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Subject[RFC v6 30/62] powerpc: implementation for arch_vma_access_permitted()
Date
This patch provides the implementation for
arch_vma_access_permitted(). Returns true if the
requested access is allowed by pkey associated with the
vma.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
arch/powerpc/include/asm/mmu_context.h | 5 +++-
arch/powerpc/mm/pkeys.c | 43 ++++++++++++++++++++++++++++++++
2 files changed, 47 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 7232484..635d4a6 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -175,6 +175,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
{
}

+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+bool arch_vma_access_permitted(struct vm_area_struct *vma,
+ bool write, bool execute, bool foreign);
+#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
bool write, bool execute, bool foreign)
{
@@ -182,7 +186,6 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
return true;
}

-#ifndef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
#define pkey_initialize()
#define pkey_mm_init(mm)

diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index 1794e17..9999ce1 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -234,3 +234,46 @@ bool arch_pte_access_permitted(u64 pte, bool write, bool execute)
return pkey_access_permitted(pte_to_pkey_bits(pte),
write, execute);
}
+
+/*
+ * We only want to enforce protection keys on the current process
+ * because we effectively have no access to AMR/IAMR for other
+ * processes or any way to tell *which * AMR/IAMR in a threaded
+ * process we could use.
+ *
+ * So do not enforce things if the VMA is not from the current
+ * mm, or if we are in a kernel thread.
+ */
+static inline bool vma_is_foreign(struct vm_area_struct *vma)
+{
+ if (!current->mm)
+ return true;
+ /*
+ * if the VMA is from another process, then AMR/IAMR has no
+ * relevance and should not be enforced.
+ */
+ if (current->mm != vma->vm_mm)
+ return true;
+
+ return false;
+}
+
+bool arch_vma_access_permitted(struct vm_area_struct *vma,
+ bool write, bool execute, bool foreign)
+{
+ int pkey;
+
+ if (!pkey_inited)
+ return true;
+
+ /* allow access if the VMA is not one from this process */
+ if (foreign || vma_is_foreign(vma))
+ return true;
+
+ pkey = vma_pkey(vma);
+
+ if (!pkey)
+ return true;
+
+ return pkey_access_permitted(pkey, write, execute);
+}
--
1.7.1
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