On 06/19/2017 11:29 PM, Ram Pai wrote: > On Mon, Jun 19, 2017 at 09:06:13PM +1000, Michael Ellerman wrote: >> Ram Pai <linux...@us.ibm.com> writes: >> >>> Signed-off-by: Ram Pai <linux...@us.ibm.com> >>> --- >>> arch/powerpc/kernel/exceptions-64s.S | 16 ++++++++++------ >>> 1 file changed, 10 insertions(+), 6 deletions(-) >>> >>> diff --git a/arch/powerpc/kernel/exceptions-64s.S >>> b/arch/powerpc/kernel/exceptions-64s.S >>> index 8db9ef8..a4de1b4 100644 >>> --- a/arch/powerpc/kernel/exceptions-64s.S >>> +++ b/arch/powerpc/kernel/exceptions-64s.S >>> @@ -493,13 +493,15 @@ EXC_COMMON_BEGIN(data_access_common) >>> ld r12,_MSR(r1) >>> ld r3,PACA_EXGEN+EX_DAR(r13) >>> lwz r4,PACA_EXGEN+EX_DSISR(r13) >>> + std r3,_DAR(r1) >>> + std r4,_DSISR(r1) >>> #ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS >>> + andis. r0,r4,DSISR_KEYFAULT@h /* save AMR only if its a key fault */ >>> + beq+ 1f >> >> This seems to be incremental on top of one of your other patches. >> >> But I don't see why, can you please just squash this into whatever patch >> adds this code in the first place. > > It was an optimization added later. But yes it can be squashed into an > earlier patch.
Could you please explain what is the optimization this achieves ?