Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-03-05 Thread Naveen N. Rao
On 2021/03/04 09:45AM, Segher Boessenkool wrote: > On Wed, Mar 03, 2021 at 10:01:27PM +0530, Naveen N. Rao wrote: > > On 2021/03/01 08:37PM, Segher Boessenkool wrote: > > > > And, r6 always ends up with 0xaea. It changes with the value I put into > > > > r6 though. > > > > > > That is exactly the

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-03-04 Thread Segher Boessenkool
On Wed, Mar 03, 2021 at 10:01:27PM +0530, Naveen N. Rao wrote: > On 2021/03/01 08:37PM, Segher Boessenkool wrote: > > > And, r6 always ends up with 0xaea. It changes with the value I put into > > > r6 though. > > > > That is exactly the behaviour specified for p8. 0aaa+0040=0aea. > > > > > Gran

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-03-04 Thread Naveen N. Rao
On 2021/03/01 08:37PM, Segher Boessenkool wrote: > Hi! > > I didn't see this until now, almost a month later, sorry about that :-) No problem. > > On Thu, Feb 04, 2021 at 01:57:53PM +0530, Naveen N. Rao wrote: > > On 2021/02/03 03:17PM, Segher Boessenkool wrote: > > > Power8 does: > > > > > >

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-03-01 Thread Segher Boessenkool
Hi! I didn't see this until now, almost a month later, sorry about that :-) On Thu, Feb 04, 2021 at 01:57:53PM +0530, Naveen N. Rao wrote: > On 2021/02/03 03:17PM, Segher Boessenkool wrote: > > Power8 does: > > > > Load with Update Instructions (RA = 0) > > EA is placed into R0. > > Load

RE: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-04 Thread David Laight
From: Segher Boessenkool > Sent: 03 February 2021 21:18 ... > Power9 does: > > Load with Update Instructions (RA = 0) > EA is placed into R0. Does that change the value of 0? Rather reminds me of some 1960s era systems that had the small integers at fixed (global) addresses. FORTRAN always

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-04 Thread Naveen N. Rao
On 2021/02/03 03:17PM, Segher Boessenkool wrote: > On Wed, Feb 03, 2021 at 03:19:09PM +0530, Naveen N. Rao wrote: > > On 2021/02/03 12:08PM, Sandipan Das wrote: > > > The Power ISA says that the fixed-point load and update > > > instructions must neither use R0 for the base address (RA) > > > nor h

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-03 Thread Michael Ellerman
Sandipan Das writes: > On 03/02/21 3:19 pm, Naveen N. Rao wrote: >> [...] >> >> Wouldn't it be easier to just do the below at the end? Or, am I missing >> something? >> >> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c >> index ede093e9623472..a2d726d2a5e9d1 100644 >> --- a/ar

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-03 Thread Segher Boessenkool
On Wed, Feb 03, 2021 at 03:19:09PM +0530, Naveen N. Rao wrote: > On 2021/02/03 12:08PM, Sandipan Das wrote: > > The Power ISA says that the fixed-point load and update > > instructions must neither use R0 for the base address (RA) > > nor have the destination (RT) and the base address (RA) as > > t

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-03 Thread Sandipan Das
On 03/02/21 3:19 pm, Naveen N. Rao wrote: > [...] > > Wouldn't it be easier to just do the below at the end? Or, am I missing > something? > > diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c > index ede093e9623472..a2d726d2a5e9d1 100644 > --- a/arch/powerpc/lib/sstep.c > +++ b

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-03 Thread Sandipan Das
On 03/02/21 3:19 pm, Naveen N. Rao wrote: > [...] > > Wouldn't it be easier to just do the below at the end? Or, am I missing > something? > > diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c > index ede093e9623472..a2d726d2a5e9d1 100644 > --- a/arch/powerpc/lib/sstep.c > +++ b/a

Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-03 Thread Naveen N. Rao
On 2021/02/03 12:08PM, Sandipan Das wrote: > The Power ISA says that the fixed-point load and update > instructions must neither use R0 for the base address (RA) > nor have the destination (RT) and the base address (RA) as > the same register. In these cases, the instruction is > invalid. This appl

[PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

2021-02-02 Thread Sandipan Das
The Power ISA says that the fixed-point load and update instructions must neither use R0 for the base address (RA) nor have the destination (RT) and the base address (RA) as the same register. In these cases, the instruction is invalid. This applies to the following instructions. * Load Byte and