diff options
| -rw-r--r-- | Documentation/firmware-guide/acpi/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/firmware-guide/acpi/method-customizing.rst | 89 | ||||
| -rw-r--r-- | drivers/acpi/Kconfig | 14 | ||||
| -rw-r--r-- | drivers/acpi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/acpi/custom_method.c | 103 |
5 files changed, 0 insertions, 208 deletions
diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst index b6a42f4ffe03..b246902f523f 100644 --- a/Documentation/firmware-guide/acpi/index.rst +++ b/Documentation/firmware-guide/acpi/index.rst @@ -14,7 +14,6 @@ ACPI Support dsd/phy enumeration osi - method-customizing method-tracing DSD-properties-rules debug diff --git a/Documentation/firmware-guide/acpi/method-customizing.rst b/Documentation/firmware-guide/acpi/method-customizing.rst deleted file mode 100644 index de3ebcaed4cf..000000000000 --- a/Documentation/firmware-guide/acpi/method-customizing.rst +++ /dev/null @@ -1,89 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0 - -======================================= -Linux ACPI Custom Control Method How To -======================================= - -:Author: Zhang Rui <rui.zhang@intel.com> - - -Linux supports customizing ACPI control methods at runtime. - -Users can use this to: - -1. override an existing method which may not work correctly, - or just for debugging purposes. -2. insert a completely new method in order to create a missing - method such as _OFF, _ON, _STA, _INI, etc. - -For these cases, it is far simpler to dynamically install a single -control method rather than override the entire DSDT, because kernel -rebuild/reboot is not needed and test result can be got in minutes. - -.. note:: - - - Only ACPI METHOD can be overridden, any other object types like - "Device", "OperationRegion", are not recognized. Methods - declared inside scope operators are also not supported. - - - The same ACPI control method can be overridden for many times, - and it's always the latest one that used by Linux/kernel. - - - To get the ACPI debug object output (Store (AAAA, Debug)), - please run:: - - echo 1 > /sys/module/acpi/parameters/aml_debug_output - - -1. override an existing method -============================== -a) get the ACPI table via ACPI sysfs I/F. e.g. to get the DSDT, - just run "cat /sys/firmware/acpi/tables/DSDT > /tmp/dsdt.dat" -b) disassemble the table by running "iasl -d dsdt.dat". -c) rewrite the ASL code of the method and save it in a new file, -d) package the new file (psr.asl) to an ACPI table format. - Here is an example of a customized \_SB._AC._PSR method:: - - DefinitionBlock ("", "SSDT", 1, "", "", 0x20080715) - { - Method (\_SB_.AC._PSR, 0, NotSerialized) - { - Store ("In AC _PSR", Debug) - Return (ACON) - } - } - - Note that the full pathname of the method in ACPI namespace - should be used. -e) assemble the file to generate the AML code of the method. - e.g. "iasl -vw 6084 psr.asl" (psr.aml is generated as a result) - If parameter "-vw 6084" is not supported by your iASL compiler, - please try a newer version. -f) mount debugfs by "mount -t debugfs none /sys/kernel/debug" -g) override the old method via the debugfs by running - "cat /tmp/psr.aml > /sys/kernel/debug/acpi/custom_method" - -2. insert a new method -====================== -This is easier than overriding an existing method. -We just need to create the ASL code of the method we want to -insert and then follow the step c) ~ g) in section 1. - -3. undo your changes -==================== -The "undo" operation is not supported for a new inserted method -right now, i.e. we can not remove a method currently. -For an overridden method, in order to undo your changes, please -save a copy of the method original ASL code in step c) section 1, -and redo step c) ~ g) to override the method with the original one. - - -.. note:: We can use a kernel with multiple custom ACPI method running, - But each individual write to debugfs can implement a SINGLE - method override. i.e. if we want to insert/override multiple - ACPI methods, we need to redo step c) ~ g) for multiple times. - -.. note:: Be aware that root can mis-use this driver to modify arbitrary - memory and gain additional rights, if root's privileges got - restricted (for example if root is not allowed to load additional - modules after boot). diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 3c3f8037ebed..c645bb453f3b 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -449,20 +449,6 @@ config ACPI_HED which is used to report some hardware errors notified via SCI, mainly the corrected errors. -config ACPI_CUSTOM_METHOD - tristate "Allow ACPI methods to be inserted/replaced at run time" - depends on DEBUG_FS - help - This debug facility allows ACPI AML methods to be inserted and/or - replaced without rebooting the system. For details refer to: - Documentation/firmware-guide/acpi/method-customizing.rst. - - NOTE: This option is security sensitive, because it allows arbitrary - kernel memory to be written to by root (uid=0) users, allowing them - to bypass certain security measures (e.g. if root is not allowed to - load additional kernel modules after boot, this feature may be used - to override that restriction). - config ACPI_BGRT bool "Boottime Graphics Resource Table support" depends on EFI && (X86 || ARM64) diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 12ef8180d272..8cc8c0d9c873 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -101,7 +101,6 @@ obj-$(CONFIG_ACPI_SBS) += sbshc.o obj-$(CONFIG_ACPI_SBS) += sbs.o obj-$(CONFIG_ACPI_HED) += hed.o obj-$(CONFIG_ACPI_EC_DEBUGFS) += ec_sys.o -obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o obj-$(CONFIG_ACPI_BGRT) += bgrt.o obj-$(CONFIG_ACPI_CPPC_LIB) += cppc_acpi.o obj-$(CONFIG_ACPI_SPCR_TABLE) += spcr.o diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c deleted file mode 100644 index d39a9b474727..000000000000 --- a/drivers/acpi/custom_method.c +++ /dev/null @@ -1,103 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-only -/* - * custom_method.c - debugfs interface for customizing ACPI control method - */ - -#include <linux/init.h> -#include <linux/module.h> -#include <linux/kernel.h> -#include <linux/uaccess.h> -#include <linux/debugfs.h> -#include <linux/acpi.h> -#include <linux/security.h> - -#include "internal.h" - -MODULE_LICENSE("GPL"); - -static struct dentry *cm_dentry; - -/* /sys/kernel/debug/acpi/custom_method */ - -static ssize_t cm_write(struct file *file, const char __user *user_buf, - size_t count, loff_t *ppos) -{ - static char *buf; - static u32 max_size; - static u32 uncopied_bytes; - - struct acpi_table_header table; - acpi_status status; - int ret; - - ret = security_locked_down(LOCKDOWN_ACPI_TABLES); - if (ret) - return ret; - - if (!(*ppos)) { - /* parse the table header to get the table length */ - if (count <= sizeof(struct acpi_table_header)) - return -EINVAL; - if (copy_from_user(&table, user_buf, - sizeof(struct acpi_table_header))) - return -EFAULT; - uncopied_bytes = max_size = table.length; - /* make sure the buf is not allocated */ - kfree(buf); - buf = kzalloc(max_size, GFP_KERNEL); - if (!buf) - return -ENOMEM; - } - - if (buf == NULL) - return -EINVAL; - - if ((*ppos > max_size) || - (*ppos + count > max_size) || - (*ppos + count < count) || - (count > uncopied_bytes)) { - kfree(buf); - buf = NULL; - return -EINVAL; - } - - if (copy_from_user(buf + (*ppos), user_buf, count)) { - kfree(buf); - buf = NULL; - return -EFAULT; - } - - uncopied_bytes -= count; - *ppos += count; - - if (!uncopied_bytes) { - status = acpi_install_method(buf); - kfree(buf); - buf = NULL; - if (ACPI_FAILURE(status)) - return -EINVAL; - add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE); - } - - return count; -} - -static const struct file_operations cm_fops = { - .write = cm_write, - .llseek = default_llseek, -}; - -static int __init acpi_custom_method_init(void) -{ - cm_dentry = debugfs_create_file("custom_method", S_IWUSR, - acpi_debugfs_dir, NULL, &cm_fops); - return 0; -} - -static void __exit acpi_custom_method_exit(void) -{ - debugfs_remove(cm_dentry); -} - -module_init(acpi_custom_method_init); -module_exit(acpi_custom_method_exit); |