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powerpc: implementation for arch_vma_access_permitted()

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Ram Pai 2018-01-18 17:50:39 -08:00 committed by Michael Ellerman
parent bca7aacfe8
commit 1137573acf
2 changed files with 38 additions and 1 deletions
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5
arch/powerpc/include/asm/mmu_context.h
View file

@ -186,6 +186,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
{ {
} }
#ifdef CONFIG_PPC_MEM_KEYS
bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,
bool execute, bool foreign);
#else /* CONFIG_PPC_MEM_KEYS */
static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
bool write, bool execute, bool foreign) bool write, bool execute, bool foreign)
{ {
@ -193,7 +197,6 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
return true; return true;
} }
#ifndef CONFIG_PPC_MEM_KEYS
#define pkey_mm_init(mm) #define pkey_mm_init(mm)
#define thread_pkey_regs_save(thread) #define thread_pkey_regs_save(thread)
#define thread_pkey_regs_restore(new_thread, old_thread) #define thread_pkey_regs_restore(new_thread, old_thread)

34
arch/powerpc/mm/pkeys.c
View file

@ -386,3 +386,37 @@ bool arch_pte_access_permitted(u64 pte, bool write, bool execute)
return pkey_access_permitted(pte_to_pkey_bits(pte), write, execute); return pkey_access_permitted(pte_to_pkey_bits(pte), write, execute);
} }
/*
* We only want to enforce protection keys on the current thread because we
* effectively have no access to AMR/IAMR for other threads 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 it is not our ->mm, it has to be foreign */
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)
{
if (static_branch_likely(&pkey_disabled))
return true;
/*
* Do not enforce our key-permissions on a foreign vma.
*/
if (foreign || vma_is_foreign(vma))
return true;
return pkey_access_permitted(vma_pkey(vma), write, execute);
}