linux/arch/powerpc/lib/xor_vmx.c
Matt Brown f718d426d7 powerpc/lib/xor_vmx: Ensure no altivec code executes before enable_kernel_altivec()
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>
2017-06-02 20:17:52 +10:00

161 lines
3.2 KiB
C

/*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) IBM Corporation, 2012
*
* Author: Anton Blanchard <anton@au.ibm.com>
*/
/*
* Sparse (as at v0.5.0) gets very, very confused by this file.
* Make it a bit simpler for it.
*/
#if !defined(__CHECKER__)
#include <altivec.h>
#else
#define vec_xor(a, b) a ^ b
#define vector __attribute__((vector_size(16)))
#endif
#include "xor_vmx.h"
typedef vector signed char unative_t;
#define DEFINE(V) \
unative_t *V = (unative_t *)V##_in; \
unative_t V##_0, V##_1, V##_2, V##_3
#define LOAD(V) \
do { \
V##_0 = V[0]; \
V##_1 = V[1]; \
V##_2 = V[2]; \
V##_3 = V[3]; \
} while (0)
#define STORE(V) \
do { \
V[0] = V##_0; \
V[1] = V##_1; \
V[2] = V##_2; \
V[3] = V##_3; \
} while (0)
#define XOR(V1, V2) \
do { \
V1##_0 = vec_xor(V1##_0, V2##_0); \
V1##_1 = vec_xor(V1##_1, V2##_1); \
V1##_2 = vec_xor(V1##_2, V2##_2); \
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)
{
DEFINE(v1);
DEFINE(v2);
unsigned long lines = bytes / (sizeof(unative_t)) / 4;
do {
LOAD(v1);
LOAD(v2);
XOR(v1, v2);
STORE(v1);
v1 += 4;
v2 += 4;
} while (--lines > 0);
}
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;
do {
LOAD(v1);
LOAD(v2);
LOAD(v3);
XOR(v1, v2);
XOR(v1, v3);
STORE(v1);
v1 += 4;
v2 += 4;
v3 += 4;
} while (--lines > 0);
}
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);
DEFINE(v3);
DEFINE(v4);
unsigned long lines = bytes / (sizeof(unative_t)) / 4;
do {
LOAD(v1);
LOAD(v2);
LOAD(v3);
LOAD(v4);
XOR(v1, v2);
XOR(v3, v4);
XOR(v1, v3);
STORE(v1);
v1 += 4;
v2 += 4;
v3 += 4;
v4 += 4;
} while (--lines > 0);
}
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);
DEFINE(v3);
DEFINE(v4);
DEFINE(v5);
unsigned long lines = bytes / (sizeof(unative_t)) / 4;
do {
LOAD(v1);
LOAD(v2);
LOAD(v3);
LOAD(v4);
LOAD(v5);
XOR(v1, v2);
XOR(v3, v4);
XOR(v1, v5);
XOR(v1, v3);
STORE(v1);
v1 += 4;
v2 += 4;
v3 += 4;
v4 += 4;
v5 += 4;
} while (--lines > 0);
}