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[Qemu-devel] Re: [RFC][PATCH] x86: CS limit checks
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [RFC][PATCH] x86: CS limit checks |
Date: |
Thu, 17 Jul 2008 23:25:20 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Jan Kiszka wrote:
> Fabrice Bellard wrote:
>> Jan Kiszka wrote:
>>> Here is a proposal for adding code segment limit checks to x86. This
>>> patch should not need the -seg-checks switch as its tests are mostly
>>> performed during translation time. Moreover, I tried to confine the
>>> small additional overhead in the TB lookup procedure to x86 and Sparc.
>>>
>>> Note that this patch depends on my debugging series, namely [1], as that
>>> one reduces the x86-specific code passages for TB generation. Also note
>>> that this patch is early and only lightly tested so far, not yet
>>> intended for inclusion, but definitely for commenting on!
>> Using more than 32 bits for cs_limit (and cs_base) in the TB is
>> wasteful, so I strongly suggest to use a uint32_t type. In that case,
>> cs_limit must be explicitely ignored in 64 bit code.
>>
>> @@ -172,6 +173,8 @@ static inline TranslationBlock *tb_find_
>> flags = env->hflags;
>> flags |= (env->eflags & (IOPL_MASK | TF_MASK | VM_MASK));
>> cs_base = env->segs[R_CS].base;
>> + if ((env->hflags & (HF_PE_MASK | HF_CS64_MASK)) == HF_PE_MASK)
>> + cs_limit = env->segs[R_CS].limit;
>> pc = cs_base + env->eip;
>>
>> This test should be suppressed for performance reasons.
>
> Yes, the test should be moved to the translator code. This will also
> allow to reduce the width of cs_base/limit.
cs_base must remain target_ulong - sparc relies on it for storing npc.
Jan
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- Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, (continued)
- Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, Paul Brook, 2008/07/17
- Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, Jan Kiszka, 2008/07/17
- Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, Paul Brook, 2008/07/17
- Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, Jan Kiszka, 2008/07/17
- Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, Paul Brook, 2008/07/17
- Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, Fabrice Bellard, 2008/07/17
- [Qemu-devel] Re: [RFC][PATCH] x86: CS limit checks, Jan Kiszka, 2008/07/17
Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks, Fabrice Bellard, 2008/07/17