While fixing bugs in the x86_64 LC_THREAD parser in ObjectFileMachO, I noticed that the other LC_THREAD parsers are all less clear than they should be. To recap, a Mach-O LC_THREAD load command has a byte size for the entire payload. Within the payload, there will be one or more register sets provided. A register set starts with a UInt32 "flavor", the type of register set defined in the system headers, and a UInt32 "count", the number of UInt32 words of memory for this register set. After one register set, there may be additional sets. A parser can skip an unknown register set flavor by using the count field to get to the next register set. When the total byte size of the LC_THREAD load command has been parsed, it is completed. This patch fixes the riscv/arm/arm64 LC_THREAD parsers to use the total byte size as the exit condition, and to skip past unrecognized register sets, instead of stopping parsing. Instead of fixing the i386 corefile support, I removed it. The last macOS that supported 32-bit Intel code was macOS 10.14 in 2018. I also removed i386 KDP support, 32-bit intel kernel debugging hasn't been supported for even longer than that. It would be preferable to do these things separately, but I couldn't bring myself to update the i386 LC_THREAD parser, and it required very few changes to remove this support entirely.
reading, and one bug in the new RegisterContextUnifiedCore class. The PR I landed a few days ago to allow Mach-O corefiles to augment their registers with additional per-thread registers in metadata exposed a few bugs in the x86_64 corefile reader when running under different CI environments. It also showed a bug in my RegisterContextUnifiedCore class where I wasn't properly handling lookups of unknown registers (e.g. the LLDB_GENERIC_RA when debugging an intel target). The Mach-O x86_64 corefile support would say that it had fpu & exc registers available in every corefile, regardless of whether they were actually present. It would only read the bytes for the first register flavor in the LC_THREAD, the GPRs, but it read them incorrectly, so sometimes you got more register context than you'd expect. The LC_THREAD register context specifies a flavor and the number of uint32_t words; the ObjectFileMachO method would read that number of uint64_t's, exceeding the GPR register space, but it was followed by FPU and then EXC register space so it didn't crash. If you had a corefile with GPR and EXC register bytes, it would be written into the GPR and then FPU register areas, with zeroes filling out the rest of the context.
lldb-server had limited support for single-stepping through the lr/sc atomic sequence. This patch enhances that support for all possible atomic sequences. The previous version contained an incorrect regex pattern in the test, causing the riscv-specific test to run on other platforms. This reland fixes the regex (see lldb/test/API/riscv/step/TestSoftwareStep.py)
The "process metadata" LC_NOTE allows for thread IDs to be specified in a Mach-O corefile. This extends the JSON recognzied in that LC_NOTE to allow for additional registers to be supplied on a per-thread basis. The registers included in a Mach-O corefile LC_THREAD load command can only be one of the register flavors that the kernel (xnu) defines in <mach/arm/thread_status.h> for arm64 -- the general purpose registers, floating point registers, exception registers. JTAG style corefile producers may have access to many additional registers beyond these that EL0 programs typically use, for instance TCR_EL1 on AArch64, and people developing low level code need access to these registers. This patch defines a format for including these registers for any thread. The JSON in "process metadata" is a dictionary that must have a `threads` key. The value is an array of entries, one per LC_THREAD in the Mach-O corefile. The number of entries must match the LC_THREADs so they can be correctly associated. Each thread's dictionary must have two keys, `sets`, and `registers`. `sets` is an array of register set names. If a register set name matches one from the LC_THREAD core registers, any registers that are defined will be added to that register set. e.g. metadata can add a register to the "General Purpose Registers" set that lldb shows users. `registers` is an array of dictionaries, one per register. Each register must have the keys `name`, `value`, `bitsize`, and `set`. It may provide additional keys like `alt-name`, that `DynamicRegisterInfo::SetRegisterInfo` recognizes. This `sets` + `registers` formatting is the same that is used by the `target.process.python-os-plugin-path` script interface uses, both are parsed by `DynamicRegisterInfo`. The one addition is that in this LC_NOTE metadata, each register must also have a `value` field, with the value provided in big-endian base 10, as usual with JSON. In RegisterContextUnifiedCore, I combine the register sets & registers from the LC_THREAD for a specific thread, and the metadata sets & registers for that thread from the LC_NOTE. Even if no LC_NOTE is present, this class ingests the LC_THREAD register contexts and reformats it to its internal stores before returning itself as the RegisterContex, instead of shortcutting and returning the core's native RegisterContext. I could have gone either way with that, but in the end I decided if the code is correct, we should live on it always. I added a test where we process save-core to create a userland corefile, then use a utility "add-lcnote" to strip the existing "process metadata" LC_NOTE that lldb put in it, and adds a new one from a JSON string. rdar://74358787 --------- Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>
.. from the guts of GDBRemoteCommunication to ~top level. This is motivated by #131519 and by the fact that's impossible to guess whether the author of a symlink intended it to be a "convenience shortcut" -- meaning it should be resolved before looking for related files; or an "implementation detail" -- meaning the related files should be located near the symlink itself. This debate is particularly ridiculous when it comes to lldb-server running in platform mode, because it also functions as a debug server, so what we really just need to do is to pass /proc/self/exe in a platform-independent manner. Moving the location logic higher up achieves that as lldb-platform (on non-macos) can pass `HostInfo::GetProgramFileSpec`, while liblldb can use the existing complex logic (which only worked on liblldb anyway as lldb-platform doesn't have a lldb_private::Platform instance). Another benefit of this patch is a reduction in dependency from GDBRemoteCommunication to the rest of liblldb (achieved by avoiding the Platform dependency).
It's not necessary on posix platforms as of #126935 and it's ignored on windows as of #138896. For both platforms, we have a better way of inheriting FDs/HANDLEs.
This fixes issues found in e066f35c6981c720e3a7e5883efc40c861b3b7, which was later reverted. The problem was with "k" message which was sent with sync_on_timeout flag set to true, so lldb was waiting for response, which is currently not being sent by lldb-server. Not waiting for response at all seems to be not a solution, because on MAC OS X lldb waits for response from "k" to gracefully kill inferior.
In the same way that memory regions may be known from a core file but
not readable, tag segments can also have no content. For example:
```
$ readelf --segments core
<...>
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
<...>
LOAD 0x0000000000002000 0x0000ffff93899000 0x0000000000000000
0x0000000000000000 0x0000000000001000 RW 0x1000
<...>
LOPROC+0x2 0x0000000000008000 0x0000ffff93899000 0x0000000000000000
0x0000000000000000 0x0000000000001000 0x0
```
This happens if you have a restricted coredump filter or size limit.
The area of virtual memory this segment covers is 0x1000, or 4096 bytes
aka one tagged page. It's FileSiz would normally be 0x80. Tags are
packed 2 per byte and granules are 16 bytes. 4096 / 16 / 2 = 128 or
0x80.
But here it has no data, and in theory a corrupt file might have some
data but not all. This triggered an assert in
UnpackTagsFromCoreFileSegment and crashed lldb.
To fix this I have made UnpackTagsFromCoreFileSegment return an expected
and returned an error in this case instead of asserting. This will be
seen by the user, as shown in the added API test.
The function was extremely messy in that it, depending on the set of arguments, it could either modify the Connection object in `this` or not. It had a lot of arguments, with each call site passing a different combination of null values. This PR: - packs "url" and "comm_fd" arguments into a variant as they are mutually exclusive - removes the (surprising) "null url *and* null comm_fd" code path which is not used as of https://github.com/llvm/llvm-project/pull/145017 - marks the function as `static` to make it clear it (now) does not operate on the `this` object. Depends on #145017
Reverts llvm/llvm-project#127505 because `riscv/step/TestSoftwareStep.py` is failing on the bots.