[PATCH 1/3] powerpc: Define empty_zero_page[] in C

[Christophe Leroy]

At the time being, empty_zero_page[] is defined in each
platform head.S.

Define it in mm/mem.c instead, and put it in BSS section instead
of the DATA section. Commit 5227cfa71f9e ("arm64: mm: place
empty_zero_page in bss") explains why it is interesting to have
it in BSS.

Signed-off-by: Christophe Leroy <***@csgroup.eu>
---
Applies on top of powerpc next-test with the Fixup for v3 "powerpc/nohash: Refactor update of BDI2000 pointers in switch_mmu_context()".
The last patch of this small series can be applied independently at the cost of a trivial conflict in asm-offsets.c

arch/powerpc/kernel/head_40x.S | 4 ----
arch/powerpc/kernel/head_44x.S | 4 ----
arch/powerpc/kernel/head_64.S | 5 -----
arch/powerpc/kernel/head_8xx.S | 6 ------
arch/powerpc/kernel/head_book3s_32.S | 5 -----
arch/powerpc/kernel/head_fsl_booke.S | 4 ----
arch/powerpc/mm/mem.c | 3 +++
7 files changed, 3 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 2717aa860cae..92b6c7356161 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -709,10 +709,6 @@ _GLOBAL(abort)
.align 12
.globl sdata
sdata:
- .globl empty_zero_page
-empty_zero_page:
- .space 4096
-EXPORT_SYMBOL(empty_zero_page)
.globl swapper_pg_dir
swapper_pg_dir:
.space PGD_TABLE_SIZE
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 2c4ffec027a2..e037eb615757 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -1241,10 +1241,6 @@ head_start_common:
.align PAGE_SHIFT
.globl sdata
sdata:
- .globl empty_zero_page
-empty_zero_page:
- .space PAGE_SIZE
-EXPORT_SYMBOL(empty_zero_page)

/*
* To support >32-bit physical addresses, we use an 8KB pgdir.
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index ece7f97bafff..730838c7ca39 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -1012,8 +1012,3 @@ start_here_common:
.globl swapper_pg_dir
swapper_pg_dir:
.space PGD_TABLE_SIZE
-
- .globl empty_zero_page
-empty_zero_page:
- .space PAGE_SIZE
-EXPORT_SYMBOL(empty_zero_page)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 817df9fe7fb3..5ce42dfac061 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -795,12 +795,6 @@ _GLOBAL(mmu_pin_tlb)
.data
.globl sdata
sdata:
- .globl empty_zero_page
- .align PAGE_SHIFT
-empty_zero_page:
- .space PAGE_SIZE
-EXPORT_SYMBOL(empty_zero_page)
-
.globl swapper_pg_dir
swapper_pg_dir:
.space PGD_TABLE_SIZE
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 326262030279..79c744afc6b6 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -1274,11 +1274,6 @@ setup_usbgecko_bat:
.data
.globl sdata
sdata:
- .globl empty_zero_page
-empty_zero_page:
- .space 4096
-EXPORT_SYMBOL(empty_zero_page)
-
.globl swapper_pg_dir
swapper_pg_dir:
.space PGD_TABLE_SIZE
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index ab718fd5e2a2..f33bc5a8e73e 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -1221,10 +1221,6 @@ _GLOBAL(restore_to_as0)
.align 12
.globl sdata
sdata:
- .globl empty_zero_page
-empty_zero_page:
- .space 4096
-EXPORT_SYMBOL(empty_zero_page)
.globl swapper_pg_dir
swapper_pg_dir:
.space PGD_TABLE_SIZE
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 043bbeaf407c..b06e5d969051 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -27,6 +27,9 @@
unsigned long long memory_limit;
bool init_mem_is_free;

+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
+EXPORT_SYMBOL(empty_zero_page);
+
pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot)
{

[Christophe Leroy]

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 <***@csgroup.eu>
---
arch/powerpc/include/asm/book3s/64/pgtable.h | 3 +++
arch/powerpc/include/asm/pgtable.h | 4 ++++
arch/powerpc/kernel/asm-offsets.c | 5 -----
arch/powerpc/kernel/head_40x.S | 11 -----------
arch/powerpc/kernel/head_44x.S | 17 +----------------
arch/powerpc/kernel/head_64.S | 15 ---------------
arch/powerpc/kernel/head_8xx.S | 12 ------------
arch/powerpc/kernel/head_book3s_32.S | 11 -----------
arch/powerpc/kernel/head_fsl_booke.S | 12 ------------
arch/powerpc/mm/pgtable.c | 2 ++
10 files changed, 10 insertions(+), 82 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index a666d561b44d..4d9941b2fe51 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/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)
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index c6a676714f04..b9c8641654f4 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/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))
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 0480f4006e0c..f1b6ff14c8a0 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -361,11 +361,6 @@ 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
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 92b6c7356161..7d72ee5ab387 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -701,14 +701,3 @@ _GLOBAL(abort)
mfspr r13,SPRN_DBCR0
oris r13,r13,***@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
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index e037eb615757..ddc978a2d381 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/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
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 730838c7ca39..79f2d1e61abd 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/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
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 5ce42dfac061..9bdb95f5694f 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/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
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 79c744afc6b6..689c9d37f193 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -1266,18 +1266,7 @@ 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
-
/* Room for two PTE pointers, usually the kernel and current user pointers
* to their respective root page table.
*/
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index f33bc5a8e73e..0f9642f36b49 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/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
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 354611940118..1707ab580ee2 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/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;

[Christophe Leroy]

PTE_SIZE means PTE page table size in most placed, whereas
in hash_low.S in means size of one entry in the table.

Rename it PTE_T_SIZE, and define it directly in hash_low.S
instead of going through asm-offsets.

Signed-off-by: Christophe Leroy <***@csgroup.eu>
---
arch/powerpc/kernel/asm-offsets.c | 2 --
arch/powerpc/mm/book3s32/hash_low.S | 6 ++++--
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index f1b6ff14c8a0..2bd936ebcae8 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -361,8 +361,6 @@ int main(void)
DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));
#endif

- DEFINE(PTE_SIZE, sizeof(pte_t));
-
#ifdef CONFIG_KVM
OFFSET(VCPU_HOST_STACK, kvm_vcpu, arch.host_stack);
OFFSET(VCPU_HOST_PID, kvm_vcpu, arch.host_pid);
diff --git a/arch/powerpc/mm/book3s32/hash_low.S b/arch/powerpc/mm/book3s32/hash_low.S
index fb4233a5bdf7..6925ce998557 100644
--- a/arch/powerpc/mm/book3s32/hash_low.S
+++ b/arch/powerpc/mm/book3s32/hash_low.S
@@ -27,8 +27,10 @@
#include <asm/code-patching-asm.h>

#ifdef CONFIG_PTE_64BIT
+#define PTE_T_SIZE 8
#define PTE_FLAGS_OFFSET 4 /* offset of PTE flags, in bytes */
#else
+#define PTE_T_SIZE 4
#define PTE_FLAGS_OFFSET 0
#endif

@@ -488,7 +490,7 @@ _GLOBAL(flush_hash_pages)
bne 2f
ble cr1,19f
addi r4,r4,0x1000
- addi r5,r5,PTE_SIZE
+ addi r5,r5,PTE_T_SIZE
addi r6,r6,-1
b 1b

@@ -573,7 +575,7 @@ _GLOBAL(flush_hash_pages)

8: ble cr1,9f /* if all ptes checked */
81: addi r6,r6,-1
- addi r5,r5,PTE_SIZE
+ addi r5,r5,PTE_T_SIZE
addi r4,r4,0x1000
lwz r0,0(r5) /* check next pte */
cmpwi cr1,r6,1