diff options
| -rw-r--r-- | Documentation/arm64/booting.txt | 10 | ||||
| -rw-r--r-- | arch/arm64/include/asm/boot.h | 14 | ||||
| -rw-r--r-- | arch/arm64/include/asm/fixmap.h | 15 | ||||
| -rw-r--r-- | arch/arm64/include/asm/mmu.h | 1 | ||||
| -rw-r--r-- | arch/arm64/kernel/head.S | 39 | ||||
| -rw-r--r-- | arch/arm64/kernel/setup.c | 30 | ||||
| -rw-r--r-- | arch/arm64/mm/Makefile | 2 | ||||
| -rw-r--r-- | arch/arm64/mm/init.c | 1 | ||||
| -rw-r--r-- | arch/arm64/mm/mmu.c | 66 |
9 files changed, 115 insertions, 63 deletions
diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index f3c05b5f9f08..1690350f16e7 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -45,11 +45,13 @@ sees fit.) Requirement: MANDATORY -The device tree blob (dtb) must be placed on an 8-byte boundary within -the first 512 megabytes from the start of the kernel image and must not -cross a 2-megabyte boundary. This is to allow the kernel to map the -blob using a single section mapping in the initial page tables. +The device tree blob (dtb) must be placed on an 8-byte boundary and must +not exceed 2 megabytes in size. Since the dtb will be mapped cacheable +using blocks of up to 2 megabytes in size, it must not be placed within +any 2M region which must be mapped with any specific attributes. +NOTE: versions prior to v4.2 also require that the DTB be placed within +the 512 MB region starting at text_offset bytes below the kernel Image. 3. Decompress the kernel image ------------------------------ diff --git a/arch/arm64/include/asm/boot.h b/arch/arm64/include/asm/boot.h new file mode 100644 index 000000000000..81151b67b26b --- /dev/null +++ b/arch/arm64/include/asm/boot.h @@ -0,0 +1,14 @@ + +#ifndef __ASM_BOOT_H +#define __ASM_BOOT_H + +#include <asm/sizes.h> + +/* + * arm64 requires the DTB to be 8 byte aligned and + * not exceed 2MB in size. + */ +#define MIN_FDT_ALIGN 8 +#define MAX_FDT_SIZE SZ_2M + +#endif diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h index 95e6b6dcbe37..c0739187a920 100644 --- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -17,6 +17,7 @@ #ifndef __ASSEMBLY__ #include <linux/kernel.h> +#include <asm/boot.h> #include <asm/page.h> /* @@ -32,6 +33,20 @@ */ 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. + */ +#define FIX_FDT_SIZE (MAX_FDT_SIZE + SZ_2M) + FIX_FDT_END, + FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1, + FIX_EARLYCON_MEM_BASE, FIX_TEXT_POKE0, __end_of_permanent_fixed_addresses, diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index 3d311761e3c2..79fcfb048884 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -34,5 +34,6 @@ extern void init_mem_pgprot(void); extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, unsigned long virt, phys_addr_t size, pgprot_t prot); +extern void *fixmap_remap_fdt(phys_addr_t dt_phys); #endif diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 19f915e8f6e0..30cffc5e7402 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -237,8 +237,6 @@ ENTRY(stext) bl el2_setup // Drop to EL1, w20=cpu_boot_mode adrp x24, __PHYS_OFFSET bl set_cpu_boot_mode_flag - - bl __vet_fdt bl __create_page_tables // x25=TTBR0, x26=TTBR1 /* * The following calls CPU setup code, see arch/arm64/mm/proc.S for @@ -270,24 +268,6 @@ preserve_boot_args: ENDPROC(preserve_boot_args) /* - * Determine validity of the x21 FDT pointer. - * The dtb must be 8-byte aligned and live in the first 512M of memory. - */ -__vet_fdt: - tst x21, #0x7 - b.ne 1f - cmp x21, x24 - b.lt 1f - mov x0, #(1 << 29) - add x0, x0, x24 - cmp x21, x0 - b.ge 1f - ret -1: - mov x21, #0 - ret -ENDPROC(__vet_fdt) -/* * Macro to create a table entry to the next page. * * tbl: page table address @@ -348,8 +328,7 @@ ENDPROC(__vet_fdt) * required to get the kernel running. The following sections are required: * - identity mapping to enable the MMU (low address, TTBR0) * - first few MB of the kernel linear mapping to jump to once the MMU has - * been enabled, including the FDT blob (TTBR1) - * - pgd entry for fixed mappings (TTBR1) + * been enabled */ __create_page_tables: adrp x25, idmap_pg_dir @@ -439,22 +418,6 @@ __create_page_tables: create_block_map x0, x7, x3, x5, x6 /* - * Map the FDT blob (maximum 2MB; must be within 512MB of - * PHYS_OFFSET). - */ - mov x3, x21 // FDT phys address - and x3, x3, #~((1 << 21) - 1) // 2MB aligned - mov x6, #PAGE_OFFSET - sub x5, x3, x24 // subtract PHYS_OFFSET - tst x5, #~((1 << 29) - 1) // within 512MB? - csel x21, xzr, x21, ne // zero the FDT pointer - b.ne 1f - add x5, x5, x6 // __va(FDT blob) - add x6, x5, #1 << 21 // 2MB for the FDT blob - sub x6, x6, #1 // inclusive range - create_block_map x0, x7, x3, x5, x6 -1: - /* * Since the page tables have been populated with non-cacheable * accesses (MMU disabled), invalidate the idmap and swapper page * tables again to remove any speculatively loaded cache lines. diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 508cca1f8dce..ffd3970721bf 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -105,18 +105,6 @@ static struct resource mem_res[] = { #define kernel_code mem_res[0] #define kernel_data mem_res[1] -void __init early_print(const char *str, ...) -{ - char buf[256]; - va_list ap; - - va_start(ap, str); - vsnprintf(buf, sizeof(buf), str, ap); - va_end(ap); - - printk("%s", buf); -} - /* * The recorded values of x0 .. x3 upon kernel entry. */ @@ -326,12 +314,14 @@ static void __init setup_processor(void) static void __init setup_machine_fdt(phys_addr_t dt_phys) { - if (!dt_phys || !early_init_dt_scan(phys_to_virt(dt_phys))) { - early_print("\n" - "Error: invalid device tree blob at physical address 0x%p (virtual address 0x%p)\n" - "The dtb must be 8-byte aligned and passed in the first 512MB of memory\n" - "\nPlease check your bootloader.\n", - dt_phys, phys_to_virt(dt_phys)); + void *dt_virt = fixmap_remap_fdt(dt_phys); + + if (!dt_virt || !early_init_dt_scan(dt_virt)) { + pr_crit("\n" + "Error: invalid device tree blob at physical address %pa (virtual address 0x%p)\n" + "The dtb must be 8-byte aligned and must not exceed 2 MB in size\n" + "\nPlease check your bootloader.", + &dt_phys, dt_virt); while (true) cpu_relax(); @@ -374,8 +364,6 @@ void __init setup_arch(char **cmdline_p) { setup_processor(); - setup_machine_fdt(__fdt_pointer); - init_mm.start_code = (unsigned long) _text; init_mm.end_code = (unsigned long) _etext; init_mm.end_data = (unsigned long) _edata; @@ -386,6 +374,8 @@ void __init setup_arch(char **cmdline_p) early_fixmap_init(); early_ioremap_init(); + setup_machine_fdt(__fdt_pointer); + parse_early_param(); /* diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile index 773d37a14039..9d84feb41a16 100644 --- a/arch/arm64/mm/Makefile +++ b/arch/arm64/mm/Makefile @@ -4,3 +4,5 @@ obj-y := dma-mapping.o extable.o fault.o init.o \ context.o proc.o pageattr.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o obj-$(CONFIG_ARM64_PTDUMP) += dump.o + +CFLAGS_mmu.o := -I$(srctree)/scripts/dtc/libfdt/ diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 89a05f467ffb..597831bdddf3 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -170,7 +170,6 @@ void __init arm64_memblock_init(void) memblock_reserve(__virt_to_phys(initrd_start), initrd_end - initrd_start); #endif - early_init_fdt_reserve_self(); early_init_fdt_scan_reserved_mem(); /* 4GB maximum for 32-bit only capable devices */ diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 5b8b664422d3..82d3435bf14f 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -21,6 +21,7 @@ #include <linux/kernel.h> #include <linux/errno.h> #include <linux/init.h> +#include <linux/libfdt.h> #include <linux/mman.h> #include <linux/nodemask.h> #include <linux/memblock.h> @@ -643,3 +644,68 @@ void __set_fixmap(enum fixed_addresses idx, flush_tlb_kernel_range(addr, addr+PAGE_SIZE); } } + +void *__init fixmap_remap_fdt(phys_addr_t dt_phys) +{ + const u64 dt_virt_base = __fix_to_virt(FIX_FDT); + pgprot_t prot = PAGE_KERNEL | PTE_RDONLY; + int granularity, size, 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 size field 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; + + /* + * Make sure that the FDT region can be mapped without the need to + * allocate additional translation table pages, so that it is safe + * to call create_mapping() this early. + * + * On 64k pages, the FDT will be mapped using PTEs, so we need to + * be in the same PMD as the rest of the fixmap. + * On 4k pages, we'll use section mappings for the FDT so we only + * have to be in the same PUD. + */ + BUILD_BUG_ON(dt_virt_base % SZ_2M); + + if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) { + BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> PMD_SHIFT != + __fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT); + + granularity = PAGE_SIZE; + } else { + BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> PUD_SHIFT != + __fix_to_virt(FIX_BTMAP_BEGIN) >> PUD_SHIFT); + + granularity = PMD_SIZE; + } + + offset = dt_phys % granularity; + dt_virt = (void *)dt_virt_base + offset; + + /* map the first chunk so we can read the size from the header */ + create_mapping(round_down(dt_phys, granularity), dt_virt_base, + granularity, prot); + + if (fdt_check_header(dt_virt) != 0) + return NULL; + + size = fdt_totalsize(dt_virt); + if (size > MAX_FDT_SIZE) + return NULL; + + if (offset + size > granularity) + create_mapping(round_down(dt_phys, granularity), dt_virt_base, + round_up(offset + size, granularity), prot); + + memblock_reserve(dt_phys, size); + + return dt_virt; +} |