1 files changed, 54 insertions, 33 deletions

diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index d4056c6be1ec..8181ac179d14 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -18,7 +18,27 @@
 
 #include "efistub.h"
 
-bool __nokaslr;
+/*
+ * This is the base address at which to start allocating virtual memory ranges
+ * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
+ * any allocation we choose, and eliminate the risk of a conflict after kexec.
+ * The value chosen is the largest non-zero power of 2 suitable for this purpose
+ * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
+ * be mapped efficiently.
+ * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
+ * map everything below 1 GB. (512 MB is a reasonable upper bound for the
+ * entire footprint of the UEFI runtime services memory regions)
+ */
+#define EFI_RT_VIRTUAL_BASE	SZ_512M
+#define EFI_RT_VIRTUAL_SIZE	SZ_512M
+
+#ifdef CONFIG_ARM64
+# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_64
+#else
+# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
+#endif
+
+static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
 
 efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
 			     void *__image, void **__fh)
@@ -118,8 +138,6 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 		goto fail;
 
-	pr_efi(sys_table, "Booting Linux Kernel...\n");
-
 	status = check_platform_features(sys_table);
 	if (status != EFI_SUCCESS)
 		goto fail;
@@ -153,17 +171,15 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 		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_EXTEND) ||
+	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
+	    cmdline_size == 0)
+		efi_parse_options(CONFIG_CMDLINE);
 
-		if (IS_ENABLED(CONFIG_CMDLINE_FORCE))
-			cmdline = default_cmdline;
-		str = strstr(cmdline, "nokaslr");
-		if (str == cmdline || (str > cmdline && *(str - 1) == ' '))
-			__nokaslr = true;
-	}
+	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
+		efi_parse_options(cmdline_ptr);
+
+	pr_efi(sys_table, "Booting Linux Kernel...\n");
 
 	si = setup_graphics(sys_table);
 
@@ -176,10 +192,6 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 		goto fail_free_cmdline;
 	}
 
-	status = efi_parse_options(cmdline_ptr);
-	if (status != EFI_SUCCESS)
-		pr_efi_err(sys_table, "Failed to parse EFI cmdline options\n");
-
 	secure_boot = efi_get_secureboot(sys_table);
 
 	/*
@@ -213,8 +225,9 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	if (!fdt_addr)
 		pr_efi(sys_table, "Generating empty DTB\n");
 
-	status = handle_cmdline_files(sys_table, image, cmdline_ptr,
-				      "initrd=", dram_base + SZ_512M,
+	status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=",
+				      efi_get_max_initrd_addr(dram_base,
+							      *image_addr),
 				      (unsigned long *)&initrd_addr,
 				      (unsigned long *)&initrd_size);
 	if (status != EFI_SUCCESS)
@@ -222,9 +235,29 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 
 	efi_random_get_seed(sys_table);
 
+	if (!nokaslr()) {
+		/*
+		 * Randomize the base of the UEFI runtime services region.
+		 * Preserve the 2 MB alignment of the region by taking a
+		 * shift of 21 bit positions into account when scaling
+		 * the headroom value using a 32-bit random value.
+		 */
+		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
+					    EFI_RT_VIRTUAL_BASE -
+					    EFI_RT_VIRTUAL_SIZE;
+		u32 rnd;
+
+		status = efi_get_random_bytes(sys_table, sizeof(rnd),
+					      (u8 *)&rnd);
+		if (status == EFI_SUCCESS) {
+			virtmap_base = EFI_RT_VIRTUAL_BASE +
+				       (((headroom >> 21) * rnd) >> (32 - 21));
+		}
+	}
+
 	new_fdt_addr = fdt_addr;
 	status = allocate_new_fdt_and_exit_boot(sys_table, handle,
-				&new_fdt_addr, dram_base + MAX_FDT_OFFSET,
+				&new_fdt_addr, efi_get_max_fdt_addr(dram_base),
 				initrd_addr, initrd_size, cmdline_ptr,
 				fdt_addr, fdt_size);
 
@@ -251,18 +284,6 @@ fail:
 	return EFI_ERROR;
 }
 
-/*
- * This is the base address at which to start allocating virtual memory ranges
- * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
- * any allocation we choose, and eliminate the risk of a conflict after kexec.
- * The value chosen is the largest non-zero power of 2 suitable for this purpose
- * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
- * be mapped efficiently.
- * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
- * map everything below 1 GB.
- */
-#define EFI_RT_VIRTUAL_BASE	SZ_512M
-
 static int cmp_mem_desc(const void *l, const void *r)
 {
 	const efi_memory_desc_t *left = l, *right = r;
@@ -312,7 +333,7 @@ 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)
 {
-	u64 efi_virt_base = EFI_RT_VIRTUAL_BASE;
+	u64 efi_virt_base = virtmap_base;
 	efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
 	int l;