Re: [Xen-devel] [PATCH] x86: move declaration of the exception_table to C

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Jan 26, 2018 at 05:46:23PM +0000, Andrew Cooper wrote:
> On 26/01/18 17:37, Roger Pau Monne wrote:
> > diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
> > index a3e8f0c9b9..be95baafe1 100644
> > --- a/xen/arch/x86/traps.c
> > +++ b/xen/arch/x86/traps.c
> > @@ -119,6 +119,25 @@ boolean_param("ler", opt_ler);
> >  #define stack_words_per_line 4
> >  #define ESP_BEFORE_EXCEPTION(regs) ((unsigned long *)regs->rsp)
> >  
> > +void (* const exception_table[TRAP_nr])(struct cpu_user_regs *regs) = {
> > +    [TRAP_divide_error] = do_trap,
> > +    [TRAP_debug] = do_debug,
> > +    [TRAP_nmi] = (void (*)(struct cpu_user_regs *))do_nmi,
> 
> Cast to (void *) is probably better, and certainly shorter.
> 
> > +    [TRAP_int3] = do_int3,
> > +    [TRAP_overflow ... TRAP_bounds] = do_trap,
> > +    [TRAP_invalid_op] = do_invalid_op,
> > +    [TRAP_no_device] = do_device_not_available,
> > +    [TRAP_double_fault ... TRAP_copro_seg] = do_reserved_trap,
> > +    [TRAP_invalid_tss ... TRAP_stack_error] = do_trap,
> > +    [TRAP_gp_fault] = do_general_protection,
> > +    [TRAP_page_fault] = do_page_fault,
> > +    [TRAP_spurious_int] = do_reserved_trap,
> > +    [TRAP_copro_error ... TRAP_alignment_check] = do_trap,
> > +    [TRAP_machine_check] = (void (*)(struct cpu_user_regs 
> > *))do_machine_check,
> > +    [TRAP_simd_error] = do_trap,
> > +    [TRAP_virtualisation ... (TRAP_nr - 1)] = do_reserved_trap,
> 
> Can we see about vertically aligning the assignments for neatness?

Done for both of the above.

> Also, I'd drop the do_reserve_trap and have the lookup check for a NULL
> pointer.  This is what we do on the hypercall path and is far less error
> prone to changes in this table.

I would rather do that in a separate change, since this is
non-functional. Do you think that's fine?

Thanks, Roger.

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