x86/entry/64: Push extra regs right away

With the fast path removed there is no point in splitting the push of the
normal and the extra register set. Just push the extra regs right away.

[ tglx: Split out from 'x86/entry/64: Remove the SYSCALL64 fast path' ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Link: https://lkml.kernel.org/r/462dff8d4d64dfbfc851fbf3130641809d980ecd.1517164461.git.luto@kernel.org

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index c46c755..c752abe 100644 (file)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -236,13 +236,17 @@ GLOBAL(entry_SYSCALL_64_after_hwframe)
        pushq   %r9                             /* pt_regs->r9 */
        pushq   %r10                            /* pt_regs->r10 */
        pushq   %r11                            /* pt_regs->r11 */
-       sub     $(6*8), %rsp                    /* pt_regs->bp, bx, r12-15 not saved */
-       UNWIND_HINT_REGS extra=0
+       pushq   %rbx                            /* pt_regs->rbx */
+       pushq   %rbp                            /* pt_regs->rbp */
+       pushq   %r12                            /* pt_regs->r12 */
+       pushq   %r13                            /* pt_regs->r13 */
+       pushq   %r14                            /* pt_regs->r14 */
+       pushq   %r15                            /* pt_regs->r15 */
+       UNWIND_HINT_REGS
 
        TRACE_IRQS_OFF
 
        /* IRQs are off. */
-       SAVE_EXTRA_REGS
        movq    %rsp, %rdi
        call    do_syscall_64           /* returns with IRQs disabled */