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Re: [RFC PATCH, i386]: Deprecate -mmitigate-rop


On 08/10/2018 05:42 AM, Uros Bizjak wrote:
> This option is fairly ineffective, and in the light of CET, nobody
> seems interested to improve it. Deprecate the option, so it won't lure
> developers to the land of false security.
> 
> 2018-08-10  Uros Bizjak  <ubizjak@gmail.com>
> 
>     * config/i386/i386.opt (mmitigate-rop): Mark as deprecated.
>     * doc/invoke.texi (mmitigate-rop): Remove.
>     * config/i386/i386.c: Do not include "regrename.h".
>     (ix86_rop_should_change_byte_p, reg_encoded_number)
>     (ix86_get_modrm_for_rop, set_rop_modrm_reg_bits, ix86_mitigate_rop):
>     Remove.
>     (ix86_reorg): Remove call to ix86_mitigate_rop.
>     * config/i386/i386.md (attr "modrm_class"): Remove.
>     (cmp<mode>_ccno_1, mov<mode>_xor, movstrict<mode>_xor,
>     x86_mov<mode>cc_0_m1. x86_mov<mode>cc_0_m1_se)
>     (x86_mov<mode>cc_0_m1_neg): Remove modrm_class attribute override.
> 
> testsuite/Changelog:
> 
> 2018-08-10  Uros Bizjak  <ubizjak@gmail.com>
> 
>     * gcc.target/i386/rop1.c: Remove.
>     * gcc.target/i386/pr83554 (dg-options): Remove -mmitigate-rop.
> 
> Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.
> 
> Any opinion against the deprecation?
As I noted privately, Red Hat is no longer investing in this space due
to the introduction of CET.

I'll ack deprecation.

jeff


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