From b05eb2cc7decc07ed044484861587b3490144d02 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 8 Jun 2016 13:04:21 +0200
Subject: [PATCH 2/3] target-i386: fix pcmpxstrx equal-ordered (strstr) mode

RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <1465391061-17748-1-git-send-email-pbonzini@redhat.com>
Patchwork-id: 70570
O-Subject: [RHEL7.3/7.2.z qemu-kvm PATCH] target-i386: fix pcmpxstrx equal-ordered (strstr) mode
Bugzilla: 1340971
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

Kindly requested by the Openstack folks, who sometimes uses TCG
instead of nested virt.

In this mode, referring an invalid element of the source forces the
result to false (table 4-7, last column) but referring an invalid
element of the destination forces the result to true, so the outer
loop should still be run even if some elements of the destination
will be invalid.  They will be avoided in the inner loop, which
correctly bounds "i" to validd, but they will still contribute to a
positive outcome of the search.

This fixes tst_strstr in glibc 2.17.

Reported-by: Florian Weimer <fweimer@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 54c54f8b56047d3c2420e1ae06a6a8890c220ac4)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 target-i386/ops_sse.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target-i386/ops_sse.h b/target-i386/ops_sse.h
index eb24b5f..5145d9e 100644
--- a/target-i386/ops_sse.h
+++ b/target-i386/ops_sse.h
@@ -2034,10 +2034,10 @@ static inline unsigned pcmpxstrx(CPUX86State *env, Reg *d, Reg *s,
         }
         break;
     case 3:
-        for (j = valids - validd; j >= 0; j--) {
+        for (j = valids; j >= 0; j--) {
             res <<= 1;
             v = 1;
-            for (i = MIN(upper - j, validd); i >= 0; i--) {
+            for (i = MIN(valids - j, validd); i >= 0; i--) {
                 v &= (pcmp_val(s, ctrl, i + j) == pcmp_val(d, ctrl, i));
             }
             res |= v;
-- 
1.8.3.1