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authorAlistair Popple <alistair@popple.id.au>2014-08-06 17:03:09 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-08-13 15:13:42 +1000
commit97b3be1e9404f4c1645f3286428abd4d2052041e (patch)
tree31e79eebdf8c4ec0cb539c7bcd6d75ee7f889034 /arch/powerpc
parent763fe0addb8fe15ccea67c0aebddc06f4bb25439 (diff)
powerpc/ppc476: Disable BTAC
This patch disables the branch target address CAM which under specific circumstances may cause the processor to skip execution of 1-4 instructions. This fixes IBM Erratum #47. Signed-off-by: Alistair Popple <alistair@popple.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/head_44x.S4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index c334f53453f7..b5061abbd2e0 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -1210,10 +1210,12 @@ clear_utlb_entry:
/* We configure icbi to invalidate 128 bytes at a time since the
* current 32-bit kernel code isn't too happy with icache != dcache
- * block size
+ * block size. We also disable the BTAC as this can cause errors
+ * in some circumstances (see IBM Erratum 47).
*/
mfspr r3,SPRN_CCR0
oris r3,r3,0x0020
+ ori r3,r3,0x0040
mtspr SPRN_CCR0,r3
isync