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Re: [PATCH] x86/Intel: don't accept bogus instructions
- From: "Jan Beulich" <JBeulich at suse dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: "Binutils" <binutils at sourceware dot org>
- Date: Thu, 30 Jun 2016 05:58:28 -0600
- Subject: Re: [PATCH] x86/Intel: don't accept bogus instructions
- Authentication-results: sourceware.org; auth=none
- References: <577511DA02000078000FA074 at prv-mh dot provo dot novell dot com> <CAMe9rOqi2N9WxrPsxJV+457nvBrG_c1VYC31aRWhmVnjgi4kTQ at mail dot gmail dot com> <577520C202000078000FA0ED at prv-mh dot provo dot novell dot com> <CAMe9rOqT-2JMkzA6jtBprX-mbYKjEBBxNTmh4KbEaW-K4qVrsw at mail dot gmail dot com>
>>> On 30.06.16 at 13:50, <firstname.lastname@example.org> wrote:
> On Thu, Jun 30, 2016 at 4:38 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>> On 30.06.16 at 13:18, <email@example.com> wrote:
>>> On Thu, Jun 30, 2016 at 3:34 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> ... due to their last byte looking like a suffix, when after its
>>>> stripping a matching instruction can be found. Since memory operand
>>>> size specifiers in Intel mode get converted into suffix representation
>>>> internally, we need to keep track of the actual mnemonic suffix which
>>>> may have got trimmed off, and check its validity while looking for a
>>>> matching template. I tripper over this quite some time again after
>>>> support for AMD's SSE5 instructions got removed, as at that point some
>>>> of the SSE5 mnemonics, other than expected, didn't fail to assemble.
>>>> But the problem affects many more instructions, namely (almost) all
>>>> MMX, SSE, and AVX ones as it looks. I don't think it makes sense to
>>>> add a testcase covering all of them, nor do I think it makes sense to
>>>> pick out some random examples for a new test case.
>>> Please open a bug report to show there is a problem.
>> I don't see the point, but anyway: 20318.
> Please add this testcase:
> phadddb %xmm0, %xmm1
> phadddd %xmm0, %xmm1
> phadddl %xmm0, %xmm1
> phadddld %xmm0, %xmm1
> phadddq %xmm0, %xmm1
> phaddds %xmm0, %xmm1
> phadddw %xmm0, %xmm1
> .intel_syntax noprefix
> phadddb xmm0, xmm1
> phadddd xmm0, xmm1
> phadddl xmm0, xmm1
> phadddld xmm0, xmm1
> phadddq xmm0, xmm1
> phaddds xmm0, xmm1
> phadddw xmm0, xmm1
> to your patch and run it with both --32 and --64. All of them should fail.
To quote the original submission: "I don't think it makes sense to add
a testcase covering all of them, nor do I think it makes sense to pick
out some random examples for a new test case."
What good does such a limited test case do? If anything, someone
should sit down and write a script to machine generate a list of all
mnemonics with invalid suffixes.