Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Catalin Marinas:
 "Here are the main arm64 updates for 4.6.  There are some relatively
  intrusive changes to support KASLR, the reworking of the kernel
  virtual memory layout and initial page table creation.

  Summary:

   - Initial page table creation reworked to avoid breaking large block
     mappings (huge pages) into smaller ones.  The ARM architecture
     requires break-before-make in such cases to avoid TLB conflicts but
     that's not always possible on live page tables

   - Kernel virtual memory layout: the kernel image is no longer linked
     to the bottom of the linear mapping (PAGE_OFFSET) but at the bottom
     of the vmalloc space, allowing the kernel to be loaded (nearly)
     anywhere in physical RAM

   - Kernel ASLR: position independent kernel Image and modules being
     randomly mapped in the vmalloc space with the randomness is
     provided by UEFI (efi_get_random_bytes() patches merged via the
     arm64 tree, acked by Matt Fleming)

   - Implement relative exception tables for arm64, required by KASLR
     (initial code for ARCH_HAS_RELATIVE_EXTABLE added to lib/extable.c
     but actual x86 conversion to deferred to 4.7 because of the merge
     dependencies)

   - Support for the User Access Override feature of ARMv8.2: this
     allows uaccess functions (get_user etc.) to be implemented using
     LDTR/STTR instructions.  Such instructions, when run by the kernel,
     perform unprivileged accesses adding an extra level of protection.
     The set_fs() macro is used to "upgrade" such instruction to
     privileged accesses via the UAO bit

   - Half-precision floating point support (part of ARMv8.2)

   - Optimisations for CPUs with or without a hardware prefetcher (using
     run-time code patching)

   - copy_page performance improvement to deal with 128 bytes at a time

   - Sanity checks on the CPU capabilities (via CPUID) to prevent
     incompatible secondary CPUs from being brought up (e.g.  weird
     big.LITTLE configurations)

   - valid_user_regs() reworked for better sanity check of the
     sigcontext information (restored pstate information)

   - ACPI parking protocol implementation

   - CONFIG_DEBUG_RODATA enabled by default

   - VDSO code marked as read-only

   - DEBUG_PAGEALLOC support

   - ARCH_HAS_UBSAN_SANITIZE_ALL enabled

   - Erratum workaround Cavium ThunderX SoC

   - set_pte_at() fix for PROT_NONE mappings

   - Code clean-ups"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (99 commits)
  arm64: kasan: Fix zero shadow mapping overriding kernel image shadow
  arm64: kasan: Use actual memory node when populating the kernel image shadow
  arm64: Update PTE_RDONLY in set_pte_at() for PROT_NONE permission
  arm64: Fix misspellings in comments.
  arm64: efi: add missing frame pointer assignment
  arm64: make mrs_s prefixing implicit in read_cpuid
  arm64: enable CONFIG_DEBUG_RODATA by default
  arm64: Rework valid_user_regs
  arm64: mm: check at build time that PAGE_OFFSET divides the VA space evenly
  arm64: KVM: Move kvm_call_hyp back to its original localtion
  arm64: mm: treat memstart_addr as a signed quantity
  arm64: mm: list kernel sections in order
  arm64: lse: deal with clobbered IP registers after branch via PLT
  arm64: mm: dump: Use VA_START directly instead of private LOWEST_ADDR
  arm64: kconfig: add submenu for 8.2 architectural features
  arm64: kernel: acpi: fix ioremap in ACPI parking protocol cpu_postboot
  arm64: Add support for Half precision floating point
  arm64: Remove fixmap include fragility
  arm64: Add workaround for Cavium erratum 27456
  arm64: mm: Mark .rodata as RO
  ...

7 files changed, 246 insertions, 37 deletions

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index aaf9c0bab42e..ad077944aa0e 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -36,7 +36,7 @@ lib-$(CONFIG_EFI_ARMSTUB)	+= arm-stub.o fdt.o string.o \
 				   $(patsubst %.c,lib-%.o,$(arm-deps))
 
 lib-$(CONFIG_ARM)		+= arm32-stub.o
-lib-$(CONFIG_ARM64)		+= arm64-stub.o
+lib-$(CONFIG_ARM64)		+= arm64-stub.o random.o
 CFLAGS_arm64-stub.o 		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 
 #
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 3397902e4040..4deb3e7faa0e 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -18,6 +18,8 @@
 
 #include "efistub.h"
 
+bool __nokaslr;
+
 static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
 {
 	static efi_guid_t const var_guid = EFI_GLOBAL_VARIABLE_GUID;
@@ -207,14 +209,6 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 		pr_efi_err(sys_table, "Failed to find DRAM base\n");
 		goto fail;
 	}
-	status = handle_kernel_image(sys_table, image_addr, &image_size,
-				     &reserve_addr,
-				     &reserve_size,
-				     dram_base, image);
-	if (status != EFI_SUCCESS) {
-		pr_efi_err(sys_table, "Failed to relocate kernel\n");
-		goto fail;
-	}
 
 	/*
 	 * Get the command line from EFI, using the LOADED_IMAGE
@@ -224,7 +218,28 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
 	if (!cmdline_ptr) {
 		pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
-		goto fail_free_image;
+		goto fail;
+	}
+
+	/* check whether 'nokaslr' was passed on the command line */
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+		static const u8 default_cmdline[] = CONFIG_CMDLINE;
+		const u8 *str, *cmdline = cmdline_ptr;
+
+		if (IS_ENABLED(CONFIG_CMDLINE_FORCE))
+			cmdline = default_cmdline;
+		str = strstr(cmdline, "nokaslr");
+		if (str == cmdline || (str > cmdline && *(str - 1) == ' '))
+			__nokaslr = true;
+	}
+
+	status = handle_kernel_image(sys_table, image_addr, &image_size,
+				     &reserve_addr,
+				     &reserve_size,
+				     dram_base, image);
+	if (status != EFI_SUCCESS) {
+		pr_efi_err(sys_table, "Failed to relocate kernel\n");
+		goto fail_free_cmdline;
 	}
 
 	status = efi_parse_options(cmdline_ptr);
@@ -244,7 +259,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 
 		if (status != EFI_SUCCESS) {
 			pr_efi_err(sys_table, "Failed to load device tree!\n");
-			goto fail_free_cmdline;
+			goto fail_free_image;
 		}
 	}
 
@@ -286,12 +301,11 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	efi_free(sys_table, initrd_size, initrd_addr);
 	efi_free(sys_table, fdt_size, fdt_addr);
 
-fail_free_cmdline:
-	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
-
 fail_free_image:
 	efi_free(sys_table, image_size, *image_addr);
 	efi_free(sys_table, reserve_size, reserve_addr);
+fail_free_cmdline:
+	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
 fail:
 	return EFI_ERROR;
 }
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index 78dfbd34b6bf..e0e6b74fef8f 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -13,6 +13,10 @@
 #include <asm/efi.h>
 #include <asm/sections.h>
 
+#include "efistub.h"
+
+extern bool __nokaslr;
+
 efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
 					unsigned long *image_addr,
 					unsigned long *image_size,
@@ -23,26 +27,52 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
 {
 	efi_status_t status;
 	unsigned long kernel_size, kernel_memsize = 0;
-	unsigned long nr_pages;
 	void *old_image_addr = (void *)*image_addr;
 	unsigned long preferred_offset;
+	u64 phys_seed = 0;
+
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+		if (!__nokaslr) {
+			status = efi_get_random_bytes(sys_table_arg,
+						      sizeof(phys_seed),
+						      (u8 *)&phys_seed);
+			if (status == EFI_NOT_FOUND) {
+				pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n");
+			} else if (status != EFI_SUCCESS) {
+				pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n");
+				return status;
+			}
+		} else {
+			pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n");
+		}
+	}
 
 	/*
 	 * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
 	 * a 2 MB aligned base, which itself may be lower than dram_base, as
 	 * long as the resulting offset equals or exceeds it.
 	 */
-	preferred_offset = round_down(dram_base, SZ_2M) + TEXT_OFFSET;
+	preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET;
 	if (preferred_offset < dram_base)
-		preferred_offset += SZ_2M;
+		preferred_offset += MIN_KIMG_ALIGN;
 
-	/* Relocate the image, if required. */
 	kernel_size = _edata - _text;
-	if (*image_addr != preferred_offset) {
-		kernel_memsize = kernel_size + (_end - _edata);
+	kernel_memsize = kernel_size + (_end - _edata);
+
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
+		/*
+		 * If KASLR is enabled, and we have some randomness available,
+		 * locate the kernel at a randomized offset in physical memory.
+		 */
+		*reserve_size = kernel_memsize + TEXT_OFFSET;
+		status = efi_random_alloc(sys_table_arg, *reserve_size,
+					  MIN_KIMG_ALIGN, reserve_addr,
+					  phys_seed);
 
+		*image_addr = *reserve_addr + TEXT_OFFSET;
+	} else {
 		/*
-		 * First, try a straight allocation at the preferred offset.
+		 * Else, try a straight allocation at the preferred offset.
 		 * This will work around the issue where, if dram_base == 0x0,
 		 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
 		 * address of the allocation to be mistaken for a FAIL return
@@ -52,27 +82,31 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
 		 * Mustang), we can still place the kernel at the address
 		 * 'dram_base + TEXT_OFFSET'.
 		 */
+		if (*image_addr == preferred_offset)
+			return EFI_SUCCESS;
+
 		*image_addr = *reserve_addr = preferred_offset;
-		nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
-			   EFI_PAGE_SIZE;
+		*reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
+
 		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
-					EFI_LOADER_DATA, nr_pages,
+					EFI_LOADER_DATA,
+					*reserve_size / EFI_PAGE_SIZE,
 					(efi_physical_addr_t *)reserve_addr);
-		if (status != EFI_SUCCESS) {
-			kernel_memsize += TEXT_OFFSET;
-			status = efi_low_alloc(sys_table_arg, kernel_memsize,
-					       SZ_2M, reserve_addr);
+	}
 
-			if (status != EFI_SUCCESS) {
-				pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
-				return status;
-			}
-			*image_addr = *reserve_addr + TEXT_OFFSET;
+	if (status != EFI_SUCCESS) {
+		*reserve_size = kernel_memsize + TEXT_OFFSET;
+		status = efi_low_alloc(sys_table_arg, *reserve_size,
+				       MIN_KIMG_ALIGN, reserve_addr);
+
+		if (status != EFI_SUCCESS) {
+			pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
+			*reserve_size = 0;
+			return status;
 		}
-		memcpy((void *)*image_addr, old_image_addr, kernel_size);
-		*reserve_size = kernel_memsize;
+		*image_addr = *reserve_addr + TEXT_OFFSET;
 	}
-
+	memcpy((void *)*image_addr, old_image_addr, kernel_size);
 
 	return EFI_SUCCESS;
 }
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index f07d4a67fa76..29ed2f9b218c 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -649,6 +649,10 @@ static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n)
 	return dst;
 }
 
+#ifndef MAX_CMDLINE_ADDRESS
+#define MAX_CMDLINE_ADDRESS	ULONG_MAX
+#endif
+
 /*
  * Convert the unicode UEFI command line to ASCII to pass to kernel.
  * Size of memory allocated return in *cmd_line_len.
@@ -684,7 +688,8 @@ char *efi_convert_cmdline(efi_system_table_t *sys_table_arg,
 
 	options_bytes++;	/* NUL termination */
 
-	status = efi_low_alloc(sys_table_arg, options_bytes, 0, &cmdline_addr);
+	status = efi_high_alloc(sys_table_arg, options_bytes, 0,
+				&cmdline_addr, MAX_CMDLINE_ADDRESS);
 	if (status != EFI_SUCCESS)
 		return NULL;
 
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 6b6548fda089..5ed3d3f38166 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -43,4 +43,11 @@ void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
 		     int *count);
 
+efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table,
+				  unsigned long size, u8 *out);
+
+efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
+			      unsigned long size, unsigned long align,
+			      unsigned long *addr, unsigned long random_seed);
+
 #endif
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index cf7b7d46302a..6dba78aef337 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -147,6 +147,20 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 	if (status)
 		goto fdt_set_fail;
 
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+		efi_status_t efi_status;
+
+		efi_status = efi_get_random_bytes(sys_table, sizeof(fdt_val64),
+						  (u8 *)&fdt_val64);
+		if (efi_status == EFI_SUCCESS) {
+			status = fdt_setprop(fdt, node, "kaslr-seed",
+					     &fdt_val64, sizeof(fdt_val64));
+			if (status)
+				goto fdt_set_fail;
+		} else if (efi_status != EFI_NOT_FOUND) {
+			return efi_status;
+		}
+	}
 	return EFI_SUCCESS;
 
 fdt_set_fail:
diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c
new file mode 100644
index 000000000000..53f6d3fe6d86
--- /dev/null
+++ b/drivers/firmware/efi/libstub/random.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2016 Linaro Ltd;  <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+struct efi_rng_protocol {
+	efi_status_t (*get_info)(struct efi_rng_protocol *,
+				 unsigned long *, efi_guid_t *);
+	efi_status_t (*get_rng)(struct efi_rng_protocol *,
+				efi_guid_t *, unsigned long, u8 *out);
+};
+
+efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg,
+				  unsigned long size, u8 *out)
+{
+	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
+	efi_status_t status;
+	struct efi_rng_protocol *rng;
+
+	status = efi_call_early(locate_protocol, &rng_proto, NULL,
+				(void **)&rng);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	return rng->get_rng(rng, NULL, size, out);
+}
+
+/*
+ * Return the number of slots covered by this entry, i.e., the number of
+ * addresses it covers that are suitably aligned and supply enough room
+ * for the allocation.
+ */
+static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
+					 unsigned long size,
+					 unsigned long align)
+{
+	u64 start, end;
+
+	if (md->type != EFI_CONVENTIONAL_MEMORY)
+		return 0;
+
+	start = round_up(md->phys_addr, align);
+	end = round_down(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - size,
+			 align);
+
+	if (start > end)
+		return 0;
+
+	return (end - start + 1) / align;
+}
+
+/*
+ * The UEFI memory descriptors have a virtual address field that is only used
+ * when installing the virtual mapping using SetVirtualAddressMap(). Since it
+ * is unused here, we can reuse it to keep track of each descriptor's slot
+ * count.
+ */
+#define MD_NUM_SLOTS(md)	((md)->virt_addr)
+
+efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
+			      unsigned long size,
+			      unsigned long align,
+			      unsigned long *addr,
+			      unsigned long random_seed)
+{
+	unsigned long map_size, desc_size, total_slots = 0, target_slot;
+	efi_status_t status;
+	efi_memory_desc_t *memory_map;
+	int map_offset;
+
+	status = efi_get_memory_map(sys_table_arg, &memory_map, &map_size,
+				    &desc_size, NULL, NULL);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	if (align < EFI_ALLOC_ALIGN)
+		align = EFI_ALLOC_ALIGN;
+
+	/* count the suitable slots in each memory map entry */
+	for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
+		efi_memory_desc_t *md = (void *)memory_map + map_offset;
+		unsigned long slots;
+
+		slots = get_entry_num_slots(md, size, align);
+		MD_NUM_SLOTS(md) = slots;
+		total_slots += slots;
+	}
+
+	/* find a random number between 0 and total_slots */
+	target_slot = (total_slots * (u16)random_seed) >> 16;
+
+	/*
+	 * target_slot is now a value in the range [0, total_slots), and so
+	 * it corresponds with exactly one of the suitable slots we recorded
+	 * when iterating over the memory map the first time around.
+	 *
+	 * So iterate over the memory map again, subtracting the number of
+	 * slots of each entry at each iteration, until we have found the entry
+	 * that covers our chosen slot. Use the residual value of target_slot
+	 * to calculate the randomly chosen address, and allocate it directly
+	 * using EFI_ALLOCATE_ADDRESS.
+	 */
+	for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
+		efi_memory_desc_t *md = (void *)memory_map + map_offset;
+		efi_physical_addr_t target;
+		unsigned long pages;
+
+		if (target_slot >= MD_NUM_SLOTS(md)) {
+			target_slot -= MD_NUM_SLOTS(md);
+			continue;
+		}
+
+		target = round_up(md->phys_addr, align) + target_slot * align;
+		pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
+
+		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
+					EFI_LOADER_DATA, pages, &target);
+		if (status == EFI_SUCCESS)
+			*addr = target;
+		break;
+	}
+
+	efi_call_early(free_pool, memory_map);
+
+	return status;
+}