On Sun, 13 Aug 2017 11:33:45 +1000
Nicholas Piggin <npig...@gmail.com> wrote:
> Change the paca array into an array of pointers to pacas. Allocate
> pacas individually.
>
> This allows flexibility in where the PACAs are allocated. Future work
> will allocate them node-local. Platforms that don't have address limits
> on PACAs would be able to defer PACA allocations until later in boot
> rather than allocate all possible ones up-front then freeing unused.
>
> This is slightly more overhead (one additional indirection) for cross
> CPU paca references, but those aren't too common.
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
Incremental fix required for this. A !SMP typo bug, and pmac
init code that was not switched from paca array to paca_ptrs
array.
In the first case I just got rid of the r13 thing completely.
I think the idea of the code was to give secondaries a different
r13 so they wouldn't overwrite CPU0's paca if they accidentally
used it.
---
arch/powerpc/kernel/head_64.S | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index f71f468ebe7f..9db29719fc32 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -386,12 +386,11 @@ generic_secondary_common_init:
* physical cpu id in r24, we need to search the pacas to find
* which logical id maps to our physical one.
*/
- LOAD_REG_ADDR(r8, paca_ptrs) /* Load paca_ptrs pointe */
- ld r8,0(r8) /* Get base vaddr of array */
#ifndef CONFIG_SMP
- li r13,r13,0 /* kill r13 if used accidentally */
b kexec_wait /* wait for next kernel if !SMP */
#else
+ LOAD_REG_ADDR(r8, paca_ptrs) /* Load paca_ptrs pointe */
+ ld r8,0(r8) /* Get base vaddr of array */
LOAD_REG_ADDR(r7, nr_cpu_ids) /* Load nr_cpu_ids address */
lwz r7,0(r7) /* also the max paca allocated */
li r5,0 /* logical cpu id */
@@ -752,10 +751,10 @@ _GLOBAL(pmac_secondary_start)
mtmsrd r3 /* RI on */
/* Set up a paca value for this processor. */
- LOAD_REG_ADDR(r4,paca) /* Load paca pointer */
- ld r4,0(r4) /* Get base vaddr of paca array */
- mulli r13,r24,PACA_SIZE /* Calculate vaddr of right paca */
- add r13,r13,r4 /* for this processor. */
+ LOAD_REG_ADDR(r4,paca_ptrs) /* Load paca pointer */
+ ld r4,0(r4) /* Get base vaddr of paca_ptrs array */
+ sldi r5,r24,3 /* get paca_ptrs[] index from cpu id */
+ ldx r13,r4,r5 /* r13 = paca_ptrs[cpu id] */
SET_PACA(r13) /* Save vaddr of paca in an SPRG*/
/* Mark interrupts soft and hard disabled (they might be enabled
--
2.13.3
