Loading Documentation/ABI/testing/sysfs-class-wakeup 0 → 100644 +76 −0 Original line number Diff line number Diff line What: /sys/class/wakeup/ Date: June 2019 Contact: Tri Vo <trong@android.com> Description: The /sys/class/wakeup/ directory contains pointers to all wakeup sources in the kernel at that moment in time. What: /sys/class/wakeup/.../name Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the name of the wakeup source. What: /sys/class/wakeup/.../active_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of times the wakeup source was activated. What: /sys/class/wakeup/.../event_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of signaled wakeup events associated with the wakeup source. What: /sys/class/wakeup/.../wakeup_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of times the wakeup source might abort suspend. What: /sys/class/wakeup/.../expire_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of times the wakeup source's timeout has expired. What: /sys/class/wakeup/.../active_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the amount of time the wakeup source has been continuously active, in milliseconds. If the wakeup source is not active, this file contains '0'. What: /sys/class/wakeup/.../total_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the total amount of time this wakeup source has been active, in milliseconds. What: /sys/class/wakeup/.../max_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the maximum amount of time this wakeup source has been continuously active, in milliseconds. What: /sys/class/wakeup/.../last_change_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the monotonic clock time when the wakeup source was touched last time, in milliseconds. What: /sys/class/wakeup/.../prevent_suspend_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: The file contains the total amount of time this wakeup source has been preventing autosleep, in milliseconds. Documentation/ABI/testing/sysfs-fs-f2fs +15 −0 Original line number Diff line number Diff line Loading @@ -243,3 +243,18 @@ Description: - Del: echo '[h/c]!extension' > /sys/fs/f2fs/<disk>/extension_list - [h] means add/del hot file extension - [c] means add/del cold file extension What: /sys/fs/f2fs/<disk>/unusable Date April 2019 Contact: "Daniel Rosenberg" <drosen@google.com> Description: If checkpoint=disable, it displays the number of blocks that are unusable. If checkpoint=enable it displays the enumber of blocks that would be unusable if checkpoint=disable were to be set. What: /sys/fs/f2fs/<disk>/encoding Date July 2019 Contact: "Daniel Rosenberg" <drosen@google.com> Description: Displays name and version of the encoding set for the filesystem. If no encoding is set, displays (none) Documentation/ABI/testing/sysfs-power +120 −0 Original line number Diff line number Diff line Loading @@ -285,3 +285,123 @@ Description: Writing a "1" to this file enables the debug messages and writing a "0" (default) to it disables them. Reads from this file return the current value. What: /sys/power/resume_offset Date: April 2018 Contact: Mario Limonciello <mario.limonciello@dell.com> Description: This file is used for telling the kernel an offset into a disk to use when hibernating the system such as with a swap file. Reads from this file will display the current offset the kernel will be using on the next hibernation attempt. Using this sysfs file will override any values that were set using the kernel command line for disk offset. What: /sys/power/suspend_stats Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats directory contains suspend related statistics. What: /sys/power/suspend_stats/success Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/success file contains the number of times entering system sleep state succeeded. What: /sys/power/suspend_stats/fail Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/fail file contains the number of times entering system sleep state failed. What: /sys/power/suspend_stats/failed_freeze Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_freeze file contains the number of times freezing processes failed. What: /sys/power/suspend_stats/failed_prepare Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_prepare file contains the number of times preparing all non-sysdev devices for a system PM transition failed. What: /sys/power/suspend_stats/failed_resume Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_resume file contains the number of times executing "resume" callbacks of non-sysdev devices failed. What: /sys/power/suspend_stats/failed_resume_early Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_resume_early file contains the number of times executing "early resume" callbacks of devices failed. What: /sys/power/suspend_stats/failed_resume_noirq Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_resume_noirq file contains the number of times executing "noirq resume" callbacks of devices failed. What: /sys/power/suspend_stats/failed_suspend Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_suspend file contains the number of times executing "suspend" callbacks of all non-sysdev devices failed. What: /sys/power/suspend_stats/failed_suspend_late Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_suspend_late file contains the number of times executing "late suspend" callbacks of all devices failed. What: /sys/power/suspend_stats/failed_suspend_noirq Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_suspend_noirq file contains the number of times executing "noirq suspend" callbacks of all devices failed. What: /sys/power/suspend_stats/last_failed_dev Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/last_failed_dev file contains the last device for which a suspend/resume callback failed. What: /sys/power/suspend_stats/last_failed_errno Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/last_failed_errno file contains the errno of the last failed attempt at entering system sleep state. What: /sys/power/suspend_stats/last_failed_step Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/last_failed_step file contains the last failed step in the suspend/resume path. Documentation/admin-guide/kernel-parameters.txt +10 −1 Original line number Diff line number Diff line Loading @@ -1581,6 +1581,15 @@ initrd= [BOOT] Specify the location of the initial ramdisk init_on_alloc= [MM] Fill newly allocated pages and heap objects with zeroes. Format: 0 | 1 Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON. init_on_free= [MM] Fill freed pages and heap objects with zeroes. Format: 0 | 1 Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. init_pkru= [x86] Specify the default memory protection keys rights register contents for all processes. 0x55555554 by default (disallow access to all but pkey 0). Can Loading Documentation/arm64/tagged-address-abi.rst 0 → 100644 +156 −0 Original line number Diff line number Diff line ========================== AArch64 TAGGED ADDRESS ABI ========================== Authors: Vincenzo Frascino <vincenzo.frascino@arm.com> Catalin Marinas <catalin.marinas@arm.com> Date: 21 August 2019 This document describes the usage and semantics of the Tagged Address ABI on AArch64 Linux. 1. Introduction --------------- On AArch64 the ``TCR_EL1.TBI0`` bit is set by default, allowing userspace (EL0) to perform memory accesses through 64-bit pointers with a non-zero top byte. This document describes the relaxation of the syscall ABI that allows userspace to pass certain tagged pointers to kernel syscalls. 2. AArch64 Tagged Address ABI ----------------------------- From the kernel syscall interface perspective and for the purposes of this document, a "valid tagged pointer" is a pointer with a potentially non-zero top-byte that references an address in the user process address space obtained in one of the following ways: - ``mmap()`` syscall where either: - flags have the ``MAP_ANONYMOUS`` bit set or - the file descriptor refers to a regular file (including those returned by ``memfd_create()``) or ``/dev/zero`` - ``brk()`` syscall (i.e. the heap area between the initial location of the program break at process creation and its current location). - any memory mapped by the kernel in the address space of the process during creation and with the same restrictions as for ``mmap()`` above (e.g. data, bss, stack). The AArch64 Tagged Address ABI has two stages of relaxation depending how the user addresses are used by the kernel: 1. User addresses not accessed by the kernel but used for address space management (e.g. ``mmap()``, ``mprotect()``, ``madvise()``). The use of valid tagged pointers in this context is always allowed. 2. User addresses accessed by the kernel (e.g. ``write()``). This ABI relaxation is disabled by default and the application thread needs to explicitly enable it via ``prctl()`` as follows: - ``PR_SET_TAGGED_ADDR_CTRL``: enable or disable the AArch64 Tagged Address ABI for the calling thread. The ``(unsigned int) arg2`` argument is a bit mask describing the control mode used: - ``PR_TAGGED_ADDR_ENABLE``: enable AArch64 Tagged Address ABI. Default status is disabled. Arguments ``arg3``, ``arg4``, and ``arg5`` must be 0. - ``PR_GET_TAGGED_ADDR_CTRL``: get the status of the AArch64 Tagged Address ABI for the calling thread. Arguments ``arg2``, ``arg3``, ``arg4``, and ``arg5`` must be 0. The ABI properties described above are thread-scoped, inherited on clone() and fork() and cleared on exec(). Calling ``prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0)`` returns ``-EINVAL`` if the AArch64 Tagged Address ABI is globally disabled by ``sysctl abi.tagged_addr_disabled=1``. The default ``sysctl abi.tagged_addr_disabled`` configuration is 0. When the AArch64 Tagged Address ABI is enabled for a thread, the following behaviours are guaranteed: - All syscalls except the cases mentioned in section 3 can accept any valid tagged pointer. - The syscall behaviour is undefined for invalid tagged pointers: it may result in an error code being returned, a (fatal) signal being raised, or other modes of failure. - The syscall behaviour for a valid tagged pointer is the same as for the corresponding untagged pointer. A definition of the meaning of tagged pointers on AArch64 can be found in Documentation/arm64/tagged-pointers.rst. 3. AArch64 Tagged Address ABI Exceptions ----------------------------------------- The following system call parameters must be untagged regardless of the ABI relaxation: - ``prctl()`` other than pointers to user data either passed directly or indirectly as arguments to be accessed by the kernel. - ``ioctl()`` other than pointers to user data either passed directly or indirectly as arguments to be accessed by the kernel. - ``shmat()`` and ``shmdt()``. Any attempt to use non-zero tagged pointers may result in an error code being returned, a (fatal) signal being raised, or other modes of failure. 4. Example of correct usage --------------------------- .. code-block:: c #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PR_SET_TAGGED_ADDR_CTRL 55 #define PR_TAGGED_ADDR_ENABLE (1UL << 0) #define TAG_SHIFT 56 int main(void) { int tbi_enabled = 0; unsigned long tag = 0; char *ptr; /* check/enable the tagged address ABI */ if (!prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0)) tbi_enabled = 1; /* memory allocation */ ptr = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (ptr == MAP_FAILED) return 1; /* set a non-zero tag if the ABI is available */ if (tbi_enabled) tag = rand() & 0xff; ptr = (char *)((unsigned long)ptr | (tag << TAG_SHIFT)); /* memory access to a tagged address */ strcpy(ptr, "tagged pointer\n"); /* syscall with a tagged pointer */ write(1, ptr, strlen(ptr)); return 0; } Loading
Documentation/ABI/testing/sysfs-class-wakeup 0 → 100644 +76 −0 Original line number Diff line number Diff line What: /sys/class/wakeup/ Date: June 2019 Contact: Tri Vo <trong@android.com> Description: The /sys/class/wakeup/ directory contains pointers to all wakeup sources in the kernel at that moment in time. What: /sys/class/wakeup/.../name Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the name of the wakeup source. What: /sys/class/wakeup/.../active_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of times the wakeup source was activated. What: /sys/class/wakeup/.../event_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of signaled wakeup events associated with the wakeup source. What: /sys/class/wakeup/.../wakeup_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of times the wakeup source might abort suspend. What: /sys/class/wakeup/.../expire_count Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the number of times the wakeup source's timeout has expired. What: /sys/class/wakeup/.../active_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the amount of time the wakeup source has been continuously active, in milliseconds. If the wakeup source is not active, this file contains '0'. What: /sys/class/wakeup/.../total_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the total amount of time this wakeup source has been active, in milliseconds. What: /sys/class/wakeup/.../max_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the maximum amount of time this wakeup source has been continuously active, in milliseconds. What: /sys/class/wakeup/.../last_change_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: This file contains the monotonic clock time when the wakeup source was touched last time, in milliseconds. What: /sys/class/wakeup/.../prevent_suspend_time_ms Date: June 2019 Contact: Tri Vo <trong@android.com> Description: The file contains the total amount of time this wakeup source has been preventing autosleep, in milliseconds.
Documentation/ABI/testing/sysfs-fs-f2fs +15 −0 Original line number Diff line number Diff line Loading @@ -243,3 +243,18 @@ Description: - Del: echo '[h/c]!extension' > /sys/fs/f2fs/<disk>/extension_list - [h] means add/del hot file extension - [c] means add/del cold file extension What: /sys/fs/f2fs/<disk>/unusable Date April 2019 Contact: "Daniel Rosenberg" <drosen@google.com> Description: If checkpoint=disable, it displays the number of blocks that are unusable. If checkpoint=enable it displays the enumber of blocks that would be unusable if checkpoint=disable were to be set. What: /sys/fs/f2fs/<disk>/encoding Date July 2019 Contact: "Daniel Rosenberg" <drosen@google.com> Description: Displays name and version of the encoding set for the filesystem. If no encoding is set, displays (none)
Documentation/ABI/testing/sysfs-power +120 −0 Original line number Diff line number Diff line Loading @@ -285,3 +285,123 @@ Description: Writing a "1" to this file enables the debug messages and writing a "0" (default) to it disables them. Reads from this file return the current value. What: /sys/power/resume_offset Date: April 2018 Contact: Mario Limonciello <mario.limonciello@dell.com> Description: This file is used for telling the kernel an offset into a disk to use when hibernating the system such as with a swap file. Reads from this file will display the current offset the kernel will be using on the next hibernation attempt. Using this sysfs file will override any values that were set using the kernel command line for disk offset. What: /sys/power/suspend_stats Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats directory contains suspend related statistics. What: /sys/power/suspend_stats/success Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/success file contains the number of times entering system sleep state succeeded. What: /sys/power/suspend_stats/fail Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/fail file contains the number of times entering system sleep state failed. What: /sys/power/suspend_stats/failed_freeze Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_freeze file contains the number of times freezing processes failed. What: /sys/power/suspend_stats/failed_prepare Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_prepare file contains the number of times preparing all non-sysdev devices for a system PM transition failed. What: /sys/power/suspend_stats/failed_resume Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_resume file contains the number of times executing "resume" callbacks of non-sysdev devices failed. What: /sys/power/suspend_stats/failed_resume_early Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_resume_early file contains the number of times executing "early resume" callbacks of devices failed. What: /sys/power/suspend_stats/failed_resume_noirq Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_resume_noirq file contains the number of times executing "noirq resume" callbacks of devices failed. What: /sys/power/suspend_stats/failed_suspend Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_suspend file contains the number of times executing "suspend" callbacks of all non-sysdev devices failed. What: /sys/power/suspend_stats/failed_suspend_late Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_suspend_late file contains the number of times executing "late suspend" callbacks of all devices failed. What: /sys/power/suspend_stats/failed_suspend_noirq Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/failed_suspend_noirq file contains the number of times executing "noirq suspend" callbacks of all devices failed. What: /sys/power/suspend_stats/last_failed_dev Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/last_failed_dev file contains the last device for which a suspend/resume callback failed. What: /sys/power/suspend_stats/last_failed_errno Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/last_failed_errno file contains the errno of the last failed attempt at entering system sleep state. What: /sys/power/suspend_stats/last_failed_step Date: July 2019 Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/last_failed_step file contains the last failed step in the suspend/resume path.
Documentation/admin-guide/kernel-parameters.txt +10 −1 Original line number Diff line number Diff line Loading @@ -1581,6 +1581,15 @@ initrd= [BOOT] Specify the location of the initial ramdisk init_on_alloc= [MM] Fill newly allocated pages and heap objects with zeroes. Format: 0 | 1 Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON. init_on_free= [MM] Fill freed pages and heap objects with zeroes. Format: 0 | 1 Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. init_pkru= [x86] Specify the default memory protection keys rights register contents for all processes. 0x55555554 by default (disallow access to all but pkey 0). Can Loading
Documentation/arm64/tagged-address-abi.rst 0 → 100644 +156 −0 Original line number Diff line number Diff line ========================== AArch64 TAGGED ADDRESS ABI ========================== Authors: Vincenzo Frascino <vincenzo.frascino@arm.com> Catalin Marinas <catalin.marinas@arm.com> Date: 21 August 2019 This document describes the usage and semantics of the Tagged Address ABI on AArch64 Linux. 1. Introduction --------------- On AArch64 the ``TCR_EL1.TBI0`` bit is set by default, allowing userspace (EL0) to perform memory accesses through 64-bit pointers with a non-zero top byte. This document describes the relaxation of the syscall ABI that allows userspace to pass certain tagged pointers to kernel syscalls. 2. AArch64 Tagged Address ABI ----------------------------- From the kernel syscall interface perspective and for the purposes of this document, a "valid tagged pointer" is a pointer with a potentially non-zero top-byte that references an address in the user process address space obtained in one of the following ways: - ``mmap()`` syscall where either: - flags have the ``MAP_ANONYMOUS`` bit set or - the file descriptor refers to a regular file (including those returned by ``memfd_create()``) or ``/dev/zero`` - ``brk()`` syscall (i.e. the heap area between the initial location of the program break at process creation and its current location). - any memory mapped by the kernel in the address space of the process during creation and with the same restrictions as for ``mmap()`` above (e.g. data, bss, stack). The AArch64 Tagged Address ABI has two stages of relaxation depending how the user addresses are used by the kernel: 1. User addresses not accessed by the kernel but used for address space management (e.g. ``mmap()``, ``mprotect()``, ``madvise()``). The use of valid tagged pointers in this context is always allowed. 2. User addresses accessed by the kernel (e.g. ``write()``). This ABI relaxation is disabled by default and the application thread needs to explicitly enable it via ``prctl()`` as follows: - ``PR_SET_TAGGED_ADDR_CTRL``: enable or disable the AArch64 Tagged Address ABI for the calling thread. The ``(unsigned int) arg2`` argument is a bit mask describing the control mode used: - ``PR_TAGGED_ADDR_ENABLE``: enable AArch64 Tagged Address ABI. Default status is disabled. Arguments ``arg3``, ``arg4``, and ``arg5`` must be 0. - ``PR_GET_TAGGED_ADDR_CTRL``: get the status of the AArch64 Tagged Address ABI for the calling thread. Arguments ``arg2``, ``arg3``, ``arg4``, and ``arg5`` must be 0. The ABI properties described above are thread-scoped, inherited on clone() and fork() and cleared on exec(). Calling ``prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0)`` returns ``-EINVAL`` if the AArch64 Tagged Address ABI is globally disabled by ``sysctl abi.tagged_addr_disabled=1``. The default ``sysctl abi.tagged_addr_disabled`` configuration is 0. When the AArch64 Tagged Address ABI is enabled for a thread, the following behaviours are guaranteed: - All syscalls except the cases mentioned in section 3 can accept any valid tagged pointer. - The syscall behaviour is undefined for invalid tagged pointers: it may result in an error code being returned, a (fatal) signal being raised, or other modes of failure. - The syscall behaviour for a valid tagged pointer is the same as for the corresponding untagged pointer. A definition of the meaning of tagged pointers on AArch64 can be found in Documentation/arm64/tagged-pointers.rst. 3. AArch64 Tagged Address ABI Exceptions ----------------------------------------- The following system call parameters must be untagged regardless of the ABI relaxation: - ``prctl()`` other than pointers to user data either passed directly or indirectly as arguments to be accessed by the kernel. - ``ioctl()`` other than pointers to user data either passed directly or indirectly as arguments to be accessed by the kernel. - ``shmat()`` and ``shmdt()``. Any attempt to use non-zero tagged pointers may result in an error code being returned, a (fatal) signal being raised, or other modes of failure. 4. Example of correct usage --------------------------- .. code-block:: c #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PR_SET_TAGGED_ADDR_CTRL 55 #define PR_TAGGED_ADDR_ENABLE (1UL << 0) #define TAG_SHIFT 56 int main(void) { int tbi_enabled = 0; unsigned long tag = 0; char *ptr; /* check/enable the tagged address ABI */ if (!prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0)) tbi_enabled = 1; /* memory allocation */ ptr = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (ptr == MAP_FAILED) return 1; /* set a non-zero tag if the ABI is available */ if (tbi_enabled) tag = rand() & 0xff; ptr = (char *)((unsigned long)ptr | (tag << TAG_SHIFT)); /* memory access to a tagged address */ strcpy(ptr, "tagged pointer\n"); /* syscall with a tagged pointer */ write(1, ptr, strlen(ptr)); return 0; }
