[M3devel] [pinozollo at gmail.com: Installation Problem]
Tony Hosking
hosking at cs.purdue.edu
Wed Apr 18 18:33:06 CEST 2007
Yes, use of setjmp/longjmp for *user*-level threads is bound to fail
in the presence of the security mangling they now do, since new
thread contexts are obtained by cloning a setjmp buffer from the root
thread, and then hacking its stack pointer appropriately to match the
new thread. This doesn't work with the secure setjmp/longjmp
implementations. On platforms like Linux where setjmp/longjmp
mangling prevent their use for user-level threading the only
alternative is to use the explicit makecontext with getcontext/
setcontext. This is how *user*-level threading is done on Solaris.
With the newer PTHREAD threading (for SOLgnu, SOLsun, LINUXLIBC6,
I386_DARWIN, PPC_DARWIN) this should not be an issue, but it does
require NPTL on Linux platforms (I don't think 2.4 kernels support
NPTL). I do know that I can successfully build from the current CVS
tree on recent releases of Fedora Core, without problems.
On Apr 18, 2007, at 12:15 PM, Rodney M. Bates wrote:
> This symptom (works when statically linked, segfaults during
> startup when
> using dynamic libraries) is, as I remember, the symptom of the
> problem with
> changes in newer setjmp/longjmp that I posted about on January 11.
>
> The newer setjmp/longjmp mangle and demangle a couple of the registers
> (apparently to prevent some security exploit). When used as a
> pair, the
> change is harmless. But some uses of setjmp in the M3 libraries
> actually
> use the contents of the setjmp buffer to get register contents for
> thread
> switching, etc.
>
> There is an assembly-coded special version of setjmp in the M3
> code, dating
> from many years back, that works with older longjmp, but not with
> the newest.
> Tony committed a change that removes this version of setjmp. but I
> don't think
> that fixes all the problems in all cases.
I don't see problems with this change. What problems are you
seeing? In this case, setjmp/longjmp is only being used for
exception handling, assuming threads are using PTHREAD (i.e., Linux
NPTL).
>
> I think existing uses of setjmp have to be split into two
> categories: those
> that just use the result to pass back to longjmp, and those that
> use the result
> for fetching registers. Then different variants of setjmp have to
> be used in
> the two cases. Antony suggested getcontext/setcontext, but I guess
> there are
> portability problems here?
>
> I looked at this briefly, and there are a very large number of uses
> of setjmp
> to check out. I have thought about working on it, but have been
> busy with
> other things for a while.
>
> I never got -DPTHREAD working and ran out of time on that approach.
> As I recall,
> -DPTHREAD is now the default, so I would guess Pino's installation
> is using it.
>
> Olaf Wagner wrote:
>> Is this the stack encryption problem again? Has anybody tried on
>> Suse 10.1?
>> Olaf
>> ----- Forwarded message from Pino Zollo <pinozollo at gmail.com> -----
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>> From: Pino Zollo <pinozollo at gmail.com>
>> To: m3-support at elego.de
>> Subject: Installation Problem
>> Date: Tue, 17 Apr 2007 18:00:50 -0400
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>> Dear Sirs,
>> I have installed the last version of cm3 but I have the following
>> problem:
>> cm3 compiles all programs, but are correctly executed only the
>> ones compiled
>> with the option build_standalone().
>> The programs which use shared libraries end in segmentation fault.
>> Also the script do-cm3-std.sh fails to compile everything for the
>> same
>> problem: the program PklFonts in the directory
>> m3-ui/juno-2/juno-app/pkl-fonts/LINUXLIBC6 ends in segmentation fault
>> because needs shared libraries.
>> Any suggestion ?
>> I am using the distribution SuSE 10.1 with kernel 2.4.27
>> In the installation I have found that the command "export" was not
>> doing
>> properly its job, so I had to put
>> the path /usr/local/cm3/bin in /etc/profile. For libraries I did
>> put the
>> path in /etc/ld.so.conf
>> I noticed that executables contain the string "/lib/ld-linux.so.2"
>> so I had
>> to make a symbolic link in /lib
>> as "ln -s ld-2.4.so ld-linux.so.2" but nothing did change.
>> I have also tried export "LD_POINTER_GUARD=0" also without any
>> change.
>> I have done quite a lot on Modula-3 programming years ago when
>> kernel was
>> 1.2.13. I would like to make public my
>> old sources under the GNU licence. For this reason I am willing to
>> check
>> them on the new version on m3.
>> I am available for doing development in Modula-3 in the limits of my
>> capabilities.
>> My name is Pino Zollo and my e-mail is pinozollo at gmail.com
>> Some of my works are on http://www.qsl.net/zp4kfx and a
>> description of my
>> profesional experience is on
>> http://www.qsl.net/zp4kfx/CV
>> Thanks for the attencion.
>> Best regards
>> Pino
>> ----- End forwarded message -----
>
> --
> -------------------------------------------------------------
> Rodney M. Bates, retired assistant professor
> Dept. of Computer Science, Wichita State University
> Wichita, KS 67260-0083
> 316-978-3922
> rodney.bates at wichita.edu
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