On 2023/12/13 16:48, Dan Li wrote: > + Likun > > On Tue, 28 Mar 2023 at 06:18, Sami Tolvanen <samitolva...@google.com> wrote: >> On Mon, Mar 27, 2023 at 2:30 AM Peter Zijlstra <pet...@infradead.org> wrote: >>> On Sat, Mar 25, 2023 at 01:54:16AM -0700, Dan Li wrote: >>> >>>> In the compiler part[4], most of the content is the same as Sami's >>>> implementation[3], except for some minor differences, mainly including: >>>> >>>> 1. The function typeid is calculated differently and it is difficult >>>> to be consistent. >>> This means there is an effective ABI break between the compilers, which >>> is sad :-( Is there really nothing to be done about this? >> I agree, this would be unfortunate, and would also be a compatibility >> issue with rustc where there's ongoing work to support >> clang-compatible CFI type hashes: >> >> https://github.com/rust-lang/rust/pull/105452 >> >> Sami
Hi Peter and Sami I am Dan Li's colleague, and I will take over and continue the work of CFI. Regarding the issue of gcc cfi type id being compatible with clang, we have analyzed and verified: 1. clang uses Mangling defined in Itanium C++ ABI to encode the function prototype, and uses the encoding result as input to generate cfi type id; 2. Currently, gcc only implements mangling for the C++ compiler, and the function prototype coding generated by these interfaces is compatible with clang, but gcc's c compiler does not support mangling.; Adding mangling to gcc's c compiler is a huge and difficult task，because we have to refactor the mangling of C++, splitting it into basic mangling and language specific mangling, and adding support for the c language which requires a deep understanding of the compiler and language processing parts. And for the kernel cfi, I suggest separating type compatibility from CFI basic functions. Type compatibility is independent from CFI basic funcitons and should be dealt with under another topic. Should we focus on the main issus of cfi, and let it work first on linux kernel, and left the compatible issue to be solved later? LiKun Wang 声明：这封邮件只允许文件接收者阅读，有很高的机密性要求。禁止其他人使用、打开、复制或转发里面的任何内容。如果本邮件错误地发给了你，请联系邮件发出者并删除这个文件。机密及法律的特权并不因为误发邮件而放弃或丧失。任何提出的观点或意见只属于作者的个人见解，并不一定代表本公司。
