diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2023-05-09 16:17:15 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-05-18 08:53:50 +0200 |
| commit | 2b55e479e6fcbb466585fd25077a50c32e10dc3a (patch) | |
| tree | 3e28da74fe09bf8f3083f4618098ad2a157ecd7c /target/i386 | |
| parent | 22e1094ca82d5518c1b69aff3e87c550776ae1eb (diff) | |
target/i386: fix operand size for VCOMI/VUCOMI instructions
Compared to other SSE instructions, VUCOMISx and VCOMISx are different:
the single and double precision versions are distinguished through a
prefix, however they use no-prefix and 0x66 for SS and SD respectively.
Scalar values usually are associated with 0xF2 and 0xF3.
Because of these, they incorrectly perform a 128-bit memory load instead
of a 32- or 64-bit load. Fix this by writing a custom decoding function.
I tested that the reproducer is fixed and the test-avx output does not
change.
Reported-by: Gabriele Svelto <gsvelto@mozilla.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1637
Fixes: f8d19eec0d53 ("target/i386: reimplement 0x0f 0x28-0x2f, add AVX", 2022-10-18)
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'target/i386')
| -rw-r--r-- | target/i386/tcg/decode-new.c.inc | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/target/i386/tcg/decode-new.c.inc b/target/i386/tcg/decode-new.c.inc index 4fdd87750b..48fefaffdf 100644 --- a/target/i386/tcg/decode-new.c.inc +++ b/target/i386/tcg/decode-new.c.inc @@ -783,6 +783,17 @@ static void decode_0F2D(DisasContext *s, CPUX86State *env, X86OpEntry *entry, ui *entry = *decode_by_prefix(s, opcodes_0F2D); } +static void decode_VxCOMISx(DisasContext *s, CPUX86State *env, X86OpEntry *entry, uint8_t *b) +{ + /* + * VUCOMISx and VCOMISx are different and use no-prefix and 0x66 for SS and SD + * respectively. Scalar values usually are associated with 0xF2 and 0xF3, for + * which X86_VEX_REPScalar exists, but here it has to be decoded by hand. + */ + entry->s1 = entry->s2 = (s->prefix & PREFIX_DATA ? X86_SIZE_sd : X86_SIZE_ss); + entry->gen = (*b == 0x2E ? gen_VUCOMI : gen_VCOMI); +} + static void decode_sse_unary(DisasContext *s, CPUX86State *env, X86OpEntry *entry, uint8_t *b) { if (!(s->prefix & (PREFIX_REPZ | PREFIX_REPNZ))) { @@ -871,8 +882,8 @@ static const X86OpEntry opcodes_0F[256] = { [0x2B] = X86_OP_GROUP0(0F2B), [0x2C] = X86_OP_GROUP0(0F2C), [0x2D] = X86_OP_GROUP0(0F2D), - [0x2E] = X86_OP_ENTRY3(VUCOMI, None,None, V,x, W,x, vex4 p_00_66), - [0x2F] = X86_OP_ENTRY3(VCOMI, None,None, V,x, W,x, vex4 p_00_66), + [0x2E] = X86_OP_GROUP3(VxCOMISx, None,None, V,x, W,x, vex3 p_00_66), /* VUCOMISS/SD */ + [0x2F] = X86_OP_GROUP3(VxCOMISx, None,None, V,x, W,x, vex3 p_00_66), /* VCOMISS/SD */ [0x38] = X86_OP_GROUP0(0F38), [0x3a] = X86_OP_GROUP0(0F3A), |