Merge branch 'for-next/mm' into for-next/core

* for-next/mm:
  arm64: mm: always map fixmap at page granularity
  arm64: mm: move fixmap code to its own file
  arm64: add FIXADDR_TOT_{START,SIZE}
  Revert "Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()""
  arm: uaccess: Remove memcpy_page_flushcache()
  mm,kfence: decouple kfence from page granularity mapping judgement

Author: willdeacon

arch/arm64/include/asm/fixmap.h

@@ -17,6 +17,7 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/kernel.h>
+#include <linux/math.h>
 #include <linux/sizes.h>
 #include <asm/boot.h>
 #include <asm/page.h>
@@ -36,17 +37,13 @@ enum fixed_addresses {
 	FIX_HOLE,
 
 	/*
-	 * Reserve a virtual window for the FDT that is 2 MB larger than the
-	 * maximum supported size, and put it at the top of the fixmap region.
-	 * The additional space ensures that any FDT that does not exceed
-	 * MAX_FDT_SIZE can be mapped regardless of whether it crosses any
-	 * 2 MB alignment boundaries.
-	 *
-	 * Keep this at the top so it remains 2 MB aligned.
+	 * Reserve a virtual window for the FDT that is a page bigger than the
+	 * maximum supported size. The additional space ensures that any FDT
+	 * that does not exceed MAX_FDT_SIZE can be mapped regardless of
+	 * whether it crosses any page boundary.
 	 */
-#define FIX_FDT_SIZE		(MAX_FDT_SIZE + SZ_2M)
 	FIX_FDT_END,
-	FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
+	FIX_FDT = FIX_FDT_END + DIV_ROUND_UP(MAX_FDT_SIZE, PAGE_SIZE) + 1,
 
 	FIX_EARLYCON_MEM_BASE,
 	FIX_TEXT_POKE0,
@@ -95,12 +92,15 @@ enum fixed_addresses {
 	__end_of_fixed_addresses
 };
 
-#define FIXADDR_SIZE	(__end_of_permanent_fixed_addresses << PAGE_SHIFT)
-#define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)
+#define FIXADDR_SIZE		(__end_of_permanent_fixed_addresses << PAGE_SHIFT)
+#define FIXADDR_START		(FIXADDR_TOP - FIXADDR_SIZE)
+#define FIXADDR_TOT_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
+#define FIXADDR_TOT_START	(FIXADDR_TOP - FIXADDR_TOT_SIZE)
 
 #define FIXMAP_PAGE_IO     __pgprot(PROT_DEVICE_nGnRE)
 
 void __init early_fixmap_init(void);
+void __init fixmap_copy(pgd_t *pgdir);
 
 #define __early_set_fixmap __set_fixmap
 

arch/arm64/include/asm/kernel-pgtable.h

@@ -59,8 +59,11 @@
 #define EARLY_KASLR	(0)
 #endif
 
+#define SPAN_NR_ENTRIES(vstart, vend, shift) \
+	((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1)
+
 #define EARLY_ENTRIES(vstart, vend, shift, add) \
-	((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1 + add)
+	(SPAN_NR_ENTRIES(vstart, vend, shift) + (add))
 
 #define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add))
 

arch/arm64/include/asm/kfence.h

@@ -19,4 +19,14 @@ static inline bool kfence_protect_page(unsigned long addr, bool protect)
 	return true;
 }
 
+#ifdef CONFIG_KFENCE
+extern bool kfence_early_init;
+static inline bool arm64_kfence_can_set_direct_map(void)
+{
+	return !kfence_early_init;
+}
+#else /* CONFIG_KFENCE */
+static inline bool arm64_kfence_can_set_direct_map(void) { return false; }
+#endif /* CONFIG_KFENCE */
+
 #endif /* __ASM_KFENCE_H */

arch/arm64/include/asm/mmu.h

@@ -65,6 +65,8 @@ extern void paging_init(void);
 extern void bootmem_init(void);
 extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
 extern void init_mem_pgprot(void);
+extern void create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
+				   phys_addr_t size, pgprot_t prot);
 extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 			       unsigned long virt, phys_addr_t size,
 			       pgprot_t prot, bool page_mappings_only);

arch/arm64/include/asm/uaccess.h

@@ -449,8 +449,6 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count);
 extern __must_check long strnlen_user(const char __user *str, long n);
 
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
-struct page;
-void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len);
 extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n);
 
 static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)

arch/arm64/lib/uaccess_flushcache.c

@@ -19,12 +19,6 @@ void memcpy_flushcache(void *dst, const void *src, size_t cnt)
 }
 EXPORT_SYMBOL_GPL(memcpy_flushcache);
 
-void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
-			    size_t len)
-{
-	memcpy_flushcache(to, page_address(page) + offset, len);
-}
-
 unsigned long __copy_user_flushcache(void *to, const void __user *from,
 				     unsigned long n)
 {

arch/arm64/mm/Makefile

@@ -2,7 +2,7 @@
 obj-y				:= dma-mapping.o extable.o fault.o init.o \
 				   cache.o copypage.o flush.o \
 				   ioremap.o mmap.o pgd.o mmu.o \
-				   context.o proc.o pageattr.o
+				   context.o proc.o pageattr.o fixmap.o
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
 obj-$(CONFIG_PTDUMP_CORE)	+= ptdump.o
 obj-$(CONFIG_PTDUMP_DEBUGFS)	+= ptdump_debugfs.o

arch/arm64/mm/dma-mapping.c

@@ -36,22 +36,7 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
 {
 	unsigned long start = (unsigned long)page_address(page);
 
-	/*
-	 * The architecture only requires a clean to the PoC here in order to
-	 * meet the requirements of the DMA API. However, some vendors (i.e.
-	 * Qualcomm) abuse the DMA API for transferring buffers from the
-	 * non-secure to the secure world, resetting the system if a non-secure
-	 * access shows up after the buffer has been transferred:
-	 *
-	 * https://lore.kernel.org/r/[email protected]
-	 *
-	 * Using clean+invalidate appears to make this issue less likely, but
-	 * the drivers themselves still need fixing as the CPU could issue a
-	 * speculative read from the buffer via the linear mapping irrespective
-	 * of the cache maintenance we use. Once the drivers are fixed, we can
-	 * relax this to a clean operation.
-	 */
-	dcache_clean_inval_poc(start, start + size);
+	dcache_clean_poc(start, start + size);
 }
 
 #ifdef CONFIG_IOMMU_DMA

arch/arm64/mm/fixmap.c

@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Fixmap manipulation code
+ */
+
+#include <linux/bug.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/libfdt.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/sizes.h>
+
+#include <asm/fixmap.h>
+#include <asm/kernel-pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+
+#define NR_BM_PTE_TABLES \
+	SPAN_NR_ENTRIES(FIXADDR_TOT_START, FIXADDR_TOP, PMD_SHIFT)
+#define NR_BM_PMD_TABLES \
+	SPAN_NR_ENTRIES(FIXADDR_TOT_START, FIXADDR_TOP, PUD_SHIFT)
+
+static_assert(NR_BM_PMD_TABLES == 1);
+
+#define __BM_TABLE_IDX(addr, shift) \
+	(((addr) >> (shift)) - (FIXADDR_TOT_START >> (shift)))
+
+#define BM_PTE_TABLE_IDX(addr)	__BM_TABLE_IDX(addr, PMD_SHIFT)
+
+static pte_t bm_pte[NR_BM_PTE_TABLES][PTRS_PER_PTE] __page_aligned_bss;
+static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused;
+static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused;
+
+static inline pte_t *fixmap_pte(unsigned long addr)
+{
+	return &bm_pte[BM_PTE_TABLE_IDX(addr)][pte_index(addr)];
+}
+
+static void __init early_fixmap_init_pte(pmd_t *pmdp, unsigned long addr)
+{
+	pmd_t pmd = READ_ONCE(*pmdp);
+	pte_t *ptep;
+
+	if (pmd_none(pmd)) {
+		ptep = bm_pte[BM_PTE_TABLE_IDX(addr)];
+		__pmd_populate(pmdp, __pa_symbol(ptep), PMD_TYPE_TABLE);
+	}
+}
+
+static void __init early_fixmap_init_pmd(pud_t *pudp, unsigned long addr,
+					 unsigned long end)
+{
+	unsigned long next;
+	pud_t pud = READ_ONCE(*pudp);
+	pmd_t *pmdp;
+
+	if (pud_none(pud))
+		__pud_populate(pudp, __pa_symbol(bm_pmd), PUD_TYPE_TABLE);
+
+	pmdp = pmd_offset_kimg(pudp, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		early_fixmap_init_pte(pmdp, addr);
+	} while (pmdp++, addr = next, addr != end);
+}
+
+
+static void __init early_fixmap_init_pud(p4d_t *p4dp, unsigned long addr,
+					 unsigned long end)
+{
+	p4d_t p4d = READ_ONCE(*p4dp);
+	pud_t *pudp;
+
+	if (CONFIG_PGTABLE_LEVELS > 3 && !p4d_none(p4d) &&
+	    p4d_page_paddr(p4d) != __pa_symbol(bm_pud)) {
+		/*
+		 * We only end up here if the kernel mapping and the fixmap
+		 * share the top level pgd entry, which should only happen on
+		 * 16k/4 levels configurations.
+		 */
+		BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
+	}
+
+	if (p4d_none(p4d))
+		__p4d_populate(p4dp, __pa_symbol(bm_pud), P4D_TYPE_TABLE);
+
+	pudp = pud_offset_kimg(p4dp, addr);
+	early_fixmap_init_pmd(pudp, addr, end);
+}
+
+/*
+ * The p*d_populate functions call virt_to_phys implicitly so they can't be used
+ * directly on kernel symbols (bm_p*d). This function is called too early to use
+ * lm_alias so __p*d_populate functions must be used to populate with the
+ * physical address from __pa_symbol.
+ */
+void __init early_fixmap_init(void)
+{
+	unsigned long addr = FIXADDR_TOT_START;
+	unsigned long end = FIXADDR_TOP;
+
+	pgd_t *pgdp = pgd_offset_k(addr);
+	p4d_t *p4dp = p4d_offset(pgdp, addr);
+
+	early_fixmap_init_pud(p4dp, addr, end);
+}
+
+/*
+ * Unusually, this is also called in IRQ context (ghes_iounmap_irq) so if we
+ * ever need to use IPIs for TLB broadcasting, then we're in trouble here.
+ */
+void __set_fixmap(enum fixed_addresses idx,
+			       phys_addr_t phys, pgprot_t flags)
+{
+	unsigned long addr = __fix_to_virt(idx);
+	pte_t *ptep;
+
+	BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);
+
+	ptep = fixmap_pte(addr);
+
+	if (pgprot_val(flags)) {
+		set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, flags));
+	} else {
+		pte_clear(&init_mm, addr, ptep);
+		flush_tlb_kernel_range(addr, addr+PAGE_SIZE);
+	}
+}
+
+void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
+{
+	const u64 dt_virt_base = __fix_to_virt(FIX_FDT);
+	phys_addr_t dt_phys_base;
+	int offset;
+	void *dt_virt;
+
+	/*
+	 * Check whether the physical FDT address is set and meets the minimum
+	 * alignment requirement. Since we are relying on MIN_FDT_ALIGN to be
+	 * at least 8 bytes so that we can always access the magic and size
+	 * fields of the FDT header after mapping the first chunk, double check
+	 * here if that is indeed the case.
+	 */
+	BUILD_BUG_ON(MIN_FDT_ALIGN < 8);
+	if (!dt_phys || dt_phys % MIN_FDT_ALIGN)
+		return NULL;
+
+	dt_phys_base = round_down(dt_phys, PAGE_SIZE);
+	offset = dt_phys % PAGE_SIZE;
+	dt_virt = (void *)dt_virt_base + offset;
+
+	/* map the first chunk so we can read the size from the header */
+	create_mapping_noalloc(dt_phys_base, dt_virt_base, PAGE_SIZE, prot);
+
+	if (fdt_magic(dt_virt) != FDT_MAGIC)
+		return NULL;
+
+	*size = fdt_totalsize(dt_virt);
+	if (*size > MAX_FDT_SIZE)
+		return NULL;
+
+	if (offset + *size > PAGE_SIZE) {
+		create_mapping_noalloc(dt_phys_base, dt_virt_base,
+				       offset + *size, prot);
+	}
+
+	return dt_virt;
+}
+
+/*
+ * Copy the fixmap region into a new pgdir.
+ */
+void __init fixmap_copy(pgd_t *pgdir)
+{
+	if (!READ_ONCE(pgd_val(*pgd_offset_pgd(pgdir, FIXADDR_TOT_START)))) {
+		/*
+		 * The fixmap falls in a separate pgd to the kernel, and doesn't
+		 * live in the carveout for the swapper_pg_dir. We can simply
+		 * re-use the existing dir for the fixmap.
+		 */
+		set_pgd(pgd_offset_pgd(pgdir, FIXADDR_TOT_START),
+			READ_ONCE(*pgd_offset_k(FIXADDR_TOT_START)));
+	} else if (CONFIG_PGTABLE_LEVELS > 3) {
+		pgd_t *bm_pgdp;
+		p4d_t *bm_p4dp;
+		pud_t *bm_pudp;
+		/*
+		 * The fixmap shares its top level pgd entry with the kernel
+		 * mapping. This can really only occur when we are running
+		 * with 16k/4 levels, so we can simply reuse the pud level
+		 * entry instead.
+		 */
+		BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
+		bm_pgdp = pgd_offset_pgd(pgdir, FIXADDR_TOT_START);
+		bm_p4dp = p4d_offset(bm_pgdp, FIXADDR_TOT_START);
+		bm_pudp = pud_set_fixmap_offset(bm_p4dp, FIXADDR_TOT_START);
+		pud_populate(&init_mm, bm_pudp, lm_alias(bm_pmd));
+		pud_clear_fixmap();
+	} else {
+		BUG();
+	}
+}