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SubjectRE: gdbserver + fsgsbase kaputt
Date
> [   26.990644] getreg: gs_base = 0xf7f8e000
> [ 26.991694] getreg: GS=0x63, GSBASE=0xf7f8e000
> [ 26.993117] PTRACE_SETREGS
> [ 26.993813] putreg: change gsbase from 0xf7f8e000 to 0x0
> [ 26.995134] putreg: write GS=0x63; old GSBASE=0x0
> [ 26.996235] PTRACE_SETREGS done
>
> That's gdbserver reading GS and GSBASE and then telling the kernel to
> set GS to the same value and GSBASE to 0.
>
> I can come up with horrible kernel hacks to try to work around this,
> but gdbserver is really giving the kernel bad instructions here.

I agree that this looks like a GDB bug rather than a kernel bug. GDB
should preserve the GS_BASE value if it doesn't intend to change it.

Markus.
Intel Deutschland GmbH
Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
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