Add initial riscv64 support #941
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| // Copyright 2015 Ted Mielczarek. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution. |
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Not a big deal but I realize we have this header in most files but there's never been a top-level COPYRIGHT file. @luser what do you suggest we do for new files?
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There's a LICENSE file in the root of the repository, I think that should cover it? I would recommend dropping the license comments from individual files. I probably picked that habit up from Breakpad.
| // in a range covered by one of our modules). If we find such an instruction, | ||
| // we assume it's an pc value that was pushed by the CALL instruction that created | ||
| // the current frame. The next frame is then assumed to end just before that | ||
| // pc value. |
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I guess this was copied from the other architectures, but RISC-V doesn't have a CALL instruction. It uses a AUIPC followed by a JALR instruction to call a function, you should amend the text above to reflect this (assume the logic below applies to RISC-V).
| // Arm leaf functions may not actually touch the stack (thanks | ||
| // to the link register allowing you to "push" the return address | ||
| // to a register), so we need to permit the stack pointer to not | ||
| // change for the first frame of the unwind. After that we need | ||
| // more strict validation to avoid infinite loops. |
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Likewise this looks like a copy-paste error, does the logic here hold true for RISC-V too? I'm not sufficiently familiar with the ABI to be able to tell.
| // A caller's ip is the return address, which is the instruction | ||
| // *after* the CALL that caused us to arrive at the callee. Set | ||
| // the value to 4 less than that, so it points to the CALL instruction | ||
| // (arm64 instructions are all 4 bytes wide). This is important because | ||
| // we use this value to lookup the CFI we need to unwind the next frame. | ||
| let ip = frame.context.get_instruction_pointer(); | ||
| frame.instruction = ip - 4; |
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This is certainly wrong for RISC-V as the “C” extension for compressed instructions allows for 2-bytes wide instructions and all jumps have an address that is a multiple of 2 bytes.
The defines for riscv64 are from Google's breakpad. This is tested on Ubuntu 23.10/riscv64 using generated minidump by Google's breakpad.