powerpc: Define swapper_pg_dir[] in C

Don't duplicate swapper_pg_dir[] in each platform's head.S

Define it in mm/pgtable.c

Define MAX_PTRS_PER_PGD because on book3s/64 PTRS_PER_PGD is
not a constant.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5e3f1b8a4695c33ccc80aa3870e016bef32b85e1.1623063174.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -232,6 +232,9 @@ extern unsigned long __pmd_frag_size_shift;
 #define PTRS_PER_PUD	(1 << PUD_INDEX_SIZE)
 #define PTRS_PER_PGD	(1 << PGD_INDEX_SIZE)
 
+#define MAX_PTRS_PER_PGD	(1 << (H_PGD_INDEX_SIZE > RADIX_PGD_INDEX_SIZE ? \
+				       H_PGD_INDEX_SIZE : RADIX_PGD_INDEX_SIZE))
+
 /* PMD_SHIFT determines what a second-level page table entry can map */
 #define PMD_SHIFT	(PAGE_SHIFT + PTE_INDEX_SIZE)
 #define PMD_SIZE	(1UL << PMD_SHIFT)

arch/powerpc/include/asm/pgtable.h

@@ -41,6 +41,10 @@ struct mm_struct;
 
 #ifndef __ASSEMBLY__
 
+#ifndef MAX_PTRS_PER_PGD
+#define MAX_PTRS_PER_PGD PTRS_PER_PGD
+#endif
+
 /* Keep these as a macros to avoid include dependency mess */
 #define pte_page(x)		pfn_to_page(pte_pfn(x))
 #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))

arch/powerpc/kernel/asm-offsets.c

@@ -354,11 +354,6 @@ int main(void)
 	DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));
 #endif
 
-#ifdef CONFIG_PPC_BOOK3S_64
-	DEFINE(PGD_TABLE_SIZE, (sizeof(pgd_t) << max(RADIX_PGD_INDEX_SIZE, H_PGD_INDEX_SIZE)));
-#else
-	DEFINE(PGD_TABLE_SIZE, PGD_TABLE_SIZE);
-#endif
 	DEFINE(PTE_SIZE, sizeof(pte_t));
 
 #ifdef CONFIG_KVM

arch/powerpc/kernel/head_40x.S

@@ -701,14 +701,3 @@ _GLOBAL(abort)
         mfspr   r13,SPRN_DBCR0
         oris    r13,r13,DBCR0_RST_SYSTEM@h
         mtspr   SPRN_DBCR0,r13
-
-/* We put a few things here that have to be page-aligned. This stuff
- * goes at the beginning of the data segment, which is page-aligned.
- */
-	.data
-	.align	12
-	.globl	sdata
-sdata:
-	.globl	swapper_pg_dir
-swapper_pg_dir:
-	.space	PGD_TABLE_SIZE

arch/powerpc/kernel/head_44x.S

@@ -1233,23 +1233,8 @@ head_start_common:
 	isync
 	blr
 
-/*
- * We put a few things here that have to be page-aligned. This stuff
- * goes at the beginning of the data segment, which is page-aligned.
- */
-	.data
-	.align	PAGE_SHIFT
-	.globl	sdata
-sdata:
-
-/*
- * To support >32-bit physical addresses, we use an 8KB pgdir.
- */
-	.globl	swapper_pg_dir
-swapper_pg_dir:
-	.space	PGD_TABLE_SIZE
-
 #ifdef CONFIG_SMP
+	.data
 	.align	12
 temp_boot_stack:
 	.space	1024

arch/powerpc/kernel/head_64.S

@@ -997,18 +997,3 @@ start_here_common:
 0:	trap
 	EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0
 	.previous
-
-/*
- * We put a few things here that have to be page-aligned.
- * This stuff goes at the beginning of the bss, which is page-aligned.
- */
-	.section ".bss"
-/*
- * pgd dir should be aligned to PGD_TABLE_SIZE which is 64K.
- * We will need to find a better way to fix this
- */
-	.align	16
-
-	.globl	swapper_pg_dir
-swapper_pg_dir:
-	.space	PGD_TABLE_SIZE

arch/powerpc/kernel/head_8xx.S

@@ -786,15 +786,3 @@ _GLOBAL(mmu_pin_tlb)
 	mtspr	SPRN_SRR1, r10
 	mtspr	SPRN_SRR0, r11
 	rfi
-
-/*
- * We put a few things here that have to be page-aligned.
- * This stuff goes at the beginning of the data segment,
- * which is page-aligned.
- */
-	.data
-	.globl	sdata
-sdata:
-	.globl	swapper_pg_dir
-swapper_pg_dir:
-	.space	PGD_TABLE_SIZE

arch/powerpc/kernel/head_book3s_32.S

@@ -1208,14 +1208,4 @@ setup_usbgecko_bat:
 	blr
 #endif
 
-/*
- * We put a few things here that have to be page-aligned.
- * This stuff goes at the beginning of the data segment,
- * which is page-aligned.
- */
 	.data
-	.globl	sdata
-sdata:
-	.globl	swapper_pg_dir
-swapper_pg_dir:
-	.space	PGD_TABLE_SIZE

arch/powerpc/kernel/head_fsl_booke.S

@@ -1212,15 +1212,3 @@ _GLOBAL(restore_to_as0)
 	*/
 3:	mr	r3,r5
 	bl	_start
-
-/*
- * We put a few things here that have to be page-aligned. This stuff
- * goes at the beginning of the data segment, which is page-aligned.
- */
-	.data
-	.align	12
-	.globl	sdata
-sdata:
-	.globl	swapper_pg_dir
-swapper_pg_dir:
-	.space	PGD_TABLE_SIZE

arch/powerpc/mm/pgtable.c

@@ -28,6 +28,8 @@
 #include <asm/hugetlb.h>
 #include <asm/pte-walk.h>
 
+pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __page_aligned_bss;
+
 static inline int is_exec_fault(void)
 {
 	return current->thread.regs && TRAP(current->thread.regs) == 0x400;