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xtensa: don't use a12 in strncpy_user

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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>
This commit is contained in:
Max Filippov 2021-07-25 16:31:34 -07:00
parent eda8dd1224
commit d191323bc0
1 changed files with 8 additions and 9 deletions
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17
arch/xtensa/lib/strncpy_user.S
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@ -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: