1 files changed, 93 insertions, 4 deletions

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;