Re: [PATCH 5/7] x86/bugs: Only harden syscalls when needed

[Josh Poimboeuf]

On Thu, Apr 11, 2024 at 11:06:37AM +0100, Andrew Cooper wrote:
> > +#define __do_syscall(table, func_direct, nr, regs)			\
> > +({									\
> > +	unsigned long __rax, __rdi, __rsi;				\
> > +									\
> > +	asm_inline volatile(						\
> > +		ALTERNATIVE("call " __stringify(func_direct) "\n\t",	\
> > +			    ANNOTATE_RETPOLINE_SAFE			\
> > +			    "call *%[func_ptr]\n\t",			\
> 
> This wants to be a plain maybe-thunk'd indirect call, and without the
> ANNOTATE_RETPOLINE_SAFE.
> 
> Or you're going to get into cases where some combinations of command
> line options do unexpected things e.g. retpolining everything except the
> syscall dispatch.

In that case won't X86_FEATURE_INDIRECT_SAFE get cleared, resulting in
the above using a direct call?  Or did I miss something?

-- 
Josh