• Andy Lutomirski's avatar
    x86/entry/64: Allocate and enable the SYSENTER stack · 1a79797b
    Andy Lutomirski authored
    This will simplify future changes that want scratch variables early in
    the SYSENTER handler -- they'll be able to spill registers to the
    stack.  It also lets us get rid of a SWAPGS_UNSAFE_STACK user.
    
    This does not depend on CONFIG_IA32_EMULATION=y because we'll want the
    stack space even without IA32 emulation.
    
    As far as I can tell, the reason that this wasn't done from day 1 is
    that we use IST for #DB and #BP, which is IMO rather nasty and causes
    a lot more problems than it solves.  But, since #DB uses IST, we don't
    actually need a real stack for SYSENTER (because SYSENTER with TF set
    will invoke #DB on the IST stack rather than the SYSENTER stack).
    
    I want to remove IST usage from these vectors some day, and this patch
    is a prerequisite for that as well.
    Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Borislav Petkov <bpetkov@suse.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: David Laight <David.Laight@aculab.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: Eduardo Valentin <eduval@amazon.com>
    Cc: Greg KH <gregkh@linuxfoundation.org>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: aliguori@amazon.com
    Cc: daniel.gruss@iaik.tugraz.at
    Cc: hughd@google.com
    Cc: keescook@google.com
    Link: https://lkml.kernel.org/r/20171204150605.312726423@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    1a79797b
asm-offsets_32.c 1.71 KB