Re: [XEN PATCH][for-4.19 v4 2/8] x86: add deviations for variables only used in asm code

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 24/10/2023 09:32, Jan Beulich wrote:
> On 23.10.2023 11:56, Nicola Vetrini wrote:
> > --- a/xen/arch/x86/include/asm/asm_defns.h
> > +++ b/xen/arch/x86/include/asm/asm_defns.h
> > @@ -31,6 +31,7 @@ asm ( "\t.equ CONFIG_INDIRECT_THUNK, "
> >   * gets set up by the containing function.
> >   */
> >  #ifdef CONFIG_FRAME_POINTER
> > +/* SAF-1-safe */
> >  register unsigned long current_stack_pointer asm("rsp");
> >  # define ASM_CALL_CONSTRAINT , "+r" (current_stack_pointer)
> >  #else
> SAF-1-safe is about symbols "used only by asm modules". This doesn't 
> apply
> to the declaration here.
The wording could change to "asm code" if that is deemed clearer.

> > --- a/xen/arch/x86/setup.c
> > +++ b/xen/arch/x86/setup.c
> > @@ -75,6 +75,7 @@ static bool __initdata opt_invpcid = true;
> >  boolean_param("invpcid", opt_invpcid);
> >  bool __read_mostly use_invpcid;
> >
> > +/* SAF-1-safe Only used in asm code and within this source file */
> >  unsigned long __read_mostly cr4_pv32_mask;
> >
> >  /* **** Linux config option: propagated to domain0. */
> > @@ -147,12 +148,13 @@ cpumask_t __read_mostly cpu_present_map;
> >  unsigned long __read_mostly xen_phys_start;
> >
> >  char __section(".init.bss.stack_aligned") __aligned(STACK_SIZE)
> > -    cpu0_stack[STACK_SIZE];
> > +    cpu0_stack[STACK_SIZE]; /* SAF-1-safe Only used in asm code and 
> > below */
> Wasn't it that such comments need to live on the earlier line?
>
> Jan
On the same line is fine as well. I personally found it less clear 
putting that in the
line above.

--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)