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Subject[PATCH v3] powerpc 8xx: Fixing issue with CONFIG_PIN_TLB
Activating CONFIG_PIN_TLB is supposed to pin the IMMR and the first three
8Mbytes pages. But the setting of the MD_CTR was missing so as the index is
decremented every DTLB update, the pinning of the third 8Mbytes page was
overwriting the DTLB entry for IMMR. At the same time, the last entry written
being entry 31, next entries would possibly get overwritten after.
We are now starting from entry 31 and decrementing.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

diff -ur linux-3.11.org/arch/powerpc/kernel/head_8xx.S linux-3.11/arch/powerpc/kernel/head_8xx.S
--- linux-3.11.org/arch/powerpc/kernel/head_8xx.S 2013-09-02 22:46:10.000000000 +0200
+++ linux-3.11/arch/powerpc/kernel/head_8xx.S 2013-09-09 11:28:54.000000000 +0200
@@ -796,8 +796,7 @@

#ifdef CONFIG_PIN_TLB
lis r10, (MD_RSV4I | MD_RESETVAL)@h
- ori r10, r10, 0x1c00
- mr r8, r10
+ ori r10, r10, 0x1f00
#else
lis r10, MD_RESETVAL@h
#endif
@@ -829,7 +828,7 @@
* internal registers (among other things).
*/
#ifdef CONFIG_PIN_TLB
- addi r10, r10, 0x0100
+ addi r10, r10, -0x0100
mtspr SPRN_MD_CTR, r10
#endif
mfspr r9, 638 /* Get current IMMR */
@@ -848,7 +847,7 @@
#ifdef CONFIG_PIN_TLB
/* Map two more 8M kernel data pages.
*/
- addi r10, r10, 0x0100
+ addi r10, r10, -0x0100
mtspr SPRN_MD_CTR, r10

lis r8, KERNELBASE@h /* Create vaddr for TLB */
@@ -862,6 +861,9 @@
addis r11, r11, 0x0080 /* Add 8M */
mtspr SPRN_MD_RPN, r11

+ addi r10, r10, -0x0100
+ mtspr SPRN_MD_CTR, r10
+
addis r8, r8, 0x0080 /* Add 8M */
mtspr SPRN_MD_EPN, r8
mtspr SPRN_MD_TWC, r9

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