lkml.org 
[lkml]   [2014]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3.16 105/357] xtensa: fix a6 and a7 handling in fast_syscall_xtensa
    Date
    3.16-stable review patch.  If anyone has any objections, please let me know.

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

    From: Max Filippov <jcmvbkbc@gmail.com>

    commit d1b6ba82a50cecf94be540a3a153aa89d97511a0 upstream.

    Remove restoring a6 on some return paths and instead modify and restore
    it in a single place, using symbolic name.
    Correctly restore a7 from PT_AREG7 in case of illegal a6 value.

    Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/xtensa/kernel/entry.S | 12 +++++-------
    1 file changed, 5 insertions(+), 7 deletions(-)

    --- a/arch/xtensa/kernel/entry.S
    +++ b/arch/xtensa/kernel/entry.S
    @@ -1001,9 +1001,8 @@ ENTRY(fast_syscall_xtensa)
    movi a7, 4 # sizeof(unsigned int)
    access_ok a3, a7, a0, a2, .Leac # a0: scratch reg, a2: sp

    - addi a6, a6, -1 # assuming SYS_XTENSA_ATOMIC_SET = 1
    - _bgeui a6, SYS_XTENSA_COUNT - 1, .Lill
    - _bnei a6, SYS_XTENSA_ATOMIC_CMP_SWP - 1, .Lnswp
    + _bgeui a6, SYS_XTENSA_COUNT, .Lill
    + _bnei a6, SYS_XTENSA_ATOMIC_CMP_SWP, .Lnswp

    /* Fall through for ATOMIC_CMP_SWP. */

    @@ -1015,27 +1014,26 @@ TRY s32i a5, a3, 0 # different, modify
    l32i a7, a2, PT_AREG7 # restore a7
    l32i a0, a2, PT_AREG0 # restore a0
    movi a2, 1 # and return 1
    - addi a6, a6, 1 # restore a6 (really necessary?)
    rfe

    1: l32i a7, a2, PT_AREG7 # restore a7
    l32i a0, a2, PT_AREG0 # restore a0
    movi a2, 0 # return 0 (note that we cannot set
    - addi a6, a6, 1 # restore a6 (really necessary?)
    rfe

    .Lnswp: /* Atomic set, add, and exg_add. */

    TRY l32i a7, a3, 0 # orig
    + addi a6, a6, -SYS_XTENSA_ATOMIC_SET
    add a0, a4, a7 # + arg
    moveqz a0, a4, a6 # set
    + addi a6, a6, SYS_XTENSA_ATOMIC_SET
    TRY s32i a0, a3, 0 # write new value

    mov a0, a2
    mov a2, a7
    l32i a7, a0, PT_AREG7 # restore a7
    l32i a0, a0, PT_AREG0 # restore a0
    - addi a6, a6, 1 # restore a6 (really necessary?)
    rfe

    CATCH
    @@ -1044,7 +1042,7 @@ CATCH
    movi a2, -EFAULT
    rfe

    -.Lill: l32i a7, a2, PT_AREG0 # restore a7
    +.Lill: l32i a7, a2, PT_AREG7 # restore a7
    l32i a0, a2, PT_AREG0 # restore a0
    movi a2, -EINVAL
    rfe



    \
     
     \ /
      Last update: 2014-10-04 00:21    [W:2.238 / U:0.052 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site