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Re: [PATCH,i386] Add -mstack-protector-guard= for i386
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Andrew Hsieh <andrewhsieh at google dot com>
- Date: Fri, 12 Apr 2013 08:45:16 +0200
- Subject: Re: [PATCH,i386] Add -mstack-protector-guard= for i386
Hello!
> Bionic in Android 4.2 starts to support stack-protector canary at TLS for x86.
>
> Android prior to 4.2 still looks at a global variable for stack
> canary. To maintain backward compatibility, I propose to add a new
> option -mstack-protector-guard={global,tls} for i386 back-end to use
> canary at global or per-thread at %gs:20, respectively.
>
> "global" is the default for bionic (*1); otherwise "tls" is the default
(define_expand "stack_protect_set"
[(match_operand 0 "memory_operand")
(match_operand 1 "memory_operand")]
- "!TARGET_HAS_BIONIC"
+ "ix86_stack_protector_guard == SSP_TLS"
Please introduce TARGET_SSP_GLOBAL_GUARD and TARGET_SSP_TLS_GUARD
defines to i386.h (please follow an example of TARGET_GNU_TLS).
target_option_default_node = target_option_current_node
= build_target_option_node ();
+
+ /* Handle stack protector */
+ if (!global_options_set.x_ix86_stack_protector_guard)
+ {
+ ix86_stack_protector_guard = TARGET_HAS_BIONIC? SSP_GLOBAL : SSP_TLS;
+ }
}
You should not need this part, JoinedVar directive should handle this
functionality by itself. Again, please see ix86_tls_dialect handling.
Uros.