Re: [PATCH] riscv: elf: add .riscv.attributes parsing

[Vineet Gupta]

On 1/11/23 08:53, Eric W. Biederman wrote:
> Vineet Gupta <vineetg@xxxxxxxxxxxx> writes:
>
> > This implements the elf loader hook to parse RV specific
> > .riscv.attributes section. This section is inserted by compilers
> > (gcc/llvm) with build related information such as -march organized as
> > tag/value attribute pairs.
> >
> > It identifies the various attribute tags (and corresponding values) as
> > currently specified in the psABI specification.
> >
> > This patch only implements the elf parsing mechanics, leaving out the
> > recording/usage of the attributes to subsequent patches.
> Why does the kernel care?
>
> Unless I am mistaken the kind of information you are describing is
> typically dealt with by the dynamic linker, rather than the kernel.
>
> As a general strategy I think it is smart to leave as much to
> userspace and the dynamic linker and possible intead of asking
> the kernel's elf loader to care.

That is true in general. But in some cases we might have to do stuff 
before kick starting usermode such as setting up a shadow stack with 
special permissions etc.

> That allows more rapid
> prototyping and reduces the impact of parsing bugs.