Our usage of `ucontext_t` in the standard library was kind of
problematic. We unnecessarily mimiced libc-specific structures, and our
`getcontext` implementation was overkill for our use case of stack
tracing.
This commit introduces a new namespace, `std.debug.cpu_context`, which
contains "context" types for various architectures (currently x86,
x86_64, ARM, and AARCH64) containing the general-purpose CPU registers;
the ones needed in practice for stack unwinding. Each implementation has
a function `current` which populates the structure using inline
assembly. The structure is user-overrideable, though that should only be
necessary if the standard library does not have an implementation for
the *architecture*: that is to say, none of this is OS-dependent.
Of course, in POSIX signal handlers, we get a `ucontext_t` from the
kernel. The function `std.debug.cpu_context.fromPosixSignalContext`
converts this to a `std.debug.cpu_context.Native` with a big ol' target
switch.
This functionality is not exposed from `std.c` or `std.posix`, and
neither are `ucontext_t`, `mcontext_t`, or `getcontext`. The rationale
is that these types and functions do not conform to a specific ABI, and
in fact tend to get updated over time based on CPU features and
extensions; in addition, different libcs use different structures which
are "partially compatible" with the kernel structure. Overall, it's a
mess, but all we need is the kernel context, so we can just define a
kernel-compatible structure as long as we don't claim C compatibility by
putting it in `std.c` or `std.posix`.
This change resulted in a few nice `std.debug` simplifications, but
nothing too noteworthy. However, the main benefit of this change is that
DWARF unwinding---sometimes necessary for collecting stack traces
reliably---now requires far less target-specific integration.
Also fix a bug I noticed in `PageAllocator` (I found this due to a bug
in my distro's QEMU distribution; thanks, broken QEMU patch!) and I
think a couple of minor bugs in `std.debug`.
Resolves: #23801Resolves: #23802
This abstraction isn't really tied to DWARF at all! Really, we're just
loading some information from an ELF file which is useful for debugging.
That *includes* DWARF, but it also includes other information. For
instance, the other change here:
Now, if DWARF information is missing, `debug.SelfInfo.ElfModule` will
name symbols by finding a matching symtab entry. We actually already do
this on Mach-O, so it makes obvious sense to do the same on ELF! This
change is what motivated the restructuring to begin with.
The symtab work is derived from #22077.
Co-authored-by: geemili <opensource@geemili.xyz>
If it's not given, we should set `first_address` to the return address
of `dumpCurrentStackTrace` to avoid the call to `writeCurrentStackTrace`
appearing in the trace. However, we must only do that if no `context` is
given; if there's a context then we're starting the stack unwind
elsewhere.
The downside of this commit is that more precise errors are no longer
propagated up. However, these errors were pretty useless in isolation
due to them having no context; and regardless, we intentionally swallow
most of them in `std.debug` anyway. Therefore, this is better in
practice, because it allows `std.debug` to give slightly more useful
warnings when handling errors. This commit does that for unwind errors,
for instance, which differentiate between the unwind info being corrupt
vs missing vs inaccessible vs unsupported.
A better solution would be to also include more detailed information via
the diagnostics pattern, but this commit is an incremental improvement.
We can't call `@frameAddress()` and then immediately `return`! That
invalidates the frame. This *usually* isn't a problem, because the stack
walk `next` call will *probably* have a stack frame and it will
*probably* be at the exact same address, but neither of those is a
guarantee. On powerpc, presumably some unfortunate inlining was going
on, so this frame was indeed invalidated when we started walking frames.
We need to explicitly pass `@frameAddress` into any function which will
return before we actually walk the stack. Pretty simple patch.
Resolves: #24970
This API is based around the unsound idea that a process can perform
checked virtual memory loads to prevent crashing. This depends on
OS-specific APIs that may be unavailable, disabled, or impossible due to
virtualization.
It also makes collecting stack traces ridiculously slow, which is a
problem for users of DebugAllocator - in other words, everybody, all the
time. It also makes strace go from being superbly clean to being awful.
This "get" is useless noise and was copied from FixedBufferWriter.
Since this API has not yet landed in a release, now is a good time
to make the breaking change to fix this.
* std.os.uefi.tables: ziggify boot and runtime services
* avoid T{} syntax
Co-authored-by: linusg <mail@linusgroh.de>
* misc fixes
* work
* self-review quickfixes
* dont make MemoryMapSlice generic
* more review fixes, work
* more work
* more work
* review fixes
* update boot/runtime services references throughout codebase
* self-review fixes
* couple of fixes i forgot to commit earlier
* fixes from integrating in my own project
* fixes from refAllDeclsRecursive
* Apply suggestions from code review
Co-authored-by: truemedian <truemedian@gmail.com>
* more fixes from review
* fixes from project integration
* make natural alignment of Guid align-8
* EventRegistration is a new opaque type
* fix getNextHighMonotonicCount
* fix locateProtocol
* fix exit
* partly revert 7372d65
* oops exit data_len is num of bytes
* fixes from project integration
* MapInfo consistency, MemoryType update per review
* turn EventRegistration back into a pointer
* forgot to finish updating MemoryType methods
* fix IntFittingRange calls
* set uefi.Page nat alignment
* Back out "set uefi.Page nat alignment"
This backs out commit cdd9bd6f7f5fb763f994b8fbe3e1a1c2996a2393.
* get rid of some error.NotFound-s
* fix .exit call in panic
* review comments, add format method
* fix resetSystem data alignment
* oops, didnt do a final refAllDeclsRecursive i guess
* review comments
* writergate update MemoryType.format
* fix rename
---------
Co-authored-by: linusg <mail@linusgroh.de>
Co-authored-by: truemedian <truemedian@gmail.com>
Basically everything that has a direct replacement or no uses left.
Notable omissions:
- std.ArrayHashMap: Too much fallout, needs a separate cleanup.
- std.debug.runtime_safety: Too much fallout.
- std.heap.GeneralPurposeAllocator: Lots of references to it remain, not
a simple find and replace as "debug allocator" is not equivalent to
"general purpose allocator".
- std.io.Reader: Is being reworked at the moment.
- std.unicode.utf8Decode(): No replacement, needs a new API first.
- Manifest backwards compat options: Removal would break test data used
by TestFetchBuilder.
- panic handler needs to be a namespace: Many tests still rely on it
being a function, needs a separate cleanup.
added adapter to AnyWriter and GenericWriter to help bridge the gap
between old and new API
make std.testing.expectFmt work at compile-time
std.fmt no longer has a dependency on std.unicode. Formatted printing
was never properly unicode-aware. Now it no longer pretends to be.
Breakage/deprecations:
* std.fs.File.reader -> std.fs.File.deprecatedReader
* std.fs.File.writer -> std.fs.File.deprecatedWriter
* std.io.GenericReader -> std.io.Reader
* std.io.GenericWriter -> std.io.Writer
* std.io.AnyReader -> std.io.Reader
* std.io.AnyWriter -> std.io.Writer
* std.fmt.format -> std.fmt.deprecatedFormat
* std.fmt.fmtSliceEscapeLower -> std.ascii.hexEscape
* std.fmt.fmtSliceEscapeUpper -> std.ascii.hexEscape
* std.fmt.fmtSliceHexLower -> {x}
* std.fmt.fmtSliceHexUpper -> {X}
* std.fmt.fmtIntSizeDec -> {B}
* std.fmt.fmtIntSizeBin -> {Bi}
* std.fmt.fmtDuration -> {D}
* std.fmt.fmtDurationSigned -> {D}
* {} -> {f} when there is a format method
* format method signature
- anytype -> *std.io.Writer
- inferred error set -> error{WriteFailed}
- options -> (deleted)
* std.fmt.Formatted
- now takes context type explicitly
- no fmt string
preparing to rearrange std.io namespace into an interface
how to upgrade:
std.io.getStdIn() -> std.fs.File.stdin()
std.io.getStdOut() -> std.fs.File.stdout()
std.io.getStdErr() -> std.fs.File.stderr()
`castTruncatedData` was a poorly worded error (all shrinking casts
"truncate bits", it's just that we assume those bits to be zext/sext of
the other bits!), and `negativeToUnsigned` was a pointless distinction
which forced the compiler to emit worse code (since two separate safety
checks were required for casting e.g. 'i32' to 'u16') and wasn't even
implemented correctly. This commit combines those safety panics into one
function, `integerOutOfBounds`. The name maybe isn't perfect, but that's
not hugely important; what matters is the new default message, which is
clearer than the old ones: "integer does not fit in destination type".
Pointers to thread-local variables do not have their addresses known
until runtime, so it is nonsensical for them to be comptime-known. There
was logic in the compiler which was essentially attempting to treat them
as not being comptime-known despite the pointer being an interned value.
This was a bit of a mess, the check was frequent enough to actually show
up in compiler profiles, and it was very awkward for backends to deal
with, because they had to grapple with the fact that a "constant" they
were lowering might actually require runtime operations.
So, instead, do not consider these pointers to be comptime-known in
*any* way. Never intern such a pointer; instead, when the address of a
threadlocal is taken, emit an AIR instruction which computes the pointer
at runtime. This avoids lots of special handling for TLVs across
basically all codegen backends; of all somewhat-functional backends, the
only one which wasn't improved by this change was the LLVM backend,
because LLVM pretends this complexity around threadlocals doesn't exist.
This change simplifies Sema and codegen, avoids a potential source of
bugs, and potentially improves Sema performance very slightly by
avoiding a non-trivial check on a hot path.
Nothing interesting here; literally just the bare minimum so I can work on this
on and off in a branch without worrying about merge conflicts in the non-backend
code.
* ucontext_t ptr is 8-byte aligned instead of 16-byte aligned which @alignCast() expects
* Retrieve pc address from ucontext_t since unwind_state is null
* Work around __mcontext_data being written incorrectly by the kernel
By returning an initialized sigset (instead of taking the set as an output
parameter), these functions can be used to directly initialize the `mask`
parameter of a `Sigaction` instance.
When linking a libc, Zig should defer to the C library for sigset
operations. The pre-filled constants signal sets (empty_sigset,
filled_sigset) are not compatible with C library initialization, so remove
them and use the runtime `sigemptyset` and `sigfillset` methods to
initialize any sigset.
