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-rw-r--r--arch/arm64/include/asm/boot.h14
-rw-r--r--arch/arm64/include/asm/fixmap.h15
-rw-r--r--arch/arm64/include/asm/mmu.h1
-rw-r--r--arch/arm64/kernel/head.S39
-rw-r--r--arch/arm64/kernel/setup.c30
-rw-r--r--arch/arm64/mm/Makefile2
-rw-r--r--arch/arm64/mm/init.c1
-rw-r--r--arch/arm64/mm/mmu.c66
8 files changed, 109 insertions, 59 deletions
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;
+}