linux-kernel - [RFC v6 16/62] powerpc: cleaup AMR,iAMR when a key is allocated or freed

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Date:   Sat, 15 Jul 2017 20:56:18 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, dave.hansen@...el.com, hbabu@...ibm.com,
        linuxram@...ibm.com, arnd@...db.de, akpm@...ux-foundation.org,
        corbet@....net, mingo@...hat.com, mhocko@...nel.org
Subject: [RFC v6 16/62] powerpc: cleaup AMR,iAMR when a key is allocated or freed

cleanup the bits corresponding to a key in the AMR, and IAMR
register, when the key is newly allocated/activated or is freed.
We dont want some residual bits cause the hardware enforce
unintended behavior when the key is activated or freed.

Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 arch/powerpc/include/asm/pkeys.h |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 4327842..7f5c21d 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -42,6 +42,8 @@ static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
 		mm_set_pkey_is_allocated(mm, pkey));
 }
 
+extern void __arch_activate_pkey(int pkey);
+extern void __arch_deactivate_pkey(int pkey);
 /*
  * Returns a positive, 5-bit key on success, or -1 on failure.
  */
@@ -70,6 +72,12 @@ static inline int mm_pkey_alloc(struct mm_struct *mm)
 		ffz((u32)mm_pkey_allocation_map(mm))
 		- 1;
 	mm_set_pkey_allocated(mm, ret);
+
+	/*
+	 * enable the key in the hardware
+	 */
+	if (ret > 0)
+		__arch_activate_pkey(ret);
 	return ret;
 }
 
@@ -81,6 +89,10 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
 	if (!mm_pkey_is_allocated(mm, pkey))
 		return -EINVAL;
 
+	/*
+	 * Disable the key in the hardware
+	 */
+	__arch_deactivate_pkey(pkey);
 	mm_set_pkey_free(mm, pkey);
 
 	return 0;
-- 
1.7.1