Oliver Kowalke <oliver.kowalke@xxxxxx> writes: > Am 30.03.2012 17:08, schrieb Ian Lance Taylor: >> "Oliver Kowalke"<oliver.kowalke@xxxxxx> writes: >> >>> I get a segfault with following app - could you verify this? >> This program works fine for me (gcc 4.4.3, glibc 2.11.1, Ubuntu Lucid) >> in 64-bit mode. But now I see that you are using 32-bit mode. I can >> confirm that the program crashes for me in that mode. >> >> Looking at the 32-bit implementation of makecontext in glibc, I can see >> that the problem is that it doesn't set up correct unwind information >> for the parameters pushed on the stack. The effect is that the first >> parameter on the stack appears to be a PC value. I think this is a bug >> in glibc. It should be possible to arrange for unwind information which >> skips %ebx words on the stack. >> >> Ian >> > > I think the test app is not correct - on ppc32/linux it never returns. Any application that tries to walk up the stack to the end is unfortunately going to be tricky and non-portable. If you want a portable program you should always have some way to stop the stack unwind yourself. That is unfortunate but true. > Could you give me some hint how the stack unwind information is > usally writen on the stack/else where (some architectures do not save > the return address on the stack). > I believe the code is somewhere in the gcc sources - unfortunately I > don't know where (for what to grep for?)! http://www.airs.com/blog/archives/460 Ian
