Acquire and release the TSAN synchronization point when calling malloc,
just as we do when calling any other C function. If we don't do this,
TSAN will report false positive errors about races calling malloc and
free.
We used to have a special code path for malloc and free, going through
the runtime functions cmalloc and cfree. The special code path for cfree
was no longer used even before this CL. This CL stops using the special
code path for malloc, because there is no place along that path where we
could conditionally insert the TSAN synchronization. This CL removes
the support for the special code path for both functions.
Instead, cgo now automatically generates the malloc function as though
it were referenced as C.malloc. We need to automatically generate it
even if C.malloc is not called, even if malloc and size_t are not
declared, to support cgo-provided functions like C.CString.
Change-Id: I829854ec0787a80f33fa0a8a0dc2ee1d617830e2
Reviewed-on: https://go-review.googlesource.com/23260
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
When the generated stub functions write back the results to the stack,
they can in some cases be writing to the same memory on the g0 stack.
There is no race here (assuming there is no race in the Go code), but
the thread sanitizer does not know that. Turn off the thread sanitizer
for the stub functions to prevent false positive warnings.
Current clang suggests the no_sanitize("thread") attribute, but that
does not work with clang 3.6 or GCC. clang 3.6, GCC, and current clang
all support the no_sanitize_thread attribute, so use that
unconditionally.
The test case and first version of the patch are from Dmitriy Vyukov.
Change-Id: I80ce92824c6c8cf88ea0fe44f21cf50cf62474c9
Reviewed-on: https://go-review.googlesource.com/23252
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
When Go code is used with C code compiled with -fsanitize=thread, adds
thread sanitizer calls so that correctly synchronized Go code does not
cause spurious failure reports from the thread sanitizer. This may
cause some false negatives, but for the thread sanitizer what is most
important is avoiding false positives.
Change-Id: If670e4a6f2874c7a2be2ff7db8728c6036340a52
Reviewed-on: https://go-review.googlesource.com/17421
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Avoids an msan error when runtime/cgo is explicitly rebuilt with
-fsanitize=memory.
Fixes#13815.
Change-Id: I70308034011fb308b63585bcd40b0d1e62ec93ef
Reviewed-on: https://go-review.googlesource.com/18263
Reviewed-by: Russ Cox <rsc@golang.org>
Fix a typo in de5b386; using `$ver` to determine linux major/minor
versions would produce those for clang, use `$linuxver` instead.
Updates #12898.
Change-Id: I2c8e84ad02749fceaa958afd65e558bb0b08dddb
Reviewed-on: https://go-review.googlesource.com/17323
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
These are simply incompatible. Clang fixed the bug but not in older versions.
Fixes#12898.
Change-Id: I74a3fd9134dadab6d0f074f8fd09e00d64558d7a
Reviewed-on: https://go-review.googlesource.com/17254
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The runtime is not instrumented, but the calls to msanread in the
runtime can sometimes refer to the system stack. An example is the call
to copy in stkbucket in mprof.go. Depending on what C code has done,
the system stack may appear uninitialized to msan.
Change-Id: Ic21705b9ac504ae5cf7601a59189302f072e7db1
Reviewed-on: https://go-review.googlesource.com/16660
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This is a fix for the -msan option when using cgo callbacks. A cgo
callback works by writing out C code that puts a struct on the stack and
passes the address of that struct into Go. The result parameters are
fields of the struct. The Go code will write to the result parameters,
but the Go code thinks it is just writing into the Go stack, and
therefore won't call msanwrite. This CL adds a call to msanwrite in the
cgo callback code so that the C knows that results were written.
Change-Id: I80438dbd4561502bdee97fad3f02893a06880ee1
Reviewed-on: https://go-review.googlesource.com/16611
Reviewed-by: David Crawshaw <crawshaw@golang.org>
The current mechanism fails if clang cannot be executed by the current
user. Using the `-x` operator for `test` return TRUE if the file is
executable by the user.
Change-Id: I0f3c8dc3880c1ce5a8a833ff3109eb96853184af
Reviewed-on: https://go-review.googlesource.com/16752
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The width of the type of an external variable defined with a type
literal may not be set when the instrumentation pass is run. There are
two cases in the standard library that fail without the call to dowidth:
../../../src/encoding/base32/base32.go:322: constant -1000000000 overflows uintptr
../../../src/encoding/base32/base32.go:329: constant -1000000000 overflows uintptr
../../../src/encoding/json/encode.go:385: constant -1000000000 overflows uintptr
../../../src/encoding/json/encode.go:387: constant -1000000000 overflows uintptr
Change-Id: I7c3334f7decdb7488595ffe4090cd262d7334283
Reviewed-on: https://go-review.googlesource.com/16331
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
On older versions of GCC we need to pass a file name before GCC will
report an unrecognized option.
Fixes#13065.
Change-Id: I7ed34c01a006966a446059025f7d10235c649072
Reviewed-on: https://go-review.googlesource.com/16589
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Also fix the msan_fail test. It was bogus, since it always aborted one
way or another.
Change-Id: Ic693327d1bddb7bc5c7d859ac047fc93cb9b5b1c
Reviewed-on: https://go-review.googlesource.com/16172
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The -msan option compiles Go code to use the memory sanitizer. This is
intended for use when linking with C/C++ code compiled with
-fsanitize=memory. When memory blocks are passed back and forth between
C/C++ and Go, code in both languages will agree as to whether the memory
is correctly initialized or not, and will report errors for any use of
uninitialized memory.
Change-Id: I2dbdbd26951eacb7d84063cfc7297f88ffadd70c
Reviewed-on: https://go-review.googlesource.com/16169
Reviewed-by: David Crawshaw <crawshaw@golang.org>
The memory sanitizer (msan) is a nice compiler feature that can
dynamically check for memory errors in C code. It's not useful for Go
code, since Go is memory safe. But it is useful to be able to use the
memory sanitizer on C code that is linked into a Go program via cgo.
Without this change it does not work, as msan considers memory passed
from Go to C as uninitialized.
To make this work, change the runtime to call the C mmap function when
using cgo. When using msan the mmap call will be intercepted and marked
as returning initialized memory.
Work around what appears to be an msan bug by calling malloc before we
call mmap.
Change-Id: I8ab7286d7595ae84782f68a98bef6d3688b946f9
Reviewed-on: https://go-review.googlesource.com/15170
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
