linux/arch/arm/lib/memzero.S
Russell King 8478132a87 Revert "arm: move exports to definitions"
This reverts commit 4dd1837d75.

Moving the exports for assembly code into the assembly files breaks
KSYM trimming, but also breaks modversions.

While fixing the KSYM trimming is trivial, fixing modversions brings
us to a technically worse position that we had prior to the above
change:

- We end up with the prototype definitions divorsed from everything
  else, which means that adding or removing assembly level ksyms
  become more fragile:
  * if adding a new assembly ksyms export, a missed prototype in
    asm-prototypes.h results in a successful build if no module in
    the selected configuration makes use of the symbol.
  * when removing a ksyms export, asm-prototypes.h will get forgotten,
    with armksyms.c, you'll get a build error if you forget to touch
    the file.

- We end up with the same amount of include files and prototypes,
  they're just in a header file instead of a .c file with their
  exports.

As for lines of code, we don't get much of a size reduction:
 (original commit)
 47 files changed, 131 insertions(+), 208 deletions(-)
 (fix for ksyms trimming)
 7 files changed, 18 insertions(+), 5 deletions(-)
 (two fixes for modversions)
 1 file changed, 34 insertions(+)
 3 files changed, 7 insertions(+), 2 deletions(-)
which results in a net total of only 25 lines deleted.

As there does not seem to be much benefit from this change of approach,
revert the change.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2016-11-23 10:00:03 +00:00

138 lines
3.0 KiB
ArmAsm

/*
* linux/arch/arm/lib/memzero.S
*
* Copyright (C) 1995-2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/unwind.h>
.text
.align 5
.word 0
/*
* Align the pointer in r0. r3 contains the number of bytes that we are
* mis-aligned by, and r1 is the number of bytes. If r1 < 4, then we
* don't bother; we use byte stores instead.
*/
UNWIND( .fnstart )
1: subs r1, r1, #4 @ 1 do we have enough
blt 5f @ 1 bytes to align with?
cmp r3, #2 @ 1
strltb r2, [r0], #1 @ 1
strleb r2, [r0], #1 @ 1
strb r2, [r0], #1 @ 1
add r1, r1, r3 @ 1 (r1 = r1 - (4 - r3))
/*
* The pointer is now aligned and the length is adjusted. Try doing the
* memzero again.
*/
ENTRY(__memzero)
mov r2, #0 @ 1
ands r3, r0, #3 @ 1 unaligned?
bne 1b @ 1
/*
* r3 = 0, and we know that the pointer in r0 is aligned to a word boundary.
*/
cmp r1, #16 @ 1 we can skip this chunk if we
blt 4f @ 1 have < 16 bytes
#if ! CALGN(1)+0
/*
* We need an extra register for this loop - save the return address and
* use the LR
*/
str lr, [sp, #-4]! @ 1
UNWIND( .fnend )
UNWIND( .fnstart )
UNWIND( .save {lr} )
mov ip, r2 @ 1
mov lr, r2 @ 1
3: subs r1, r1, #64 @ 1 write 32 bytes out per loop
stmgeia r0!, {r2, r3, ip, lr} @ 4
stmgeia r0!, {r2, r3, ip, lr} @ 4
stmgeia r0!, {r2, r3, ip, lr} @ 4
stmgeia r0!, {r2, r3, ip, lr} @ 4
bgt 3b @ 1
ldmeqfd sp!, {pc} @ 1/2 quick exit
/*
* No need to correct the count; we're only testing bits from now on
*/
tst r1, #32 @ 1
stmneia r0!, {r2, r3, ip, lr} @ 4
stmneia r0!, {r2, r3, ip, lr} @ 4
tst r1, #16 @ 1 16 bytes or more?
stmneia r0!, {r2, r3, ip, lr} @ 4
ldr lr, [sp], #4 @ 1
UNWIND( .fnend )
#else
/*
* This version aligns the destination pointer in order to write
* whole cache lines at once.
*/
stmfd sp!, {r4-r7, lr}
UNWIND( .fnend )
UNWIND( .fnstart )
UNWIND( .save {r4-r7, lr} )
mov r4, r2
mov r5, r2
mov r6, r2
mov r7, r2
mov ip, r2
mov lr, r2
cmp r1, #96
andgts ip, r0, #31
ble 3f
rsb ip, ip, #32
sub r1, r1, ip
movs ip, ip, lsl #(32 - 4)
stmcsia r0!, {r4, r5, r6, r7}
stmmiia r0!, {r4, r5}
movs ip, ip, lsl #2
strcs r2, [r0], #4
3: subs r1, r1, #64
stmgeia r0!, {r2-r7, ip, lr}
stmgeia r0!, {r2-r7, ip, lr}
bgt 3b
ldmeqfd sp!, {r4-r7, pc}
tst r1, #32
stmneia r0!, {r2-r7, ip, lr}
tst r1, #16
stmneia r0!, {r4-r7}
ldmfd sp!, {r4-r7, lr}
UNWIND( .fnend )
#endif
UNWIND( .fnstart )
4: tst r1, #8 @ 1 8 bytes or more?
stmneia r0!, {r2, r3} @ 2
tst r1, #4 @ 1 4 bytes or more?
strne r2, [r0], #4 @ 1
/*
* When we get here, we've got less than 4 bytes to zero. We
* may have an unaligned pointer as well.
*/
5: tst r1, #2 @ 1 2 bytes or more?
strneb r2, [r0], #1 @ 1
strneb r2, [r0], #1 @ 1
tst r1, #1 @ 1 a byte left over
strneb r2, [r0], #1 @ 1
ret lr @ 1
UNWIND( .fnend )
ENDPROC(__memzero)