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Subject[PATCH] powerpc: simplify BDI switch
Date
There is no reason to re-read each time the pointer at
location 0xf0 as it is fixed and known.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/include/asm/mmu.h | 2 ++
arch/powerpc/kernel/head_32.S | 5 ++---
arch/powerpc/kernel/head_40x.S | 5 ++---
arch/powerpc/kernel/head_8xx.S | 1 +
arch/powerpc/mm/8xx_mmu.c | 7 ++-----
5 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 25607604a7a5..6d22a8e78fe2 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -356,6 +356,8 @@ extern void early_init_mmu_secondary(void);
extern void setup_initial_memory_limit(phys_addr_t first_memblock_base,
phys_addr_t first_memblock_size);
static inline void mmu_early_init_devtree(void) { }
+
+extern void *abatron_pteptrs[2];
#endif /* __ASSEMBLY__ */
#endif

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 05b08db3901d..c2f564690778 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -1027,9 +1027,8 @@ _ENTRY(switch_mmu_context)
* The PGDIR is passed as second argument.
*/
lwz r4,MM_PGD(r4)
- lis r5, KERNELBASE@h
- lwz r5, 0xf0(r5)
- stw r4, 0x4(r5)
+ lis r5, abatron_pteptrs@ha
+ stw r4, abatron_pteptrs@l + 0x4(r5)
#endif
li r4,0
isync
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index b19d78410511..11dd09d0ce1a 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -953,9 +953,8 @@ _GLOBAL(set_context)
/* Context switch the PTE pointer for the Abatron BDI2000.
* The PGDIR is the second parameter.
*/
- lis r5, KERNELBASE@h
- lwz r5, 0xf0(r5)
- stw r4, 0x4(r5)
+ lis r5, abatron_pteptrs@ha
+ stw r4, abatron_pteptrs@l + 0x4(r5)
#endif
sync
mtspr SPRN_PID,r3
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 20cc816b3508..ec12abc2a8ce 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -989,5 +989,6 @@ swapper_pg_dir:
/* Room for two PTE table poiners, usually the kernel and current user
* pointer to their respective root page table (pgdir).
*/
+ .globl abatron_pteptrs
abatron_pteptrs:
.space 8
diff --git a/arch/powerpc/mm/8xx_mmu.c b/arch/powerpc/mm/8xx_mmu.c
index 92b677faea8c..174452f7b5db 100644
--- a/arch/powerpc/mm/8xx_mmu.c
+++ b/arch/powerpc/mm/8xx_mmu.c
@@ -156,14 +156,11 @@ void set_context(unsigned long id, pgd_t *pgd)
{
s16 offset = (s16)(__pa(swapper_pg_dir));

-#ifdef CONFIG_BDI_SWITCH
- pgd_t **ptr = *(pgd_t ***)(KERNELBASE + 0xf0);
-
/* Context switch the PTE pointer for the Abatron BDI2000.
* The PGDIR is passed as second argument.
*/
- *(ptr + 1) = pgd;
-#endif
+ if (IS_ENABLED(CONFIG_BDI_SWITCH))
+ abatron_pteptrs[1] = pgd;

/* Register M_TWB will contain base address of level 1 table minus the
* lower part of the kernel PGDIR base address, so that all accesses to
--
2.13.3
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