[MIPS] R4000/R4400 daddiu erratum workaround
This complements the generic R4000/R4400 errata workaround code and adds
bits for the daddiu problem. In most places it just modifies handwritten
assembly code so that the assembler is allowed to use a temporary register
as daddiu may now be treated as a macro that expands to a sequence of li
and daddu. It is the AT register or, where AT is unavailable or used
explicitly for another purpose, an explicitly-named register is selected,
using the .set at=<reg> feature added recently to gas. This feature is
only used if CONFIG_CPU_DADDI_WORKAROUNDS has been set, so if the
workaround remains disabled, the required version of binutils stays
unchanged.
Similarly, daddiu instructions put in branch delay slots in noreorder
fragments are now taken out of them and the assembler is allowed to
reorder them itself as possible (which it does making the whole idea of
scheduling them into delay slots manually questionable).
Also in the very few places where such a simple conversion was not
possible, a handcoded longer sequence is implemented.
Other than that there are changes to code responsible for building the
TLB fault and page clear/copy handlers to avoid daddiu as appropriate.
These are only effective if the erratum is verified to be present at the
run time.
Finally there is a trivial update to __delay(), because it uses daddiu in
a branch delay slot.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/lib/csum_partial.S b/arch/mips/lib/csum_partial.S
index c0a77fe..957a824 100644
--- a/arch/mips/lib/csum_partial.S
+++ b/arch/mips/lib/csum_partial.S
@@ -7,6 +7,7 @@
*
* Copyright (C) 1998, 1999 Ralf Baechle
* Copyright (C) 1999 Silicon Graphics, Inc.
+ * Copyright (C) 2007 Maciej W. Rozycki
*/
#include <linux/errno.h>
#include <asm/asm.h>
@@ -52,9 +53,12 @@
#define UNIT(unit) ((unit)*NBYTES)
#define ADDC(sum,reg) \
+ .set push; \
+ .set noat; \
ADD sum, reg; \
sltu v1, sum, reg; \
- ADD sum, v1
+ ADD sum, v1; \
+ .set pop
#define CSUM_BIGCHUNK1(src, offset, sum, _t0, _t1, _t2, _t3) \
LOAD _t0, (offset + UNIT(0))(src); \
@@ -178,8 +182,10 @@
CSUM_BIGCHUNK(src, 0x40, sum, t0, t1, t3, t4)
CSUM_BIGCHUNK(src, 0x60, sum, t0, t1, t3, t4)
LONG_SUBU t8, t8, 0x01
+ .set reorder /* DADDI_WAR */
+ PTR_ADDU src, src, 0x80
bnez t8, move_128bytes
- PTR_ADDU src, src, 0x80
+ .set noreorder
1:
beqz t2, 1f
@@ -208,8 +214,10 @@
lw t0, (src)
LONG_SUBU t8, t8, 0x1
ADDC(sum, t0)
+ .set reorder /* DADDI_WAR */
+ PTR_ADDU src, src, 0x4
bnez t8, end_words
- PTR_ADDU src, src, 0x4
+ .set noreorder
/* unknown src alignment and < 8 bytes to go */
small_csumcpy:
@@ -246,6 +254,8 @@
1: ADDC(sum, t1)
/* fold checksum */
+ .set push
+ .set noat
#ifdef USE_DOUBLE
dsll32 v1, sum, 0
daddu sum, v1
@@ -266,6 +276,7 @@
srl sum, sum, 8
or sum, v1
andi sum, 0xffff
+ .set pop
1:
.set reorder
/* Add the passed partial csum. */
@@ -373,7 +384,11 @@
#define ADDRMASK (NBYTES-1)
+#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
.set noat
+#else
+ .set at=v1
+#endif
LEAF(__csum_partial_copy_user)
PTR_ADDU AT, src, len /* See (1) above. */
@@ -441,8 +456,10 @@
ADDC(sum, t6)
EXC( STORE t7, UNIT(7)(dst), s_exc)
ADDC(sum, t7)
+ .set reorder /* DADDI_WAR */
+ ADD dst, dst, 8*NBYTES
bgez len, 1b
- ADD dst, dst, 8*NBYTES
+ .set noreorder
ADD len, 8*NBYTES # revert len (see above)
/*
@@ -471,8 +488,10 @@
ADDC(sum, t2)
EXC( STORE t3, UNIT(3)(dst), s_exc)
ADDC(sum, t3)
+ .set reorder /* DADDI_WAR */
+ ADD dst, dst, 4*NBYTES
beqz len, done
- ADD dst, dst, 4*NBYTES
+ .set noreorder
less_than_4units:
/*
* rem = len % NBYTES
@@ -485,8 +504,10 @@
SUB len, len, NBYTES
EXC( STORE t0, 0(dst), s_exc)
ADDC(sum, t0)
+ .set reorder /* DADDI_WAR */
+ ADD dst, dst, NBYTES
bne rem, len, 1b
- ADD dst, dst, NBYTES
+ .set noreorder
/*
* src and dst are aligned, need to copy rem bytes (rem < NBYTES)
@@ -572,8 +593,10 @@
ADDC(sum, t2)
EXC( STORE t3, UNIT(3)(dst), s_exc)
ADDC(sum, t3)
+ .set reorder /* DADDI_WAR */
+ ADD dst, dst, 4*NBYTES
bne len, rem, 1b
- ADD dst, dst, 4*NBYTES
+ .set noreorder
cleanup_src_unaligned:
beqz len, done
@@ -587,8 +610,10 @@
SUB len, len, NBYTES
EXC( STORE t0, 0(dst), s_exc)
ADDC(sum, t0)
+ .set reorder /* DADDI_WAR */
+ ADD dst, dst, NBYTES
bne len, rem, 1b
- ADD dst, dst, NBYTES
+ .set noreorder
copy_bytes_checklen:
beqz len, done
@@ -631,6 +656,8 @@
ADDC(sum, t2)
done:
/* fold checksum */
+ .set push
+ .set noat
#ifdef USE_DOUBLE
dsll32 v1, sum, 0
daddu sum, v1
@@ -651,6 +678,7 @@
srl sum, sum, 8
or sum, v1
andi sum, 0xffff
+ .set pop
1:
.set reorder
ADDC(sum, psum)
@@ -678,8 +706,10 @@
SLLV t1, t1, t2
addu t2, SHIFT_INC
ADDC(sum, t1)
+ .set reorder /* DADDI_WAR */
+ ADD dst, dst, 1
bne src, t0, 1b
- ADD dst, dst, 1
+ .set noreorder
l_exc:
LOAD t0, TI_TASK($28)
nop
@@ -697,12 +727,22 @@
* Clear len bytes starting at dst. Can't call __bzero because it
* might modify len. An inefficient loop for these rare times...
*/
+ .set reorder /* DADDI_WAR */
+ SUB src, len, 1
beqz len, done
- SUB src, len, 1
+ .set noreorder
1: sb zero, 0(dst)
ADD dst, dst, 1
+ .set push
+ .set noat
+#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
bnez src, 1b
SUB src, src, 1
+#else
+ li v1, 1
+ bnez src, 1b
+ SUB src, src, v1
+#endif
li v1, -EFAULT
b done
sw v1, (errptr)
@@ -712,4 +752,5 @@
li v1, -EFAULT
jr ra
sw v1, (errptr)
+ .set pop
END(__csum_partial_copy_user)