[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/emul: only emulate possibly operand sizes for POPA
On 07/11/2012 16:08, "Jan Beulich" <JBeulich@xxxxxxxx> wrote: > This opcode neither support 1-byte operands, nor does it support 8-byte > ones (since the opcode is undefined in 64-bit mode). Simplify the code > accordingly. > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> > > --- a/xen/arch/x86/x86_emulate/x86_emulate.c > +++ b/xen/arch/x86/x86_emulate/x86_emulate.c > @@ -1996,13 +1996,10 @@ x86_emulate( > if ( (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes), > &dst.val, op_bytes, ctxt, ops)) != 0 ) > goto done; > - switch ( op_bytes ) > - { > - case 1: *(uint8_t *)regs[i] = (uint8_t)dst.val; break; > - case 2: *(uint16_t *)regs[i] = (uint16_t)dst.val; break; > - case 4: *regs[i] = (uint32_t)dst.val; break; /* 64b: zero-ext */ > - case 8: *regs[i] = dst.val; break; > - } > + if ( op_bytes != 2 ) > + *regs[i] = (uint32_t)dst.val; /* 64b: zero-ext */ > + else > + *(uint16_t *)regs[i] = (uint16_t)dst.val; Would prefer: if ( op_bytes == 2 ) *(uint16_t *)regs[i] = (uint16_t)dst.val; else *regs[i] = dst.val; Handles the exceptional case immediately after its predicate. And the cast from uint32_t, and 64b-related comment, are pointless and in fact misleading in the default case, since as you say the instruction is invalid in 64-bit mode. Apart from that: Acked-by: Keir Fraser <keir@xxxxxxx> -- Keir > } > break; > } > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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