linux-kernel - Re: [patch 1/9] Conditional Calls

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 31 May 2007 12:34:15 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [patch 1/9] Conditional Calls - Architecture Independent Code

* Andrew Morton (akpm@...ux-foundation.org) wrote:
> > +#ifdef CONFIG_COND_CALL_ENABLE_OPTIMIZATION
> > +#include <asm/condcall.h>		/* optimized cond_call flavor */
> > +#else
> > +#include <asm-generic/condcall.h>	/* fallback on generic cond_call */
> > +#endif
> 
> The preferred way to do this is to give every architecture an
> asm/condcall.h and from within that, include asm-generic/condcall.h.  Your
> [patch 3/9] does most of that, but it didn't remove the above ifdef, and I
> don't think it removed the should-be-unneeded
> CONFIG_COND_CALL_ENABLE_OPTIMIZATION either?
> 

Conditional calls works just like the previous markers in this aspect :
in order to support embedded systems with read-only memory for the text
segment, I leave the choice to disable the "optimized" cond_call as a
config option even if the architecture has the optimized marker flavor.

I use this include scheme because I want to support both the generic and
optimized version at the same time : if a _cond_call is declared with
the CF_OPTIMIZED flags unset, it will use the generic version. This is
useful when we must place cond_calls in locations that present specific
reentrancy issues, such as cond_call, printk, some trap handlers. The
optimized version, when it uses the i386 mechanism to insure correct
code modification, can trigger a trap, which will call into lockdep and
might have other side-effects.

(I am adding this text in the condcall.h header)

Mathieu

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/