| Message ID | 20240710141328.388955-1-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | target/i386/tcg: fix POP to memory in long mode | expand |
On 7/10/24 07:13, Paolo Bonzini wrote: > In long mode, POP to memory will write a full 64-bit value. However, > the call to gen_writeback() in gen_POP will use MO_32 because the > decoding table is incorrect. > > The bug was latent until commit aea49fbb01a ("target/i386: use gen_writeback() > within gen_POP()", 2024-06-08), and then became visible because gen_op_st_v > now receives op->ot instead of the "ot" returned by gen_pop_T0. > > Analyzed-by: Clément Chigot<chigot@adacore.com> > Fixes: 5e9e21bcc4d ("target/i386: move 60-BF opcodes to new decoder", 2024-05-07) > Tested-by: Clément Chigot<chigot@adacore.com> > Signed-off-by: Paolo Bonzini<pbonzini@redhat.com> > --- > target/i386/tcg/decode-new.c.inc | 2 +- > target/i386/tcg/emit.c.inc | 2 ++ > 2 files changed, 3 insertions(+), 1 deletion(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/target/i386/tcg/decode-new.c.inc b/target/i386/tcg/decode-new.c.inc index 0d846c32c22..d2da1d396d5 100644 --- a/target/i386/tcg/decode-new.c.inc +++ b/target/i386/tcg/decode-new.c.inc @@ -1717,7 +1717,7 @@ static const X86OpEntry opcodes_root[256] = { [0x8C] = X86_OP_ENTRYwr(MOV, E,v, S,w, op0_Mw), [0x8D] = X86_OP_ENTRYwr(LEA, G,v, M,v, nolea), [0x8E] = X86_OP_ENTRYwr(MOV, S,w, E,w), - [0x8F] = X86_OP_GROUPw(group1A, E,v), + [0x8F] = X86_OP_GROUPw(group1A, E,d64), [0x98] = X86_OP_ENTRY1(CBW, 0,v), /* rAX */ [0x99] = X86_OP_ENTRYwr(CWD, 2,v, 0,v), /* rDX, rAX */ diff --git a/target/i386/tcg/emit.c.inc b/target/i386/tcg/emit.c.inc index fc7477833bc..c6c2c7257b9 100644 --- a/target/i386/tcg/emit.c.inc +++ b/target/i386/tcg/emit.c.inc @@ -2788,6 +2788,8 @@ static void gen_POP(DisasContext *s, X86DecodedInsn *decode) X86DecodedOp *op = &decode->op[0]; MemOp ot = gen_pop_T0(s); + /* Only 16/32-bit access in 32-bit mode, 16/64-bit access in long mode. */ + assert(ot == op->ot); if (op->has_ea || op->unit == X86_OP_SEG) { /* NOTE: order is important for MMU exceptions */ gen_writeback(s, decode, 0, s->T0);
In long mode, POP to memory will write a full 64-bit value. However, the call to gen_writeback() in gen_POP will use MO_32 because the decoding table is incorrect. The bug was latent until commit aea49fbb01a ("target/i386: use gen_writeback() within gen_POP()", 2024-06-08), and then became visible because gen_op_st_v now receives op->ot instead of the "ot" returned by gen_pop_T0. Analyzed-by: Clément Chigot <chigot@adacore.com> Fixes: 5e9e21bcc4d ("target/i386: move 60-BF opcodes to new decoder", 2024-05-07) Tested-by: Clément Chigot <chigot@adacore.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- target/i386/tcg/decode-new.c.inc | 2 +- target/i386/tcg/emit.c.inc | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-)