Merge branch 'x86-acpi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 ACPI update from Peter Anvin: "This is a patchset which didn't make the last merge window. It adds a debugging capability to feed ACPI tables via the initramfs. On a grander scope, it formalizes using the initramfs protocol for feeding arbitrary blobs which need to be accessed early to the kernel: they are fed first in the initramfs blob (lots of bootloaders can concatenate this at boot time, others can use a single file) in an uncompressed cpio archive using filenames starting with "kernel/". The ACPI maintainers requested that this patchset be fed via the x86 tree rather than the ACPI tree as the footprint in the general x86 code is much bigger than in the ACPI code proper." * 'x86-acpi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: X86 ACPI: Use #ifdef not #if for CONFIG_X86 check ACPI: Fix build when disabled ACPI: Document ACPI table overriding via initrd ACPI: Create acpi_table_taint() function to avoid code duplication ACPI: Implement physical address table override ACPI: Store valid ACPI tables passed via early initrd in reserved memblock areas x86, acpi: Introduce x86 arch specific arch_reserve_mem_area() for e820 handling lib: Add early cpio decoder

Merge branch 'x86-acpi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 ACPI update from Peter Anvin: "This is a patchset which didn't make the last merge window. It adds a debugging capability to feed ACPI tables via the initramfs. On a grander scope, it formalizes using the initramfs protocol for feeding arbitrary blobs which need to be accessed early to the kernel: they are fed first in the initramfs blob (lots of bootloaders can concatenate this at boot time, others can use a single file) in an uncompressed cpio archive using filenames starting with "kernel/". The ACPI maintainers requested that this patchset be fed via the x86 tree rather than the ACPI tree as the footprint in the general x86 code is much bigger than in the ACPI code proper." * 'x86-acpi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: X86 ACPI: Use #ifdef not #if for CONFIG_X86 check ACPI: Fix build when disabled ACPI: Document ACPI table overriding via initrd ACPI: Create acpi_table_taint() function to avoid code duplication ACPI: Implement physical address table override ACPI: Store valid ACPI tables passed via early initrd in reserved memblock areas x86, acpi: Introduce x86 arch specific arch_reserve_mem_area() for e820 handling lib: Add early cpio decoder
Linus Torvalds
2 parents 2d9c8b5d6a 385ddeac7e
Showing 9 changed files Side-by-side Diff
Documentation/acpi/initrd_table_override.txt
arch/x86/kernel/acpi/boot.c
arch/x86/kernel/setup.c
drivers/acpi/Kconfig
drivers/acpi/osl.c
include/linux/acpi.h
include/linux/earlycpio.h
lib/Makefile
lib/earlycpio.c
+Overriding ACPI tables via initrd
+=================================
+
+1) Introduction (What is this about)
+2) What is this for
+3) How does it work
+4) References (Where to retrieve userspace tools)
+
+1) What is this about
+---------------------
+
+If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible to
+override nearly any ACPI table provided by the BIOS with an instrumented,
+modified one.
+
+For a full list of ACPI tables that can be overridden, take a look at
+the char *table_sigs[MAX_ACPI_SIGNATURE]; definition in drivers/acpi/osl.c
+All ACPI tables iasl (Intel's ACPI compiler and disassembler) knows should
+be overridable, except:
+   - ACPI_SIG_RSDP (has a signature of 6 bytes)
+   - ACPI_SIG_FACS (does not have an ordinary ACPI table header)
+Both could get implemented as well.
+
+
+2) What is this for
+-------------------
+
+Please keep in mind that this is a debug option.
+ACPI tables should not get overridden for productive use.
+If BIOS ACPI tables are overridden the kernel will get tainted with the
+TAINT_OVERRIDDEN_ACPI_TABLE flag.
+Complain to your platform/BIOS vendor if you find a bug which is so sever
+that a workaround is not accepted in the Linux kernel.
+
+Still, it can and should be enabled in any kernel, because:
+  - There is no functional change with not instrumented initrds
+  - It provides a powerful feature to easily debug and test ACPI BIOS table
+    compatibility with the Linux kernel.
+
+
+3) How does it work
+-------------------
+
+# Extract the machine's ACPI tables:
+cd /tmp
+acpidump >acpidump
+acpixtract -a acpidump
+# Disassemble, modify and recompile them:
+iasl -d *.dat
+# For example add this statement into a _PRT (PCI Routing Table) function
+# of the DSDT:
+Store("HELLO WORLD", debug)
+iasl -sa dsdt.dsl
+# Add the raw ACPI tables to an uncompressed cpio archive.
+# They must be put into a /kernel/firmware/acpi directory inside the
+# cpio archive.
+# The uncompressed cpio archive must be the first.
+# Other, typically compressed cpio archives, must be
+# concatenated on top of the uncompressed one.
+mkdir -p kernel/firmware/acpi
+cp dsdt.aml kernel/firmware/acpi
+# A maximum of: #define ACPI_OVERRIDE_TABLES 10
+# tables are  currently allowed (see osl.c):
+iasl -sa facp.dsl
+iasl -sa ssdt1.dsl
+cp facp.aml kernel/firmware/acpi
+cp ssdt1.aml kernel/firmware/acpi
+# Create the uncompressed cpio archive and concatenate the original initrd
+# on top:
+find kernel | cpio -H newc --create > /boot/instrumented_initrd
+cat /boot/initrd >>/boot/instrumented_initrd
+# reboot with increased acpi debug level, e.g. boot params:
+acpi.debug_level=0x2 acpi.debug_layer=0xFFFFFFFF
+# and check your syslog:
+[    1.268089] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT]
+[    1.272091] [ACPI Debug]  String [0x0B] "HELLO WORLD"
+
+iasl is able to disassemble and recompile quite a lot different,
+also static ACPI tables.
+
+
+4) Where to retrieve userspace tools
+------------------------------------
+
+iasl and acpixtract are part of Intel's ACPICA project:
+http://acpica.org/
+and should be packaged by distributions (for example in the acpica package
+on SUSE).
+
+acpidump can be found in Len Browns pmtools:
+ftp://kernel.org/pub/linux/kernel/people/lenb/acpi/utils/pmtools/acpidump
+This tool is also part of the acpica package on SUSE.
+Alternatively, used ACPI tables can be retrieved via sysfs in latest kernels:
+/sys/firmware/acpi/tables
@@ -1706,4 +1706,10 @@
 	} while (unlikely (val != old));
 	return old & 0x1;
 }
+
+void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
+{
+	e820_add_region(addr, size, E820_ACPI);
+	update_e820();
+}
@@ -952,6 +952,10 @@
  
 	reserve_initrd();
  
+#if defined(CONFIG_ACPI) && defined(CONFIG_BLK_DEV_INITRD)
+	acpi_initrd_override((void *)initrd_start, initrd_end - initrd_start);
+#endif
+
 	reserve_crashkernel();
  
 	vsmp_init();
@@ -267,6 +267,15 @@
 	bool
 	default ACPI_CUSTOM_DSDT_FILE != ""
  
+config ACPI_INITRD_TABLE_OVERRIDE
+	bool "ACPI tables can be passed via uncompressed cpio in initrd"
+	default n
+	help
+	  This option provides functionality to override arbitrary ACPI tables
+	  via initrd. No functional change if no ACPI tables are passed via
+	  initrd, therefore it's safe to say Y.
+	  See Documentation/acpi/initrd_table_override.txt for details
+
 config ACPI_BLACKLIST_YEAR
 	int "Disable ACPI for systems before Jan 1st this year" if X86_32
 	default 0
@@ -534,6 +534,137 @@
 	return AE_OK;
 }
  
+#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
+#include <linux/earlycpio.h>
+#include <linux/memblock.h>
+
+static u64 acpi_tables_addr;
+static int all_tables_size;
+
+/* Copied from acpica/tbutils.c:acpi_tb_checksum() */
+u8 __init acpi_table_checksum(u8 *buffer, u32 length)
+{
+	u8 sum = 0;
+	u8 *end = buffer + length;
+
+	while (buffer < end)
+		sum = (u8) (sum + *(buffer++));
+	return sum;
+}
+
+/* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */
+static const char * const table_sigs[] = {
+	ACPI_SIG_BERT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, ACPI_SIG_EINJ,
+	ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT, ACPI_SIG_MSCT,
+	ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT, ACPI_SIG_ASF,
+	ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR, ACPI_SIG_HPET,
+	ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG, ACPI_SIG_MCHI,
+	ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA,
+	ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT,
+	ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT,
+	ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, NULL };
+
+/* Non-fatal errors: Affected tables/files are ignored */
+#define INVALID_TABLE(x, path, name)					\
+	{ pr_err("ACPI OVERRIDE: " x " [%s%s]\n", path, name); continue; }
+
+#define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)
+
+/* Must not increase 10 or needs code modification below */
+#define ACPI_OVERRIDE_TABLES 10
+
+void __init acpi_initrd_override(void *data, size_t size)
+{
+	int sig, no, table_nr = 0, total_offset = 0;
+	long offset = 0;
+	struct acpi_table_header *table;
+	char cpio_path[32] = "kernel/firmware/acpi/";
+	struct cpio_data file;
+	struct cpio_data early_initrd_files[ACPI_OVERRIDE_TABLES];
+	char *p;
+
+	if (data == NULL || size == 0)
+		return;
+
+	for (no = 0; no < ACPI_OVERRIDE_TABLES; no++) {
+		file = find_cpio_data(cpio_path, data, size, &offset);
+		if (!file.data)
+			break;
+
+		data += offset;
+		size -= offset;
+
+		if (file.size < sizeof(struct acpi_table_header))
+			INVALID_TABLE("Table smaller than ACPI header",
+				      cpio_path, file.name);
+
+		table = file.data;
+
+		for (sig = 0; table_sigs[sig]; sig++)
+			if (!memcmp(table->signature, table_sigs[sig], 4))
+				break;
+
+		if (!table_sigs[sig])
+			INVALID_TABLE("Unknown signature",
+				      cpio_path, file.name);
+		if (file.size != table->length)
+			INVALID_TABLE("File length does not match table length",
+				      cpio_path, file.name);
+		if (acpi_table_checksum(file.data, table->length))
+			INVALID_TABLE("Bad table checksum",
+				      cpio_path, file.name);
+
+		pr_info("%4.4s ACPI table found in initrd [%s%s][0x%x]\n",
+			table->signature, cpio_path, file.name, table->length);
+
+		all_tables_size += table->length;
+		early_initrd_files[table_nr].data = file.data;
+		early_initrd_files[table_nr].size = file.size;
+		table_nr++;
+	}
+	if (table_nr == 0)
+		return;
+
+	acpi_tables_addr =
+		memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT,
+				       all_tables_size, PAGE_SIZE);
+	if (!acpi_tables_addr) {
+		WARN_ON(1);
+		return;
+	}
+	/*
+	 * Only calling e820_add_reserve does not work and the
+	 * tables are invalid (memory got used) later.
+	 * memblock_reserve works as expected and the tables won't get modified.
+	 * But it's not enough on X86 because ioremap will
+	 * complain later (used by acpi_os_map_memory) that the pages
+	 * that should get mapped are not marked "reserved".
+	 * Both memblock_reserve and e820_add_region (via arch_reserve_mem_area)
+	 * works fine.
+	 */
+	memblock_reserve(acpi_tables_addr, acpi_tables_addr + all_tables_size);
+	arch_reserve_mem_area(acpi_tables_addr, all_tables_size);
+
+	p = early_ioremap(acpi_tables_addr, all_tables_size);
+
+	for (no = 0; no < table_nr; no++) {
+		memcpy(p + total_offset, early_initrd_files[no].data,
+		       early_initrd_files[no].size);
+		total_offset += early_initrd_files[no].size;
+	}
+	early_iounmap(p, all_tables_size);
+}
+#endif /* CONFIG_ACPI_INITRD_TABLE_OVERRIDE */
+
+static void acpi_table_taint(struct acpi_table_header *table)
+{
+	pr_warn(PREFIX
+		"Override [%4.4s-%8.8s], this is unsafe: tainting kernel\n",
+		table->signature, table->oem_table_id);
+	add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
+}
+
+
 acpi_status
 acpi_os_table_override(struct acpi_table_header * existing_table,
 		       struct acpi_table_header ** new_table)
  
  
  
@@ -547,24 +678,73 @@
 	if (strncmp(existing_table->signature, "DSDT", 4) == 0)
 		*new_table = (struct acpi_table_header *)AmlCode;
 #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);
-	}
+	if (*new_table != NULL)
+		acpi_table_taint(existing_table);
 	return AE_OK;
 }
  
 acpi_status
 acpi_os_physical_table_override(struct acpi_table_header *existing_table,
-				acpi_physical_address * new_address,
-				u32 *new_table_length)
+				acpi_physical_address *address,
+				u32 *table_length)
 {
-	return AE_SUPPORT;
-}
+#ifndef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
+	*table_length = 0;
+	*address = 0;
+	return AE_OK;
+#else
+	int table_offset = 0;
+	struct acpi_table_header *table;
  
+	*table_length = 0;
+	*address = 0;
+
+	if (!acpi_tables_addr)
+		return AE_OK;
+
+	do {
+		if (table_offset + ACPI_HEADER_SIZE > all_tables_size) {
+			WARN_ON(1);
+			return AE_OK;
+		}
+
+		table = acpi_os_map_memory(acpi_tables_addr + table_offset,
+					   ACPI_HEADER_SIZE);
+
+		if (table_offset + table->length > all_tables_size) {
+			acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+			WARN_ON(1);
+			return AE_OK;
+		}
+
+		table_offset += table->length;
+
+		if (memcmp(existing_table->signature, table->signature, 4)) {
+			acpi_os_unmap_memory(table,
+				     ACPI_HEADER_SIZE);
+			continue;
+		}
+
+		/* Only override tables with matching oem id */
+		if (memcmp(table->oem_table_id, existing_table->oem_table_id,
+			   ACPI_OEM_TABLE_ID_SIZE)) {
+			acpi_os_unmap_memory(table,
+				     ACPI_HEADER_SIZE);
+			continue;
+		}
+
+		table_offset -= table->length;
+		*table_length = table->length;
+		acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
+		*address = acpi_tables_addr + table_offset;
+		break;
+	} while (table_offset + ACPI_HEADER_SIZE < all_tables_size);
+
+	if (*address != 0)
+		acpi_table_taint(existing_table);
+	return AE_OK;
+#endif
+}
  
 static irqreturn_t acpi_irq(int irq, void *dev_id)
 {
@@ -78,6 +78,14 @@
  
 typedef int (*acpi_table_entry_handler) (struct acpi_subtable_header *header, const unsigned long end);
  
+#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
+void acpi_initrd_override(void *data, size_t size);
+#else
+static inline void acpi_initrd_override(void *data, size_t size)
+{
+}
+#endif
+
 char * __acpi_map_table (unsigned long phys_addr, unsigned long size);
 void __acpi_unmap_table(char *map, unsigned long size);
 int early_acpi_boot_init(void);
@@ -479,6 +487,14 @@
  
 acpi_status acpi_os_prepare_sleep(u8 sleep_state,
 				  u32 pm1a_control, u32 pm1b_control);
+#ifdef CONFIG_X86
+void arch_reserve_mem_area(acpi_physical_address addr, size_t size);
+#else
+static inline void arch_reserve_mem_area(acpi_physical_address addr,
+					  size_t size)
+{
+}
+#endif /* CONFIG_X86 */
 #else
 #define acpi_os_set_prepare_sleep(func, pm1a_ctrl, pm1b_ctrl) do { } while (0)
 #endif
+#ifndef _LINUX_EARLYCPIO_H
+#define _LINUX_EARLYCPIO_H
+
+#include <linux/types.h>
+
+#define MAX_CPIO_FILE_NAME 18
+
+struct cpio_data {
+	void *data;
+	size_t size;
+	char name[MAX_CPIO_FILE_NAME];
+};
+
+struct cpio_data find_cpio_data(const char *path, void *data, size_t len,
+				long *offset);
+
+#endif /* _LINUX_EARLYCPIO_H */
@@ -12,7 +12,8 @@
 	 idr.o int_sqrt.o extable.o \
 	 sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
-	 is_single_threaded.o plist.o decompress.o kobject_uevent.o
+	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
+	 earlycpio.o
  
 lib-$(CONFIG_MMU) += ioremap.o
 lib-$(CONFIG_SMP) += cpumask.o
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2012 Intel Corporation; author H. Peter Anvin
+ *
+ *   This file is part of the Linux kernel, and is made available
+ *   under the terms of the GNU General Public License version 2, as
+ *   published by the Free Software Foundation.
+ *
+ *   This program is distributed in the hope it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *   General Public License for more details.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * earlycpio.c
+ *
+ * Find a specific cpio member; must precede any compressed content.
+ * This is used to locate data items in the initramfs used by the
+ * kernel itself during early boot (before the main initramfs is
+ * decompressed.)  It is the responsibility of the initramfs creator
+ * to ensure that these items are uncompressed at the head of the
+ * blob.  Depending on the boot loader or package tool that may be a
+ * separate file or part of the same file.
+ */
+
+#include <linux/earlycpio.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+
+enum cpio_fields {
+	C_MAGIC,
+	C_INO,
+	C_MODE,
+	C_UID,
+	C_GID,
+	C_NLINK,
+	C_MTIME,
+	C_FILESIZE,
+	C_MAJ,
+	C_MIN,
+	C_RMAJ,
+	C_RMIN,
+	C_NAMESIZE,
+	C_CHKSUM,
+	C_NFIELDS
+};
+
+/**
+ * cpio_data find_cpio_data - Search for files in an uncompressed cpio
+ * @path:   The directory to search for, including a slash at the end
+ * @data:   Pointer to the the cpio archive or a header inside
+ * @len:    Remaining length of the cpio based on data pointer
+ * @offset: When a matching file is found, this is the offset to the
+ *          beginning of the cpio. It can be used to iterate through
+ *          the cpio to find all files inside of a directory path
+ *
+ * @return: struct cpio_data containing the address, length and
+ *          filename (with the directory path cut off) of the found file.
+ *          If you search for a filename and not for files in a directory,
+ *          pass the absolute path of the filename in the cpio and make sure
+ *          the match returned an empty filename string.
+ */
+
+struct cpio_data __cpuinit find_cpio_data(const char *path, void *data,
+					  size_t len,  long *offset)
+{
+	const size_t cpio_header_len = 8*C_NFIELDS - 2;
+	struct cpio_data cd = { NULL, 0, "" };
+	const char *p, *dptr, *nptr;
+	unsigned int ch[C_NFIELDS], *chp, v;
+	unsigned char c, x;
+	size_t mypathsize = strlen(path);
+	int i, j;
+
+	p = data;
+
+	while (len > cpio_header_len) {
+		if (!*p) {
+			/* All cpio headers need to be 4-byte aligned */
+			p += 4;
+			len -= 4;
+			continue;
+		}
+
+		j = 6;		/* The magic field is only 6 characters */
+		chp = ch;
+		for (i = C_NFIELDS; i; i--) {
+			v = 0;
+			while (j--) {
+				v <<= 4;
+				c = *p++;
+
+				x = c - '0';
+				if (x < 10) {
+					v += x;
+					continue;
+				}
+
+				x = (c | 0x20) - 'a';
+				if (x < 6) {
+					v += x + 10;
+					continue;
+				}
+
+				goto quit; /* Invalid hexadecimal */
+			}
+			*chp++ = v;
+			j = 8;	/* All other fields are 8 characters */
+		}
+
+		if ((ch[C_MAGIC] - 0x070701) > 1)
+			goto quit; /* Invalid magic */
+
+		len -= cpio_header_len;
+
+		dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);
+		nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4);
+
+		if (nptr > p + len || dptr < p || nptr < dptr)
+			goto quit; /* Buffer overrun */
+
+		if ((ch[C_MODE] & 0170000) == 0100000 &&
+		    ch[C_NAMESIZE] >= mypathsize &&
+		    !memcmp(p, path, mypathsize)) {
+			*offset = (long)nptr - (long)data;
+			if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
+				pr_warn(
+				"File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",
+				p, MAX_CPIO_FILE_NAME);
+			}
+			strlcpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME);
+
+			cd.data = (void *)dptr;
+			cd.size = ch[C_FILESIZE];
+			return cd; /* Found it! */
+		}
+		len -= (nptr - p);
+		p = nptr;
+	}
+
+quit:
+	return cd;
+}
	1	+Overriding ACPI tables via initrd
	2	+=================================
	3	+
	4	+1) Introduction (What is this about)
	5	+2) What is this for
	6	+3) How does it work
	7	+4) References (Where to retrieve userspace tools)
	8	+
	9	+1) What is this about
	10	+---------------------
	11	+
	12	+If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible to
	13	+override nearly any ACPI table provided by the BIOS with an instrumented,
	14	+modified one.
	15	+
	16	+For a full list of ACPI tables that can be overridden, take a look at
	17	+the char *table_sigs[MAX_ACPI_SIGNATURE]; definition in drivers/acpi/osl.c
	18	+All ACPI tables iasl (Intel's ACPI compiler and disassembler) knows should
	19	+be overridable, except:
	20	+ - ACPI_SIG_RSDP (has a signature of 6 bytes)
	21	+ - ACPI_SIG_FACS (does not have an ordinary ACPI table header)
	22	+Both could get implemented as well.
	23	+
	24	+
	25	+2) What is this for
	26	+-------------------
	27	+
	28	+Please keep in mind that this is a debug option.
	29	+ACPI tables should not get overridden for productive use.
	30	+If BIOS ACPI tables are overridden the kernel will get tainted with the
	31	+TAINT_OVERRIDDEN_ACPI_TABLE flag.
	32	+Complain to your platform/BIOS vendor if you find a bug which is so sever
	33	+that a workaround is not accepted in the Linux kernel.
	34	+
	35	+Still, it can and should be enabled in any kernel, because:
	36	+ - There is no functional change with not instrumented initrds
	37	+ - It provides a powerful feature to easily debug and test ACPI BIOS table
	38	+ compatibility with the Linux kernel.
	39	+
	40	+
	41	+3) How does it work
	42	+-------------------
	43	+
	44	+# Extract the machine's ACPI tables:
	45	+cd /tmp
	46	+acpidump >acpidump
	47	+acpixtract -a acpidump
	48	+# Disassemble, modify and recompile them:
	49	+iasl -d *.dat
	50	+# For example add this statement into a _PRT (PCI Routing Table) function
	51	+# of the DSDT:
	52	+Store("HELLO WORLD", debug)
	53	+iasl -sa dsdt.dsl
	54	+# Add the raw ACPI tables to an uncompressed cpio archive.
	55	+# They must be put into a /kernel/firmware/acpi directory inside the
	56	+# cpio archive.
	57	+# The uncompressed cpio archive must be the first.
	58	+# Other, typically compressed cpio archives, must be
	59	+# concatenated on top of the uncompressed one.
	60	+mkdir -p kernel/firmware/acpi
	61	+cp dsdt.aml kernel/firmware/acpi
	62	+# A maximum of: #define ACPI_OVERRIDE_TABLES 10
	63	+# tables are currently allowed (see osl.c):
	64	+iasl -sa facp.dsl
	65	+iasl -sa ssdt1.dsl
	66	+cp facp.aml kernel/firmware/acpi
	67	+cp ssdt1.aml kernel/firmware/acpi
	68	+# Create the uncompressed cpio archive and concatenate the original initrd
	69	+# on top:
	70	+find kernel \| cpio -H newc --create > /boot/instrumented_initrd
	71	+cat /boot/initrd >>/boot/instrumented_initrd
	72	+# reboot with increased acpi debug level, e.g. boot params:
	73	+acpi.debug_level=0x2 acpi.debug_layer=0xFFFFFFFF
	74	+# and check your syslog:
	75	+[ 1.268089] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT]
	76	+[ 1.272091] [ACPI Debug] String [0x0B] "HELLO WORLD"
	77	+
	78	+iasl is able to disassemble and recompile quite a lot different,
	79	+also static ACPI tables.
	80	+
	81	+
	82	+4) Where to retrieve userspace tools
	83	+------------------------------------
	84	+
	85	+iasl and acpixtract are part of Intel's ACPICA project:
	86	+http://acpica.org/
	87	+and should be packaged by distributions (for example in the acpica package
	88	+on SUSE).
	89	+
	90	+acpidump can be found in Len Browns pmtools:
	91	+ftp://kernel.org/pub/linux/kernel/people/lenb/acpi/utils/pmtools/acpidump
	92	+This tool is also part of the acpica package on SUSE.
	93	+Alternatively, used ACPI tables can be retrieved via sysfs in latest kernels:
	94	+/sys/firmware/acpi/tables
...	...	@@ -1706,4 +1706,10 @@
1706	1706	} while (unlikely (val != old));
1707	1707	return old & 0x1;
1708	1708	}
	1709	+
	1710	+void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
	1711	+{
	1712	+ e820_add_region(addr, size, E820_ACPI);
	1713	+ update_e820();
	1714	+}
...	...	@@ -952,6 +952,10 @@
952	952
953	953	reserve_initrd();
954	954
	955	+#if defined(CONFIG_ACPI) && defined(CONFIG_BLK_DEV_INITRD)
	956	+ acpi_initrd_override((void *)initrd_start, initrd_end - initrd_start);
	957	+#endif
	958	+
955	959	reserve_crashkernel();
956	960
957	961	vsmp_init();
...	...	@@ -267,6 +267,15 @@
267	267	bool
268	268	default ACPI_CUSTOM_DSDT_FILE != ""
269	269
	270	+config ACPI_INITRD_TABLE_OVERRIDE
	271	+ bool "ACPI tables can be passed via uncompressed cpio in initrd"
	272	+ default n
	273	+ help
	274	+ This option provides functionality to override arbitrary ACPI tables
	275	+ via initrd. No functional change if no ACPI tables are passed via
	276	+ initrd, therefore it's safe to say Y.
	277	+ See Documentation/acpi/initrd_table_override.txt for details
	278	+
270	279	config ACPI_BLACKLIST_YEAR
271	280	int "Disable ACPI for systems before Jan 1st this year" if X86_32
272	281	default 0
...	...	@@ -534,6 +534,137 @@
534	534	return AE_OK;
535	535	}
536	536
	537	+#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
	538	+#include <linux/earlycpio.h>
	539	+#include <linux/memblock.h>
	540	+
	541	+static u64 acpi_tables_addr;
	542	+static int all_tables_size;
	543	+
	544	+/* Copied from acpica/tbutils.c:acpi_tb_checksum() */
	545	+u8 __init acpi_table_checksum(u8 *buffer, u32 length)
	546	+{
	547	+ u8 sum = 0;
	548	+ u8 *end = buffer + length;
	549	+
	550	+ while (buffer < end)
	551	+ sum = (u8) (sum + *(buffer++));
	552	+ return sum;
	553	+}
	554	+
	555	+/* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */
	556	+static const char * const table_sigs[] = {
	557	+ ACPI_SIG_BERT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, ACPI_SIG_EINJ,
	558	+ ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT, ACPI_SIG_MSCT,
	559	+ ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT, ACPI_SIG_ASF,
	560	+ ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR, ACPI_SIG_HPET,
	561	+ ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG, ACPI_SIG_MCHI,
	562	+ ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA,
	563	+ ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT,
	564	+ ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT,
	565	+ ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, NULL };
	566	+
	567	+/* Non-fatal errors: Affected tables/files are ignored */
	568	+#define INVALID_TABLE(x, path, name) \
	569	+ { pr_err("ACPI OVERRIDE: " x " [%s%s]\n", path, name); continue; }
	570	+
	571	+#define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)
	572	+
	573	+/* Must not increase 10 or needs code modification below */
	574	+#define ACPI_OVERRIDE_TABLES 10
	575	+
	576	+void __init acpi_initrd_override(void *data, size_t size)
	577	+{
	578	+ int sig, no, table_nr = 0, total_offset = 0;
	579	+ long offset = 0;
	580	+ struct acpi_table_header *table;
	581	+ char cpio_path[32] = "kernel/firmware/acpi/";
	582	+ struct cpio_data file;
	583	+ struct cpio_data early_initrd_files[ACPI_OVERRIDE_TABLES];
	584	+ char *p;
	585	+
	586	+ if (data == NULL \|\| size == 0)
	587	+ return;
	588	+
	589	+ for (no = 0; no < ACPI_OVERRIDE_TABLES; no++) {
	590	+ file = find_cpio_data(cpio_path, data, size, &offset);
	591	+ if (!file.data)
	592	+ break;
	593	+
	594	+ data += offset;
	595	+ size -= offset;
	596	+
	597	+ if (file.size < sizeof(struct acpi_table_header))
	598	+ INVALID_TABLE("Table smaller than ACPI header",
	599	+ cpio_path, file.name);
	600	+
	601	+ table = file.data;
	602	+
	603	+ for (sig = 0; table_sigs[sig]; sig++)
	604	+ if (!memcmp(table->signature, table_sigs[sig], 4))
	605	+ break;
	606	+
	607	+ if (!table_sigs[sig])
	608	+ INVALID_TABLE("Unknown signature",
	609	+ cpio_path, file.name);
	610	+ if (file.size != table->length)
	611	+ INVALID_TABLE("File length does not match table length",
	612	+ cpio_path, file.name);
	613	+ if (acpi_table_checksum(file.data, table->length))
	614	+ INVALID_TABLE("Bad table checksum",
	615	+ cpio_path, file.name);
	616	+
	617	+ pr_info("%4.4s ACPI table found in initrd [%s%s][0x%x]\n",
	618	+ table->signature, cpio_path, file.name, table->length);
	619	+
	620	+ all_tables_size += table->length;
	621	+ early_initrd_files[table_nr].data = file.data;
	622	+ early_initrd_files[table_nr].size = file.size;
	623	+ table_nr++;
	624	+ }
	625	+ if (table_nr == 0)
	626	+ return;
	627	+
	628	+ acpi_tables_addr =
	629	+ memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT,
	630	+ all_tables_size, PAGE_SIZE);
	631	+ if (!acpi_tables_addr) {
	632	+ WARN_ON(1);
	633	+ return;
	634	+ }
	635	+ /*
	636	+ * Only calling e820_add_reserve does not work and the
	637	+ * tables are invalid (memory got used) later.
	638	+ * memblock_reserve works as expected and the tables won't get modified.
	639	+ * But it's not enough on X86 because ioremap will
	640	+ * complain later (used by acpi_os_map_memory) that the pages
	641	+ * that should get mapped are not marked "reserved".
	642	+ * Both memblock_reserve and e820_add_region (via arch_reserve_mem_area)
	643	+ * works fine.
	644	+ */
	645	+ memblock_reserve(acpi_tables_addr, acpi_tables_addr + all_tables_size);
	646	+ arch_reserve_mem_area(acpi_tables_addr, all_tables_size);
	647	+
	648	+ p = early_ioremap(acpi_tables_addr, all_tables_size);
	649	+
	650	+ for (no = 0; no < table_nr; no++) {
	651	+ memcpy(p + total_offset, early_initrd_files[no].data,
	652	+ early_initrd_files[no].size);
	653	+ total_offset += early_initrd_files[no].size;
	654	+ }
	655	+ early_iounmap(p, all_tables_size);
	656	+}
	657	+#endif /* CONFIG_ACPI_INITRD_TABLE_OVERRIDE */
	658	+
	659	+static void acpi_table_taint(struct acpi_table_header *table)
	660	+{
	661	+ pr_warn(PREFIX
	662	+ "Override [%4.4s-%8.8s], this is unsafe: tainting kernel\n",
	663	+ table->signature, table->oem_table_id);
	664	+ add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
	665	+}
	666	+
	667	+
537	668	acpi_status
538	669	acpi_os_table_override(struct acpi_table_header * existing_table,
539	670	struct acpi_table_header ** new_table)
540	671
541	672
542	673
...	...	@@ -547,24 +678,73 @@
547	678	if (strncmp(existing_table->signature, "DSDT", 4) == 0)
548	679	new_table = (struct acpi_table_header )AmlCode;
549	680	#endif
550		- if (*new_table != NULL) {
551		- printk(KERN_WARNING PREFIX "Override [%4.4s-%8.8s], "
552		- "this is unsafe: tainting kernel\n",
553		- existing_table->signature,
554		- existing_table->oem_table_id);
555		- add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
556		- }
	681	+ if (*new_table != NULL)
	682	+ acpi_table_taint(existing_table);
557	683	return AE_OK;
558	684	}
559	685
560	686	acpi_status
561	687	acpi_os_physical_table_override(struct acpi_table_header *existing_table,
562		- acpi_physical_address * new_address,
563		- u32 *new_table_length)
	688	+ acpi_physical_address *address,
	689	+ u32 *table_length)
564	690	{
565		- return AE_SUPPORT;
566		-}
	691	+#ifndef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
	692	+ *table_length = 0;
	693	+ *address = 0;
	694	+ return AE_OK;
	695	+#else
	696	+ int table_offset = 0;
	697	+ struct acpi_table_header *table;
567	698
	699	+ *table_length = 0;
	700	+ *address = 0;
	701	+
	702	+ if (!acpi_tables_addr)
	703	+ return AE_OK;
	704	+
	705	+ do {
	706	+ if (table_offset + ACPI_HEADER_SIZE > all_tables_size) {
	707	+ WARN_ON(1);
	708	+ return AE_OK;
	709	+ }
	710	+
	711	+ table = acpi_os_map_memory(acpi_tables_addr + table_offset,
	712	+ ACPI_HEADER_SIZE);
	713	+
	714	+ if (table_offset + table->length > all_tables_size) {
	715	+ acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
	716	+ WARN_ON(1);
	717	+ return AE_OK;
	718	+ }
	719	+
	720	+ table_offset += table->length;
	721	+
	722	+ if (memcmp(existing_table->signature, table->signature, 4)) {
	723	+ acpi_os_unmap_memory(table,
	724	+ ACPI_HEADER_SIZE);
	725	+ continue;
	726	+ }
	727	+
	728	+ /* Only override tables with matching oem id */
	729	+ if (memcmp(table->oem_table_id, existing_table->oem_table_id,
	730	+ ACPI_OEM_TABLE_ID_SIZE)) {
	731	+ acpi_os_unmap_memory(table,
	732	+ ACPI_HEADER_SIZE);
	733	+ continue;
	734	+ }
	735	+
	736	+ table_offset -= table->length;
	737	+ *table_length = table->length;
	738	+ acpi_os_unmap_memory(table, ACPI_HEADER_SIZE);
	739	+ *address = acpi_tables_addr + table_offset;
	740	+ break;
	741	+ } while (table_offset + ACPI_HEADER_SIZE < all_tables_size);
	742	+
	743	+ if (*address != 0)
	744	+ acpi_table_taint(existing_table);
	745	+ return AE_OK;
	746	+#endif
	747	+}
568	748
569	749	static irqreturn_t acpi_irq(int irq, void *dev_id)
570	750	{
...	...	@@ -78,6 +78,14 @@
78	78
79	79	typedef int (acpi_table_entry_handler) (struct acpi_subtable_header header, const unsigned long end);
80	80
	81	+#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
	82	+void acpi_initrd_override(void *data, size_t size);
	83	+#else
	84	+static inline void acpi_initrd_override(void *data, size_t size)
	85	+{
	86	+}
	87	+#endif
	88	+
81	89	char * __acpi_map_table (unsigned long phys_addr, unsigned long size);
82	90	void __acpi_unmap_table(char *map, unsigned long size);
83	91	int early_acpi_boot_init(void);
...	...	@@ -479,6 +487,14 @@
479	487
480	488	acpi_status acpi_os_prepare_sleep(u8 sleep_state,
481	489	u32 pm1a_control, u32 pm1b_control);
	490	+#ifdef CONFIG_X86
	491	+void arch_reserve_mem_area(acpi_physical_address addr, size_t size);
	492	+#else
	493	+static inline void arch_reserve_mem_area(acpi_physical_address addr,
	494	+ size_t size)
	495	+{
	496	+}
	497	+#endif /* CONFIG_X86 */
482	498	#else
483	499	#define acpi_os_set_prepare_sleep(func, pm1a_ctrl, pm1b_ctrl) do { } while (0)
484	500	#endif
	1	+#ifndef _LINUX_EARLYCPIO_H
	2	+#define _LINUX_EARLYCPIO_H
	3	+
	4	+#include <linux/types.h>
	5	+
	6	+#define MAX_CPIO_FILE_NAME 18
	7	+
	8	+struct cpio_data {
	9	+ void *data;
	10	+ size_t size;
	11	+ char name[MAX_CPIO_FILE_NAME];
	12	+};
	13	+
	14	+struct cpio_data find_cpio_data(const char path, void data, size_t len,
	15	+ long *offset);
	16	+
	17	+#endif /* _LINUX_EARLYCPIO_H */
...	...	@@ -12,7 +12,8 @@
12	12	idr.o int_sqrt.o extable.o \
13	13	sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
14	14	proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
15		- is_single_threaded.o plist.o decompress.o kobject_uevent.o
	15	+ is_single_threaded.o plist.o decompress.o kobject_uevent.o \
	16	+ earlycpio.o
16	17
17	18	lib-$(CONFIG_MMU) += ioremap.o
18	19	lib-$(CONFIG_SMP) += cpumask.o
	1	+/* ----------------------------------------------------------------------- *
	2	+ *
	3	+ * Copyright 2012 Intel Corporation; author H. Peter Anvin
	4	+ *
	5	+ * This file is part of the Linux kernel, and is made available
	6	+ * under the terms of the GNU General Public License version 2, as
	7	+ * published by the Free Software Foundation.
	8	+ *
	9	+ * This program is distributed in the hope it will be useful, but
	10	+ * WITHOUT ANY WARRANTY; without even the implied warranty of
	11	+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	12	+ * General Public License for more details.
	13	+ *
	14	+ * ----------------------------------------------------------------------- */
	15	+
	16	+/*
	17	+ * earlycpio.c
	18	+ *
	19	+ * Find a specific cpio member; must precede any compressed content.
	20	+ * This is used to locate data items in the initramfs used by the
	21	+ * kernel itself during early boot (before the main initramfs is
	22	+ * decompressed.) It is the responsibility of the initramfs creator
	23	+ * to ensure that these items are uncompressed at the head of the
	24	+ * blob. Depending on the boot loader or package tool that may be a
	25	+ * separate file or part of the same file.
	26	+ */
	27	+
	28	+#include <linux/earlycpio.h>
	29	+#include <linux/kernel.h>
	30	+#include <linux/string.h>
	31	+
	32	+enum cpio_fields {
	33	+ C_MAGIC,
	34	+ C_INO,
	35	+ C_MODE,
	36	+ C_UID,
	37	+ C_GID,
	38	+ C_NLINK,
	39	+ C_MTIME,
	40	+ C_FILESIZE,
	41	+ C_MAJ,
	42	+ C_MIN,
	43	+ C_RMAJ,
	44	+ C_RMIN,
	45	+ C_NAMESIZE,
	46	+ C_CHKSUM,
	47	+ C_NFIELDS
	48	+};
	49	+
	50	+/**
	51	+ * cpio_data find_cpio_data - Search for files in an uncompressed cpio
	52	+ * @path: The directory to search for, including a slash at the end
	53	+ * @data: Pointer to the the cpio archive or a header inside
	54	+ * @len: Remaining length of the cpio based on data pointer
	55	+ * @offset: When a matching file is found, this is the offset to the
	56	+ * beginning of the cpio. It can be used to iterate through
	57	+ * the cpio to find all files inside of a directory path
	58	+ *
	59	+ * @return: struct cpio_data containing the address, length and
	60	+ * filename (with the directory path cut off) of the found file.
	61	+ * If you search for a filename and not for files in a directory,
	62	+ * pass the absolute path of the filename in the cpio and make sure
	63	+ * the match returned an empty filename string.
	64	+ */
	65	+
	66	+struct cpio_data __cpuinit find_cpio_data(const char path, void data,
	67	+ size_t len, long *offset)
	68	+{
	69	+ const size_t cpio_header_len = 8*C_NFIELDS - 2;
	70	+ struct cpio_data cd = { NULL, 0, "" };
	71	+ const char p, dptr, *nptr;
	72	+ unsigned int ch[C_NFIELDS], *chp, v;
	73	+ unsigned char c, x;
	74	+ size_t mypathsize = strlen(path);
	75	+ int i, j;
	76	+
	77	+ p = data;
	78	+
	79	+ while (len > cpio_header_len) {
	80	+ if (!*p) {
	81	+ /* All cpio headers need to be 4-byte aligned */
	82	+ p += 4;
	83	+ len -= 4;
	84	+ continue;
	85	+ }
	86	+
	87	+ j = 6; /* The magic field is only 6 characters */
	88	+ chp = ch;
	89	+ for (i = C_NFIELDS; i; i--) {
	90	+ v = 0;
	91	+ while (j--) {
	92	+ v <<= 4;
	93	+ c = *p++;
	94	+
	95	+ x = c - '0';
	96	+ if (x < 10) {
	97	+ v += x;
	98	+ continue;
	99	+ }
	100	+
	101	+ x = (c \| 0x20) - 'a';
	102	+ if (x < 6) {
	103	+ v += x + 10;
	104	+ continue;
	105	+ }
	106	+
	107	+ goto quit; /* Invalid hexadecimal */
	108	+ }
	109	+ *chp++ = v;
	110	+ j = 8; /* All other fields are 8 characters */
	111	+ }
	112	+
	113	+ if ((ch[C_MAGIC] - 0x070701) > 1)
	114	+ goto quit; /* Invalid magic */
	115	+
	116	+ len -= cpio_header_len;
	117	+
	118	+ dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);
	119	+ nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4);
	120	+
	121	+ if (nptr > p + len \|\| dptr < p \|\| nptr < dptr)
	122	+ goto quit; /* Buffer overrun */
	123	+
	124	+ if ((ch[C_MODE] & 0170000) == 0100000 &&
	125	+ ch[C_NAMESIZE] >= mypathsize &&
	126	+ !memcmp(p, path, mypathsize)) {
	127	+ *offset = (long)nptr - (long)data;
	128	+ if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
	129	+ pr_warn(
	130	+ "File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",
	131	+ p, MAX_CPIO_FILE_NAME);
	132	+ }
	133	+ strlcpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME);
	134	+
	135	+ cd.data = (void *)dptr;
	136	+ cd.size = ch[C_FILESIZE];
	137	+ return cd; /* Found it! */
	138	+ }
	139	+ len -= (nptr - p);
	140	+ p = nptr;
	141	+ }
	142	+
	143	+quit:
	144	+ return cd;
	145	+}