Linus, All,
On 2013-12-31 16:16 -0800, Linus Torvalds spake thusly:
> On Mon, Dec 30, 2013 at 4:45 PM, Kees Cook <[email protected]> wrote:
> >
> > NAK. If you have selected CONFIG_CC_STACKPROTECTOR_STRONG, the build
> > the fail hard. Without this, it means you'll end up with kernels that
> > build and show a stackprotector option in their config, which is
> > false.
>
> What we really really want to do is to have some way to add config
> options based on shell scripts and compiler support. That would also
> get rid of a lot of Makefile trickery etc.
>
> Then we could just make CC_STACKPROTECTOR_STRONG depend on
> CC_SUPPORTS_STACKPROTECTOR_STRONG or whatever.
Sam Ravnborg suggested somethink along those lines back in July:
http://marc.info/?l=linux-kbuild&m=137399785206527&w=2
and a tentative implementation:
http://marc.info/?l=linux-kbuild&m=137409581406434&w=2
Basically, that would give something like:
config CC_SUPPORTS_STACKPROTECTOR_STRONG
bool
option exec="some/script/to/test-gcc -fstack-protector-strong"
config CC_STACKPROTECTOR_STRONG
bool "enable stack-protector strong"
depends on CC_SUPPORTS_STACKPROTECTOR_STRONG
Would that be something that match what you suggested above?
Sam, there were some comments on that patch of yours. Do you want to
update it and resubmit it?
And, Happy New Year to All!
Regards,
Yann E. MORIN.
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On Wed, Jan 1, 2014 at 3:42 AM, Yann E. MORIN <[email protected]> wrote:
>
> On 2013-12-31 16:16 -0800, Linus Torvalds spake thusly:
>>
>> What we really really want to do is to have some way to add config
>> options based on shell scripts and compiler support. That would also
>> get rid of a lot of Makefile trickery etc.
>>
>> Then we could just make CC_STACKPROTECTOR_STRONG depend on
>> CC_SUPPORTS_STACKPROTECTOR_STRONG or whatever.
>
> Sam Ravnborg suggested somethink along those lines back in July:
> http://marc.info/?l=linux-kbuild&m=137399785206527&w=2
> and a tentative implementation:
> http://marc.info/?l=linux-kbuild&m=137409581406434&w=2
Ack. Looks good to me. I've wanted this for a long time for other
reasons, we should finally just do it.
That said, we should make sure that the shell execution thing gets
access to $(CC) etc variables that we have in
> Basically, that would give something like:
>
> config CC_SUPPORTS_STACKPROTECTOR_STRONG
> bool
> option exec="some/script/to/test-gcc -fstack-protector-strong"
For the compiler options, it would hopefully be sufficient to just do
something like
config CC_SUPPORTS_STACKPROTECTOR_STRONG
bool
option exec="$CC -fstack-protector-strong -c empty.c"
or something like that. No?
Linus
On 01/01/2014 11:33 AM, Linus Torvalds wrote:
>
> Ack. Looks good to me. I've wanted this for a long time for other
> reasons, we should finally just do it.
>
Yes, we keep avoiding doing this by layering hack upon hack, but
really... it needs to be done.
The chief objection I've heard is that it makes "make oldconfig"
necessary after a compiler change, but that seems entirely reasonable.
-hpa
Linus, All,
On 2014-01-01 11:33 -0800, Linus Torvalds spake thusly:
> On Wed, Jan 1, 2014 at 3:42 AM, Yann E. MORIN <[email protected]> wrote:
> >
> > On 2013-12-31 16:16 -0800, Linus Torvalds spake thusly:
> >>
> >> What we really really want to do is to have some way to add config
> >> options based on shell scripts and compiler support. That would also
> >> get rid of a lot of Makefile trickery etc.
> >>
> >> Then we could just make CC_STACKPROTECTOR_STRONG depend on
> >> CC_SUPPORTS_STACKPROTECTOR_STRONG or whatever.
> >
> > Sam Ravnborg suggested somethink along those lines back in July:
> > http://marc.info/?l=linux-kbuild&m=137399785206527&w=2
> > and a tentative implementation:
> > http://marc.info/?l=linux-kbuild&m=137409581406434&w=2
>
> Ack. Looks good to me. I've wanted this for a long time for other
> reasons, we should finally just do it.
>
> That said, we should make sure that the shell execution thing gets
> access to $(CC) etc variables that we have in
This requires exporting them from the Makefiles (they are, in Makefile:391
and below).
> > Basically, that would give something like:
> >
> > config CC_SUPPORTS_STACKPROTECTOR_STRONG
> > bool
> > option exec="some/script/to/test-gcc -fstack-protector-strong"
>
> For the compiler options, it would hopefully be sufficient to just do
> something like
>
> config CC_SUPPORTS_STACKPROTECTOR_STRONG
> bool
> option exec="$CC -fstack-protector-strong -c empty.c"
>
> or something like that. No?
This is an implementation detail, but the original patch expected the
result to be 'y' or 'n' (or empty=='n') on stdout. That way, it could
also be used to fill-in config options that are strings, or ints. Hence
the use of a script.
But H. Peter suggested it should only return a boolean, which seems
entirely reasonable, given the purpose of this. In this case, using 'y'
or 'n' from stdout, or 0 or !0 from the exit code are equally easy.
Also, using a single shell script allows to fix/enhance all of those
calls in a single place, and avoids duplicating all the check logic in
every tests (eg. who is going to create empty.c in your example? Clean
up the output file?). And since kconfig is run from the top-level of the
Linux source tree (even for out-of-tree builds), we can safely use a
path relative to that to call our script(s).
I'll wait a bit until the end of the holiday season before I poke Sam
again on this.
Regards,
Yann E. MORIN.
--
.-----------------.--------------------.------------------.--------------------.
| Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ |
| +33 223 225 172 `------------.-------: X AGAINST | \e/ There is no |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. |
'------------------------------^-------^------------------^--------------------'
Hi all.
> >
> > config CC_SUPPORTS_STACKPROTECTOR_STRONG
> > bool
> > option exec="$CC -fstack-protector-strong -c empty.c"
> >
> > or something like that. No?
>
> This is an implementation detail, but the original patch expected the
> result to be 'y' or 'n' (or empty=='n') on stdout. That way, it could
> also be used to fill-in config options that are strings, or ints. Hence
> the use of a script.
>
> But H. Peter suggested it should only return a boolean, which seems
> entirely reasonable, given the purpose of this. In this case, using 'y'
> or 'n' from stdout, or 0 or !0 from the exit code are equally easy.
>
> Also, using a single shell script allows to fix/enhance all of those
> calls in a single place, and avoids duplicating all the check logic in
> every tests (eg. who is going to create empty.c in your example? Clean
> up the output file?). And since kconfig is run from the top-level of the
> Linux source tree (even for out-of-tree builds), we can safely use a
> path relative to that to call our script(s).
>
> I'll wait a bit until the end of the holiday season before I poke Sam
> again on this.
The thinking behind the exec option was that it should return a string,
and then the content of the string were parsed depending on the type used in
the kconfig language.
So for a bool "y" and "n" would be recognized.
For tristate in adddition "m" would be recognized.
For int we should be able to parse numbers.
And string would be string.
An if an exec'ed command gave e return code != 0 then this should result in a warning,
so user is told that the attempt to execute /bin/some_thing_random failed.
Otherwise we would end in situations were this would be difficult to debug.
I have no time to actually implement the above proposal - sorry!
But things are busy at my day-time job etc.
So I hope someone can step in and help here.
PS. I have suffered from a faulty linux box + change of mail provider.
And in the end I deleted all mails from the last three months.
This was much quicker than to actually read them :-)
Sam