame that technically is gone
once we hit the RET instruction. Clearly it's working OK, but better not to depend
on data below SP being preserved, even for just a few instructions.
Store the value we need in other registers instead.
(This code is only used for pushing a sigpanic call, which does not
actually return to the site of the fault and therefore doesn't need to
preserve any of the registers.)
This CL is part of a stack adding windows/arm64
support (#36439), intended to land in the Go 1.17 cycle.
This CL is, however, not windows/arm64-specific.
It is cleanup meant to make the port (and future ports) easier.
Change-Id: Id1e3ef5e54f7ad786e4b87043f2626eba7c3bbd9
Reviewed-on: https://go-review.googlesource.com/c/go/+/288799
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Somehow I missed that one. It works fine.
Change-Id: I0b1286bf1e6a8f40b9f3f114f49b3034079e0b85
Reviewed-on: https://go-review.googlesource.com/c/go/+/280156
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
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CL 258938 changed the way C to Go calls work such that they now
construct a C struct on the C side for the arguments and space for the
results. Any pointers in the result space must be zeroed, so we just
zero the whole struct.
However, C makes it surprisingly hard to robustly zero any struct
type. We had used a "{0}" initializer, which works in the vast
majority of cases, but fails if the type is empty or effectively
empty.
This CL fixes this by changing how the cgo tool zero-initializes the
argument struct to be more robust.
Fixes#42495.
Change-Id: Id1749b9d751e59eb7a02a9d44fec0698a2bf63cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/269337
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TestSetuidEtc() was failing sporadically on linux-ppc64. From the
three https://build.golang.org/ logs, it looked like the logged
errors could be associated with threads dying, but proc reads
were, in some way, racing with their demise.
Exploring ways to increase thread demise, revealed that races
of this type can happen on non-ppc64 systems, and that
os.IsNotExist(err) was not a sufficient error condition test
for a thread's status file disappearing. This change includes a
fix for that to.
The actual issue on linux-ppc64 appears to be tied to PID reaping
and reuse latency on whatever the build test environment is for
linux-ppc64-buildlet. I suspect this can happen on any linux
system, however, especially where the container has a limited PID
range.
The fix for this, limited to the test (the runtime syscall support
is unchanged), is to confirm that the Pid for the interrogated
thread's /proc/<TID>/status file confirms that it is still
associated with the test-process' PID.
linux-ppc64-buildlet:
go/bin/go test syscall -run=TestSetuidEtc -count=10000
ok syscall 104.285s
Fixes#42462
Change-Id: I55c84ab8361003570a405fa52ffec4949bf91113
Reviewed-on: https://go-review.googlesource.com/c/go/+/268717
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Fixes#36641
Change-Id: I51868d83ce341d78d33b221d184c5a5110c60d14
Reviewed-on: https://go-review.googlesource.com/c/go/+/263598
Trust: Joel Sing <joel@sing.id.au>
Run-TryBot: Joel Sing <joel@sing.id.au>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Allocate a C enum object, and test if it can be assigned a value
successfully.
For #39537
Change-Id: I7b5482112486440b9d99f2ee4051328d87f45dca
GitHub-Last-Rev: 81890f40ac
GitHub-Pull-Request: golang/go#39977
Reviewed-on: https://go-review.googlesource.com/c/go/+/240697
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
This redesigns the way calls work from C to exported Go functions. It
removes several steps from the call path, makes cmd/cgo no longer
sensitive to the Go calling convention, and eliminates the use of
reflectcall from cgo.
In order to avoid generating a large amount of FFI glue between the C
and Go ABIs, the cgo tool has long depended on generating a C function
that marshals the arguments into a struct, and then the actual ABI
switch happens in functions with fixed signatures that simply take a
pointer to this struct. In a way, this CL simply pushes this idea
further.
Currently, the cgo tool generates this argument struct in the exact
layout of the Go stack frame and depends on reflectcall to unpack it
into the appropriate Go call (even though it's actually
reflectcall'ing a function generated by cgo).
In this CL, we decouple this struct from the Go stack layout. Instead,
cgo generates a Go function that takes the struct, unpacks it, and
calls the exported function. Since this generated function has a
generic signature (like the rest of the call path), we don't need
reflectcall and can instead depend on the Go compiler itself to
implement the call to the exported Go function.
One complication is that syscall.NewCallback on Windows, which
converts a Go function into a C function pointer, depends on
cgocallback's current dynamic calling approach since the signatures of
the callbacks aren't known statically. For this specific case, we
continue to depend on reflectcall. Really, the current approach makes
some overly simplistic assumptions about translating the C ABI to the
Go ABI. Now we're at least in a much better position to do a proper
ABI translation.
For comparison, the current cgo call path looks like:
GoF (generated C function) ->
crosscall2 (in cgo/asm_*.s) ->
_cgoexp_GoF (generated Go function) ->
cgocallback (in asm_*.s) ->
cgocallback_gofunc (in asm_*.s) ->
cgocallbackg (in cgocall.go) ->
cgocallbackg1 (in cgocall.go) ->
reflectcall (in asm_*.s) ->
_cgoexpwrap_GoF (generated Go function) ->
p.GoF
Now the call path looks like:
GoF (generated C function) ->
crosscall2 (in cgo/asm_*.s) ->
cgocallback (in asm_*.s) ->
cgocallbackg (in cgocall.go) ->
cgocallbackg1 (in cgocall.go) ->
_cgoexp_GoF (generated Go function) ->
p.GoF
Notably:
1. We combine _cgoexp_GoF and _cgoexpwrap_GoF and move the combined
operation to the end of the sequence. This combined function also
handles reflectcall's previous role.
2. We combined cgocallback and cgocallback_gofunc since the only
purpose of having both was to convert a raw PC into a Go function
value. We instead construct the Go function value in cgocallbackg1.
3. cgocallbackg1 no longer reaches backwards through the stack to get
the arguments to cgocallback_gofunc. Instead, we just pass the
arguments down.
4. Currently, we need an explicit msanwrite to mark the results struct
as written because reflectcall doesn't do this. Now, the results are
written by regular Go assignments, so the Go compiler generates the
necessary MSAN annotations. This also means we no longer need to track
the size of the arguments frame.
Updates #40724, since now we don't need to teach cgo about the
register ABI or change how it uses reflectcall.
Change-Id: I7840489a2597962aeb670e0c1798a16a7359c94f
Reviewed-on: https://go-review.googlesource.com/c/go/+/258938
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
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 <emm.odeke@gmail.com>
Trust: Ian Lance Taylor <iant@golang.org>
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Cgo programs work as well. Still not enabled by default for now.
Enable internal linking tests.
Updates #38485.
Change-Id: I8324a5c263fba221eb4e67d71207ca84fa241e6c
Reviewed-on: https://go-review.googlesource.com/c/go/+/263637
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This CL adds support of PIE internal linking on darwin/amd64.
This is also preparation for supporting internal linking on
darwin/arm64 (macOS), which requires PIE for everything.
Updates #38485.
Change-Id: I2ed58583dcc102f5e0521982491fc7ba6f2754ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/261642
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Currently we don't use sigaltstack on darwin/arm64, as is not
supported on iOS. However, it is supported on macOS. Use it.
(iOS remains unchanged.)
Change-Id: Icc154c5e2edf2dbdc8ca68741ad9157fc15a72ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/256917
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
In the rare case when a cgo type makes it into an object file, we need
the go:notinheap annotation to go with it.
Fixes#41761
Change-Id: I541500cb1a03de954881aef659f96fc0b7738848
Reviewed-on: https://go-review.googlesource.com/c/go/+/259297
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Introduce GOOS=ios for iOS systems. GOOS=ios matches "darwin"
build tag, like GOOS=android matches "linux" and GOOS=illumos
matches "solaris". Only ios/arm64 is supported (ios/amd64 is
not).
GOOS=ios and GOOS=darwin remain essentially the same at this
point. They will diverge at later time, to differentiate macOS
and iOS.
Uses of GOOS=="darwin" are changed to (GOOS=="darwin" || GOOS=="ios"),
except if it clearly means macOS (e.g. GOOS=="darwin" && GOARCH=="amd64"),
it remains GOOS=="darwin".
Updates #38485.
Change-Id: I4faacdc1008f42434599efb3c3ad90763a83b67c
Reviewed-on: https://go-review.googlesource.com/c/go/+/254740
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
cgo effectively prepends -I${SRCDIR} to the header include path of all
preambles it processes, so when an #include <> matches a header file
both in the source directory and also another include directory, the
local copy will be used in preference.
This behaviour is surprising but unfortunately also longstanding and
relied upon by packages in the wild, so the best we can do is to
document it.
Fixes#41059
Change-Id: If6d2818294b2bd94ea0fe5fd6ce77e54b3e167a6
Reviewed-on: https://go-review.googlesource.com/c/go/+/251758
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Consider this test package:
package p
// enum E { E0 };
// union U { long x; };
// void f(enum E e, union U* up) {}
import "C"
func f() {
C.f(C.enum_E(C.E0), (*C.union_U)(nil))
}
In Go 1.14, cgo translated this to (omitting irrelevant details):
type _Ctype_union_U [8]byte
func f() {
_Cfunc_f(uint32(_Ciconst_E0), (*[8]byte)(nil))
}
func _Cfunc_f(p0 uint32, p1 *[8]byte) (r1 _Ctype_void) { ... }
Notably, _Ctype_union_U was declared as a defined type, but uses were
being rewritten into uses of the underlying type, which matched how
_Cfunc_f was declared.
After CL 230037, cgo started consistently rewriting "C.foo" type
expressions as "_Ctype_foo", which caused it to start emitting:
type _Ctype_enum_E uint32
type _Ctype_union_U [8]byte
func f() {
_Cfunc_f(_Ctype_enum_E(_Ciconst_E0), (*_Ctype_union_U)(nil))
}
// _Cfunc_f unchanged
Of course, this fails to type-check because _Ctype_enum_E and
_Ctype_union_U are defined types.
This CL changes cgo to emit:
type _Ctype_enum_E = uint32
type _Ctype_union_U = [8]byte
// f unchanged since CL 230037
// _Cfunc_f still unchanged
It would probably be better to fix this in (*typeConv).loadType so
that cgo generated code uses the _Ctype_foo aliases too. But as it
wouldn't have any effect on actual compilation, it's not worth the
risk of touching it at this point in the release cycle.
Updates #39537.
Fixes#40494.
Change-Id: I88269660b40aeda80a9a9433777601a781b48ac0
Reviewed-on: https://go-review.googlesource.com/c/go/+/246057
Reviewed-by: Ian Lance Taylor <iant@golang.org>
CL 230037 changed cmd/cgo to emit "type _Ctype_foo = bar" aliases for
all C.foo types mentioned in the original Go source files. However,
cmd/cgo already emits an appropriate type definition for _Ctype_void.
So if a source file explicitly mentions C.void, this resulted in
_Ctype_void being declared multiple times.
This CL fixes the issue by suppressing the "type _Ctype_void =
_Ctype_void" alias before printing it. This should be safe because
_Ctype_void is the only type that's specially emitted in out.go at the
moment.
A somewhat better fix might be to fix how _Ctype_void is declared in
the cmd/cgo "frontend", but this is a less invasive fix.
Fixes#39877.
Change-Id: Ief264b3847c8ef8df1478a6333647ff2cf09b63d
Reviewed-on: https://go-review.googlesource.com/c/go/+/240180
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Similarly to EGLDisplay, EGLConfig is declared as a pointer but may
contain non-pointer values.
I believe this is the root cause of https://todo.sr.ht/~eliasnaur/gio/121.
Change-Id: I412c4fbc2eef4aa028534d68bda95db98e3a365d
Reviewed-on: https://go-review.googlesource.com/c/go/+/235817
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Cgo's initial design for handling "#define foo int*" involved
rewriting "C.foo" to "*_Ctype_int" everywhere. But now that we have
type aliases, we can declare "type _Ctype_foo = *_Ctype_int" once, and
then rewrite "C.foo" to just "_Ctype_foo".
This is important for go/types's UsesCgo mode, where go/types needs to
be able to figure out a type for each C.foo identifier using only the
information written into _cgo_gotypes.go.
Fixes#38649.
Change-Id: Ia0f8c2d82df81efb1be5bc26195ea9154c0af871
Reviewed-on: https://go-review.googlesource.com/c/go/+/230037
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This removes all conditions and conditional code (that I could find)
that depended on darwin/386.
Fixes#37610.
Change-Id: I630d9ea13613fb7c0bcdb981e8367facff250ba0
Reviewed-on: https://go-review.googlesource.com/c/go/+/227582
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
