[PATCH 3.4 17/45] xtensa: fix a6 and a7 handling in fast_syscall_xtensa

Zefan Li
2014-09-23T02:37:16Z

From: Max Filippov <jcmvbkbc@gmail.com>

3.4.104-rc1 review patch. If anyone has any objections, please let me know.

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

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: Zefan Li <lizefan@huawei.com>
---
arch/xtensa/kernel/entry.S | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index bc9f78e..e01cffc 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -1053,9 +1053,8 @@ 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. */

@@ -1067,27 +1066,26 @@ TRY s32i a5, a3, 0 # different, modify value
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
@@ -1096,7 +1094,7 @@ 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
--
1.7.9.5