powerpc/nohash: Refactor update of BDI2000 pointers in switch_mmu_context()

Instead of duplicating the update of BDI2000 pointers in
set_context(), do it directly from switch_mmu_context().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4c54997edd3548fa54717915e7c6ebaf60f208c0.1622712515.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/head_40x.S

@@ -703,14 +703,6 @@ _GLOBAL(abort)
         mtspr   SPRN_DBCR0,r13
 
 _GLOBAL(set_context)
-
-#ifdef CONFIG_BDI_SWITCH
-	/* Context switch the PTE pointer for the Abatron BDI2000.
-	 * The PGDIR is the second parameter.
-	 */
-	lis	r5, abatron_pteptrs@ha
-	stw	r4, abatron_pteptrs@l + 0x4(r5)
-#endif
 	sync
 	mtspr	SPRN_PID,r3
 	isync				/* Need an isync to flush shadow */
@@ -731,9 +723,3 @@ EXPORT_SYMBOL(empty_zero_page)
 	.globl	swapper_pg_dir
 swapper_pg_dir:
 	.space	PGD_TABLE_SIZE
-
-/* Room for two PTE pointers, usually the kernel and current user pointers
- * to their respective root page table.
- */
-abatron_pteptrs:
-	.space	8

arch/powerpc/kernel/head_44x.S

@@ -789,15 +789,6 @@ _GLOBAL(__fixup_440A_mcheck)
 	blr
 
 _GLOBAL(set_context)
-
-#ifdef CONFIG_BDI_SWITCH
-	/* Context switch the PTE pointer for the Abatron BDI2000.
-	 * The PGDIR is the second parameter.
-	 */
-	lis	r5, abatron_pteptrs@h
-	ori	r5, r5, abatron_pteptrs@l
-	stw	r4, 0x4(r5)
-#endif
 	mtspr	SPRN_PID,r3
 	isync			/* Force context change */
 	blr
@@ -1267,13 +1258,6 @@ EXPORT_SYMBOL(empty_zero_page)
 swapper_pg_dir:
 	.space	PGD_TABLE_SIZE
 
-/*
- * Room for two PTE pointers, usually the kernel and current user pointers
- * to their respective root page table.
- */
-abatron_pteptrs:
-	.space	8
-
 #ifdef CONFIG_SMP
 	.align	12
 temp_boot_stack:

arch/powerpc/kernel/head_8xx.S

@@ -804,10 +804,3 @@ EXPORT_SYMBOL(empty_zero_page)
 	.globl	swapper_pg_dir
 swapper_pg_dir:
 	.space	PGD_TABLE_SIZE
-
-/* Room for two PTE table pointers, usually the kernel and current user
- * pointer to their respective root page table (pgdir).
- */
-	.globl	abatron_pteptrs
-abatron_pteptrs:
-	.space	8

arch/powerpc/kernel/head_fsl_booke.S

@@ -986,15 +986,6 @@ _GLOBAL(abort)
 	isync
 
 _GLOBAL(set_context)
-
-#ifdef CONFIG_BDI_SWITCH
-	/* Context switch the PTE pointer for the Abatron BDI2000.
-	 * The PGDIR is the second parameter.
-	 */
-	lis	r5, abatron_pteptrs@h
-	ori	r5, r5, abatron_pteptrs@l
-	stw	r4, 0x4(r5)
-#endif
 	mtspr	SPRN_PID,r3
 	isync			/* Force context change */
 	blr
@@ -1242,10 +1233,3 @@ EXPORT_SYMBOL(empty_zero_page)
 	.globl	swapper_pg_dir
 swapper_pg_dir:
 	.space	PGD_TABLE_SIZE
-
-/*
- * Room for two PTE pointers, usually the kernel and current user pointers
- * to their respective root page table.
- */
-abatron_pteptrs:
-	.space	8

arch/powerpc/mm/nohash/8xx.c

@@ -224,12 +224,6 @@ void set_context(unsigned long id, pgd_t *pgd)
 {
 	s16 offset = (s16)(__pa(swapper_pg_dir));
 
-	/* Context switch the PTE pointer for the Abatron BDI2000.
-	 * The PGDIR is passed as second argument.
-	 */
-	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
 	 * level 1 table are done relative to lower part of kernel PGDIR base

arch/powerpc/mm/nohash/mmu_context.c

@@ -50,6 +50,12 @@
 
 #include <mm/mmu_decl.h>
 
+/*
+ * Room for two PTE table pointers, usually the kernel and current user
+ * pointer to their respective root page table (pgdir).
+ */
+void *abatron_pteptrs[2];
+
 /*
  * The MPC8xx has only 16 contexts. We rotate through them on each task switch.
  * A better way would be to keep track of tasks that own contexts, and implement
@@ -357,6 +363,8 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next,
 
 	/* Flick the MMU and release lock */
 	pr_hardcont(" -> %d\n", id);
+	if (IS_ENABLED(CONFIG_BDI_SWITCH))
+		abatron_pteptrs[1] = next->pgd;
 	set_context(id, next->pgd);
 	raw_spin_unlock(&context_lock);
 }

arch/powerpc/mm/nohash/tlb_low.S

@@ -362,14 +362,6 @@ _GLOBAL(_tlbivax_bcast)
 	blr
 
 _GLOBAL(set_context)
-#ifdef CONFIG_BDI_SWITCH
-	/* Context switch the PTE pointer for the Abatron BDI2000.
-	 * The PGDIR is the second parameter.
-	 */
-	lis	r5, abatron_pteptrs@h
-	ori	r5, r5, abatron_pteptrs@l
-	stw	r4, 0x4(r5)
-#endif
 	mtspr	SPRN_PID,r3
 	isync			/* Force context change */
 	blr