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Subject[PATCH v3 2/2] powerpc/8xx: Map 32Mb of RAM at init.
Date
At the time being, initial MMU setup allows 24 Mbytes
of DATA and 8 Mbytes of code.

Some debug setup like CONFIG_KASAN generate huge
kernels with text size over the 8M limit and data over the
24 Mbytes limit.

Here is an 8xx kernel compiled with CONFIG_KASAN_INLINE for
one of my boards:

[root@po16846vm linux-powerpc]# size -x vmlinux
text data bss dec hex filename
0x111019c 0x41b0d4 0x490de0 26984528 19bc050 vmlinux

This patch maps up to 32 Mbytes code based on _einittext symbol
and allows 32 Mbytes of memory instead of 24.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v3: Maps 32M of both data and text.

v2: Using IS_ENABLED() instead of #ifdef in 8xx_mmu.c

arch/powerpc/kernel/head_8xx.S | 51 +++++++++++++++++++++++++-----------------
arch/powerpc/mm/8xx_mmu.c | 7 ++++--
2 files changed, 36 insertions(+), 22 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 20cc816b3508..fe2857ef0309 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 first 32M */
+0: cmpli cr7, r10, (PAGE_OFFSET + 0x2000000)@h
patch_site 0b, patch__itlbmiss_linmem_top
#endif
#endif
@@ -434,7 +434,7 @@ DataStoreTLBMiss:
#ifndef CONFIG_PIN_TLB_IMMR
cmpli cr6, r10, VIRT_IMMR_BASE@h
#endif
-0: cmpli cr7, r10, (PAGE_OFFSET + 0x1800000)@h
+0: cmpli cr7, r10, (PAGE_OFFSET + 0x2000000)@h
patch_site 0b, patch__dtlbmiss_linmem_top

mfspr r10, SPRN_M_TWB /* Get level 1 table */
@@ -886,28 +886,11 @@ initial_mmu:
mtspr SPRN_MD_CTR, r10 /* remove PINNED DTLB entries */

tlbia /* Invalidate all TLB entries */
-#ifdef CONFIG_PIN_TLB_TEXT
- lis r8, MI_RSV4I@h
- ori r8, r8, 0x1c00
-
- mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
-#endif
-
#ifdef CONFIG_PIN_TLB_DATA
oris r10, r10, MD_RSV4I@h
mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
#endif

- /* Now map the lower 8 Meg into the ITLB. */
- lis r8, KERNELBASE@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 */
- mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
-
lis r8, MI_APG_INIT@h /* Set protection modes */
ori r8, r8, MI_APG_INIT@l
mtspr SPRN_MI_AP, r8
@@ -937,6 +920,34 @@ initial_mmu:
mtspr SPRN_MD_RPN, r8
#endif

+ /* Now map the lower RAM (up to 32 Mbytes) into the ITLB. */
+#ifdef CONFIG_PIN_TLB_TEXT
+ lis r8, MI_RSV4I@h
+ ori r8, r8, 0x1c00
+#endif
+ li r9, 4 /* up to 4 pages of 8M */
+ mtctr r9
+ lis r9, KERNELBASE@h /* Create vaddr for TLB */
+ li r10, MI_PS8MEG | MI_SVALID /* Set 8M byte page */
+ li r11, MI_BOOTINIT /* Create RPN for address 0 */
+ lis r12, _einittext@h
+ ori r12, r12, _einittext@l
+1:
+#ifdef CONFIG_PIN_TLB_TEXT
+ mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
+ addi r8, r8, 0x100
+#endif
+
+ ori r0, r9, MI_EVALID /* Mark it valid */
+ mtspr SPRN_MI_EPN, r0
+ mtspr SPRN_MI_TWC, r10
+ mtspr SPRN_MI_RPN, r11 /* Store TLB entry */
+ addis r9, r9, 0x80
+ addis r11, r11, 0x80
+
+ cmpl cr0, r9, r12
+ bdnzf gt, 1b
+
/* Since the cache is enabled according to the information we
* just loaded into the TLB, invalidate and enable the caches here.
* We should probably check/set other modes....later.
diff --git a/arch/powerpc/mm/8xx_mmu.c b/arch/powerpc/mm/8xx_mmu.c
index 92b677faea8c..50c8cd8d3cb9 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);
@@ -140,8 +143,8 @@ void __init setup_initial_memory_limit(phys_addr_t first_memblock_base,
*/
BUG_ON(first_memblock_base != 0);

- /* 8xx can only access 24MB at the moment */
- memblock_set_current_limit(min_t(u64, first_memblock_size, 0x01800000));
+ /* 8xx can only access 32MB at the moment */
+ memblock_set_current_limit(min_t(u64, first_memblock_size, 0x02000000));
}

/*
--
2.13.3
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