riscv: mm: Prepare pt_ops helper functions for sv57

This patch prepare some pt_ops helper functions which will be used in
creating sv57 mappings during boot time.

Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/fixmap.h

@@ -25,6 +25,7 @@ enum fixed_addresses {
 	FIX_PTE,
 	FIX_PMD,
 	FIX_PUD,
+	FIX_P4D,
 	FIX_TEXT_POKE1,
 	FIX_TEXT_POKE0,
 	FIX_EARLYCON_MEM_BASE,

arch/riscv/include/asm/pgtable.h

@@ -133,6 +133,8 @@ struct pt_alloc_ops {
 	phys_addr_t (*alloc_pmd)(uintptr_t va);
 	pud_t *(*get_pud_virt)(phys_addr_t pa);
 	phys_addr_t (*alloc_pud)(uintptr_t va);
+	p4d_t *(*get_p4d_virt)(phys_addr_t pa);
+	phys_addr_t (*alloc_p4d)(uintptr_t va);
 #endif
 };
 

arch/riscv/mm/init.c

@@ -229,6 +229,7 @@ pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
 static pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;
 
 pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
+static p4d_t __maybe_unused early_dtb_p4d[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
 static pud_t __maybe_unused early_dtb_pud[PTRS_PER_PUD] __initdata __aligned(PAGE_SIZE);
 static pmd_t __maybe_unused early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
 
@@ -319,6 +320,16 @@ static pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
 #define early_pmd      ((pmd_t *)XIP_FIXUP(early_pmd))
 #endif /* CONFIG_XIP_KERNEL */
 
+static p4d_t trampoline_p4d[PTRS_PER_P4D] __page_aligned_bss;
+static p4d_t fixmap_p4d[PTRS_PER_P4D] __page_aligned_bss;
+static p4d_t early_p4d[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
+
+#ifdef CONFIG_XIP_KERNEL
+#define trampoline_p4d ((p4d_t *)XIP_FIXUP(trampoline_p4d))
+#define fixmap_p4d     ((p4d_t *)XIP_FIXUP(fixmap_p4d))
+#define early_p4d      ((p4d_t *)XIP_FIXUP(early_p4d))
+#endif /* CONFIG_XIP_KERNEL */
+
 static pud_t trampoline_pud[PTRS_PER_PUD] __page_aligned_bss;
 static pud_t fixmap_pud[PTRS_PER_PUD] __page_aligned_bss;
 static pud_t early_pud[PTRS_PER_PUD] __initdata __aligned(PAGE_SIZE);
@@ -433,6 +444,44 @@ static phys_addr_t alloc_pud_late(uintptr_t va)
 	return __pa(vaddr);
 }
 
+static p4d_t *__init get_p4d_virt_early(phys_addr_t pa)
+{
+	return (p4d_t *)((uintptr_t)pa);
+}
+
+static p4d_t *__init get_p4d_virt_fixmap(phys_addr_t pa)
+{
+	clear_fixmap(FIX_P4D);
+	return (p4d_t *)set_fixmap_offset(FIX_P4D, pa);
+}
+
+static p4d_t *__init get_p4d_virt_late(phys_addr_t pa)
+{
+	return (p4d_t *)__va(pa);
+}
+
+static phys_addr_t __init alloc_p4d_early(uintptr_t va)
+{
+	/* Only one P4D is available for early mapping */
+	BUG_ON((va - kernel_map.virt_addr) >> PGDIR_SHIFT);
+
+	return (uintptr_t)early_p4d;
+}
+
+static phys_addr_t __init alloc_p4d_fixmap(uintptr_t va)
+{
+	return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
+}
+
+static phys_addr_t alloc_p4d_late(uintptr_t va)
+{
+	unsigned long vaddr;
+
+	vaddr = __get_free_page(GFP_KERNEL);
+	BUG_ON(!vaddr);
+	return __pa(vaddr);
+}
+
 static void __init create_pud_mapping(pud_t *pudp,
 				      uintptr_t va, phys_addr_t pa,
 				      phys_addr_t sz, pgprot_t prot)
@@ -460,21 +509,55 @@ static void __init create_pud_mapping(pud_t *pudp,
 	create_pmd_mapping(nextp, va, pa, sz, prot);
 }
 
-#define pgd_next_t		pud_t
-#define alloc_pgd_next(__va)	(pgtable_l4_enabled ?			\
-		pt_ops.alloc_pud(__va) : pt_ops.alloc_pmd(__va))
-#define get_pgd_next_virt(__pa)	(pgtable_l4_enabled ?			\
-		pt_ops.get_pud_virt(__pa) : (pgd_next_t *)pt_ops.get_pmd_virt(__pa))
+static void __init create_p4d_mapping(p4d_t *p4dp,
+				      uintptr_t va, phys_addr_t pa,
+				      phys_addr_t sz, pgprot_t prot)
+{
+	pud_t *nextp;
+	phys_addr_t next_phys;
+	uintptr_t p4d_index = p4d_index(va);
+
+	if (sz == P4D_SIZE) {
+		if (p4d_val(p4dp[p4d_index]) == 0)
+			p4dp[p4d_index] = pfn_p4d(PFN_DOWN(pa), prot);
+		return;
+	}
+
+	if (p4d_val(p4dp[p4d_index]) == 0) {
+		next_phys = pt_ops.alloc_pud(va);
+		p4dp[p4d_index] = pfn_p4d(PFN_DOWN(next_phys), PAGE_TABLE);
+		nextp = pt_ops.get_pud_virt(next_phys);
+		memset(nextp, 0, PAGE_SIZE);
+	} else {
+		next_phys = PFN_PHYS(_p4d_pfn(p4dp[p4d_index]));
+		nextp = pt_ops.get_pud_virt(next_phys);
+	}
+
+	create_pud_mapping(nextp, va, pa, sz, prot);
+}
+
+#define pgd_next_t		p4d_t
+#define alloc_pgd_next(__va)	(pgtable_l5_enabled ?			\
+		pt_ops.alloc_p4d(__va) : (pgtable_l4_enabled ?		\
+		pt_ops.alloc_pud(__va) : pt_ops.alloc_pmd(__va)))
+#define get_pgd_next_virt(__pa)	(pgtable_l5_enabled ?			\
+		pt_ops.get_p4d_virt(__pa) : (pgd_next_t *)(pgtable_l4_enabled ?	\
+		pt_ops.get_pud_virt(__pa) : (pud_t *)pt_ops.get_pmd_virt(__pa)))
 #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot)	\
+				(pgtable_l5_enabled ?			\
+		create_p4d_mapping(__nextp, __va, __pa, __sz, __prot) : \
 				(pgtable_l4_enabled ?			\
-		create_pud_mapping(__nextp, __va, __pa, __sz, __prot) :	\
-		create_pmd_mapping((pmd_t *)__nextp, __va, __pa, __sz, __prot))
-#define fixmap_pgd_next		(pgtable_l4_enabled ?			\
-		(uintptr_t)fixmap_pud : (uintptr_t)fixmap_pmd)
-#define trampoline_pgd_next	(pgtable_l4_enabled ?			\
-		(uintptr_t)trampoline_pud : (uintptr_t)trampoline_pmd)
-#define early_dtb_pgd_next	(pgtable_l4_enabled ?			\
-		(uintptr_t)early_dtb_pud : (uintptr_t)early_dtb_pmd)
+		create_pud_mapping((pud_t *)__nextp, __va, __pa, __sz, __prot) :	\
+		create_pmd_mapping((pmd_t *)__nextp, __va, __pa, __sz, __prot)))
+#define fixmap_pgd_next		(pgtable_l5_enabled ?			\
+		(uintptr_t)fixmap_p4d : (pgtable_l4_enabled ?		\
+		(uintptr_t)fixmap_pud : (uintptr_t)fixmap_pmd))
+#define trampoline_pgd_next	(pgtable_l5_enabled ?			\
+		(uintptr_t)trampoline_p4d : (pgtable_l4_enabled ?	\
+		(uintptr_t)trampoline_pud : (uintptr_t)trampoline_pmd))
+#define early_dtb_pgd_next	(pgtable_l5_enabled ?			\
+		(uintptr_t)early_dtb_p4d : (pgtable_l4_enabled ?	\
+		(uintptr_t)early_dtb_pud : (uintptr_t)early_dtb_pmd))
 #else
 #define pgd_next_t		pte_t
 #define alloc_pgd_next(__va)	pt_ops.alloc_pte(__va)
@@ -483,6 +566,7 @@ static void __init create_pud_mapping(pud_t *pudp,
 	create_pte_mapping(__nextp, __va, __pa, __sz, __prot)
 #define fixmap_pgd_next		((uintptr_t)fixmap_pte)
 #define early_dtb_pgd_next	((uintptr_t)early_dtb_pmd)
+#define create_p4d_mapping(__pmdp, __va, __pa, __sz, __prot)
 #define create_pud_mapping(__pmdp, __va, __pa, __sz, __prot)
 #define create_pmd_mapping(__pmdp, __va, __pa, __sz, __prot)
 #endif /* __PAGETABLE_PMD_FOLDED */
@@ -693,10 +777,13 @@ static void __init create_fdt_early_page_table(pgd_t *pgdir, uintptr_t dtb_pa)
 			   PGDIR_SIZE,
 			   IS_ENABLED(CONFIG_64BIT) ? PAGE_TABLE : PAGE_KERNEL);
 
-	if (pgtable_l4_enabled) {
+	if (pgtable_l5_enabled)
+		create_p4d_mapping(early_dtb_p4d, DTB_EARLY_BASE_VA,
+				   (uintptr_t)early_dtb_pud, P4D_SIZE, PAGE_TABLE);
+
+	if (pgtable_l4_enabled)
 		create_pud_mapping(early_dtb_pud, DTB_EARLY_BASE_VA,
 				   (uintptr_t)early_dtb_pmd, PUD_SIZE, PAGE_TABLE);
-	}
 
 	if (IS_ENABLED(CONFIG_64BIT)) {
 		create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA,
@@ -732,6 +819,8 @@ void __init pt_ops_set_early(void)
 	pt_ops.get_pmd_virt = get_pmd_virt_early;
 	pt_ops.alloc_pud = alloc_pud_early;
 	pt_ops.get_pud_virt = get_pud_virt_early;
+	pt_ops.alloc_p4d = alloc_p4d_early;
+	pt_ops.get_p4d_virt = get_p4d_virt_early;
 #endif
 }
 
@@ -752,6 +841,8 @@ void __init pt_ops_set_fixmap(void)
 	pt_ops.get_pmd_virt = kernel_mapping_pa_to_va((uintptr_t)get_pmd_virt_fixmap);
 	pt_ops.alloc_pud = kernel_mapping_pa_to_va((uintptr_t)alloc_pud_fixmap);
 	pt_ops.get_pud_virt = kernel_mapping_pa_to_va((uintptr_t)get_pud_virt_fixmap);
+	pt_ops.alloc_p4d = kernel_mapping_pa_to_va((uintptr_t)alloc_p4d_fixmap);
+	pt_ops.get_p4d_virt = kernel_mapping_pa_to_va((uintptr_t)get_p4d_virt_fixmap);
 #endif
 }
 
@@ -768,6 +859,8 @@ void __init pt_ops_set_late(void)
 	pt_ops.get_pmd_virt = get_pmd_virt_late;
 	pt_ops.alloc_pud = alloc_pud_late;
 	pt_ops.get_pud_virt = get_pud_virt_late;
+	pt_ops.alloc_p4d = alloc_p4d_late;
+	pt_ops.get_p4d_virt = get_p4d_virt_late;
 #endif
 }
 
@@ -828,6 +921,10 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 			   fixmap_pgd_next, PGDIR_SIZE, PAGE_TABLE);
 
 #ifndef __PAGETABLE_PMD_FOLDED
+	/* Setup fixmap P4D and PUD */
+	if (pgtable_l5_enabled)
+		create_p4d_mapping(fixmap_p4d, FIXADDR_START,
+				   (uintptr_t)fixmap_pud, P4D_SIZE, PAGE_TABLE);
 	/* Setup fixmap PUD and PMD */
 	if (pgtable_l4_enabled)
 		create_pud_mapping(fixmap_pud, FIXADDR_START,
@@ -837,6 +934,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 	/* Setup trampoline PGD and PMD */
 	create_pgd_mapping(trampoline_pg_dir, kernel_map.virt_addr,
 			   trampoline_pgd_next, PGDIR_SIZE, PAGE_TABLE);
+	if (pgtable_l5_enabled)
+		create_p4d_mapping(trampoline_p4d, kernel_map.virt_addr,
+				   (uintptr_t)trampoline_pud, P4D_SIZE, PAGE_TABLE);
 	if (pgtable_l4_enabled)
 		create_pud_mapping(trampoline_pud, kernel_map.virt_addr,
 				   (uintptr_t)trampoline_pmd, PUD_SIZE, PAGE_TABLE);
@@ -938,6 +1038,7 @@ static void __init setup_vm_final(void)
 	clear_fixmap(FIX_PTE);
 	clear_fixmap(FIX_PMD);
 	clear_fixmap(FIX_PUD);
+	clear_fixmap(FIX_P4D);
 
 	/* Move to swapper page table */
 	csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | satp_mode);