Allocate subpage protect related variables only if we use the feature.
This helps in reducing the hash related mm context struct by around 4K
Before the patch
sizeof(struct hash_mm_context) = 8288
After the patch
sizeof(struct hash_mm_context) = 4160
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
---
arch/powerpc/include/asm/book3s/64/mmu-hash.h | 4 +--
arch/powerpc/include/asm/book3s/64/mmu.h | 2 +-
arch/powerpc/mm/hash_utils_64.c | 3 ++
arch/powerpc/mm/mmu_context_book3s64.c | 17 +++++++++--
arch/powerpc/mm/subpage-prot.c | 28 ++++++++++++++-----
5 files changed, 40 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 4481bedbb5be..eeb40091b46b 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
@@ -687,10 +687,8 @@ struct subpage_prot_table {
#define SBP_L3_SHIFT (SBP_L2_SHIFT + SBP_L2_BITS)
extern void subpage_prot_free(struct mm_struct *mm);
-extern void subpage_prot_init_new_context(struct mm_struct *mm);
#else
static inline void subpage_prot_free(struct mm_struct *mm) {}
-static inline void subpage_prot_init_new_context(struct mm_struct *mm) { }
#endif /* CONFIG_PPC_SUBPAGE_PROT */
/*
@@ -720,7 +718,7 @@ struct hash_mm_context {
#endif
#ifdef CONFIG_PPC_SUBPAGE_PROT
- struct subpage_prot_table spt;
+ struct subpage_prot_table *spt;
#endif /* CONFIG_PPC_SUBPAGE_PROT */
};
diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h
b/arch/powerpc/include/asm/book3s/64/mmu.h
index 3bc94baf5ed5..62ae73df93d2 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu.h
@@ -191,7 +191,7 @@ static inline struct slice_mask
*mm_ctx_slice_mask_16g(mm_context_t *ctx)
#ifdef CONFIG_PPC_SUBPAGE_PROT
static inline struct subpage_prot_table *mm_ctx_subpage_prot(mm_context_t *ctx)
{
- return &ctx->hash_context->spt;
+ return ctx->hash_context->spt;
}
#endif
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 04ac7c36d380..33bd4a1b4d75 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1155,6 +1155,9 @@ static int subpage_protection(struct mm_struct *mm,
unsigned long ea)
u32 spp = 0;
u32 **sbpm, *sbpp;
+ if (!spt)
+ return 0;
+
if (ea >= spt->maxaddr)
return 0;
if (ea < 0x100000000UL) {
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c
b/arch/powerpc/mm/mmu_context_book3s64.c
index 6eef5a36b2e9..cb2b08635508 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -63,7 +63,8 @@ static int hash__init_new_context(struct mm_struct *mm)
if (index < 0)
return index;
- mm->context.hash_context = kmalloc(sizeof(struct hash_mm_context),
GFP_KERNEL);
+ mm->context.hash_context = kmalloc(sizeof(struct hash_mm_context),
+ GFP_KERNEL);
if (!mm->context.hash_context) {
ida_free(&mmu_context_ida, index);
return -ENOMEM;
@@ -89,11 +90,21 @@ static int hash__init_new_context(struct mm_struct *mm)
} else {
/* This is fork. Copy hash_context details from current->mm */
memcpy(mm->context.hash_context,
current->mm->context.hash_context, sizeof(struct hash_mm_context));
+#ifdef CONFIG_PPC_SUBPAGE_PROT
+ /* inherit subpage prot detalis if we have one. */
+ if (current->mm->context.hash_context->spt) {
+ mm->context.hash_context->spt = kmalloc(sizeof(struct
subpage_prot_table),
+ GFP_KERNEL);
+ if (!mm->context.hash_context->spt) {
+ ida_free(&mmu_context_ida, index);
+ kfree(mm->context.hash_context);
+ return -ENOMEM;
+ }
+ }
+#endif
}
- subpage_prot_init_new_context(mm);
-
pkey_mm_init(mm);
return index;
}
diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
index c72252542210..c9dff4e1f295 100644
--- a/arch/powerpc/mm/subpage-prot.c
+++ b/arch/powerpc/mm/subpage-prot.c
@@ -29,6 +29,9 @@ void subpage_prot_free(struct mm_struct *mm)
unsigned long i, j, addr;
u32 **p;
+ if (!spt)
+ return;
+
for (i = 0; i < 4; ++i) {
if (spt->low_prot[i]) {
free_page((unsigned long)spt->low_prot[i]);
@@ -48,13 +51,7 @@ void subpage_prot_free(struct mm_struct *mm)
free_page((unsigned long)p);
}
spt->maxaddr = 0;
-}
-
-void subpage_prot_init_new_context(struct mm_struct *mm)
-{
- struct subpage_prot_table *spt = mm_ctx_subpage_prot(&mm->context);
-
- memset(spt, 0, sizeof(*spt));
+ kfree(spt);
}
static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
@@ -99,6 +96,9 @@ static void subpage_prot_clear(unsigned long addr, unsigned
long len)
size_t nw;
unsigned long next, limit;
+ if (!spt)
+ return ;
+
down_write(&mm->mmap_sem);
limit = addr + len;
if (limit > spt->maxaddr)
@@ -218,6 +218,20 @@ SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,
return -EFAULT;
down_write(&mm->mmap_sem);
+
+ if (!spt) {
+ /*
+ * Allocate subpage prot table if not already done.
+ * Do this with mmap_sem held
+ */
+ spt = kzalloc(sizeof(struct subpage_prot_table), GFP_KERNEL);
+ if (!spt) {
+ err = -ENOMEM;
+ goto out;
+ }
+ mm->context.hash_context->spt = spt;
+ }
+
subpage_mark_vma_nohuge(mm, addr, len);
for (limit = addr + len; addr < limit; addr = next) {
next = pmd_addr_end(addr, limit);
--
2.20.1
