[PATCH] ARM: KVM: perform save/restore of PAR

[Marc Zyngier]

On Fri, 7 Jun 2013 23:38:19 +0100, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:

Hi Russell,

> On Fri, Jun 07, 2013 at 06:53:13PM +0100, Marc Zyngier wrote:
>> @@ -37,16 +37,18 @@
>>  #define c5_AIFSR	15	/* Auxilary Instrunction Fault Status R */
>>  #define c6_DFAR		16	/* Data Fault Address Register */
>>  #define c6_IFAR		17	/* Instruction Fault Address Register */
>> -#define c9_L2CTLR	18	/* Cortex A15 L2 Control Register */
>> -#define c10_PRRR	19	/* Primary Region Remap Register */
>> -#define c10_NMRR	20	/* Normal Memory Remap Register */
>> -#define c12_VBAR	21	/* Vector Base Address Register */
>> -#define c13_CID		22	/* Context ID Register */
>> -#define c13_TID_URW	23	/* Thread ID, User R/W */
>> -#define c13_TID_URO	24	/* Thread ID, User R/O */
>> -#define c13_TID_PRIV	25	/* Thread ID, Privileged */
>> -#define c14_CNTKCTL	26	/* Timer Control Register (PL1) */
>> -#define NR_CP15_REGS	27	/* Number of regs (incl. invalid) */
>> +#define c7_PAR		18	/* Physical Address Register */
>> +#define c7_PAR_high	19	/* PAR top 32 bits */
>> +#define c9_L2CTLR	20	/* Cortex A15 L2 Control Register */
>> +#define c10_PRRR	21	/* Primary Region Remap Register */
>> +#define c10_NMRR	22	/* Normal Memory Remap Register */
>> +#define c12_VBAR	23	/* Vector Base Address Register */
>> +#define c13_CID		24	/* Context ID Register */
>> +#define c13_TID_URW	25	/* Thread ID, User R/W */
>> +#define c13_TID_URO	26	/* Thread ID, User R/O */
>> +#define c13_TID_PRIV	27	/* Thread ID, Privileged */
>> +#define c14_CNTKCTL	28	/* Timer Control Register (PL1) */
>> +#define NR_CP15_REGS	29	/* Number of regs (incl. invalid) */
> 
> Umm, the fact that you've just had to renumber everything above 17
> suggests that maybe this should have been an enum?

That would have been ideal indeed. Unfortunately, these values are
directly used from assembly code.

One possible workaround would be to define each value in terms of the
previous ones:
#define c7_PAR      (c6_IFAR + 1)
#define c7_PAR_high (c7_PAR + 1)
#define c9_L2CTLR   (c7_PAR_high + 1)
...

Another possibility would be not to use these values in the assembly code,
but instead to generate all the offsets from asm-offset.c and use that
instead.

What do you think?

        M.
-- 
Fast, cheap, reliable. Pick two.