From f718d426d7e42eec6e5d2932f52a51de23bd3b30 Mon Sep 17 00:00:00 2001
From: Matt Brown <matthew.brown.dev@gmail.com>
Date: Wed, 24 May 2017 09:45:59 +1000
Subject: [PATCH] powerpc/lib/xor_vmx: Ensure no altivec code executes before
enable_kernel_altivec()
References: bsc#1065729
Patch-mainline: v4.13-rc1
Git-commit: f718d426d7e42eec6e5d2932f52a51de23bd3b30
The xor_vmx.c file is used for the RAID5 xor operations. In these functions
altivec is enabled to run the operation and then disabled.
The code uses enable_kernel_altivec() around the core of the algorithm, however
the whole file is built with -maltivec, so the compiler is within its rights to
generate altivec code anywhere. This has been seen at least once in the wild:
0:mon> di $xor_altivec_2
c0000000000b97d0 3c4c01d9 addis r2,r12,473
c0000000000b97d4 3842db30 addi r2,r2,-9424
c0000000000b97d8 7c0802a6 mflr r0
c0000000000b97dc f8010010 std r0,16(r1)
c0000000000b97e0 60000000 nop
c0000000000b97e4 7c0802a6 mflr r0
c0000000000b97e8 faa1ffa8 std r21,-88(r1)
...
c0000000000b981c f821ff41 stdu r1,-192(r1)
c0000000000b9820 7f8101ce stvx v28,r1,r0 <-- POP
c0000000000b9824 38000030 li r0,48
c0000000000b9828 7fa101ce stvx v29,r1,r0
...
c0000000000b984c 4bf6a06d bl c0000000000238b8 # enable_kernel_altivec
This patch splits the non-altivec code into xor_vmx_glue.c which calls the
altivec functions in xor_vmx.c. By compiling xor_vmx_glue.c without
-maltivec we can guarantee that altivec instruction will not be executed
outside of the enable/disable block.
Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
[mpe: Rework change log and include disassembly]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/lib/Makefile | 2 +-
arch/powerpc/lib/xor_vmx.c | 53 ++++++++---------------------------
arch/powerpc/lib/xor_vmx.h | 20 +++++++++++++
arch/powerpc/lib/xor_vmx_glue.c | 62 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 94 insertions(+), 43 deletions(-)
create mode 100644 arch/powerpc/lib/xor_vmx.h
create mode 100644 arch/powerpc/lib/xor_vmx_glue.c
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 2c56f4636c2b..3c3146ba62da 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -37,7 +37,7 @@ obj-$(CONFIG_PPC_LIB_RHEAP) += rheap.o
obj-$(CONFIG_FTR_FIXUP_SELFTEST) += feature-fixups-test.o
-obj-$(CONFIG_ALTIVEC) += xor_vmx.o
+obj-$(CONFIG_ALTIVEC) += xor_vmx.o xor_vmx_glue.o
CFLAGS_xor_vmx.o += -maltivec $(call cc-option,-mabi=altivec)
obj-$(CONFIG_PPC64) += $(obj64-y)
diff --git a/arch/powerpc/lib/xor_vmx.c b/arch/powerpc/lib/xor_vmx.c
index f9de69a04e88..4df240aa5f81 100644
--- a/arch/powerpc/lib/xor_vmx.c
+++ b/arch/powerpc/lib/xor_vmx.c
@@ -29,10 +29,7 @@
#define vector __attribute__((vector_size(16)))
#endif
-#include <linux/preempt.h>
-#include <linux/export.h>
-#include <linux/sched.h>
-#include <asm/switch_to.h>
+#include "xor_vmx.h"
typedef vector signed char unative_t;
@@ -64,16 +61,13 @@ typedef vector signed char unative_t;
V1##_3 = vec_xor(V1##_3, V2##_3); \
} while (0)
-void xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
- unsigned long *v2_in)
+void __xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in)
{
DEFINE(v1);
DEFINE(v2);
unsigned long lines = bytes / (sizeof(unative_t)) / 4;
- preempt_disable();
- enable_kernel_altivec();
-
do {
LOAD(v1);
LOAD(v2);
@@ -83,23 +77,16 @@ void xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
v1 += 4;
v2 += 4;
} while (--lines > 0);
-
- disable_kernel_altivec();
- preempt_enable();
}
-EXPORT_SYMBOL(xor_altivec_2);
-void xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
- unsigned long *v2_in, unsigned long *v3_in)
+void __xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in)
{
DEFINE(v1);
DEFINE(v2);
DEFINE(v3);
unsigned long lines = bytes / (sizeof(unative_t)) / 4;
- preempt_disable();
- enable_kernel_altivec();
-
do {
LOAD(v1);
LOAD(v2);
@@ -112,15 +99,11 @@ void xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
v2 += 4;
v3 += 4;
} while (--lines > 0);
-
- disable_kernel_altivec();
- preempt_enable();
}
-EXPORT_SYMBOL(xor_altivec_3);
-void xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
- unsigned long *v2_in, unsigned long *v3_in,
- unsigned long *v4_in)
+void __xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in,
+ unsigned long *v4_in)
{
DEFINE(v1);
DEFINE(v2);
@@ -128,9 +111,6 @@ void xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
DEFINE(v4);
unsigned long lines = bytes / (sizeof(unative_t)) / 4;
- preempt_disable();
- enable_kernel_altivec();
-
do {
LOAD(v1);
LOAD(v2);
@@ -146,15 +126,11 @@ void xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
v3 += 4;
v4 += 4;
} while (--lines > 0);
-
- disable_kernel_altivec();
- preempt_enable();
}
-EXPORT_SYMBOL(xor_altivec_4);
-void xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
- unsigned long *v2_in, unsigned long *v3_in,
- unsigned long *v4_in, unsigned long *v5_in)
+void __xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in,
+ unsigned long *v4_in, unsigned long *v5_in)
{
DEFINE(v1);
DEFINE(v2);
@@ -163,9 +139,6 @@ void xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
DEFINE(v5);
unsigned long lines = bytes / (sizeof(unative_t)) / 4;
- preempt_disable();
- enable_kernel_altivec();
-
do {
LOAD(v1);
LOAD(v2);
@@ -184,8 +157,4 @@ void xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
v4 += 4;
v5 += 4;
} while (--lines > 0);
-
- disable_kernel_altivec();
- preempt_enable();
}
-EXPORT_SYMBOL(xor_altivec_5);
diff --git a/arch/powerpc/lib/xor_vmx.h b/arch/powerpc/lib/xor_vmx.h
new file mode 100644
index 000000000000..4746708451ae
--- /dev/null
+++ b/arch/powerpc/lib/xor_vmx.h
@@ -0,0 +1,20 @@
+/*
+ * Simple interface to link xor_vmx.c and xor_vmx_glue.c
+ *
+ * Separating these file ensures that no altivec instructions are run
+ * outside of the enable/disable altivec block.
+ */
+
+void __xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in);
+
+void __xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in);
+
+void __xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in,
+ unsigned long *v4_in);
+
+void __xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in,
+ unsigned long *v4_in, unsigned long *v5_in);
diff --git a/arch/powerpc/lib/xor_vmx_glue.c b/arch/powerpc/lib/xor_vmx_glue.c
new file mode 100644
index 000000000000..6521fe5e8cef
--- /dev/null
+++ b/arch/powerpc/lib/xor_vmx_glue.c
@@ -0,0 +1,62 @@
+/*
+ * Altivec XOR operations
+ *
+ * Copyright 2017 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/preempt.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <asm/switch_to.h>
+#include "xor_vmx.h"
+
+void xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in)
+{
+ preempt_disable();
+ enable_kernel_altivec();
+ __xor_altivec_2(bytes, v1_in, v2_in);
+ disable_kernel_altivec();
+ preempt_enable();
+}
+EXPORT_SYMBOL(xor_altivec_2);
+
+void xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in)
+{
+ preempt_disable();
+ enable_kernel_altivec();
+ __xor_altivec_3(bytes, v1_in, v2_in, v3_in);
+ disable_kernel_altivec();
+ preempt_enable();
+}
+EXPORT_SYMBOL(xor_altivec_3);
+
+void xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in,
+ unsigned long *v4_in)
+{
+ preempt_disable();
+ enable_kernel_altivec();
+ __xor_altivec_4(bytes, v1_in, v2_in, v3_in, v4_in);
+ disable_kernel_altivec();
+ preempt_enable();
+}
+EXPORT_SYMBOL(xor_altivec_4);
+
+void xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
+ unsigned long *v2_in, unsigned long *v3_in,
+ unsigned long *v4_in, unsigned long *v5_in)
+{
+ preempt_disable();
+ enable_kernel_altivec();
+ __xor_altivec_5(bytes, v1_in, v2_in, v3_in, v4_in, v5_in);
+ disable_kernel_altivec();
+ preempt_enable();
+}
+EXPORT_SYMBOL(xor_altivec_5);
--
2.13.6