Joel Dice [Sat, 7 Oct 2023 00:10:58 +0000 (18:10 -0600)]
remove `-nostdlib` from libc.so link command (#440)
Per https://reviews.llvm.org/D156205 (which we're planning to backport to LLVM
17 and pull into `wasi-sdk`), we want to link crt1-reactor.o into libc.so so it
exports `_initialize` instead of `__wasm_call_ctors`.
* add `-nodefaultlibs` to libc.so link command
This ensures that `-lc` is not passed to `wasm-ld`.
Joel Dice [Thu, 28 Sep 2023 13:11:09 +0000 (07:11 -0600)]
add shared library support (#429)
* add shared library support
This adds support for building WASI shared libraries per
https://github.com/WebAssembly/tool-conventions/blob/main/DynamicLinking.md.
For the time being, the goal is to allow "pseudo-dynamic" linking using the
Component Model per
https://github.com/WebAssembly/component-model/blob/main/design/mvp/examples/SharedEverythingDynamicLinking.md.
This requires all libraries to be available when the component is created, but
still allows runtime symbol resolution via `dlopen`/`dlsym` backed by a static
lookup table. This is sufficient to support Python native extensions, for
example. A complete demo using `wit-component` is available at
https://github.com/dicej/component-linking-demo.
This commit adds support for building `libc.so`, `libc++.so`, and `libc++abi.so`
alongside their static counterparts.
Notes:
- I had to refactor `errno` support a bit to avoid a spurious `_ZTH5errno` (AKA "thread-local initialization routine for errno") import in `libc++.so`.
- Long double print and scan are included by default in `libc.so` rather than in a separate library.
- `__main_argc_argv` is now a weak symbol since it's not relevant for reactors.
- `dlopen`/`dlsym` rely on a lookup table provided by the "dynamic" linker via `__wasm_set_libraries`. Not all flags are supported yet, and unrecognized flags will result in an error.
- This requires https://reviews.llvm.org/D153293, which we will need to backport to LLVM 16 until 17 is released. I'll open a `wasi-sdk` PR with that change and various Makefile tweaks to support shared libraries.
- `libc.so` is temporarily disabled for the `wasi-threads` build until someone can make `wasi_thread_start.s` position-independent.
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
build `-fPIC` .o files separately from non-`-fPIC` ones
This allows us to build both libc.so and libc.a without incurring indirection
penalties in the latter.
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
only build libc.so when explicitly requested
Shared library support in LLVM for non-Emscripten Wasm targets will be added in
version 17, which has not yet been released, so we should not attempt to build
libc.so by default (at least not yet).
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
remove dl.c
I'll open a separate PR for this later.
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
update `check-symbols` files
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* generate separate .so files for emulated features
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* revert errno changes in favor of a smaller change
@yamt pointed out there's an easier way to address the `_ZTH5errno` issue I
described in an earlier commit: use `_Thread_local` for both C and C++. This
gives us a simpler ABI and avoids needing to import a thread-local initializer
for `errno` in libc++.so.
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* remove redundant `$(OBJDIR)/%.long-double.pic.o` rule in Makefile
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* consolidate libwasi-emulated-*.so into a single library
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* add comment explaining use of `--whole-archive`
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* Revert "remove redundant `$(OBJDIR)/%.long-double.pic.o` rule in Makefile"
* move `__main_void` from __main_void.c to crt1-command.c
This and `__main_argc_argv` are only relevant for commands (not reactors), so it
makes sense to scope them accordingly. In addition, the latter was being
imported from libc.so, forcing applications to provide it even if it wasn't
relevant.
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* Revert "consolidate libwasi-emulated-*.so into a single library"
Andrew Brown [Fri, 13 Jan 2023 02:56:52 +0000 (18:56 -0800)]
threads: change `wasm32-wasi-pthread` to `wasm32-wasi-threads` (#381)
* Change `wasm32-wasi-pthread` to `wasm32-wasi-threads`
After some thought, I think that we should rename the `THREAD_MODEL=posix` build to avoid confusion. Why? Though in this project the use of this target does involve pthreads, it will not be so in other standard libraries or languages (see, e.g., https://github.com/rust-lang/compiler-team/issues/574). I think it would be preferable to emphasize the "threads" Wasm-level proposal and the "wasi-threads" proposal rather than the specific details of which threading API is being exposed.
* fix: rename the `expected` output directory as well
Alex Crichton [Mon, 9 Jan 2023 16:33:05 +0000 (10:33 -0600)]
Don't use sbrk(0) to determine the initial heap size (#377)
* Don't use sbrk(0) to determine the initial heap size
This commit changes the `try_init_allocator` function as part of
dlmalloc to not use `sbrk(0)` to determine the initial heap size. The
purpose of this function is to use the extra memory at the end of linear
memory for the initial allocation heap before `memory.grow` is used to
allocate more memory. To learn the extent of this region the code
previously would use `sbrk(0)` to find the current size of linear
memory. This does not work, however, when other systems have called
`memory.grow` before this function is called. For example if another
allocator is used or if another component of a wasm binary grows memory
for its own purposes then that memory will be incorrectly claimed to be
owned by dlmalloc.
Instead this commit rounds up the `__heap_base` address to the nearest
page size, since that must be allocatable. Otherwise anything above this
rounded address is assumed to be used by something else, even if it's
addressable.
Dan Gohman [Wed, 21 Dec 2022 23:47:53 +0000 (15:47 -0800)]
Use `ENOENT` rather than `ENOTCAPABLE` for missing preopens. (#370)
When a user calls `open` with a path that does not have a corresponding
preopen, set errno to `ENOENT` rather than `ENOTCAPABLE`. This
conceptually represents an attempt to open a path which has not been
provided within the sandbox, so it's more accurately represented as
"not present" rather than "insufficient capabilities".
YAMAMOTO Takashi [Wed, 21 Dec 2022 01:24:09 +0000 (10:24 +0900)]
Disable pthread_exit for now (#366)
The current wasi-threads has no thread-exit functionality.
Thus it isn't straightforward to implement pthread_exit
without leaking thread context. This commit simply disables
pthread_exit for now.
Also, instead of abusing `wasi_proc_exit` for thread exit,
make `wasi_thread_start` return.
Note: `wasi_proc_exit` is supposed to terminate all threads
in the "process", not only the calling thread.
Note: Depending on the conclusion of the discussion about
`wasi_thread_exit`, we might revisit this change later.
Marcin Kolny [Mon, 19 Dec 2022 12:18:19 +0000 (12:18 +0000)]
threads: Retrieve default stack size from __heap_base/__data_end (#350)
When compiling with `-z stack-size` flag, only the main thread's stack
size is set to the specified value and other threads use musl's default value.
That's inconsistent with LLD's `-Wl,-stack_size`.
I think we can make it similar to MUSL's behavior, where thread's stack
size can be set via `PT_GNU_STACK` program header (via `-Wl,-z,stack-size`
flag).
Configuring stack size through `pthread_attr_t` still work as expected and
overrides the defaults ([pthread_create.c](https://github.com/WebAssembly/wasi-libc/blob/be1ffd6a9eba1704085987482557c2a32724227f/libc-top-half/musl/src/thread/pthread_create.c#L362))
default settings.
Andrew Brown [Tue, 13 Dec 2022 17:19:32 +0000 (09:19 -0800)]
threads: enable access to `pthread_barrier_*` functions (#358)
In building some `libc-test` tests, I found these functions were not
compiled in. This change adds `pthread_barrier_init`,
`pthread_barrier_wait`, and `pthread_barrier_destroy` to the
`THREAD_MODEL=posix` build. As has been done with previous pthreads PRs,
this PR skips any inter-process locking by removing any calls to
`__vm_lock` and friends. If in the future WASI gains the "process"
concept, then these locations (and the pre-existing ones) will need to
be modified.
Andrew Brown [Thu, 8 Dec 2022 22:55:42 +0000 (14:55 -0800)]
threads: enable access to `pthread_attr_get` functions (#357)
The pthreads API exposes functions for querying the attributes of a
thread. This change allows these functions to be compiled in the
`THREAD_MODEL=posix` build. Some functions are skipped (and documented);
they can be added if/when needed. This change is motivated by a
`libc-test` test that uses these functions.
__wasi_thread_spawn: stop truncating the return value (#353)
as __wasi_errno_t is uint16_t, with the current coding,
__pthread_create will never see negative return values from
wasi:thread_spawn.
eg. (int)(uint16_t)-1 == 65535.
Mike Hommey [Wed, 7 Dec 2022 16:27:06 +0000 (01:27 +0900)]
Adjust Makefile for LLVM trunk (16) as of 2022-11-08 (#344)
https://github.com/llvm/llvm-project/commit/1e4e2433bcd1a0296ef1043c462252f0d087d90c
enabled sign-ext and mutable-globals by default, which adds
corresponding __wasm_-prefixed #defines.
https://github.com/llvm/llvm-project/commit/9e956995db1fc7e792e3dfb3a465a52626195557
changed the definition of __GNUC_VA_LIST to match that of GCC headers,
leaving it without a value.
YAMAMOTO Takashi [Mon, 21 Aug 2023 17:21:37 +0000 (02:21 +0900)]
Fix recursive mutex (#433)
the robust mutex logic in musl seems to assume that
the bit 29 of TIDs is always zero for some reasons.
from https://git.musl-libc.org/cgit/musl/commit/?id=099b89d3840c30d7dd962e18668c2e6d39f0c626
> note that the kernel ABI also reserves bit 29
> not to appear in any tid,
i'm not sure if the assumption is true or not, given that
FUTEX_TID_MASK is 0x3fffffff.
anyway, when using non-default type of mutex like recursive mutex,
it causes problems as we actually use TID 0x3fffffff for the main thread.
as we don't support robust mutex anyway, this commit simply
comments out the problematic condition.
Marcin Kolny [Thu, 13 Jul 2023 16:18:08 +0000 (17:18 +0100)]
Add definitions for PF_INET, PF_INET6 and PF_UNSPEC (#426)
Given there are already AF_* definitions, and they are (now) essentially
synonyms, we add those definitions to enable compilation of code that
already use PF_* macros.
Moritz Sichert [Tue, 11 Jul 2023 22:33:07 +0000 (00:33 +0200)]
Acquire the global lock before initializing malloc (#410)
In a multi-threaded execution we need to make sure that only exactly one
thread initializes malloc. The function try_init_allocator() can't
easily be made thread-safe, so just move the call to
try_init_allocator() inside the block that holds the lock.
This commit effectively drops the support of older wasm-ld. (LLVM <15.0.7).
We have two relevant use cases:
* `memory.grow` use outside of malloc
(eg. used by polyfill preview1 binaries)
* `--init-memory` to somehow preallocate heap
(eg. avoid dynamic allocations, especially on small environments)
While https://github.com/WebAssembly/wasi-libc/pull/377
fixed the former, it broke the latter if you are using
an older LLVM, which doesn't provide the `__heap_end` symbol,
to link your module.
As we couldn't come up with a solution which satisfies all parties,
this commit simply makes it require new enough LLVM which provides
`__heap_end`. After all, a link-time failure is more friendly to users
than failing later in a subtle way.
Andrew Brown [Fri, 23 Jun 2023 20:24:08 +0000 (13:24 -0700)]
Improve `README.md` (#425)
This changes the front-page documentation to:
- use `wasi-libc` instead of "WASI Libc"
- explain how to build the pthreads-enabled `wasm32-wasi-threads` target
Dan Gohman [Wed, 3 May 2023 19:44:21 +0000 (12:44 -0700)]
Convert preopen initialization to be lazy. (#408)
* Convert preopen initialization to be lazy.
Insteead of eagerly initializing the preopens in a static constructor,
perform preopen initialization the first time it's needed, or before a
close or a renumber which might disrupt the file descriptor space.
And, use a weak symbol with a stub function for use by `close` or
`fd_renumber`, we that they can trigger preopen initialization only
if it's actually needed.
This way, if a program doesn't contain any calls to any function that
needs preopens, it can avoid linking in the preopen initialization code.
And if it contains calls but doesn't execute them at runtime, it can
avoid executing the preopen intiailization code.
A downside here is that this may cause problems for users that call
`__wasi_fd_close` or `__wasi_fd_renumber` directly and close over
overwrite some preopens before libc has a chance to scan them. To
partially address this, this PR does add a declaration for
`__wasilibc_populate_preopens` to <wasi/libc.h> so that users can call
it manually if they need to.
* Fix calling `internal_register_preopened_fd` with the lock held.
Factor out the lock acquisition from the implementation of
`internal_register_preopened_fd` so that we can call it from
`__wasilibc_populate_preopens` with the lock held.
Alex Crichton [Wed, 5 Apr 2023 19:13:39 +0000 (14:13 -0500)]
Fix debug build's `predefined-macros.txt` (#407)
This commit fixes the ability to build `wasi-libc` with `-g` options and
possibly without `-O2` options as well. I've found this useful when
debugging issues as historically that the build fails when `-g` is
passed or optimizations are removed due to the checks against these
expectation files. This commit adds more filters to the list of macros
to ensure that optimization/debug related ones are all removed from the
expectation lists.
Sam Clegg [Thu, 2 Mar 2023 01:14:42 +0000 (17:14 -0800)]
Avoid using absolute pathnames in Makefile. NFC (#400)
This makes the output of the build a lot more concise and easy to read.
The only real change here is to build each of the crt1 startup files
individually instead to trying to build them all in a single clang
invocation (that latter doesn't allow for -o to be specified which is
a pretty severe limitation, so its best avoided anyway).
It also reduces the size of the `ar` command line for libc itself from
78017 to 43609 (on my machine), which sadly is still tool long for win32
I believe.
Cheng Shao [Mon, 30 Jan 2023 12:30:02 +0000 (13:30 +0100)]
Add a check to reactor modules to ensure _initialize is only called once (#388)
Calling _initialize multiple times is undefined behavior, since the
ctors are not guaranteed to be idempotent. We should have this safety
check which is similar to #329.
Andrew Brown [Fri, 13 Jan 2023 02:56:52 +0000 (18:56 -0800)]
threads: change `wasm32-wasi-pthread` to `wasm32-wasi-threads` (#381)
* Change `wasm32-wasi-pthread` to `wasm32-wasi-threads`
After some thought, I think that we should rename the `THREAD_MODEL=posix` build to avoid confusion. Why? Though in this project the use of this target does involve pthreads, it will not be so in other standard libraries or languages (see, e.g., https://github.com/rust-lang/compiler-team/issues/574). I think it would be preferable to emphasize the "threads" Wasm-level proposal and the "wasi-threads" proposal rather than the specific details of which threading API is being exposed.
* fix: rename the `expected` output directory as well
Alex Crichton [Mon, 9 Jan 2023 16:33:05 +0000 (10:33 -0600)]
Don't use sbrk(0) to determine the initial heap size (#377)
* Don't use sbrk(0) to determine the initial heap size
This commit changes the `try_init_allocator` function as part of
dlmalloc to not use `sbrk(0)` to determine the initial heap size. The
purpose of this function is to use the extra memory at the end of linear
memory for the initial allocation heap before `memory.grow` is used to
allocate more memory. To learn the extent of this region the code
previously would use `sbrk(0)` to find the current size of linear
memory. This does not work, however, when other systems have called
`memory.grow` before this function is called. For example if another
allocator is used or if another component of a wasm binary grows memory
for its own purposes then that memory will be incorrectly claimed to be
owned by dlmalloc.
Instead this commit rounds up the `__heap_base` address to the nearest
page size, since that must be allocatable. Otherwise anything above this
rounded address is assumed to be used by something else, even if it's
addressable.
Dan Gohman [Wed, 21 Dec 2022 23:47:53 +0000 (15:47 -0800)]
Use `ENOENT` rather than `ENOTCAPABLE` for missing preopens. (#370)
When a user calls `open` with a path that does not have a corresponding
preopen, set errno to `ENOENT` rather than `ENOTCAPABLE`. This
conceptually represents an attempt to open a path which has not been
provided within the sandbox, so it's more accurately represented as
"not present" rather than "insufficient capabilities".
YAMAMOTO Takashi [Wed, 21 Dec 2022 01:24:09 +0000 (10:24 +0900)]
Disable pthread_exit for now (#366)
The current wasi-threads has no thread-exit functionality.
Thus it isn't straightforward to implement pthread_exit
without leaking thread context. This commit simply disables
pthread_exit for now.
Also, instead of abusing `wasi_proc_exit` for thread exit,
make `wasi_thread_start` return.
Note: `wasi_proc_exit` is supposed to terminate all threads
in the "process", not only the calling thread.
Note: Depending on the conclusion of the discussion about
`wasi_thread_exit`, we might revisit this change later.
Marcin Kolny [Mon, 19 Dec 2022 12:18:19 +0000 (12:18 +0000)]
threads: Retrieve default stack size from __heap_base/__data_end (#350)
When compiling with `-z stack-size` flag, only the main thread's stack
size is set to the specified value and other threads use musl's default value.
That's inconsistent with LLD's `-Wl,-stack_size`.
I think we can make it similar to MUSL's behavior, where thread's stack
size can be set via `PT_GNU_STACK` program header (via `-Wl,-z,stack-size`
flag).
Configuring stack size through `pthread_attr_t` still work as expected and
overrides the defaults ([pthread_create.c](https://github.com/WebAssembly/wasi-libc/blob/be1ffd6a9eba1704085987482557c2a32724227f/libc-top-half/musl/src/thread/pthread_create.c#L362))
default settings.
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