1 files changed, 234 insertions, 0 deletions
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
new file mode 100644
index 000000000000..4a06cb342da2
--- /dev/null
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * This file contains the routines for initializing the MMU
+ * on the 8xx series of chips.
+ *  -- christophe
+ *
+ *  Derived from arch/powerpc/mm/40x_mmu.c:
+ */
+
+#include <linux/memblock.h>
+#include <linux/mmu_context.h>
+#include <asm/fixmap.h>
+#include <asm/code-patching.h>
+
+#include <mm/mmu_decl.h>
+
+#define IMMR_SIZE (FIX_IMMR_SIZE << PAGE_SHIFT)
+
+extern int __map_without_ltlbs;
+
+static unsigned long block_mapped_ram;
+
+/*
+ * Return PA for this VA if it is in an area mapped with LTLBs.
+ * Otherwise, returns 0
+ */
+phys_addr_t v_block_mapped(unsigned long va)
+{
+	unsigned long p = PHYS_IMMR_BASE;
+
+	if (__map_without_ltlbs)
+		return 0;
+	if (va >= VIRT_IMMR_BASE && va < VIRT_IMMR_BASE + IMMR_SIZE)
+		return p + va - VIRT_IMMR_BASE;
+	if (va >= PAGE_OFFSET && va < PAGE_OFFSET + block_mapped_ram)
+		return __pa(va);
+	return 0;
+}
+
+/*
+ * Return VA for a given PA mapped with LTLBs or 0 if not mapped
+ */
+unsigned long p_block_mapped(phys_addr_t pa)
+{
+	unsigned long p = PHYS_IMMR_BASE;
+
+	if (__map_without_ltlbs)
+		return 0;
+	if (pa >= p && pa < p + IMMR_SIZE)
+		return VIRT_IMMR_BASE + pa - p;
+	if (pa < block_mapped_ram)
+		return (unsigned long)__va(pa);
+	return 0;
+}
+
+#define LARGE_PAGE_SIZE_8M	(1<<23)
+
+/*
+ * MMU_init_hw does the chip-specific initialization of the MMU hardware.
+ */
+void __init MMU_init_hw(void)
+{
+	/* PIN up to the 3 first 8Mb after IMMR in DTLB table */
+	if (IS_ENABLED(CONFIG_PIN_TLB_DATA)) {
+		unsigned long ctr = mfspr(SPRN_MD_CTR) & 0xfe000000;
+		unsigned long flags = 0xf0 | MD_SPS16K | _PAGE_SH | _PAGE_DIRTY;
+		int i = IS_ENABLED(CONFIG_PIN_TLB_IMMR) ? 29 : 28;
+		unsigned long addr = 0;
+		unsigned long mem = total_lowmem;
+
+		for (; i < 32 && mem >= LARGE_PAGE_SIZE_8M; i++) {
+			mtspr(SPRN_MD_CTR, ctr | (i << 8));
+			mtspr(SPRN_MD_EPN, (unsigned long)__va(addr) | MD_EVALID);
+			mtspr(SPRN_MD_TWC, MD_PS8MEG | MD_SVALID);
+			mtspr(SPRN_MD_RPN, addr | flags | _PAGE_PRESENT);
+			addr += LARGE_PAGE_SIZE_8M;
+			mem -= LARGE_PAGE_SIZE_8M;
+		}
+	}
+}
+
+static void __init mmu_mapin_immr(void)
+{
+	unsigned long p = PHYS_IMMR_BASE;
+	unsigned long v = VIRT_IMMR_BASE;
+	int offset;
+
+	for (offset = 0; offset < IMMR_SIZE; offset += PAGE_SIZE)
+		map_kernel_page(v + offset, p + offset, PAGE_KERNEL_NCG);
+}
+
+static void mmu_patch_cmp_limit(s32 *site, unsigned long mapped)
+{
+	modify_instruction_site(site, 0xffff, (unsigned long)__va(mapped) >> 16);
+}
+
+static void mmu_patch_addis(s32 *site, long simm)
+{
+	unsigned int instr = *(unsigned int *)patch_site_addr(site);
+
+	instr &= 0xffff0000;
+	instr |= ((unsigned long)simm) >> 16;
+	patch_instruction_site(site, instr);
+}
+
+unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
+{
+	unsigned long mapped;
+
+	if (__map_without_ltlbs) {
+		mapped = 0;
+		mmu_mapin_immr();
+		if (!IS_ENABLED(CONFIG_PIN_TLB_IMMR))
+			patch_instruction_site(&patch__dtlbmiss_immr_jmp, PPC_INST_NOP);
+		if (!IS_ENABLED(CONFIG_PIN_TLB_TEXT))
+			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);
+	mmu_patch_cmp_limit(&patch__fixupdar_linmem_top, mapped);
+
+	/* If the size of RAM is not an exact power of two, we may not
+	 * have covered RAM in its entirety with 8 MiB
+	 * pages. Consequently, restrict the top end of RAM currently
+	 * allocable so that calls to the MEMBLOCK to allocate PTEs for "tail"
+	 * coverage with normal-sized pages (or other reasons) do not
+	 * attempt to allocate outside the allowed range.
+	 */
+	if (mapped)
+		memblock_set_current_limit(mapped);
+
+	block_mapped_ram = mapped;
+
+	return mapped;
+}
+
+void mmu_mark_initmem_nx(void)
+{
+	if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) && CONFIG_ETEXT_SHIFT < 23)
+		mmu_patch_addis(&patch__itlbmiss_linmem_top8,
+				-((long)_etext & ~(LARGE_PAGE_SIZE_8M - 1)));
+	if (!IS_ENABLED(CONFIG_PIN_TLB_TEXT))
+		mmu_patch_cmp_limit(&patch__itlbmiss_linmem_top, __pa(_etext));
+}
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void mmu_mark_rodata_ro(void)
+{
+	if (CONFIG_DATA_SHIFT < 23)
+		mmu_patch_addis(&patch__dtlbmiss_romem_top8,
+				-__pa(((unsigned long)_sinittext) &
+				      ~(LARGE_PAGE_SIZE_8M - 1)));
+	mmu_patch_addis(&patch__dtlbmiss_romem_top, -__pa(_sinittext));
+}
+#endif
+
+void __init setup_initial_memory_limit(phys_addr_t first_memblock_base,
+				       phys_addr_t first_memblock_size)
+{
+	/* We don't currently support the first MEMBLOCK not mapping 0
+	 * physical on those processors
+	 */
+	BUG_ON(first_memblock_base != 0);
+
+	/* 8xx can only access 32MB at the moment */
+	memblock_set_current_limit(min_t(u64, first_memblock_size, 0x02000000));
+}
+
+/*
+ * Set up to use a given MMU context.
+ * id is context number, pgd is PGD pointer.
+ *
+ * We place the physical address of the new task page directory loaded
+ * into the MMU base register, and set the ASID compare register with
+ * the new "context."
+ */
+void set_context(unsigned long id, pgd_t *pgd)
+{
+	s16 offset = (s16)(__pa(swapper_pg_dir));
+
+	/* Context switch the PTE pointer for the Abatron BDI2000.
+	 * The PGDIR is passed as second argument.
+	 */
+	if (IS_ENABLED(CONFIG_BDI_SWITCH))
+		abatron_pteptrs[1] = pgd;
+
+	/* Register M_TWB will contain base address of level 1 table minus the
+	 * lower part of the kernel PGDIR base address, so that all accesses to
+	 * level 1 table are done relative to lower part of kernel PGDIR base
+	 * address.
+	 */
+	mtspr(SPRN_M_TWB, __pa(pgd) - offset);
+
+	/* Update context */
+	mtspr(SPRN_M_CASID, id - 1);
+	/* sync */
+	mb();
+}
+
+void flush_instruction_cache(void)
+{
+	isync();
+	mtspr(SPRN_IC_CST, IDC_INVALL);
+	isync();
+}
+
+#ifdef CONFIG_PPC_KUEP
+void __init setup_kuep(bool disabled)
+{
+	if (disabled)
+		return;
+
+	pr_info("Activating Kernel Userspace Execution Prevention\n");
+
+	mtspr(SPRN_MI_AP, MI_APG_KUEP);
+}
+#endif
+
+#ifdef CONFIG_PPC_KUAP
+void __init setup_kuap(bool disabled)
+{
+	pr_info("Activating Kernel Userspace Access Protection\n");
+
+	if (disabled)
+		pr_warn("KUAP cannot be disabled yet on 8xx when compiled in\n");
+
+	mtspr(SPRN_MD_AP, MD_APG_KUAP);
+}
+#endif