9 files changed, 187 insertions, 9 deletions

diff --git a/Documentation/acpi/dsdt-override.txt b/Documentation/acpi/dsdt-override.txt
new file mode 100644
index 000000000000..5008f256a2db
--- /dev/null
+++ b/Documentation/acpi/dsdt-override.txt
@@ -0,0 +1,15 @@
+Linux supports two methods of overriding the BIOS DSDT:
+
+CONFIG_ACPI_CUSTOM_DSDT builds the image into the kernel.
+
+CONFIG_ACPI_CUSTOM_DSDT_INITRD adds the image to the initrd.
+
+When to use these methods is described in detail on the
+Linux/ACPI home page:
+http://www.lesswatts.org/projects/acpi/overridingDSDT.php
+
+Note that if both options are used, the DSDT supplied
+by the INITRD method takes precedence.
+
+Documentation/initramfs-add-dsdt.sh is provided for convenience
+for use with the CONFIG_ACPI_CUSTOM_DSDT_INITRD method.
diff --git a/Documentation/acpi/initramfs-add-dsdt.sh b/Documentation/acpi/initramfs-add-dsdt.sh
new file mode 100755
index 000000000000..17ef6e838e14
--- /dev/null
+++ b/Documentation/acpi/initramfs-add-dsdt.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+# Adds a DSDT file to the initrd (if it's an initramfs)
+# first argument is the name of archive
+# second argument is the name of the file to add
+# The file will be copied as /DSDT.aml
+
+# 20060126: fix "Premature end of file" with some old cpio (Roland Robic)
+# 20060205: this time it should really work
+
+# check the arguments
+if [ $# -ne 2 ]; then
+        program_name=$(basename $0)
+        echo "\
+$program_name: too few arguments
+Usage: $program_name initrd-name.img DSDT-to-add.aml
+Adds a DSDT file to an initrd (in initramfs format)
+
+  initrd-name.img: filename of the initrd in initramfs format
+  DSDT-to-add.aml: filename of the DSDT file to add
+  " 1>&2
+    exit 1
+fi
+
+# we should check it's an initramfs
+
+tempcpio=$(mktemp -d)
+# cleanup on exit, hangup, interrupt, quit, termination
+trap 'rm -rf $tempcpio' 0 1 2 3 15
+
+# extract the archive
+gunzip -c "$1" > "$tempcpio"/initramfs.cpio || exit 1
+
+# copy the DSDT file at the root of the directory so that we can call it "/DSDT.aml"
+cp -f "$2" "$tempcpio"/DSDT.aml
+
+# add the file
+cd "$tempcpio"
+(echo DSDT.aml | cpio --quiet -H newc -o -A -O "$tempcpio"/initramfs.cpio) || exit 1
+cd "$OLDPWD"
+
+# re-compress the archive
+gzip -c "$tempcpio"/initramfs.cpio > "$1"
+
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 8ea41b6e6a85..0dcbd266b442 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -177,6 +177,9 @@ and is between 256 and 4096 characters. It is defined in the file
 
         acpi_no_auto_ssdt       [HW,ACPI] Disable automatic loading of SSDT
 
+        acpi_no_initrd_override [KNL,ACPI]
+                        Disable loading custom ACPI tables from the initramfs
+
         acpi_os_name=   [HW,ACPI] Tell ACPI BIOS the name of the OS
                         Format: To spoof as Windows 98: ="Microsoft Windows"
 
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index d141bdb3a7d4..7ef172c2a1d6 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -276,8 +276,10 @@ config ACPI_CUSTOM_DSDT
         depends on !STANDALONE
         default n 
         help
-          This option is to load a custom ACPI DSDT
-          If you don't know what that is, say N.
+          This option supports a custom DSDT by linking it into the kernel.
+          See Documentation/acpi/dsdt-override.txt
+
+          If unsure, say N.
 
 config ACPI_CUSTOM_DSDT_FILE
         string "Custom DSDT Table file to include"
@@ -287,6 +289,17 @@ config ACPI_CUSTOM_DSDT_FILE
           Enter the full path name to the file which includes the AmlCode
           declaration.
 
+config ACPI_CUSTOM_DSDT_INITRD
+        bool "Read Custom DSDT from initramfs"
+        depends on BLK_DEV_INITRD
+        default n
+        help
+          This option supports a custom DSDT by optionally loading it from initrd.
+          See Documentation/acpi/dsdt-override.txt
+
+          If you are not using this feature now, but may use it later,
+          it is safe to say Y here.
+
 config ACPI_BLACKLIST_YEAR
         int "Disable ACPI for systems before Jan 1st this year" if X86_32
         default 0
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index c2c585366fa6..27ccd68b8f46 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -91,6 +91,10 @@ static DEFINE_SPINLOCK(acpi_res_lock);
 #define OSI_STRING_LENGTH_MAX 64        /* arbitrary */
 static char osi_additional_string[OSI_STRING_LENGTH_MAX];
 
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+static int acpi_no_initrd_override;
+#endif
+
 /*
  * "Ode to _OSI(Linux)"
  *
@@ -329,6 +333,67 @@ acpi_os_predefined_override(const struct acpi_predefined_names *init_val,
         return AE_OK;
 }
 
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+struct acpi_table_header *acpi_find_dsdt_initrd(void)
+{
+        struct file *firmware_file;
+        mm_segment_t oldfs;
+        unsigned long len, len2;
+        struct acpi_table_header *dsdt_buffer, *ret = NULL;
+        struct kstat stat;
+        char *ramfs_dsdt_name = "/DSDT.aml";
+
+        printk(KERN_INFO PREFIX "Checking initramfs for custom DSDT");
+
+        /*
+         * Never do this at home, only the user-space is allowed to open a file.
+         * The clean way would be to use the firmware loader.
+         * But this code must be run before there is any userspace available.
+         * A static/init firmware infrastructure doesn't exist yet...
+         */
+        if (vfs_stat(ramfs_dsdt_name, &stat) < 0)
+                return ret;
+
+        len = stat.size;
+        /* check especially against empty files */
+        if (len <= 4) {
+                printk(KERN_ERR PREFIX "Failed: DSDT only %lu bytes.\n", len);
+                return ret;
+        }
+
+        firmware_file = filp_open(ramfs_dsdt_name, O_RDONLY, 0);
+        if (IS_ERR(firmware_file)) {
+                printk(KERN_ERR PREFIX "Failed to open %s.\n", ramfs_dsdt_name);
+                return ret;
+        }
+
+        dsdt_buffer = kmalloc(len, GFP_ATOMIC);
+        if (!dsdt_buffer) {
+                printk(KERN_ERR PREFIX "Failed to allocate %lu bytes.\n", len);
+                goto err;
+        }
+
+        oldfs = get_fs();
+        set_fs(KERNEL_DS);
+        len2 = vfs_read(firmware_file, (char __user *)dsdt_buffer, len,
+                &firmware_file->f_pos);
+        set_fs(oldfs);
+        if (len2 < len) {
+                printk(KERN_ERR PREFIX "Failed to read %lu bytes from %s.\n",
+                        len, ramfs_dsdt_name);
+                ACPI_FREE(dsdt_buffer);
+                goto err;
+        }
+
+        printk(KERN_INFO PREFIX "Found %lu byte DSDT in %s.\n",
+                        len, ramfs_dsdt_name);
+        ret = dsdt_buffer;
+err:
+        filp_close(firmware_file, NULL);
+        return ret;
+}
+#endif
+
 acpi_status
 acpi_os_table_override(struct acpi_table_header * existing_table,
                        struct acpi_table_header ** new_table)
@@ -336,17 +401,41 @@ acpi_os_table_override(struct acpi_table_header * existing_table,
         if (!existing_table || !new_table)
                 return AE_BAD_PARAMETER;
 
+        *new_table = NULL;
+
 #ifdef CONFIG_ACPI_CUSTOM_DSDT
         if (strncmp(existing_table->signature, "DSDT", 4) == 0)
                 *new_table = (struct acpi_table_header *)AmlCode;
-        else
-                *new_table = NULL;
-#else
-        *new_table = NULL;
 #endif
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+        if ((strncmp(existing_table->signature, "DSDT", 4) == 0) &&
+            !acpi_no_initrd_override) {
+                struct acpi_table_header *initrd_table;
+
+                initrd_table = acpi_find_dsdt_initrd();
+                if (initrd_table)
+                        *new_table = initrd_table;
+        }
+#endif
+        if (*new_table != NULL) {
+                printk(KERN_WARNING PREFIX "Override [%4.4s-%8.8s], "
+                           "this is unsafe: tainting kernel\n",
+                       existing_table->signature,
+                       existing_table->oem_table_id);
+                add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
+        }
         return AE_OK;
 }
 
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+int __init acpi_no_initrd_override_setup(char *s)
+{
+        acpi_no_initrd_override = 1;
+        return 1;
+}
+__setup("acpi_no_initrd_override", acpi_no_initrd_override_setup);
+#endif
+
 static irqreturn_t acpi_irq(int irq, void *dev_id)
 {
         u32 handled;
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 18222f267bc4..9e01f376840a 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -243,6 +243,7 @@ extern enum system_states {
 #define TAINT_BAD_PAGE                  (1<<5)
 #define TAINT_USER                      (1<<6)
 #define TAINT_DIE                       (1<<7)
+#define TAINT_OVERRIDDEN_ACPI_TABLE     (1<<8)
 
 extern void dump_stack(void) __cold;
 
diff --git a/init/initramfs.c b/init/initramfs.c
index d53fee8d8604..c0b1e0533d80 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -538,7 +538,7 @@ skip:
         initrd_end = 0;
 }
 
-static int __init populate_rootfs(void)
+int __init populate_rootfs(void)
 {
         char *err = unpack_to_rootfs(__initramfs_start,
                          __initramfs_end - __initramfs_start, 0);
@@ -577,4 +577,10 @@ static int __init populate_rootfs(void)
         }
         return 0;
 }
+#ifndef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+/*
+ * if this option is enabled, populate_rootfs() is called _earlier_ in the
+ * boot sequence. This insures that the ACPI initialisation can find the file.
+ */
 rootfs_initcall(populate_rootfs);
+#endif
diff --git a/init/main.c b/init/main.c
index c691f5f7fc27..2a78932f6c07 100644
--- a/init/main.c
+++ b/init/main.c
@@ -102,6 +102,12 @@ static inline void mark_rodata_ro(void) { }
 extern void tc_init(void);
 #endif
 
+#ifdef CONFIG_ACPI_CUSTOM_DSDT_INITRD
+extern int populate_rootfs(void);
+#else
+static inline void populate_rootfs(void) {}
+#endif
+
 enum system_states system_state;
 EXPORT_SYMBOL(system_state);
 
@@ -648,6 +654,7 @@ asmlinkage void __init start_kernel(void)
 
         check_bugs();
 
+        populate_rootfs(); /* For DSDT override from initramfs */
         acpi_early_init(); /* before LAPIC and SMP init */
 
         /* Do the rest non-__init'ed, we're now alive */
diff --git a/kernel/panic.c b/kernel/panic.c
index d9e90cfe3298..24af9f8bac99 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -161,7 +161,7 @@ const char *print_tainted(void)
 {
         static char buf[20];
         if (tainted) {
-                snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c",
+                snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c%c",
                         tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
                         tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
                         tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
@@ -169,7 +169,8 @@ const char *print_tainted(void)
                         tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
                         tainted & TAINT_BAD_PAGE ? 'B' : ' ',
                         tainted & TAINT_USER ? 'U' : ' ',
-                        tainted & TAINT_DIE ? 'D' : ' ');
+                        tainted & TAINT_DIE ? 'D' : ' ',
+                        tainted & TAINT_OVERRIDDEN_ACPI_TABLE ? 'A' : ' ');
         }
         else
                 snprintf(buf, sizeof(buf), "Not tainted");