[PULL 20/42] tcg/i386: Generalize multi-part load overlap test

Richard Henderson posted 42 patches 2 years ago
Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Laurent Vivier <laurent@vivier.eu>, Aurelien Jarno <aurelien@aurel32.net>, Peter Maydell <peter.maydell@linaro.org>, "Alex Bennée" <alex.bennee@linaro.org>, Michael Rolnik <mrolnik@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Taylor Simpson <tsimpson@quicinc.com>, Alessandro Di Federico <ale@rev.ng>, Anton Johansson <anjo@rev.ng>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Thomas Huth <thuth@redhat.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>, Max Filippov <jcmvbkbc@gmail.com>, WANG Xuerui <git@xen0n.name>, Huacai Chen <chenhuacai@kernel.org>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <Alistair.Francis@wdc.com>
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[PULL 20/42] tcg/i386: Generalize multi-part load overlap test
Posted by Richard Henderson 2 years ago
Test for both base and index; use datahi as a temporary, overwritten
by the final load.  Always perform the loads in ascending order, so
that any (user-only) fault sees the correct address.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/i386/tcg-target.c.inc | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index cfa2349b03..173f3c3172 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -2221,23 +2221,22 @@ static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
         if (TCG_TARGET_REG_BITS == 64) {
             tcg_out_modrm_sib_offset(s, movop + P_REXW + seg, datalo,
                                      base, index, 0, ofs);
+            break;
+        }
+        if (use_movbe) {
+            TCGReg t = datalo;
+            datalo = datahi;
+            datahi = t;
+        }
+        if (base == datalo || index == datalo) {
+            tcg_out_modrm_sib_offset(s, OPC_LEA, datahi, base, index, 0, ofs);
+            tcg_out_modrm_offset(s, movop + seg, datalo, datahi, 0);
+            tcg_out_modrm_offset(s, movop + seg, datahi, datahi, 4);
         } else {
-            if (use_movbe) {
-                TCGReg t = datalo;
-                datalo = datahi;
-                datahi = t;
-            }
-            if (base != datalo) {
-                tcg_out_modrm_sib_offset(s, movop + seg, datalo,
-                                         base, index, 0, ofs);
-                tcg_out_modrm_sib_offset(s, movop + seg, datahi,
-                                         base, index, 0, ofs + 4);
-            } else {
-                tcg_out_modrm_sib_offset(s, movop + seg, datahi,
-                                         base, index, 0, ofs + 4);
-                tcg_out_modrm_sib_offset(s, movop + seg, datalo,
-                                         base, index, 0, ofs);
-            }
+            tcg_out_modrm_sib_offset(s, movop + seg, datalo,
+                                     base, index, 0, ofs);
+            tcg_out_modrm_sib_offset(s, movop + seg, datahi,
+                                     base, index, 0, ofs + 4);
         }
         break;
     default:
-- 
2.34.1