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SubjectRe: [patch part-III V2 05/23] x86/entry/32: Provide macro to emit IDT entry stubs
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Brian Gerst <brgerst@gmail.com> writes:
> On Sun, Mar 8, 2020 at 7:24 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>> +#ifdef CONFIG_X86_INVD_BUG
>> +.macro idtentry_push_func vector cfunc
>> + .if \vector == X86_TRAP_XF
>> + /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
>> + ALTERNATIVE "pushl $do_general_protection", \
>> + "pushl $do_simd_coprocessor_error", \
>> + X86_FEATURE_XMM
>> + .else
>> + pushl $\cfunc
>> + .endif
>> +.endm
>> +#else
>> +.macro idtentry_push_func vector cfunc
>> + pushl $\cfunc
>> +.endm
>> +#endif
>
> IMHO it would be better to push this to the C code and not make the
> asm more complicated. Something like:
>
> dotraplinkage void
> do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
> {
> #ifdef CONFIG_X86_INVD_BUG
> /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
> if (!static_cpu_has(X86_FEATURE_XMM)) {
> do_general_protection(regs, error_code);
> return;
> }
> #endif
> RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
> math_error(regs, error_code, X86_TRAP_XF);
> }

That's too obvious :)

Thanks for catching that!

tglx

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