diff mbox series

[Stable-9.0.1,27/44] target/i386: fix operand size for DATA16 REX.W POPCNT

Message ID 20240527082138.66217-27-mjt@tls.msk.ru (mailing list archive)
State New
Headers show
Series Patch Round-up for stable 9.0.1, freeze on 2024-06-07 | expand

Commit Message

Michael Tokarev May 27, 2024, 8:21 a.m. UTC 
From: Paolo Bonzini <pbonzini@redhat.com>

According to the manual, 32-bit vs 64-bit is governed by REX.W
and REX ignores the 0x66 prefix.  This can be confirmed with this
program:

    #include <stdio.h>
    int main()
    {
       int x = 0x12340000;
       int y;
       asm("popcntl %1, %0" : "=r" (y) : "r" (x)); printf("%x\n", y);
       asm("mov $-1, %0; .byte 0x66; popcntl %1, %0" : "+r" (y) : "r" (x)); printf("%x\n", y);
       asm("mov $-1, %0; .byte 0x66; popcntq %q1, %q0" : "+r" (y) : "r" (x)); printf("%x\n", y);
    }

which prints 5/ffff0000/5 on real hardware and 5/ffff0000/ffff0000
on QEMU.

Cc: qemu-stable@nongnu.org
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 41c685dc59bb611096f3bb6a663cfa82e4cba97b)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: drop removal of mo_64_32() helper function in target/i386/tcg/translate.c
 due to missing-in-9.0 v9.0.0-542-gaef4f4affde2
 "target/i386: remove now-converted opcodes from old decoder"
 which removed other user of it)
diff mbox series

Patch

diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index c84196c00b..ebfee15d77 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -6805,12 +6805,7 @@  static bool disas_insn(DisasContext *s, CPUState *cpu)
         modrm = x86_ldub_code(env, s);
         reg = ((modrm >> 3) & 7) | REX_R(s);
 
-        if (s->prefix & PREFIX_DATA) {
-            ot = MO_16;
-        } else {
-            ot = mo_64_32(dflag);
-        }
-
+        ot = dflag;
         gen_ldst_modrm(env, s, modrm, ot, OR_TMP0, 0);
         gen_extu(ot, s->T0);
         tcg_gen_mov_tl(cpu_cc_src, s->T0);