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powerpc/mm: e300c2/c3/c4 TLB errata workaround

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Complete workaround for DTLB errata in e300c2/c3/c4 processors.

Due to the bug, the hardware-implemented LRU algorythm always goes to way
1 of the TLB. This fix implements the proposed software workaround in
form of a LRW table for chosing the TLB-way.

Based on patch from David Jander <david@protonic.nl>

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Kumar Gala 2009-03-19 03:55:41 +00:00 committed by Benjamin Herrenschmidt
parent eb3436a013
commit 2319f12395
4 changed files with 45 additions and 7 deletions
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6
arch/powerpc/include/asm/mmu.h
View File

@ -46,6 +46,12 @@
*/
#define MMU_FTR_LOCK_BCAST_INVAL ASM_CONST(0x00100000)
/* This indicates that the processor doesn't handle way selection
* properly and needs SW to track and update the LRU state. This
* is specific to an errata on e300c2/c3/c4 class parts
*/
#define MMU_FTR_NEED_DTLB_SW_LRU ASM_CONST(0x00200000)
#ifndef __ASSEMBLY__
#include <asm/cputable.h>

5
arch/powerpc/kernel/cpu_setup_6xx.S
View File

@ -15,9 +15,14 @@
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/cache.h>
#include <asm/mmu.h>
_GLOBAL(__setup_cpu_603)
mflr r4
BEGIN_MMU_FTR_SECTION
li r10,0
mtspr SPRN_SPRG4,r10 /* init SW LRU tracking */
END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
BEGIN_FTR_SECTION
bl __init_fpu_registers
END_FTR_SECTION_IFCLR(CPU_FTR_FPU_UNAVAILABLE)

9
arch/powerpc/kernel/cputable.c
View File

@ -1090,7 +1090,8 @@ static struct cpu_spec __initdata cpu_specs[] = {
.cpu_name = "e300c2",
.cpu_features = CPU_FTRS_E300C2,
.cpu_user_features = PPC_FEATURE_32 | PPC_FEATURE_HAS_MMU,
.mmu_features = MMU_FTR_USE_HIGH_BATS,
.mmu_features = MMU_FTR_USE_HIGH_BATS |
MMU_FTR_NEED_DTLB_SW_LRU,
.icache_bsize = 32,
.dcache_bsize = 32,
.cpu_setup = __setup_cpu_603,
@ -1103,7 +1104,8 @@ static struct cpu_spec __initdata cpu_specs[] = {
.cpu_name = "e300c3",
.cpu_features = CPU_FTRS_E300,
.cpu_user_features = COMMON_USER,
.mmu_features = MMU_FTR_USE_HIGH_BATS,
.mmu_features = MMU_FTR_USE_HIGH_BATS |
MMU_FTR_NEED_DTLB_SW_LRU,
.icache_bsize = 32,
.dcache_bsize = 32,
.cpu_setup = __setup_cpu_603,
@ -1118,7 +1120,8 @@ static struct cpu_spec __initdata cpu_specs[] = {
.cpu_name = "e300c4",
.cpu_features = CPU_FTRS_E300,
.cpu_user_features = COMMON_USER,
.mmu_features = MMU_FTR_USE_HIGH_BATS,
.mmu_features = MMU_FTR_USE_HIGH_BATS |
MMU_FTR_NEED_DTLB_SW_LRU,
.icache_bsize = 32,
.dcache_bsize = 32,
.cpu_setup = __setup_cpu_603,

32
arch/powerpc/kernel/head_32.S
View File

@ -593,9 +593,21 @@ BEGIN_FTR_SECTION
rlwinm r1,r1,0,~_PAGE_COHERENT /* clear M (coherence not required) */
END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
mtspr SPRN_RPA,r1
mfspr r2,SPRN_SRR1 /* Need to restore CR0 */
mtcrf 0x80,r2
BEGIN_MMU_FTR_SECTION
li r0,1
mfspr r1,SPRN_SPRG4
rlwinm r2,r3,20,27,31 /* Get Address bits 15:19 */
slw r0,r0,r2
xor r1,r0,r1
srw r0,r1,r2
mtspr SPRN_SPRG4,r1
mfspr r2,SPRN_SRR1
rlwimi r2,r0,31-14,14,14
mtspr SPRN_SRR1,r2
END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
tlbld r3
mfspr r3,SPRN_SRR1 /* Need to restore CR0 */
mtcrf 0x80,r3
rfi
DataAddressInvalid:
mfspr r3,SPRN_SRR1
@ -661,9 +673,21 @@ BEGIN_FTR_SECTION
rlwinm r1,r1,0,~_PAGE_COHERENT /* clear M (coherence not required) */
END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
mtspr SPRN_RPA,r1
mfspr r2,SPRN_SRR1 /* Need to restore CR0 */
mtcrf 0x80,r2
BEGIN_MMU_FTR_SECTION
li r0,1
mfspr r1,SPRN_SPRG4
rlwinm r2,r3,20,27,31 /* Get Address bits 15:19 */
slw r0,r0,r2
xor r1,r0,r1
srw r0,r1,r2
mtspr SPRN_SPRG4,r1
mfspr r2,SPRN_SRR1
rlwimi r2,r0,31-14,14,14
mtspr SPRN_SRR1,r2
END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
tlbld r3
mfspr r3,SPRN_SRR1 /* Need to restore CR0 */
mtcrf 0x80,r3
rfi
#ifndef CONFIG_ALTIVEC