• Andy Lutomirski's avatar
    x86_64, traps: Stop using IST for #SS · 6f442be2
    Andy Lutomirski authored
    On a 32-bit kernel, this has no effect, since there are no IST stacks.
    On a 64-bit kernel, #SS can only happen in user code, on a failed iret
    to user space, a canonical violation on access via RSP or RBP, or a
    genuine stack segment violation in 32-bit kernel code.  The first two
    cases don't need IST, and the latter two cases are unlikely fatal bugs,
    and promoting them to double faults would be fine.
    This fixes a bug in which the espfix64 code mishandles a stack segment
    This saves 4k of memory per CPU and a tiny bit of code.
    Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
    Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
entry_64.S 42.6 KB