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 converting local variable 'union vsx_reg buf' into an array.
Also consider function argument 'union vsx_reg *reg' as array instead
of pointer because callers are actually passing an array to it.

Fixes: af99da74333b ("powerpc/sstep: Support VSX vector paired storage access 
instructions")
Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com>
---
 arch/powerpc/lib/sstep.c | 61 ++++++++++++++++++++--------------------
 1 file changed, 31 insertions(+), 30 deletions(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index bf7a7d62ae8b..5b4281ade5b6 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -723,7 +723,8 @@ void emulate_vsx_load(struct instruction_op *op, union 
vsx_reg *reg,
        const unsigned char *bp;
 
        size = GETSIZE(op->type);
-       reg->d[0] = reg->d[1] = 0;
+       reg[0].d[0] = reg[0].d[1] = 0;
+       reg[1].d[0] = reg[1].d[1] = 0;
 
        switch (op->element_size) {
        case 32:
@@ -742,25 +743,25 @@ void emulate_vsx_load(struct instruction_op *op, union 
vsx_reg *reg,
                /* scalar loads, lxvd2x, lxvdsx */
                read_size = (size >= 8) ? 8 : size;
                i = IS_LE ? 8 : 8 - read_size;
-               memcpy(&reg->b[i], mem, read_size);
+               memcpy(&reg[0].b[i], mem, read_size);
                if (rev)
-                       do_byte_reverse(&reg->b[i], 8);
+                       do_byte_reverse(&reg[0].b[i], 8);
                if (size < 8) {
                        if (op->type & SIGNEXT) {
                                /* size == 4 is the only case here */
-                               reg->d[IS_LE] = (signed int) reg->d[IS_LE];
+                               reg[0].d[IS_LE] = (signed int)reg[0].d[IS_LE];
                        } else if (op->vsx_flags & VSX_FPCONV) {
                                preempt_disable();
-                               conv_sp_to_dp(&reg->fp[1 + IS_LE],
-                                             &reg->dp[IS_LE]);
+                               conv_sp_to_dp(&reg[0].fp[1 + IS_LE],
+                                             &reg[0].dp[IS_LE]);
                                preempt_enable();
                        }
                } else {
                        if (size == 16) {
                                unsigned long v = *(unsigned long *)(mem + 8);
-                               reg->d[IS_BE] = !rev ? v : byterev_8(v);
+                               reg[0].d[IS_BE] = !rev ? v : byterev_8(v);
                        } else if (op->vsx_flags & VSX_SPLAT)
-                               reg->d[IS_BE] = reg->d[IS_LE];
+                               reg[0].d[IS_BE] = reg[0].d[IS_LE];
                }
                break;
        case 4:
@@ -768,13 +769,13 @@ void emulate_vsx_load(struct instruction_op *op, union 
vsx_reg *reg,
                wp = mem;
                for (j = 0; j < size / 4; ++j) {
                        i = IS_LE ? 3 - j : j;
-                       reg->w[i] = !rev ? *wp++ : byterev_4(*wp++);
+                       reg[0].w[i] = !rev ? *wp++ : byterev_4(*wp++);
                }
                if (op->vsx_flags & VSX_SPLAT) {
-                       u32 val = reg->w[IS_LE ? 3 : 0];
+                       u32 val = reg[0].w[IS_LE ? 3 : 0];
                        for (; j < 4; ++j) {
                                i = IS_LE ? 3 - j : j;
-                               reg->w[i] = val;
+                               reg[0].w[i] = val;
                        }
                }
                break;
@@ -783,7 +784,7 @@ void emulate_vsx_load(struct instruction_op *op, union 
vsx_reg *reg,
                hp = mem;
                for (j = 0; j < size / 2; ++j) {
                        i = IS_LE ? 7 - j : j;
-                       reg->h[i] = !rev ? *hp++ : byterev_2(*hp++);
+                       reg[0].h[i] = !rev ? *hp++ : byterev_2(*hp++);
                }
                break;
        case 1:
@@ -791,7 +792,7 @@ void emulate_vsx_load(struct instruction_op *op, union 
vsx_reg *reg,
                bp = mem;
                for (j = 0; j < size; ++j) {
                        i = IS_LE ? 15 - j : j;
-                       reg->b[i] = *bp++;
+                       reg[0].b[i] = *bp++;
                }
                break;
        }
@@ -804,7 +805,7 @@ void emulate_vsx_store(struct instruction_op *op, const 
union vsx_reg *reg,
 {
        int size, write_size;
        int i, j;
-       union vsx_reg buf;
+       union vsx_reg buf[2];
        unsigned int *wp;
        unsigned short *hp;
        unsigned char *bp;
@@ -818,11 +819,11 @@ 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;
+                       buf[0].d[0] = byterev_8(reg[1].d[1]);
+                       buf[0].d[1] = byterev_8(reg[1].d[0]);
+                       buf[1].d[0] = byterev_8(reg[0].d[1]);
+                       buf[1].d[1] = byterev_8(reg[0].d[0]);
+                       reg = buf;
                }
                memcpy(mem, reg, size);
                break;
@@ -834,9 +835,9 @@ void emulate_vsx_store(struct instruction_op *op, const 
union vsx_reg *reg,
                        rev = !rev;
                if (rev) {
                        /* reverse 16 bytes */
-                       buf.d[0] = byterev_8(reg->d[1]);
-                       buf.d[1] = byterev_8(reg->d[0]);
-                       reg = &buf;
+                       buf[0].d[0] = byterev_8(reg[0].d[1]);
+                       buf[0].d[1] = byterev_8(reg[0].d[0]);
+                       reg = buf;
                }
                memcpy(mem, reg, size);
                break;
@@ -845,15 +846,15 @@ void emulate_vsx_store(struct instruction_op *op, const 
union vsx_reg *reg,
                write_size = (size >= 8) ? 8 : size;
                i = IS_LE ? 8 : 8 - write_size;
                if (size < 8 && op->vsx_flags & VSX_FPCONV) {
-                       buf.d[0] = buf.d[1] = 0;
+                       buf[0].d[0] = buf[0].d[1] = 0;
                        preempt_disable();
-                       conv_dp_to_sp(&reg->dp[IS_LE], &buf.fp[1 + IS_LE]);
+                       conv_dp_to_sp(&reg[0].dp[IS_LE], &buf[0].fp[1 + IS_LE]);
                        preempt_enable();
-                       reg = &buf;
+                       reg = buf;
                }
-               memcpy(mem, &reg->b[i], write_size);
+               memcpy(mem, &reg[0].b[i], write_size);
                if (size == 16)
-                       memcpy(mem + 8, &reg->d[IS_BE], 8);
+                       memcpy(mem + 8, &reg[0].d[IS_BE], 8);
                if (unlikely(rev)) {
                        do_byte_reverse(mem, write_size);
                        if (size == 16)
@@ -865,7 +866,7 @@ void emulate_vsx_store(struct instruction_op *op, const 
union vsx_reg *reg,
                wp = mem;
                for (j = 0; j < size / 4; ++j) {
                        i = IS_LE ? 3 - j : j;
-                       *wp++ = !rev ? reg->w[i] : byterev_4(reg->w[i]);
+                       *wp++ = !rev ? reg[0].w[i] : byterev_4(reg[0].w[i]);
                }
                break;
        case 2:
@@ -873,7 +874,7 @@ void emulate_vsx_store(struct instruction_op *op, const 
union vsx_reg *reg,
                hp = mem;
                for (j = 0; j < size / 2; ++j) {
                        i = IS_LE ? 7 - j : j;
-                       *hp++ = !rev ? reg->h[i] : byterev_2(reg->h[i]);
+                       *hp++ = !rev ? reg[0].h[i] : byterev_2(reg[0].h[i]);
                }
                break;
        case 1:
@@ -881,7 +882,7 @@ void emulate_vsx_store(struct instruction_op *op, const 
union vsx_reg *reg,
                bp = mem;
                for (j = 0; j < size; ++j) {
                        i = IS_LE ? 15 - j : j;
-                       *bp++ = reg->b[i];
+                       *bp++ = reg[0].b[i];
                }
                break;
        }
-- 
2.26.2

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