Re: [PATCH 01/11] riscv: add landing pad for asm routines.

[Deepak Gupta]

On Fri, Jul 25, 2025 at 03:27:45PM +0000, Sami Tolvanen wrote:
> On Thu, Jul 24, 2025 at 04:36:54PM -0700, Deepak Gupta wrote:
> > SYM_* macros are used to define assembly routines. In this patch series,
> > re-define those macros in risc-v arch specific include file to include
> > a landing pad instruction at the beginning. This is done only when the
> > compiler flag for landing pad is enabled (i.e. __riscv_zicfilp).
> >
> > TODO: Update `lpad 0` with `lpad %lpad_hash(name)` after toolchain
> > support.
>
> I glanced through the proposed signature based landing pad labeling
> scheme, but didn't see any mentions of lpad_hash for labeling assembly
> functions. Is there more information somewhere about how this is going
> to be implemented?

Take a look here for generation of type string
https://github.com/sifive/riscv-gcc/blob/f26ae78e21e591f78802a975b68dbde9a224a192/gcc/config/riscv/riscv-func-sig.cc

For hash scheme, take a look here
https://github.com/sifive/riscv-binutils-gdb/commit/1d027fd590c8ad79eba997bcf9b979872ff38eef
`riscv_lpad_hash` function has detail about how 20bit hash is extracted.


> Sami