From 730856651c2f53cb0eb26e0e6756339be829d2b2 Mon Sep 17 00:00:00 2001
From: Ram Pai <linuxram@us.ibm.com>
Date: Thu, 18 Jan 2018 17:50:37 -0800
Subject: [PATCH 35/45] powerpc: helper to validate key-access permissions of a
pte
References: FATE#322447, bsc#1078248
Patch-mainline: v4.16-rc1
Git-commit: f2407ef3ba225665ee24965f69bc84435fb590cf
helper function that checks if the read/write/execute is allowed
on the pte.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/include/asm/book3s/64/pgtable.h | 2 ++
arch/powerpc/include/asm/pkeys.h | 9 +++++++++
arch/powerpc/mm/pkeys.c | 28 ++++++++++++++++++++++++++++
3 files changed, 39 insertions(+)
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 43bfcf9076e0..817094321ef1 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -564,6 +564,8 @@ static inline int pte_present(pte_t pte)
return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT));
}
+extern bool arch_pte_access_permitted(u64 pte, bool write, bool execute);
+
#define pte_access_permitted pte_access_permitted
static inline bool pte_access_permitted(pte_t pte, bool write)
{
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index a8ef7fa5360e..2298771b066b 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -71,6 +71,15 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL));
}
+static inline u16 pte_to_pkey_bits(u64 pteflags)
+{
+ return (((pteflags & H_PTE_PKEY_BIT0) ? 0x10 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT1) ? 0x8 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT2) ? 0x4 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT3) ? 0x2 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT4) ? 0x1 : 0x0UL));
+}
+
#define pkey_alloc_mask(pkey) (0x1 << pkey)
#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index 010c90c1f5da..5071778fdd20 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -358,3 +358,31 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot,
/* Nothing to override. */
return vma_pkey(vma);
}
+
+static bool pkey_access_permitted(int pkey, bool write, bool execute)
+{
+ int pkey_shift;
+ u64 amr;
+
+ if (!pkey)
+ return true;
+
+ if (!is_pkey_enabled(pkey))
+ return true;
+
+ pkey_shift = pkeyshift(pkey);
+ if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift)))
+ return true;
+
+ amr = read_amr(); /* Delay reading amr until absolutely needed */
+ return ((!write && !(amr & (AMR_RD_BIT << pkey_shift))) ||
+ (write && !(amr & (AMR_WR_BIT << pkey_shift))));
+}
+
+bool arch_pte_access_permitted(u64 pte, bool write, bool execute)
+{
+ if (static_branch_likely(&pkey_disabled))
+ return true;
+
+ return pkey_access_permitted(pte_to_pkey_bits(pte), write, execute);
+}
--
2.13.6