xtensa: don't use a12 in strncpy_user

a12 is callee-saved register in xtensa call0 ABI, so a function must not
change it. a10 is not used in this function at all, use it instead of
a12 to avoid saving/restoring it.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

diff --git a/arch/xtensa/lib/strncpy_user.S b/arch/xtensa/lib/strncpy_user.S
index 4faf46f..0731912 100644 (file)
--- a/arch/xtensa/lib/strncpy_user.S
+++ b/arch/xtensa/lib/strncpy_user.S
@@ -45,7 +45,6 @@
 #   a9/ tmp
 #   a10/ tmp
 #   a11/ dst
-#   a12/ tmp
 
 .text
 ENTRY(__strncpy_user)
@@ -61,7 +60,7 @@ ENTRY(__strncpy_user)
        bbsi.l  a3, 0, .Lsrc1mod2 # if only  8-bit aligned
        bbsi.l  a3, 1, .Lsrc2mod4 # if only 16-bit aligned
 .Lsrcaligned:  # return here when src is word-aligned
-       srli    a12, a4, 2      # number of loop iterations with 4B per loop
+       srli    a10, a4, 2      # number of loop iterations with 4B per loop
        movi    a9, 3
        bnone   a11, a9, .Laligned
        j       .Ldstunaligned
@@ -102,11 +101,11 @@ EX(10f)   s8i     a9, a11, 0              # store byte 0
        .byte   0               # (0 mod 4 alignment for LBEG)
 .Laligned:
 #if XCHAL_HAVE_LOOPS
-       loopnez a12, .Loop1done
+       loopnez a10, .Loop1done
 #else
-       beqz    a12, .Loop1done
-       slli    a12, a12, 2
-       add     a12, a12, a11   # a12 = end of last 4B chunck
+       beqz    a10, .Loop1done
+       slli    a10, a10, 2
+       add     a10, a10, a11   # a10 = end of last 4B chunck
 #endif
 .Loop1:
 EX(11f)        l32i    a9, a3, 0               # get word from src
@@ -118,7 +117,7 @@ EX(10f)     s32i    a9, a11, 0              # store word to dst
        bnone   a9, a8, .Lz3            # if byte 3 is zero
        addi    a11, a11, 4             # advance dst pointer
 #if !XCHAL_HAVE_LOOPS
-       blt     a11, a12, .Loop1
+       blt     a11, a10, .Loop1
 #endif
 
 .Loop1done:
@@ -185,7 +184,7 @@ EX(10f)     s8i     a9, a11, 2
        loopnez a4, .Lunalignedend
 #else
        beqz    a4, .Lunalignedend
-       add     a12, a11, a4            # a12 = ending address
+       add     a10, a11, a4            # a10 = ending address
 #endif /* XCHAL_HAVE_LOOPS */
 .Lnextbyte:
 EX(11f)        l8ui    a9, a3, 0
@@ -194,7 +193,7 @@ EX(10f)     s8i     a9, a11, 0
        beqz    a9, .Lunalignedend
        addi    a11, a11, 1
 #if !XCHAL_HAVE_LOOPS
-       blt     a11, a12, .Lnextbyte
+       blt     a11, a10, .Lnextbyte
 #endif
 
 .Lunalignedend: