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Commit 18dd0bf2 authored by Linus Torvalds's avatar Linus Torvalds
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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
parents 2d9c8b5d 385ddeac

Documentation/acpi/initrd_table_override.txt

0 → 100644
+94 −0
Original line number Diff line number Diff line 
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

arch/x86/kernel/acpi/boot.c

+6 −0
Original line number Diff line number Diff line
@@ -1706,3 +1706,9 @@ int __acpi_release_global_lock(unsigned int *lock) 
	} 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();

}

arch/x86/kernel/setup.c

+4 −0
Original line number Diff line number Diff line
@@ -952,6 +952,10 @@ void __init setup_arch(char **cmdline_p) 


	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();

drivers/acpi/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -267,6 +267,15 @@ config ACPI_CUSTOM_DSDT 
	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

drivers/acpi/osl.c

+191 −11
Original line number Diff line number Diff line
@@ -534,6 +534,137 @@ acpi_os_predefined_override(const struct acpi_predefined_names *init_val, 
	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 @@ acpi_os_table_override(struct acpi_table_header * existing_table, 
	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)

{