Re: [Pv-drivers] [PATCH 29/36] cpuidle, xenpv: Make more PARAVIRT_XXL noinstr clean

[Nadav Amit]

On Jun 13, 2022, at 11:48 AM, Srivatsa S. Bhat <srivatsa@xxxxxxxxxxxxx> wrote:

> ⚠ External Email
> 
> On 6/8/22 4:27 PM, Peter Zijlstra wrote:
>> vmlinux.o: warning: objtool: acpi_idle_enter_s2idle+0xde: call to wbinvd() leaves .noinstr.text section
>> vmlinux.o: warning: objtool: default_idle+0x4: call to arch_safe_halt() leaves .noinstr.text section
>> vmlinux.o: warning: objtool: xen_safe_halt+0xa: call to HYPERVISOR_sched_op.constprop.0() leaves .noinstr.text section
>> 
>> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> 
> Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@xxxxxxxxxxxxx>
> 
>> 
>> -static inline void wbinvd(void)
>> +extern noinstr void pv_native_wbinvd(void);
>> +
>> +static __always_inline void wbinvd(void)
>> {
>>      PVOP_ALT_VCALL0(cpu.wbinvd, "wbinvd", ALT_NOT(X86_FEATURE_XENPV));
>> }

I guess it is yet another instance of wrong accounting of GCC for
the assembly blocks’ weight. I guess it is not a solution for older
GCCs, but presumably ____PVOP_ALT_CALL() and friends should have
used asm_inline or some new “asm_volatile_inline” variant.