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    Subject[PATCH 4.14 035/159] x86/entry/64: Remove the restore_c_regs_and_iret label
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Andy Lutomirski <luto@kernel.org>

    commit 9da78ba6b47b46428cfdfc0851511ab29c869798 upstream.

    The only user was the 64-bit opportunistic SYSRET failure path, and
    that path didn't really need it. This change makes the
    opportunistic SYSRET code a bit more straightforward and gets rid of
    the label.

    Signed-off-by: Andy Lutomirski <luto@kernel.org>
    Reviewed-by: Borislav Petkov <bp@suse.de>
    Cc: Borislav Petkov <bpetkov@suse.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/be3006a7ad3326e3458cf1cc55d416252cbe1986.1509609304.git.luto@kernel.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/entry/entry_64.S | 5 ++---
    1 file changed, 2 insertions(+), 3 deletions(-)

    --- a/arch/x86/entry/entry_64.S
    +++ b/arch/x86/entry/entry_64.S
    @@ -246,7 +246,6 @@ entry_SYSCALL64_slow_path:
    call do_syscall_64 /* returns with IRQs disabled */

    return_from_SYSCALL_64:
    - RESTORE_EXTRA_REGS
    TRACE_IRQS_IRETQ /* we're about to change IF */

    /*
    @@ -315,6 +314,7 @@ return_from_SYSCALL_64:
    */
    syscall_return_via_sysret:
    /* rcx and r11 are already restored (see code above) */
    + RESTORE_EXTRA_REGS
    RESTORE_C_REGS_EXCEPT_RCX_R11
    movq RSP(%rsp), %rsp
    UNWIND_HINT_EMPTY
    @@ -322,7 +322,7 @@ syscall_return_via_sysret:

    opportunistic_sysret_failed:
    SWAPGS
    - jmp restore_c_regs_and_iret
    + jmp restore_regs_and_iret
    END(entry_SYSCALL_64)

    ENTRY(stub_ptregs_64)
    @@ -639,7 +639,6 @@ retint_kernel:
    */
    GLOBAL(restore_regs_and_iret)
    RESTORE_EXTRA_REGS
    -restore_c_regs_and_iret:
    RESTORE_C_REGS
    REMOVE_PT_GPREGS_FROM_STACK 8
    INTERRUPT_RETURN

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