From 344717a14cd7272f88346022a77742323346299e Mon Sep 17 00:00:00 2001
From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Date: Fri, 29 Jan 2021 12:47:45 +0530
Subject: [PATCH] powerpc/sstep: Fix array out of bound warning

References: bsc#1180581 ltc#190174
Patch-mainline: v5.11-rc7
Git-commit: 344717a14cd7272f88346022a77742323346299e

Compiling kernel with -Warray-bounds throws below warning:

  In function 'emulate_vsx_store':
  warning: array subscript is above array bounds [-Warray-bounds]
  buf.d[2] = byterev_8(reg->d[1]);
  ~~~~~^~~
  buf.d[3] = byterev_8(reg->d[0]);
  ~~~~~^~~

Fix it by using temporary array variable 'union vsx_reg buf32[]' in
that code block. Also, with element_size = 32, 'union vsx_reg *reg'
is an array of size 2. So, use 'reg' as an array instead of pointer
in the same code block.

Fixes: af99da74333b ("powerpc/sstep: Support VSX vector paired storage access instructions")
Suggested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210129071745.111466-1-ravi.bangoria@linux.ibm.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/lib/sstep.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index bf7a7d62ae8b..ede093e96234 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -818,13 +818,15 @@ void emulate_vsx_store(struct instruction_op *op, const union vsx_reg *reg,
 			break;
 		if (rev) {
 			/* reverse 32 bytes */
-			buf.d[0] = byterev_8(reg->d[3]);
-			buf.d[1] = byterev_8(reg->d[2]);
-			buf.d[2] = byterev_8(reg->d[1]);
-			buf.d[3] = byterev_8(reg->d[0]);
-			reg = &buf;
+			union vsx_reg buf32[2];
+			buf32[0].d[0] = byterev_8(reg[1].d[1]);
+			buf32[0].d[1] = byterev_8(reg[1].d[0]);
+			buf32[1].d[0] = byterev_8(reg[0].d[1]);
+			buf32[1].d[1] = byterev_8(reg[0].d[0]);
+			memcpy(mem, buf32, size);
+		} else {
+			memcpy(mem, reg, size);
 		}
-		memcpy(mem, reg, size);
 		break;
 	case 16:
 		/* stxv, stxvx, stxvl, stxvll */
-- 
2.26.2