[RFC PATCH] LoongArch: Fix intermittent nptl/tst-cancel32 failure

[Xi Ruoyao]

On Wed, 2026-08-05 at 11:47 +0800, mengqinggang wrote:
> 
> 在 2026/8/5 11:33, Xi Ruoyao 写道:
> > On Wed, 2026-08-05 at 10:09 +0800, mengqinggang wrote:
> > >   
> > > Hi Wilco,
> > >   
> > > I'm sorry, I don't think I fully understood your point.
> > >   On LoongArch64:
> > >   PTR_DEMANGLE2 (sp, t0, t1)
> > > expand to:
> > > 
> > > rotri.d         $sp, $t0, 0x11
> > > xor             $sp, $sp, $t1
> > >   
> > >   The SP register is partially updated between the rotri.d and xor
> > > instructions.
> > >   Using this value in the pthread_cancel path may cause a SIGSEGV.
> > > I think this issue is not relate to t0 register.
> > Meaning we can simply expand it to
> > 
> > rotri.d $t0, $t0, 0x11
> > xor     $sp, $sp, $t1
> 
> Perhaps it should be:
> rotri.d $t0, $t0, 0x11
> xor     $sp, $t0, $t1

Yes.
> 
> > instead of introducing t2.  (With a comment for PTR_DEMANGLE2 saying
> > it
> > will clobber the input in t0.)
> > 

-- 
Xi Ruoyao <xry111@xry111.site>