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Date:   Wed,  6 May 2020 16:48:46 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 40/45] powerpc/8xx: Map linear memory with huge pages

Map linear memory space with 512k and 8M pages whenever
possible.

Three mappings are performed:
- One for kernel text
- One for RO data
- One for the rest

Separating the mappings is done to be able to update the
protection later when using STRICT_KERNEL_RWX.

The ITLB miss handler now need to also handle huge TLBs
unless kernel text in pinned.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/head_8xx.S |  4 +--
 arch/powerpc/mm/nohash/8xx.c   | 50 +++++++++++++++++++++++++++++++++-
 2 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 9a117b9f0998..abb71fad7d6a 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -224,7 +224,7 @@ InstructionTLBMiss:
 3:
 	mtcr	r11
 #endif
-#ifdef CONFIG_HUGETLBFS
+#if defined(CONFIG_HUGETLBFS) || !defined(CONFIG_PIN_TLB_TEXT)
 	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r10)	/* Get level 1 entry */
 	mtspr	SPRN_MD_TWC, r11
 #else
@@ -234,7 +234,7 @@ InstructionTLBMiss:
 #endif
 	mfspr	r10, SPRN_MD_TWC
 	lwz	r10, 0(r10)	/* Get the pte */
-#ifdef CONFIG_HUGETLBFS
+#if defined(CONFIG_HUGETLBFS) || !defined(CONFIG_PIN_TLB_TEXT)
 	rlwimi	r11, r10, 32 - 9, _PMD_PAGE_512K
 	mtspr	SPRN_MI_TWC, r11
 #endif
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index fb31a0c1c2a4..c62cab996d4d 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -126,20 +126,68 @@ void __init mmu_mapin_immr(void)
 				    PAGE_KERNEL_NCG, MMU_PAGE_512K, true);
 }
 
+static void __init mmu_mapin_ram_chunk(unsigned long offset, unsigned long top,
+				       pgprot_t prot, bool new)
+{
+	unsigned long v = PAGE_OFFSET + offset;
+	unsigned long p = offset;
+
+	WARN_ON(!IS_ALIGNED(offset, SZ_512K) || !IS_ALIGNED(top, SZ_512K));
+
+	for (; p < ALIGN(p, SZ_8M) && p < top; p += SZ_512K, v += SZ_512K)
+		__early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);
+	for (; p < ALIGN_DOWN(top, SZ_8M) && p < top; p += SZ_8M, v += SZ_8M)
+		__early_map_kernel_hugepage(v, p, prot, MMU_PAGE_8M, new);
+	for (; p < ALIGN_DOWN(top, SZ_512K) && p < top; p += SZ_512K, v += SZ_512K)
+		__early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);
+
+	if (!new)
+		flush_tlb_kernel_range(PAGE_OFFSET + v, PAGE_OFFSET + top);
+}
+
 unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 {
+	unsigned long etext8 = ALIGN(__pa(_etext), SZ_8M);
+	unsigned long sinittext = __pa(_sinittext);
+	unsigned long boundary = strict_kernel_rwx_enabled() ? sinittext : etext8;
+	unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);
+
+	WARN_ON(top < einittext8);
+
 	mmu_mapin_immr();
 
-	return 0;
+	if (__map_without_ltlbs)
+		return 0;
+
+	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, true);
+	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL_TEXT, true);
+	mmu_mapin_ram_chunk(einittext8, top, PAGE_KERNEL, true);
+
+	if (top > SZ_32M)
+		memblock_set_current_limit(top);
+
+	block_mapped_ram = top;
+
+	return top;
 }
 
 void mmu_mark_initmem_nx(void)
 {
+	unsigned long etext8 = ALIGN(__pa(_etext), SZ_8M);
+	unsigned long sinittext = __pa(_sinittext);
+	unsigned long boundary = strict_kernel_rwx_enabled() ? sinittext : etext8;
+	unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);
+
+	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
+	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
 }
 
 #ifdef CONFIG_STRICT_KERNEL_RWX
 void mmu_mark_rodata_ro(void)
 {
+	unsigned long sinittext = __pa(_sinittext);
+
+	mmu_mapin_ram_chunk(0, sinittext, PAGE_KERNEL_ROX, false);
 }
 #endif
 
-- 
2.25.0

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