Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-17 Thread Segher Boessenkool
>>> Way back when, I distinctly recall aborting my plans to implement >>> per-page exec on 40x, precisely because of executables like this. >> >> I noticed some comments to that effect in the BookE code, >> yes. It seems userland has been fixed enough that you >> could think about enabling it agai

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-17 Thread Kumar Gala
On Jul 17, 2007, at 10:18 AM, Segher Boessenkool wrote: > Yeah. Giving the warning is a good thing though. No, it isn't; it's just noise, if we're not ever going to do anything to prevent the behaviour - and we can't. >>> >>> The same userland code will not run correctly

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-17 Thread Segher Boessenkool
Yeah. Giving the warning is a good thing though. >>> >>> No, it isn't; it's just noise, if we're not ever going to do >>> anything >>> to prevent the behaviour - and we can't. >> >> The same userland code will not run correctly on PPC64 or BookE >> systems. Is that not a reason to warn? >

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-16 Thread David Gibson
On Wed, Jul 11, 2007 at 02:03:24AM +0200, Segher Boessenkool wrote: > >> Yeah. Giving the warning is a good thing though. > > > > No, it isn't; it's just noise, if we're not ever going to do anything > > to prevent the behaviour - and we can't. > > The same userland code will not run correctly on

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-10 Thread Paul Mackerras
Segher Boessenkool writes: > >> Yeah. Giving the warning is a good thing though. > > > > No, it isn't; it's just noise, if we're not ever going to do anything > > to prevent the behaviour - and we can't. > > The same userland code will not run correctly on PPC64 or BookE > systems. Is that not

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-10 Thread Segher Boessenkool
>> Yeah. Giving the warning is a good thing though. > > No, it isn't; it's just noise, if we're not ever going to do anything > to prevent the behaviour - and we can't. The same userland code will not run correctly on PPC64 or BookE systems. Is that not a reason to warn? Segher __

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-10 Thread Paul Mackerras
Segher Boessenkool writes: > Yeah. Giving the warning is a good thing though. No, it isn't; it's just noise, if we're not ever going to do anything to prevent the behaviour - and we can't. Paul. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org ht

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-10 Thread Segher Boessenkool
> In older versions of glibc (through 2.3), the dynamic linker > executes a > small amount of code from the data segment, which is not marked as > executable. A recent change (commit > 9ba4ace39fdfe22268daca9f28c5df384ae462cf) > stops this from working; there should be a deprecation period bef

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-10 Thread Segher Boessenkool
>> I may be missing the obvious, but doesn't that defeat the purpose of >> non-executable mappings? > > The hardware in question doesn't support non-executable mappings; Not on a per-page basis, anyway. > otherwise, it'd never have worked in the first place. Note that > this is > only allowed

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-09 Thread Arnd Bergmann
On Monday 09 July 2007, Scott Wood wrote: > The hardware in question doesn't support non-executable mappings; > otherwise, it'd never have worked in the first place.  Note that this is > only allowed on 32-bit, non-book-E. > > There isn't much value in enforcing non-exec mappings only if it happ

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-09 Thread Scott Wood
Scott Wood wrote: > Arnd Bergmann wrote: >> I may be missing the obvious, but doesn't that defeat the purpose of >> non-executable mappings? > > > The hardware in question doesn't support non-executable mappings; > otherwise, it'd never have worked in the first place. Note that this is > only

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-09 Thread Linas Vepstas
On Mon, Jul 09, 2007 at 04:16:40PM -0500, Scott Wood wrote: > Arnd Bergmann wrote: > > I may be missing the obvious, but doesn't that defeat the purpose of > > non-executable mappings? > > The hardware in question doesn't support non-executable mappings; > otherwise, it'd never have worked in the

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-09 Thread Scott Wood
Arnd Bergmann wrote: > On Monday 09 July 2007, Scott Wood wrote: > >>In older versions of glibc (through 2.3), the dynamic linker executes a >>small amount of code from the data segment, which is not marked as >>executable. A recent change (commit 9ba4ace39fdfe22268daca9f28c5df384ae462cf) >>stops

Re: [PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-09 Thread Arnd Bergmann
On Monday 09 July 2007, Scott Wood wrote: > In older versions of glibc (through 2.3), the dynamic linker executes a > small amount of code from the data segment, which is not marked as > executable.  A recent change (commit 9ba4ace39fdfe22268daca9f28c5df384ae462cf) > stops this from working; there

[PATCH] Allow exec on 32-bit from readable, non-exec pages, with a warning.

2007-07-09 Thread Scott Wood
In older versions of glibc (through 2.3), the dynamic linker executes a small amount of code from the data segment, which is not marked as executable. A recent change (commit 9ba4ace39fdfe22268daca9f28c5df384ae462cf) stops this from working; there should be a deprecation period before older glibc