[Backtracing][Linux] Add Linux support. #66248
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Linux backtraces work (yay)!
Registers in Linux are in `int64_t`s, so casting to `UInt64` could fail when they're negative. Also, the vaddrs in loaded images don't get updated, so we need to add the image base address.
We were (a) stuck in an infinite loop fetching threads, and (b) all the threads were spinning at 100% CPU. Both of these were wrong, so fix them.
We sort the threads by ID, with the proviso that the main thread always sorts first (even if the IDs have wrapped). We also now scan through the list to find the correct index for the crashing thread.
This needs testing; the issue here is we need to extract data from the mcontext_t structure, which is different for every architecture.
I can't easily test 32-bit Linux at the moment, so only enable backtracing for 64-bit x86 and ARM.
Adds support for zlib, zstd and liblzma compressed debug information, as well as debug info in alternate files.
Add tests for debug section lookup, including in cases where it's compressed.
Warnings should go through the runtime's error/warning output code.
No demangling or line numbers yet.
We're only interested in looking up functions. So ignore everything else.
Also fix a bug wherein we weren't fetching debug symbols.
libdispatch, it turns out, sets threads' signal masks to block all signals except for a handful that get delivered directly to the affected thread. Unfortunately, this includes SIGUSR1, which is what we were using the pause threads. SIGPROF is a reasonable alternative, so switch to using that.
We support async frames on Linux as long as we have symbols for them. Also fix a demangling issue (the return from the outputBufferSize argument of `_swift_backtrace_demangle` is the buffer size, not the result length).
Added support for line number/source file information.
A few fixes and some additional Dwarf attribute support were required, but the Backtracing tests now all pass on Linux.
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A handful of fixes to get the build going again on macOS after the Linux work changed a few things. Most of this is due to rearranging the way we import the various bits of OS functionality (especially SPI) to not rely on SwiftShims.
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A couple of tests needed tweaking, as did the precise behaviour of one or two things. Also, include definitions for zlib/zstd/liblzma directly, so that we don't create an unnecessary build dependency while we're soft linking.
We sometimes picked the wrong symbol because of this.
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It turns out that major and minor numbers can be larger than 0xff.
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@swift-ci Please smoke test Linux platform |
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Add Linux support for the backtracer.