Hi, so there's a breakage of a use case with gdbserver on fsgsbase machines, see
https://sourceware.org/bugzilla/show_bug.cgi?id=26804 Tom has an even simpler reproducer: $ cat test.c int main (void) { return 0; } $ gcc test.c -m32 $ gdbserver localhost:12345 a.out ... other terminal ... $ gdb -batch -q -ex "target remote localhost:12345" -ex continue Program received signal SIGSEGV, Segmentation fault. 0xf7dd8bd2 in init_cacheinfo () at ../sysdeps/x86/cacheinfo.c:761 The correct output is, of course: ... [Inferior 1 (process 1860) exited normally] I tried to bisect this but it led me to: b745cfba44c1 ("x86/cpu: Enable FSGSBASE on 64bit by default and add a chicken bit") which simply enables fsgsbase so I could've made a small mistake in the bisection. I say small because booting with "nofsgsbase" cures it so it must be something fsgsbase + ptrace especially since the symptom is a corrupted stack canary in %gs... Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
