Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull EFI fixes from Ingo Molnar:
 "Three EFI fixes:

   - Fix a slow-boot-scrolling regression but making sure we use WC for
     EFI earlycon framebuffer mappings on x86

   - Fix a mixed EFI mode boot crash

   - Disable paging explicitly before entering startup_32() in mixed
     mode bootup"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/efistub: Disable paging at mixed mode entry
  efi/libstub/random: Initialize pointer variables to zero for mixed mode
  efi/earlycon: Fix write-combine mapping on x86

Author: torvalds

arch/x86/boot/compressed/head_64.S

@@ -244,6 +244,11 @@ SYM_FUNC_START(efi32_stub_entry)
 	leal	efi32_config(%ebp), %eax
 	movl	%eax, efi_config(%ebp)
 
+	/* Disable paging */
+	movl	%cr0, %eax
+	btrl	$X86_CR0_PG_BIT, %eax
+	movl	%eax, %cr0
+
 	jmp	startup_32
 SYM_FUNC_END(efi32_stub_entry)
 #endif

drivers/firmware/efi/earlycon.c

@@ -17,7 +17,7 @@ static const struct console *earlycon_console __initdata;
 static const struct font_desc *font;
 static u32 efi_x, efi_y;
 static u64 fb_base;
-static pgprot_t fb_prot;
+static bool fb_wb;
 static void *efi_fb;
 
 /*
@@ -33,10 +33,8 @@ static int __init efi_earlycon_remap_fb(void)
 	if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
 		return 0;
 
-	if (pgprot_val(fb_prot) == pgprot_val(PAGE_KERNEL))
-		efi_fb = memremap(fb_base, screen_info.lfb_size, MEMREMAP_WB);
-	else
-		efi_fb = memremap(fb_base, screen_info.lfb_size, MEMREMAP_WC);
+	efi_fb = memremap(fb_base, screen_info.lfb_size,
+			  fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
 
 	return efi_fb ? 0 : -ENOMEM;
 }
@@ -53,9 +51,12 @@ late_initcall(efi_earlycon_unmap_fb);
 
 static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
 {
+	pgprot_t fb_prot;
+
 	if (efi_fb)
 		return efi_fb + start;
 
+	fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
 	return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
 }
 
@@ -215,10 +216,7 @@ static int __init efi_earlycon_setup(struct earlycon_device *device,
 	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
 		fb_base |= (u64)screen_info.ext_lfb_base << 32;
 
-	if (opt && !strcmp(opt, "ram"))
-		fb_prot = PAGE_KERNEL;
-	else
-		fb_prot = pgprot_writecombine(PAGE_KERNEL);
+	fb_wb = opt && !strcmp(opt, "ram");
 
 	si = &screen_info;
 	xres = si->lfb_width;

drivers/firmware/efi/libstub/random.c

@@ -33,7 +33,7 @@ efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg,
 {
 	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
 	efi_status_t status;
-	struct efi_rng_protocol *rng;
+	struct efi_rng_protocol *rng = NULL;
 
 	status = efi_call_early(locate_protocol, &rng_proto, NULL,
 				(void **)&rng);
@@ -162,8 +162,8 @@ efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg)
 	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
 	efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW;
 	efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID;
-	struct efi_rng_protocol *rng;
-	struct linux_efi_random_seed *seed;
+	struct efi_rng_protocol *rng = NULL;
+	struct linux_efi_random_seed *seed = NULL;
 	efi_status_t status;
 
 	status = efi_call_early(locate_protocol, &rng_proto, NULL,