* [PATCH 1/1 v2] powerpc: pkey-mprotect must allow pkey-0
@ 2018-03-14 7:45 Ram Pai
0 siblings, 0 replies; only message in thread
From: Ram Pai @ 2018-03-14 7:45 UTC (permalink / raw)
To: mpe
Cc: linuxppc-dev, linux-mm, x86, linux-arch, linux-kernel, mingo,
akpm, dave.hansen, benh, paulus, khandual, aneesh.kumar,
bsingharora, hbabu, mhocko, bauerman, ebiederm, linuxram, corbet,
arnd, fweimer, msuchanek
Once an address range is associated with an allocated pkey, it cannot be
reverted back to key-0. There is no valid reason for the above behavior. On
the contrary applications need the ability to do so.
The patch relaxes the restriction.
Tested on powerpc.
cc: Dave Hansen <dave.hansen@intel.com>
cc: Michael Ellermen <mpe@ellerman.id.au>
cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
arch/powerpc/include/asm/pkeys.h | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 0409c80..3c1deec 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -101,10 +101,18 @@ static inline u16 pte_to_pkey_bits(u64 pteflags)
static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
{
- /* A reserved key is never considered as 'explicitly allocated' */
- return ((pkey < arch_max_pkey()) &&
- !__mm_pkey_is_reserved(pkey) &&
- __mm_pkey_is_allocated(mm, pkey));
+ /* pkey 0 is allocated by default. */
+ if (!pkey)
+ return true;
+
+ if (pkey < 0 || pkey >= arch_max_pkey())
+ return false;
+
+ /* Reserved keys are never allocated. */
+ if (__mm_pkey_is_reserved(pkey))
+ return false;
+
+ return __mm_pkey_is_allocated(mm, pkey);
}
extern void __arch_activate_pkey(int pkey);
@@ -150,7 +158,8 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
if (static_branch_likely(&pkey_disabled))
return -1;
- if (!mm_pkey_is_allocated(mm, pkey))
+ /* pkey 0 cannot be freed */
+ if (!pkey || !mm_pkey_is_allocated(mm, pkey))
return -EINVAL;
/*
--
1.8.3.1
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