mirror of
https://github.com/torvalds/linux.git
synced 2024-12-18 17:12:55 +00:00
9d378dfac8
Previously SPRG3 was marked for use by both VDSO and critical
interrupts (though critical interrupts were not fully implemented).
In commit 8b64a9dfb0 ("powerpc/booke64:
Use SPRG0/3 scratch for bolted TLB miss & crit int"), Mihai Caraman
made an attempt to resolve this conflict by restoring the VDSO value
early in the critical interrupt, but this has some issues:
- It's incompatible with EXCEPTION_COMMON which restores r13 from the
by-then-overwritten scratch (this cost me some debugging time).
- It forces critical exceptions to be a special case handled
differently from even machine check and debug level exceptions.
- It didn't occur to me that it was possible to make this work at all
(by doing a final "ld r13, PACA_EXCRIT+EX_R13(r13)") until after
I made (most of) this patch. :-)
It might be worth investigating using a load rather than SPRG on return
from all exceptions (except TLB misses where the scratch never leaves
the SPRG) -- it could save a few cycles. Until then, let's stick with
SPRG for all exceptions.
Since we cannot use SPRG4-7 for scratch without corrupting the state of
a KVM guest, move VDSO to SPRG7 on book3e. Since neither SPRG4-7 nor
critical interrupts exist on book3s, SPRG3 is still used for VDSO
there.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: Mihai Caraman <mihai.caraman@freescale.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: kvm-ppc@vger.kernel.org
46 lines
1.3 KiB
ArmAsm
46 lines
1.3 KiB
ArmAsm
/*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*
|
|
* Copyright (C) IBM Corporation, 2012
|
|
*
|
|
* Author: Anton Blanchard <anton@au.ibm.com>
|
|
*/
|
|
#include <asm/ppc_asm.h>
|
|
#include <asm/vdso.h>
|
|
|
|
.text
|
|
/*
|
|
* Exact prototype of getcpu
|
|
*
|
|
* int __kernel_getcpu(unsigned *cpu, unsigned *node);
|
|
*
|
|
*/
|
|
V_FUNCTION_BEGIN(__kernel_getcpu)
|
|
.cfi_startproc
|
|
mfspr r5,SPRN_SPRG_VDSO_READ
|
|
cmpdi cr0,r3,0
|
|
cmpdi cr1,r4,0
|
|
clrlwi r6,r5,16
|
|
rlwinm r7,r5,16,31-15,31-0
|
|
beq cr0,1f
|
|
stw r6,0(r3)
|
|
1: beq cr1,2f
|
|
stw r7,0(r4)
|
|
2: crclr cr0*4+so
|
|
li r3,0 /* always success */
|
|
blr
|
|
.cfi_endproc
|
|
V_FUNCTION_END(__kernel_getcpu)
|