[PATCH] jump_label: align jump_entry table to at least 4-bytes

From: Jason Baron <jbaron@akamai.com>
To: rostedt@goodmis.org
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mips@linux-mips.org,
	linuxppc-dev@lists.ozlabs.org, Ingo Molnar <mingo@kernel.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Anton Blanchard <anton@samba.org>, Rabin Vincent <rabin@rab.in>,
	Russell King <linux@armlinux.org.uk>,
	Ralf Baechle <ralf@linux-mips.org>,
	Chris Metcalf <cmetcalf@mellanox.com>,
	Zhigang Lu <zlu@ezchip.com>,
	David Daney <ddaney@caviumnetworks.com>
Subject: [PATCH] jump_label: align jump_entry table to at least 4-bytes
Date: Mon, 27 Feb 2017 13:49:24 -0500	[thread overview]
Message-ID: <1488221364-13905-1-git-send-email-jbaron@akamai.com> (raw)

The core jump_label code makes use of the 2 lower bits of the
static_key::[type|entries|next] field. Thus, ensure that the jump_entry
table is at least 4-byte aligned.

Reported-and-tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Anton Blanchard <anton@samba.org>
Cc: Rabin Vincent <rabin@rab.in>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Zhigang Lu <zlu@ezchip.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
---
 arch/arm/include/asm/jump_label.h     | 2 ++
 arch/mips/include/asm/jump_label.h    | 2 ++
 arch/powerpc/include/asm/jump_label.h | 3 +++
 arch/tile/include/asm/jump_label.h    | 2 ++
 4 files changed, 9 insertions(+)

diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
index 34f7b6980d21..9c017bb04d1c 100644
--- a/arch/arm/include/asm/jump_label.h
+++ b/arch/arm/include/asm/jump_label.h
@@ -13,6 +13,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 	asm_volatile_goto("1:\n\t"
 		 WASM(nop) "\n\t"
 		 ".pushsection __jump_table,  \"aw\"\n\t"
+		 ".balign 4\n\t"
 		 ".word 1b, %l[l_yes], %c0\n\t"
 		 ".popsection\n\t"
 		 : :  "i" (&((char *)key)[branch]) :  : l_yes);
@@ -27,6 +28,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
 	asm_volatile_goto("1:\n\t"
 		 WASM(b) " %l[l_yes]\n\t"
 		 ".pushsection __jump_table,  \"aw\"\n\t"
+		 ".balign 4\n\t"
 		 ".word 1b, %l[l_yes], %c0\n\t"
 		 ".popsection\n\t"
 		 : :  "i" (&((char *)key)[branch]) :  : l_yes);
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index e77672539e8e..243791f3ae71 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -31,6 +31,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 	asm_volatile_goto("1:\t" NOP_INSN "\n\t"
 		"nop\n\t"
 		".pushsection __jump_table,  \"aw\"\n\t"
+		".balign 4\n\t"
 		WORD_INSN " 1b, %l[l_yes], %0\n\t"
 		".popsection\n\t"
 		: :  "i" (&((char *)key)[branch]) : : l_yes);
@@ -45,6 +46,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
 	asm_volatile_goto("1:\tj %l[l_yes]\n\t"
 		"nop\n\t"
 		".pushsection __jump_table,  \"aw\"\n\t"
+		".balign 4\n\t"
 		WORD_INSN " 1b, %l[l_yes], %0\n\t"
 		".popsection\n\t"
 		: :  "i" (&((char *)key)[branch]) : : l_yes);
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index 9a287e0ac8b1..bfe83496b590 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -24,6 +24,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 	asm_volatile_goto("1:\n\t"
 		 "nop # arch_static_branch\n\t"
 		 ".pushsection __jump_table,  \"aw\"\n\t"
+		 ".balign 4\n\t"
 		 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
 		 ".popsection \n\t"
 		 : :  "i" (&((char *)key)[branch]) : : l_yes);
@@ -38,6 +39,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
 	asm_volatile_goto("1:\n\t"
 		 "b %l[l_yes] # arch_static_branch_jump\n\t"
 		 ".pushsection __jump_table,  \"aw\"\n\t"
+		 ".balign 4\n\t"
 		 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
 		 ".popsection \n\t"
 		 : :  "i" (&((char *)key)[branch]) : : l_yes);
@@ -63,6 +65,7 @@ struct jump_entry {
 #define ARCH_STATIC_BRANCH(LABEL, KEY)		\
 1098:	nop;					\
 	.pushsection __jump_table, "aw";	\
+	.balign 4;				\
 	FTR_ENTRY_LONG 1098b, LABEL, KEY;	\
 	.popsection
 #endif
diff --git a/arch/tile/include/asm/jump_label.h b/arch/tile/include/asm/jump_label.h
index cde7573f397b..a964e6135ea3 100644
--- a/arch/tile/include/asm/jump_label.h
+++ b/arch/tile/include/asm/jump_label.h
@@ -25,6 +25,7 @@ static __always_inline bool arch_static_branch(struct static_key *key,
 	asm_volatile_goto("1:\n\t"
 		"nop" "\n\t"
 		".pushsection __jump_table,  \"aw\"\n\t"
+		".balign 4\n\t"
 		".quad 1b, %l[l_yes], %0 + %1 \n\t"
 		".popsection\n\t"
 		: :  "i" (key), "i" (branch) : : l_yes);
@@ -39,6 +40,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key,
 	asm_volatile_goto("1:\n\t"
 		"j %l[l_yes]" "\n\t"
 		".pushsection __jump_table,  \"aw\"\n\t"
+		".balign 4\n\t"
 		".quad 1b, %l[l_yes], %0 + %1 \n\t"
 		".popsection\n\t"
 		: :  "i" (key), "i" (branch) : : l_yes);
-- 
2.6.1
