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SubjectRe: [PATCH v3 0/6] locking/rwsem/x86: Add stack frame dependency for some inline asm
On Wed, Sep 20, 2017 at 04:24:18PM -0500, Josh Poimboeuf wrote:
> On Tue, Sep 19, 2017 at 06:37:39PM -0500, Miguel Bernal Marin wrote:
> > Some warning were showed by objtool using gcc 7.2.0
> >
> > kernel/locking/rwsem.o: warning: objtool: up_read()+0x11: call without frame pointer save/setup
> > kernel/locking/rwsem.o: warning: objtool: up_write()+0x17: call without frame pointer save/setup
> > kernel/locking/rwsem.o: warning: objtool: downgrade_write()+0x22: call without frame pointer save/setup
> >
> > which means gcc placed an inline asm function and its call instruction before
> > the frame pointer setup.
> >
> > This series forces a stack frame to be created before the call instruction
> > by listing the stack pointer as an output operand in the inline asm statement.
> >
> > Also to be easy to maintain and understand the operands from the extended
> > assembler instructions were converted to named operands.
> I've got a patch going around which will change the way we do this, so
> you'll probably need to do a v3 after my patch gets merged. I'll add
> you to cc for the next revision.

With your new patches (at v4.14.-rc2) the warning is not seen any more,
so I will send only the named operand patches (in separate thread), as
this fix is not more needed.

> --
> Josh


Miguel Bernal Marin Open Source Technology Center Intel Corporation

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