This implements part of the proposal in issue 12416 by adding dynamic
checks for passing pointers from Go to C. This code is intended to be
on at all times. It does not try to catch every case. It does not
implement checks on calling Go functions from C.
The new cgo checks may be disabled using GODEBUG=cgocheck=0.
Update #12416.
Change-Id: I48de130e7e2e83fb99a1e176b2c856be38a4d3c8
Reviewed-on: https://go-review.googlesource.com/16003
Reviewed-by: Russ Cox <rsc@golang.org>
Fixes these warnings from go vet:
buildid_linux.go:25: no formatting directive in Fatalf call
callback.go:180: arg pc[i] for printf verb %p of wrong type: uintptr
env.go:34: possible misuse of unsafe.Pointer
issue7665.go:22: possible misuse of unsafe.Pointer
Change-Id: I83811b9c10c617139713a626b4a34ab05564d4fe
Reviewed-on: https://go-review.googlesource.com/15802
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This memory is untyped and can't be used anymore.
The next version of SWIG won't need it.
Change-Id: I592b287c5f5186975ee09a9b28d8efe3b57134e7
Reviewed-on: https://go-review.googlesource.com/8956
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This test is doing pointer graph manipulation from C, and we
cannot support that with concurrent GC. The wbshadow mode
correctly diagnoses missing write barriers.
Disable the test in that mode for now. There is a bigger issue
behind it, namely SWIG, but for now we are focused on making
all.bash pass with wbshadow enabled.
Change-Id: I55891596d4c763e39b74082191d4a5fac7161642
Reviewed-on: https://go-review.googlesource.com/2346
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Use typedmemmove, typedslicecopy, and adjust reflect.call
to execute the necessary write barriers.
Found with GODEBUG=wbshadow=2 mode.
Eventually that will run automatically, but right now
it still detects other missing write barriers.
Change-Id: Iec5b5b0c1be5589295e28e5228e37f1a92e07742
Reviewed-on: https://go-review.googlesource.com/2312
Reviewed-by: Keith Randall <khr@golang.org>
For Go 1.5, we can use go:linkname rather than assembly thunk for gc.
Gccgo already has support for //extern.
Change-Id: I5505aa247dd5b555112f7261ed2f192c81cf0bdf
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/1888
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
During a cgo call, the stack can be copied. This copy invalidates
the pointer that cgo has into the return value area. To fix this
problem, pass the address of the location containing the stack
top value (which is in the G struct). For cgo functions which
return values, read the stktop before and after the cgo call to
compute the adjustment necessary to write the return value.
Fixes#8771
LGTM=iant, rsc
R=iant, rsc, khr
CC=golang-codereviews
https://golang.org/cl/144130043
Now it's two allocations. I don't see much downside to that,
since the two pieces were in different cache lines anyway.
Rename 'conservative' to 'cgo_conservative_type' and make
clear that _cgo_allocate is the only allowed user.
This depends on CL 141490043, which removes the other
use of conservative (in defer).
LGTM=dvyukov, iant
R=khr, dvyukov, iant
CC=golang-codereviews, rlh
https://golang.org/cl/139610043
newstackcall creates a new stack segment, and we want to
be able to throw away all that code.
LGTM=khr
R=khr, iant
CC=dvyukov, golang-codereviews, r
https://golang.org/cl/139270043
Instead of making asmcgocall call asmcgocall_errno,
make both load args into registers and call a shared
assembly function.
On amd64, this costs 1 word in the asmcgocall_errno path
but saves 3 words in the asmcgocall path, and the latter
is what happens on critical nosplit paths on Windows.
On arm, this fixes build failures: asmcgocall was writing
the arguments for asmcgocall_errno into the wrong
place on the stack. Passing them in registers avoids the
decision entirely.
On 386, this isn't really needed, since the nosplit paths
have twice as many words to work with, but do it for consistency.
Update #8635
Fixes arm build (except GOARM=5).
TBR=iant
CC=golang-codereviews
https://golang.org/cl/134390043
Basically a partial rollback of 12053043 until I can
figure out what is really going on.
Fixes bug 6051.
R=golang-dev
CC=golang-dev
https://golang.org/cl/12496043
Split stack checks (morestack) corrupt g->sched,
but g->sched must be preserved consistent for GC/traceback.
The change implements runtime.notetsleepg function,
which does entersyscall/exitsyscall and is carefully arranged
to not call any split functions in between.
R=rsc
CC=golang-dev
https://golang.org/cl/11575044
Don't require a full-scale callback for calls to the special
prologue functions.
Always use a simple wrapper function for C functions, so that
we can handle static functions defined in the import "C"
comment.
Disable a test that relies on gc-specific function names.
Fixes#5905.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/11406047
Add gostartcall and gostartcallfn.
The old gogocall = gostartcall + gogo.
The old gogocallfn = gostartcallfn + gogo.
R=dvyukov, minux.ma
CC=golang-dev
https://golang.org/cl/10036044
The arm gentraceback mishandled frame linkage values pointing
to the assembly return function. This function is special as
its frame size is zero and it contains only one instruction.
These conditions would preserve the frame pointer and result
in an off by one error when unwinding the caller.
Fixes#5124
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/8023043
The ARM implementation of runtime.cgocallback_gofunc diverged
from the calling convention by leaving a word of garbage at
the top of the stack and storing the return PC above the
locals. This change stores the return PC at the top of the
stack and removes the save area above the locals.
Update #5124
This CL fixes first part of the ARM issues and added the unwind test.
R=golang-dev, bradfitz, minux.ma, cshapiro, rsc
CC=golang-dev
https://golang.org/cl/7728045
The new gotest ignores Test functions outside *_test.go files
(the old shell script allowed them), so replace one clumsy hack
with another.
The root problem is that the package makefiles only know
how to run cgo for source files in the package proper, not
for test files. Making it work for test files is probably more
trouble than it's worth.
R=bradfitz
CC=golang-dev
https://golang.org/cl/4452060
* Change use of m->g0 stack (aka scheduler stack).
* Provide runtime.mcall(f) to invoke f() on m->g0 stack.
* Replace scheduler loop entry with runtime.mcall(schedule).
Runtime.mcall eliminates the need for fake scheduler states that
exist just to run a bit of code on the m->g0 stack
(Grecovery, Gstackalloc).
The elimination of the scheduler as a loop that stops and
starts using gosave and gogo fixes a bad interaction with the
way cgo uses the m->g0 stack. Cgo runs external (gcc-compiled)
C functions on that stack, and then when calling back into Go,
it sets m->g0->sched.sp below the added call frames, so that
other uses of m->g0's stack will not interfere with those frames.
Unfortunately, gogo (longjmp) back to the scheduler loop at
this point would end up running scheduler with the lower
sp, which no longer points at a valid stack frame for
a call to scheduler. If scheduler then wrote any function call
arguments or local variables to where it expected the stack
frame to be, it would overwrite other data on the stack.
I realized this possibility while debugging a problem with
calling complex Go code in a Go -> C -> Go cgo callback.
This wasn't the bug I was looking for, it turns out, but I believe
it is a real bug nonetheless. Switching to runtime.mcall, which
only adds new frames to the stack and never jumps into
functions running in existing ones, fixes this bug.
* Move cgo-related code out of proc.c into cgocall.c.
* Add very large comment describing cgo call sequences.
* Simpilify, regularize cgo function implementations and names.
* Add test suite as misc/cgo/test.
Now the Go -> C path calls cgocall, which calls asmcgocall,
and the C -> Go path calls cgocallback, which calls cgocallbackg.
The shuffling, which affects mainly the callback case, moves
most of the callback implementation to cgocallback running
on the m->curg stack (not the m->g0 scheduler stack) and
only while accounted for with $GOMAXPROCS (between calls
to exitsyscall and entersyscall).
The previous callback code did not block in startcgocallback's
approximation to exitsyscall, so if, say, the garbage collector
were running, it would still barge in and start doing things
like call malloc. Similarly endcgocallback's approximation of
entersyscall did not call matchmg to kick off new OS threads
when necessary, which caused the bug in issue 1560.
Fixes#1560.
R=iant
CC=golang-dev
https://golang.org/cl/4253054
