• Andy Lutomirski's avatar
    x86/arch_prctl: Fix ARCH_GET_FS and ARCH_GET_GS · d47b50e7
    Andy Lutomirski authored
    ARCH_GET_FS and ARCH_GET_GS attempted to figure out the fsbase and
    gsbase respectively from saved thread state.  This was wrong: fsbase
    and gsbase live in registers while a thread is running, not in
    memory.
    
    For reasons I can't fathom, the fsbase and gsbase code were
    different.  Since neither was correct, I didn't try to figure out
    what the point of the difference was.
    
    Change it to simply read the MSRs.
    
    The code for reading the base for a remote thread is also completely
    wrong if the target thread uses its own descriptors (which is the case
    for all 32-bit threaded programs), but fixing that is a different
    story.
    Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
    Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Rudolf Marek <r.marek@assembler.cz>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/c6e7b507c72ca3bdbf6c7a8a3ceaa0334e873bd9.1460075211.git.luto@kernel.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    d47b50e7
process_64.c 16.6 KB