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Subject[PATCH v2 2/2] powerpc/8xx: Map a second 8M text page at startup when needed.
Date
Some debug setup like CONFIG_KASAN generate huge
kernels with text size over the 8M limit.

This patch maps a second 8M page when _einittext is over 8M.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: Using IS_ENABLED() instead of #ifdef in 8xx_mmu.c

arch/powerpc/kernel/head_8xx.S | 27 +++++++++++++++++++++++++--
arch/powerpc/mm/8xx_mmu.c | 3 +++
2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 20cc816b3508..3b3b7846247f 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -337,8 +337,8 @@ InstructionTLBMiss:
rlwinm r10, r10, 16, 0xfff8
cmpli cr0, r10, PAGE_OFFSET@h
#ifndef CONFIG_PIN_TLB_TEXT
- /* It is assumed that kernel code fits into the first 8M page */
-0: cmpli cr7, r10, (PAGE_OFFSET + 0x0800000)@h
+ /* It is assumed that kernel code fits into the two first 8M pages */
+0: cmpli cr7, r10, (PAGE_OFFSET + 0x1000000)@h
patch_site 0b, patch__itlbmiss_linmem_top
#endif
#endif
@@ -908,6 +908,29 @@ initial_mmu:
li r8, MI_BOOTINIT /* Create RPN for address 0 */
mtspr SPRN_MI_RPN, r8 /* Store TLB entry */

+ /* Map a second 8M page if needed */
+ lis r9, _einittext@h
+ oris r9, r9, _einittext@l
+ cmpli cr0, r9, (PAGE_OFFSET + 0x8000000)@h
+ blt 1f
+
+#ifdef CONFIG_PIN_TLB_TEXT
+ lis r8, MI_RSV4I@h
+ ori r8, r8, 0x1d00
+
+ mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
+#endif
+
+ lis r8, (KERNELBASE + 0x800000)@h /* Create vaddr for TLB */
+ ori r8, r8, MI_EVALID /* Mark it valid */
+ mtspr SPRN_MI_EPN, r8
+ li r8, MI_PS8MEG /* Set 8M byte page */
+ ori r8, r8, MI_SVALID /* Make it valid */
+ mtspr SPRN_MI_TWC, r8
+ li r8, MI_BOOTINIT /* Create RPN for address 0 */
+ addis r8, r8, 0x80
+ mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
+1:
lis r8, MI_APG_INIT@h /* Set protection modes */
ori r8, r8, MI_APG_INIT@l
mtspr SPRN_MI_AP, r8
diff --git a/arch/powerpc/mm/8xx_mmu.c b/arch/powerpc/mm/8xx_mmu.c
index 92b677faea8c..b5f6d794281d 100644
--- a/arch/powerpc/mm/8xx_mmu.c
+++ b/arch/powerpc/mm/8xx_mmu.c
@@ -112,6 +112,9 @@ unsigned long __init mmu_mapin_ram(unsigned long top)
mmu_patch_cmp_limit(&patch__itlbmiss_linmem_top, 0);
} else {
mapped = top & ~(LARGE_PAGE_SIZE_8M - 1);
+ if (!IS_ENABLED(CONFIG_PIN_TLB_TEXT))
+ mmu_patch_cmp_limit(&patch__itlbmiss_linmem_top,
+ _ALIGN(__pa(_einittext), 8 << 20));
}

mmu_patch_cmp_limit(&patch__dtlbmiss_linmem_top, mapped);
--
2.13.3
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