redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

MIPS: memset.S: Add comments to fault fixup handlers 

It is not immediately obvious what the expected inputs to these fault
handlers is and how they calculate the number of unset bytes. Having
stared deeply at this in order to fix some corner cases, add some
comments to assist those who follow.

Signed-off-by: Matt Redfearn <matt.redfearn@mips.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/19339/
Cc: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: <linux-mips@linux-mips.org>
Cc: <linux-kernel@vger.kernel.org>
hifive-unleashed-5.1
Matt Redfearn 2018-05-23 14:39:59 +01:00 committed by Paul Burton
parent b1c03f1ef4
commit 6312455a04
No known key found for this signature in database
GPG Key ID: 3EA79FACB57500DD
1 changed files with 18 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
arch/mips/lib/memset.S
View File

@ -232,16 +232,25 @@
#ifdef CONFIG_CPU_MIPSR6
.Lbyte_fixup\@:
/*
* unset_bytes = (#bytes - (#unaligned bytes)) - (-#unaligned bytes remaining + 1) + 1
* a2 = a2 - t0 + 1
*/
PTR_SUBU a2, t0
jr ra
PTR_ADDIU a2, 1
#endif /* CONFIG_CPU_MIPSR6 */
.Lfirst_fixup\@:
/* unset_bytes already in a2 */
jr ra
nop
.Lfwd_fixup\@:
/*
* unset_bytes = partial_start_addr + #bytes - fault_addr
* a2 = t1 + (a2 & 3f) - $28->task->BUADDR
*/
PTR_L t0, TI_TASK($28)
andi a2, 0x3f
LONG_L t0, THREAD_BUADDR(t0)
@ -250,6 +259,10 @@
LONG_SUBU a2, t0
.Lpartial_fixup\@:
/*
* unset_bytes = partial_end_addr + #bytes - fault_addr
* a2 = a0 + (a2 & STORMASK) - $28->task->BUADDR
*/
PTR_L t0, TI_TASK($28)
andi a2, STORMASK
LONG_L t0, THREAD_BUADDR(t0)
@ -258,10 +271,15 @@
LONG_SUBU a2, t0
.Llast_fixup\@:
/* unset_bytes already in a2 */
jr ra
nop
.Lsmall_fixup\@:
/*
* unset_bytes = end_addr - current_addr + 1
* a2 = t1 - a0 + 1
*/
PTR_SUBU a2, t1, a0
jr ra
PTR_ADDIU a2, 1