linux-kernel - [PATCH 4.9 17/21] parisc: Fix alignment of pa_tlb

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Date:   Mon,  8 Jan 2018 13:59:37 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Helge Deller <deller@....de>
Subject: [PATCH 4.9 17/21] parisc: Fix alignment of pa_tlb_lock in assembly on 32-bit SMP kernel

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Helge Deller <deller@....de>

commit 88776c0e70be0290f8357019d844aae15edaa967 upstream.

Qemu for PARISC reported on a 32bit SMP parisc kernel strange failures
about "Not-handled unaligned insn 0x0e8011d6 and 0x0c2011c9."

Those opcodes evaluate to the ldcw() assembly instruction which requires
(on 32bit) an alignment of 16 bytes to ensure atomicity.

As it turns out, qemu is correct and in our assembly code in entry.S and
pacache.S we don't pay attention to the required alignment.

This patch fixes the problem by aligning the lock offset in assembly
code in the same manner as we do in our C-code.

Signed-off-by: Helge Deller <deller@....de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/parisc/include/asm/ldcw.h |    2 ++
 arch/parisc/kernel/entry.S     |   13 +++++++++++--
 arch/parisc/kernel/pacache.S   |    9 +++++++--
 3 files changed, 20 insertions(+), 4 deletions(-)

--- a/arch/parisc/include/asm/ldcw.h
+++ b/arch/parisc/include/asm/ldcw.h
@@ -11,6 +11,7 @@
    for the semaphore.  */
 
 #define __PA_LDCW_ALIGNMENT	16
+#define __PA_LDCW_ALIGN_ORDER	4
 #define __ldcw_align(a) ({					\
 	unsigned long __ret = (unsigned long) &(a)->lock[0];	\
 	__ret = (__ret + __PA_LDCW_ALIGNMENT - 1)		\
@@ -28,6 +29,7 @@
    ldcd). */
 
 #define __PA_LDCW_ALIGNMENT	4
+#define __PA_LDCW_ALIGN_ORDER	2
 #define __ldcw_align(a) (&(a)->slock)
 #define __LDCW	"ldcw,co"
 
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -35,6 +35,7 @@
 #include <asm/pgtable.h>
 #include <asm/signal.h>
 #include <asm/unistd.h>
+#include <asm/ldcw.h>
 #include <asm/thread_info.h>
 
 #include <linux/linkage.h>
@@ -46,6 +47,14 @@
 #endif
 
 	.import		pa_tlb_lock,data
+	.macro  load_pa_tlb_lock reg
+#if __PA_LDCW_ALIGNMENT > 4
+	load32	PA(pa_tlb_lock) + __PA_LDCW_ALIGNMENT-1, \reg
+	depi	0,31,__PA_LDCW_ALIGN_ORDER, \reg
+#else
+	load32	PA(pa_tlb_lock), \reg
+#endif
+	.endm
 
 	/* space_to_prot macro creates a prot id from a space id */
 
@@ -457,7 +466,7 @@
 	.macro		tlb_lock	spc,ptp,pte,tmp,tmp1,fault
 #ifdef CONFIG_SMP
 	cmpib,COND(=),n	0,\spc,2f
-	load32		PA(pa_tlb_lock),\tmp
+	load_pa_tlb_lock \tmp
 1:	LDCW		0(\tmp),\tmp1
 	cmpib,COND(=)	0,\tmp1,1b
 	nop
@@ -480,7 +489,7 @@
 	/* Release pa_tlb_lock lock. */
 	.macro		tlb_unlock1	spc,tmp
 #ifdef CONFIG_SMP
-	load32		PA(pa_tlb_lock),\tmp
+	load_pa_tlb_lock \tmp
 	tlb_unlock0	\spc,\tmp
 #endif
 	.endm
--- a/arch/parisc/kernel/pacache.S
+++ b/arch/parisc/kernel/pacache.S
@@ -36,6 +36,7 @@
 #include <asm/assembly.h>
 #include <asm/pgtable.h>
 #include <asm/cache.h>
+#include <asm/ldcw.h>
 #include <linux/linkage.h>
 
 	.text
@@ -333,8 +334,12 @@ ENDPROC_CFI(flush_data_cache_local)
 
 	.macro	tlb_lock	la,flags,tmp
 #ifdef CONFIG_SMP
-	ldil		L%pa_tlb_lock,%r1
-	ldo		R%pa_tlb_lock(%r1),\la
+#if __PA_LDCW_ALIGNMENT > 4
+	load32		pa_tlb_lock + __PA_LDCW_ALIGNMENT-1, \la
+	depi		0,31,__PA_LDCW_ALIGN_ORDER, \la
+#else
+	load32		pa_tlb_lock, \la
+#endif
 	rsm		PSW_SM_I,\flags
 1:	LDCW		0(\la),\tmp
 	cmpib,<>,n	0,\tmp,3f