efi: Fix the ACPI BGRT driver for images located in EFI boot services memory

The ACPI BGRT driver accesses the BIOS logo image when it initializes.
However, ACPI 5.0 (which introduces the BGRT) recommends putting the
logo image in EFI boot services memory, so that the OS can reclaim that
memory. Production systems follow this recommendation, breaking the
ACPI BGRT driver.

Move the bulk of the BGRT code to run during a new EFI late
initialization phase, which occurs after switching EFI to virtual mode,
and after initializing ACPI, but before freeing boot services memory.
Copy the BIOS logo image to kernel memory at that point, and make it
accessible to the BGRT driver. Rework the existing ACPI BGRT driver to
act as a simple wrapper exposing that image (and the properties from the
BGRT) via sysfs.

Signed-off-by: Josh Triplett <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/platform/efi/Makefile

···
 obj-$(CONFIG_EFI) 		+= efi.o efi_$(BITS).o efi_stub_$(BITS).o
+obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o

arch/x86/platform/efi/efi-bgrt.c

···
+/*
+ * Copyright 2012 Intel Corporation
+ * Author: Josh Triplett <[e-mail]>
+ *
+ * Based on the bgrt driver:
+ * Copyright 2012 Red Hat, Inc <[e-mail]>
+ * Author: Matthew Garrett
+ *
+ * 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/kernel.h>
+#include <linux/acpi.h>
+#include <linux/efi.h>
+#include <linux/efi-bgrt.h>
+
+struct acpi_table_bgrt *bgrt_tab;
+void *bgrt_image;
+size_t bgrt_image_size;
+
+struct bmp_header {
+	u16 id;
+	u32 size;
+} __packed;
+
+void efi_bgrt_init(void)
+{
+	acpi_status status;
+	void __iomem *image;
+	bool ioremapped = false;
+	struct bmp_header bmp_header;
+
+	if (acpi_disabled)
+		return;
+
+	status = acpi_get_table("BGRT", 0,
+	                        (struct acpi_table_header **)&bgrt_tab);
+	if (ACPI_FAILURE(status))
+		return;
+
+	if (bgrt_tab->version != 1)
+		return;
+	if (bgrt_tab->image_type != 0 || !bgrt_tab->image_address)
+		return;
+
+	image = efi_lookup_mapped_addr(bgrt_tab->image_address);
+	if (!image) {
+		image = ioremap(bgrt_tab->image_address, sizeof(bmp_header));
+		ioremapped = true;
+		if (!image)
+			return;
+	}
+
+	memcpy_fromio(&bmp_header, image, sizeof(bmp_header));
+	if (ioremapped)
+		iounmap(image);
+	bgrt_image_size = bmp_header.size;
+
+	bgrt_image = kmalloc(bgrt_image_size, GFP_KERNEL);
+	if (!bgrt_image)
+		return;
+
+	if (ioremapped) {
+		image = ioremap(bgrt_tab->image_address, bmp_header.size);
+		if (!image) {
+			kfree(bgrt_image);
+			bgrt_image = NULL;
+			return;
+		}
+	}
+
+	memcpy_fromio(bgrt_image, image, bgrt_image_size);
+	if (ioremapped)
+		iounmap(image);
+}

arch/x86/platform/efi/efi.c

···
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/efi.h>
+#include <linux/efi-bgrt.h>
 #include <linux/export.h>
 #include <linux/bootmem.h>
 #include <linux/memblock.h>
···
 #if EFI_DEBUG
 	print_efi_memmap();
 #endif
+}
+
+void __init efi_late_init(void)
+{
+	efi_bgrt_init();
 }
 
 void __init efi_set_executable(efi_memory_desc_t *md, bool executable)

drivers/acpi/Kconfig

···
 	  to override that restriction).
 
 config ACPI_BGRT
-        tristate "Boottime Graphics Resource Table support"
-        default n
+	bool "Boottime Graphics Resource Table support"
+	depends on EFI
         help
 	  This driver adds support for exposing the ACPI Boottime Graphics
 	  Resource Table, which allows the operating system to obtain

drivers/acpi/bgrt.c

···
 /*
  * Copyright 2012 Red Hat, Inc <[e-mail]>
+ * Copyright 2012 Intel Corporation
  *
  * 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
···
 #include <linux/init.h>
 #include <linux/device.h>
 #include <linux/sysfs.h>
-#include <linux/io.h>
-#include <acpi/acpi.h>
-#include <acpi/acpi_bus.h>
+#include <linux/efi-bgrt.h>
 
-static struct acpi_table_bgrt *bgrt_tab;
 static struct kobject *bgrt_kobj;
-
-struct bmp_header {
-	u16 id;
-	u32 size;
-} __attribute ((packed));
-
-static struct bmp_header bmp_header;
 
 static ssize_t show_version(struct device *dev,
 			    struct device_attribute *attr, char *buf)
···
 static ssize_t show_image(struct file *file, struct kobject *kobj,
 	       struct bin_attribute *attr, char *buf, loff_t off, size_t count)
 {
-	int size = attr->size;
-	void __iomem *image = attr->private;
-
-	if (off >= size) {
-		count = 0;
-	} else {
-		if (off + count > size)
-			count = size - off;
-
-		memcpy_fromio(buf, image+off, count);
-	}
-
+	memcpy(buf, attr->private + off, count);
 	return count;
 }
 
···
 
 static int __init bgrt_init(void)
 {
-	acpi_status status;
 	int ret;
-	void __iomem *bgrt;
 
-	if (acpi_disabled)
-		return -ENODEV;
-
-	status = acpi_get_table("BGRT", 0,
-				(struct acpi_table_header **)&bgrt_tab);
-
-	if (ACPI_FAILURE(status))
+	if (!bgrt_image)
 		return -ENODEV;
 
 	sysfs_bin_attr_init(&image_attr);
-
-	bgrt = ioremap(bgrt_tab->image_address, sizeof(struct bmp_header));
-
-	if (!bgrt) {
-		ret = -EINVAL;
-		goto out_err;
-	}
-
-	memcpy_fromio(&bmp_header, bgrt, sizeof(bmp_header));
-	image_attr.size = bmp_header.size;
-	iounmap(bgrt);
-
-	image_attr.private = ioremap(bgrt_tab->image_address, image_attr.size);
-
-	if (!image_attr.private) {
-		ret = -EINVAL;
-		goto out_err;
-	}
-
+	image_attr.private = bgrt_image;
+	image_attr.size = bgrt_image_size;
 
 	bgrt_kobj = kobject_create_and_add("bgrt", acpi_kobj);
-	if (!bgrt_kobj) {
-		ret = -EINVAL;
-		goto out_iounmap;
-	}
+	if (!bgrt_kobj)
+		return -EINVAL;
 
 	ret = sysfs_create_group(bgrt_kobj, &bgrt_attribute_group);
 	if (ret)
···
 	sysfs_remove_group(bgrt_kobj, &bgrt_attribute_group);
 out_kobject:
 	kobject_put(bgrt_kobj);
-out_iounmap:
-	iounmap(image_attr.private);
-out_err:
 	return ret;
 }
 
-static void __exit bgrt_exit(void)
-{
-	iounmap(image_attr.private);
-	sysfs_remove_group(bgrt_kobj, &bgrt_attribute_group);
-	sysfs_remove_bin_file(bgrt_kobj, &image_attr);
-}
-
 module_init(bgrt_init);
-module_exit(bgrt_exit);
 
-MODULE_AUTHOR("Matthew Garrett");
+MODULE_AUTHOR("Matthew Garrett, Josh Triplett <[e-mail]>");
 MODULE_DESCRIPTION("BGRT boot graphic support");
 MODULE_LICENSE("GPL");

include/linux/efi-bgrt.h

···
+#ifndef _LINUX_EFI_BGRT_H
+#define _LINUX_EFI_BGRT_H
+
+#ifdef CONFIG_ACPI_BGRT
+
+#include <linux/acpi.h>
+
+void efi_bgrt_init(void);
+
+/* The BGRT data itself; only valid if bgrt_image != NULL. */
+extern void *bgrt_image;
+extern size_t bgrt_image_size;
+extern struct acpi_table_bgrt *bgrt_tab;
+
+#else /* !CONFIG_ACPI_BGRT */
+
+static inline void efi_bgrt_init(void) {}
+
+#endif /* !CONFIG_ACPI_BGRT */
+
+#endif /* _LINUX_EFI_BGRT_H */

include/linux/efi.h

···
 extern void efi_gettimeofday (struct timespec *ts);
 extern void efi_enter_virtual_mode (void);	/* switch EFI to virtual mode, if possible */
 #ifdef CONFIG_X86
+extern void efi_late_init(void);
 extern void efi_free_boot_services(void);
 #else
+static inline void efi_late_init(void) {}
 static inline void efi_free_boot_services(void) {}
 #endif
 extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);

init/main.c

···
 	acpi_early_init(); /* before LAPIC and SMP init */
 	sfi_init_late();
 
-	if (efi_enabled)
+	if (efi_enabled) {
+		efi_late_init();
 		efi_free_boot_services();
+	}
 
 	ftrace_init();