Documentation/acpi/apei/einj.txt - LeafOS-Devices/android_kernel_samsung_exynos9820 - Gitiles

 			APEI Error INJection
 			~~~~~~~~~~~~~~~~~~~~

 EINJ provides a hardware error injection mechanism. It is very useful
 for debugging and testing APEI and RAS features in general.

 You need to check whether your BIOS supports EINJ first. For that, look
 for early boot messages similar to this one:

 ACPI: EINJ 0x000000007370A000 000150 (v01 INTEL           00000001 INTL 00000001)

 which shows that the BIOS is exposing an EINJ table - it is the
 mechanism through which the injection is done.

 Alternatively, look in /sys/firmware/acpi/tables for an "EINJ" file,
 which is a different representation of the same thing.

 It doesn't necessarily mean that EINJ is not supported if those above
 don't exist: before you give up, go into BIOS setup to see if the BIOS
 has an option to enable error injection. Look for something called WHEA
 or similar. Often, you need to enable an ACPI5 support option prior, in
 order to see the APEI,EINJ,... functionality supported and exposed by
 the BIOS menu.

 To use EINJ, make sure the following are options enabled in your kernel
 configuration:

 CONFIG_DEBUG_FS
 CONFIG_ACPI_APEI
 CONFIG_ACPI_APEI_EINJ

 The EINJ user interface is in <debugfs mount point>/apei/einj.

 The following files belong to it:

 - available_error_type

   This file shows which error types are supported:

   Error Type Value	Error Description
   ================	=================
   0x00000001		Processor Correctable
   0x00000002		Processor Uncorrectable non-fatal
   0x00000004		Processor Uncorrectable fatal
   0x00000008		Memory Correctable
   0x00000010		Memory Uncorrectable non-fatal
   0x00000020		Memory Uncorrectable fatal
   0x00000040		PCI Express Correctable
   0x00000080		PCI Express Uncorrectable fatal
   0x00000100		PCI Express Uncorrectable non-fatal
   0x00000200		Platform Correctable
   0x00000400		Platform Uncorrectable non-fatal
   0x00000800		Platform Uncorrectable fatal

   The format of the file contents are as above, except present are only
   the available error types.

 - error_type

   Set the value of the error type being injected. Possible error types
   are defined in the file available_error_type above.

 - error_inject

   Write any integer to this file to trigger the error injection. Make
   sure you have specified all necessary error parameters, i.e. this
   write should be the last step when injecting errors.

 - flags

   Present for kernel versions 3.13 and above. Used to specify which
   of param{1..4} are valid and should be used by the firmware during
   injection. Value is a bitmask as specified in ACPI5.0 spec for the
   SET_ERROR_TYPE_WITH_ADDRESS data structure:

 	Bit 0 - Processor APIC field valid (see param3 below).
 	Bit 1 - Memory address and mask valid (param1 and param2).
 	Bit 2 - PCIe (seg,bus,dev,fn) valid (see param4 below).

   If set to zero, legacy behavior is mimicked where the type of
   injection specifies just one bit set, and param1 is multiplexed.

 - param1

   This file is used to set the first error parameter value. Its effect
   depends on the error type specified in error_type. For example, if
   error type is memory related type, the param1 should be a valid
   physical memory address. [Unless "flag" is set - see above]

 - param2

   Same use as param1 above. For example, if error type is of memory
   related type, then param2 should be a physical memory address mask.
   Linux requires page or narrower granularity, say, 0xfffffffffffff000.

 - param3

   Used when the 0x1 bit is set in "flags" to specify the APIC id

 - param4
   Used when the 0x4 bit is set in "flags" to specify target PCIe device

 - notrigger

   The error injection mechanism is a two-step process. First inject the
   error, then perform some actions to trigger it. Setting "notrigger"
   to 1 skips the trigger phase, which *may* allow the user to cause the
   error in some other context by a simple access to the CPU, memory
   location, or device that is the target of the error injection. Whether
   this actually works depends on what operations the BIOS actually
   includes in the trigger phase.

 BIOS versions based on the ACPI 4.0 specification have limited options
 in controlling where the errors are injected. Your BIOS may support an
 extension (enabled with the param_extension=1 module parameter, or boot
 command line einj.param_extension=1). This allows the address and mask
 for memory injections to be specified by the param1 and param2 files in
 apei/einj.

 BIOS versions based on the ACPI 5.0 specification have more control over
 the target of the injection. For processor-related errors (type 0x1, 0x2
 and 0x4), you can set flags to 0x3 (param3 for bit 0, and param1 and
 param2 for bit 1) so that you have more information added to the error
 signature being injected. The actual data passed is this:

 	memory_address = param1;
 	memory_address_range = param2;
 	apicid = param3;
 	pcie_sbdf = param4;

 For memory errors (type 0x8, 0x10 and 0x20) the address is set using
 param1 with a mask in param2 (0x0 is equivalent to all ones). For PCI
 express errors (type 0x40, 0x80 and 0x100) the segment, bus, device and
 function are specified using param1:

          31     24 23    16 15    11 10      8  7        0
 	+-------------------------------------------------+
 	| segment |   bus  | device | function | reserved |
 	+-------------------------------------------------+

 Anyway, you get the idea, if there's doubt just take a look at the code
 in drivers/acpi/apei/einj.c.

 An ACPI 5.0 BIOS may also allow vendor-specific errors to be injected.
 In this case a file named vendor will contain identifying information
 from the BIOS that hopefully will allow an application wishing to use
 the vendor-specific extension to tell that they are running on a BIOS
 that supports it. All vendor extensions have the 0x80000000 bit set in
 error_type. A file vendor_flags controls the interpretation of param1
 and param2 (1 = PROCESSOR, 2 = MEMORY, 4 = PCI). See your BIOS vendor
 documentation for details (and expect changes to this API if vendors
 creativity in using this feature expands beyond our expectations).


 An error injection example:

 # cd /sys/kernel/debug/apei/einj
 # cat available_error_type		# See which errors can be injected
 0x00000002	Processor Uncorrectable non-fatal
 0x00000008	Memory Correctable
 0x00000010	Memory Uncorrectable non-fatal
 # echo 0x12345000 > param1		# Set memory address for injection
 # echo $((-1 << 12)) > param2		# Mask 0xfffffffffffff000 - anywhere in this page
 # echo 0x8 > error_type			# Choose correctable memory error
 # echo 1 > error_inject			# Inject now

 You should see something like this in dmesg:

 [22715.830801] EDAC sbridge MC3: HANDLING MCE MEMORY ERROR
 [22715.834759] EDAC sbridge MC3: CPU 0: Machine Check Event: 0 Bank 7: 8c00004000010090
 [22715.834759] EDAC sbridge MC3: TSC 0
 [22715.834759] EDAC sbridge MC3: ADDR 12345000 EDAC sbridge MC3: MISC 144780c86
 [22715.834759] EDAC sbridge MC3: PROCESSOR 0:306e7 TIME 1422553404 SOCKET 0 APIC 0
 [22716.616173] EDAC MC3: 1 CE memory read error on CPU_SrcID#0_Channel#0_DIMM#0 (channel:0 slot:0 page:0x12345 offset:0x0 grain:32 syndrome:0x0 -  area:DRAM err_code:0001:0090 socket:0 channel_mask:1 rank:0)

 For more information about EINJ, please refer to ACPI specification
 version 4.0, section 17.5 and ACPI 5.0, section 18.6.
	APEI Error INJection
	~~~~~~~~~~~~~~~~~~~~

	EINJ provides a hardware error injection mechanism. It is very useful
	for debugging and testing APEI and RAS features in general.

	You need to check whether your BIOS supports EINJ first. For that, look
	for early boot messages similar to this one:

	ACPI: EINJ 0x000000007370A000 000150 (v01 INTEL 00000001 INTL 00000001)

	which shows that the BIOS is exposing an EINJ table - it is the
	mechanism through which the injection is done.

	Alternatively, look in /sys/firmware/acpi/tables for an "EINJ" file,
	which is a different representation of the same thing.

	It doesn't necessarily mean that EINJ is not supported if those above
	don't exist: before you give up, go into BIOS setup to see if the BIOS
	has an option to enable error injection. Look for something called WHEA
	or similar. Often, you need to enable an ACPI5 support option prior, in
	order to see the APEI,EINJ,... functionality supported and exposed by
	the BIOS menu.

	To use EINJ, make sure the following are options enabled in your kernel
	configuration:

	CONFIG_DEBUG_FS
	CONFIG_ACPI_APEI
	CONFIG_ACPI_APEI_EINJ

	The EINJ user interface is in <debugfs mount point>/apei/einj.

	The following files belong to it:

	- available_error_type

	This file shows which error types are supported:

	Error Type Value Error Description
	================ =================
	0x00000001 Processor Correctable
	0x00000002 Processor Uncorrectable non-fatal
	0x00000004 Processor Uncorrectable fatal
	0x00000008 Memory Correctable
	0x00000010 Memory Uncorrectable non-fatal
	0x00000020 Memory Uncorrectable fatal
	0x00000040 PCI Express Correctable
	0x00000080 PCI Express Uncorrectable fatal
	0x00000100 PCI Express Uncorrectable non-fatal
	0x00000200 Platform Correctable
	0x00000400 Platform Uncorrectable non-fatal
	0x00000800 Platform Uncorrectable fatal

	The format of the file contents are as above, except present are only
	the available error types.

	- error_type

	Set the value of the error type being injected. Possible error types
	are defined in the file available_error_type above.

	- error_inject

	Write any integer to this file to trigger the error injection. Make
	sure you have specified all necessary error parameters, i.e. this
	write should be the last step when injecting errors.

	- flags

	Present for kernel versions 3.13 and above. Used to specify which
	of param{1..4} are valid and should be used by the firmware during
	injection. Value is a bitmask as specified in ACPI5.0 spec for the
	SET_ERROR_TYPE_WITH_ADDRESS data structure:

	Bit 0 - Processor APIC field valid (see param3 below).
	Bit 1 - Memory address and mask valid (param1 and param2).
	Bit 2 - PCIe (seg,bus,dev,fn) valid (see param4 below).

	If set to zero, legacy behavior is mimicked where the type of
	injection specifies just one bit set, and param1 is multiplexed.

	- param1

	This file is used to set the first error parameter value. Its effect
	depends on the error type specified in error_type. For example, if
	error type is memory related type, the param1 should be a valid
	physical memory address. [Unless "flag" is set - see above]

	- param2

	Same use as param1 above. For example, if error type is of memory
	related type, then param2 should be a physical memory address mask.
	Linux requires page or narrower granularity, say, 0xfffffffffffff000.

	- param3

	Used when the 0x1 bit is set in "flags" to specify the APIC id

	- param4
	Used when the 0x4 bit is set in "flags" to specify target PCIe device

	- notrigger

	The error injection mechanism is a two-step process. First inject the
	error, then perform some actions to trigger it. Setting "notrigger"
	to 1 skips the trigger phase, which may allow the user to cause the
	error in some other context by a simple access to the CPU, memory
	location, or device that is the target of the error injection. Whether
	this actually works depends on what operations the BIOS actually
	includes in the trigger phase.

	BIOS versions based on the ACPI 4.0 specification have limited options
	in controlling where the errors are injected. Your BIOS may support an
	extension (enabled with the param_extension=1 module parameter, or boot
	command line einj.param_extension=1). This allows the address and mask
	for memory injections to be specified by the param1 and param2 files in
	apei/einj.

	BIOS versions based on the ACPI 5.0 specification have more control over
	the target of the injection. For processor-related errors (type 0x1, 0x2
	and 0x4), you can set flags to 0x3 (param3 for bit 0, and param1 and
	param2 for bit 1) so that you have more information added to the error
	signature being injected. The actual data passed is this:

	memory_address = param1;
	memory_address_range = param2;
	apicid = param3;
	pcie_sbdf = param4;

	For memory errors (type 0x8, 0x10 and 0x20) the address is set using
	param1 with a mask in param2 (0x0 is equivalent to all ones). For PCI
	express errors (type 0x40, 0x80 and 0x100) the segment, bus, device and
	function are specified using param1:

	31 24 23 16 15 11 10 8 7 0
	+-------------------------------------------------+
	\| segment \| bus \| device \| function \| reserved \|
	+-------------------------------------------------+

	Anyway, you get the idea, if there's doubt just take a look at the code
	in drivers/acpi/apei/einj.c.

	An ACPI 5.0 BIOS may also allow vendor-specific errors to be injected.
	In this case a file named vendor will contain identifying information
	from the BIOS that hopefully will allow an application wishing to use
	the vendor-specific extension to tell that they are running on a BIOS
	that supports it. All vendor extensions have the 0x80000000 bit set in
	error_type. A file vendor_flags controls the interpretation of param1
	and param2 (1 = PROCESSOR, 2 = MEMORY, 4 = PCI). See your BIOS vendor
	documentation for details (and expect changes to this API if vendors
	creativity in using this feature expands beyond our expectations).


	An error injection example:

	# cd /sys/kernel/debug/apei/einj
	# cat available_error_type # See which errors can be injected
	0x00000002 Processor Uncorrectable non-fatal
	0x00000008 Memory Correctable
	0x00000010 Memory Uncorrectable non-fatal
	# echo 0x12345000 > param1 # Set memory address for injection
	# echo $((-1 << 12)) > param2 # Mask 0xfffffffffffff000 - anywhere in this page
	# echo 0x8 > error_type # Choose correctable memory error
	# echo 1 > error_inject # Inject now

	You should see something like this in dmesg:

	[22715.830801] EDAC sbridge MC3: HANDLING MCE MEMORY ERROR
	[22715.834759] EDAC sbridge MC3: CPU 0: Machine Check Event: 0 Bank 7: 8c00004000010090
	[22715.834759] EDAC sbridge MC3: TSC 0
	[22715.834759] EDAC sbridge MC3: ADDR 12345000 EDAC sbridge MC3: MISC 144780c86
	[22715.834759] EDAC sbridge MC3: PROCESSOR 0:306e7 TIME 1422553404 SOCKET 0 APIC 0
	[22716.616173] EDAC MC3: 1 CE memory read error on CPU_SrcID#0_Channel#0_DIMM#0 (channel:0 slot:0 page:0x12345 offset:0x0 grain:32 syndrome:0x0 - area:DRAM err_code:0001:0090 socket:0 channel_mask:1 rank:0)

	For more information about EINJ, please refer to ACPI specification
	version 4.0, section 17.5 and ACPI 5.0, section 18.6.