Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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In case of a Secure-Storage-Access exception the effective aka virtual
address which caused the exception is contained within the TEID.
do_secure_storage_access() incorrectly uses phys_to_folio() instead of
virt_to_folio() to translate the virtual address to the corresponding
folio.
Fix this by using virt_to_folio() instead of phys_to_folio().
Fixes: 084ea4d611a3 ("s390/mm: add (non)secure page access exceptions handlers")
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Remove the SCLP_OFB Kconfig option and enable the guarded code
unconditionally. This guards only a few lines of code, so the impact is
very low while at the same time this reduces the large number of Kconfig
options.
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Add myself as co-maintainer for s390/pci, replacing Gerald Schaefer who
has moved his focus to s390/mm. Thank you Gerald!
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Acked-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
debug_input_flush_fn() always copies one byte from the userspace buffer
with copy_from_user() regardless of the supplied write length. A
zero-length write therefore reads one byte beyond the caller's buffer.
If the stale byte happens to be '-' or a digit the debug log is
silently flushed. With an unmapped buffer the call returns -EFAULT.
Reject zero-length writes before copying from userspace.
Cc: stable@vger.kernel.org # v5.10+
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
debug_get_user_string() duplicates the userspace buffer with
memdup_user_nul() and then unconditionally looks at buffer[user_len - 1]
to strip a trailing newline.
A zero-length write reaches this helper unchanged, so the newline trim
reads before the start of the allocated buffer.
Reject empty writes before accessing the last input byte.
Fixes: 66a464dbc8e0 ("[PATCH] s390: debug feature changes")
Cc: stable@vger.kernel.org
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20260417073530.96002-1-pengpeng@iscas.ac.cn
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Pull clk fix from Stephen Boyd:
"One more fix for the merge window to avoid a boot hang on
Raspberry Pi 3B by marking the VEC clk critical so that it
doesn't get turned off and hang the bus"
* tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
clk: bcm: rpi: Mark VEC clock as CLK_IGNORE_UNUSED
Pull PCIe TSP update from Dan Williams:
"A small update for the TSM core. It is arguably a fix and coming in
late as I have been offline the past few weeks:
- Drop class_create() for the 'tsm' class"
* tag 'tsm-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/devsec/tsm:
virt: coco: change tsm_class to a const struct
On Raspberry Pi 3B, the VEC clock is used by the VideoCore firmware
display driver, which remains active until the vc4 driver loads and
sends NOTIFY_DISPLAY_DONE. If this clock is disabled during boot, a bus
lockup happens and the firmware becomes unresponsive, causing a complete
system lockup.
Mark the VEC clock with CLK_IGNORE_UNUSED so it survives the unused
clock disablement and remains available until the vc4 driver takes over
display management.
Fixes: 672299736af6 ("clk: bcm: rpi: Manage clock rate in prepare/unprepare callbacks")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/r/5f0bec08-f458-4fba-8bf3-06817a100c4c@sirena.org.uk
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Link: https://patch.msgid.link/20260401111416.562279-2-mcanal@igalia.com
Tested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Brian Masney <bmasney@redhat.com> # Active contributor to clk
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Pull Kbuild fixes from Nicolas Schier:
- builddeb - avoid recompiles for non-cross-compiles
Avoid triggering complete rebuilds for non-cross-compile Debian
package builds by only triggering the rebuild of host tools for
actual cross-compile builds
- Never respect CONFIG_WERROR / W=e to fixdep
Avoid spurious rebuilds of fixdep w/ and w/o -Werror during a single
kbuild invocation by never respecting CONFIG_WERROR for fixdep
* tag 'kbuild-fixes-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
kbuild: Never respect CONFIG_WERROR / W=e to fixdep
kbuild: builddeb - avoid recompiles for non-cross-compiles
The class_create() call has been deprecated in favor of class_register()
as the driver core now allows for a struct class to be in read-only
memory. Change tsm_class to be a const struct class and drop the
class_create() call. Compile tested only.
Link: https://lore.kernel.org/all/2023040244-duffel-pushpin-f738@gregkh/
Changes with v1:
- Removed redundant int err variable.
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20260306183325.245254-1-jkoolstra@xs4all.nl
Signed-off-by: Dan Williams <djbw@kernel.org>
* clk-samsung:
clk: samsung: exynos850: Add APM-to-AP mailbox clock
dt-bindings: clock: exynos850: Add APM_AP MAILBOX clock
clk: samsung: Use %pe format to simplify
clk: samsung: pll: Fix possible truncation in a9fraco recalc rate
clk: samsung: exynosautov920: add block G3D clock support
dt-bindings: clock: exynosautov920: add G3D clock definitions
clk: samsung: gs101: harmonise symbol names (clock arrays)
clk: samsung: artpec-9: Add initial clock support for ARTPEC-9 SoC
clk: samsung: Add clock PLL support for ARTPEC-9 SoC
dt-bindings: clock: Add ARTPEC-9 clock controller
* clk-qcom: (67 commits)
clk: qcom: gcc: Add multiple global clock controller driver for Nord SoC
clk: qcom: rpmh: Add support for Nord rpmh clocks
clk: qcom: Add TCSR clock driver for Nord SoC
dt-bindings: clock: qcom: Add Nord Global Clock Controller
dt-bindings: clock: qcom-rpmhcc: Add support for Nord SoCs
dt-bindings: clock: qcom: Document the Nord SoC TCSR Clock Controller
clk: qcom: gcc-x1e80100: Keep GCC USB QTB clock always ON
clk: qcom: Constify list of critical CBCR registers
clk: qcom: Constify qcom_cc_driver_data
clk: qcom: videocc-glymur: Constify qcom_cc_desc
clk: qcom: Add a driver for SM8750 GPU clocks
dt-bindings: clock: qcom: Add SM8750 GPU clocks
clk: qcom: ipq-cmn-pll: Add IPQ8074 SoC support
dt-bindings: clock: qcom: Add CMN PLL support for IPQ8074
clk: qcom: ipq-cmn-pll: Add IPQ6018 SoC support
dt-bindings: clock: qcom: Add CMN PLL support for IPQ6018
clk: qcom: gdsc: Fix error path on registration of multiple pm subdomains
dt-bindings: clock: qcom: Add missing power-domains property
clk: qcom: gcc-eliza: Enable FORCE_MEM_CORE_ON for UFS AXI PHY clock
clk: qcom: dispcc-sc7180: Add missing MDSS resets
...
* clk-round:
clk: divider: remove divider_round_rate() and divider_round_rate_parent()
clk: divider: remove divider_ro_round_rate_parent()
clk: remove round_rate() clk ops
clk: composite: convert from round_rate() to determine_rate()
clk: test: remove references to clk_ops.round_rate
* clk-sai:
clk: fsl-sai: Add MCLK generation support
clk: fsl-sai: Extract clock setup into fsl_sai_clk_register()
dt-bindings: clock: fsl-sai: Document clock-cells = <1> support
clk: fsl-sai: Add i.MX8M support with 8 byte register offset
clk: fsl-sai: Sort the headers
dt-bindings: clock: fsl-sai: Document i.MX8M support
* clk-cleanup:
clk: visconti: pll: initialize clk_init_data to zero
clk: xgene: Fix mapping leak in xgene_pllclk_init()
clk: Simplify clk_is_match()
clk: baikal-t1: Remove not-going-to-be-supported code for Baikal SoC
clk: mvebu: armada-37xx-periph: fix __iomem casts in structure init
clk: qoriq: avoid format string warning
Pull power utility updates from Len Brown:
"x86_energy_perf_policy:
- Initial SoC Slider support
turbostat:
- Display HT siblings in cpu# order
- Add Module-ID column
- Print Core-ID and APIC-ID in hex
- Fix misc bugs"
* tag 'power-utilities-2026.04.25' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux:
tools/power x86_energy_perf_policy: Version 2026.04.25
tools/power x86_energy_perf_policy.8: Document SoC Slider Options
tools/power x86_energy_perf_policy: Enhances SoC Slider related checks
tools/power turbostat: v2026.04.21
tools/power turbostat: Process HT siblings in CPU order
tools/power turbostat: Show module_id column
tools/power turbostat: Print core_id and apic_id in hex
tools/power turbostat: Cleanup print helper functions
tools/power turbostat: Fix --cpu-set 1 regression on HT systems
tools/power turbostat: Fix --cpu-set 0 regression on HT systems
tools/power turbostat: Fix unrecognized option '-P'
tools/power turbostat: Fix AMD RAPL regression on big systems
tools/power/x86: Add SOC slider and platform profile support
The fixdep hostprog may be built multiple times during a single build.
Once during the configuration phase and later during the regular phase.
As only the regular build phase respects CONFIG_WERROR / W=e, the
compiler flags might change between the phases, leading to rebuilds.
Example, the rebuilds will happen twice on each invocation of the build:
$ make allyesconfig prepare
make[1]: Entering directory '/tmp/deleteme'
HOSTCC scripts/basic/fixdep
#
# No change to .config
#
HOSTCC scripts/basic/fixdep
DESCEND objtool
INSTALL libsubcmd_headers
make[1]: Leaving directory '/tmp/deleteme'
Fix the compilation flags used for scripts/basic/ before
scripts/Makefile.warn is evaluated to stop CONFIG_WERROR / W=e
influencing the fixdep build to avoid the spurious rebuilds.
Fixes: 7ded7d37e5f5 ("scripts/Makefile.extrawarn: Respect CONFIG_WERROR / W=e for hostprogs")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260422-kbuild-scripts-basic-werror-v1-1-8c6912ff22e0@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
* clk-tenstorrent:
clk: tenstorrent: Add Atlantis clock controller driver
reset: tenstorrent: Add reset controller for Atlantis
dt-bindings: clk: tenstorrent: Add tenstorrent,atlantis-prcm-rcpu
* clk-rockchip:
clk: rockchip: rk3568: Add PCIe pipe clock gates
clk: rockchip: Add clock controller for the RV1103B
dt-bindings: clock: rockchip: Add RV1103B CRU support
* clk-imx:
clk: imx8mq: Correct the CSI PHY sels
clk: vf610: Add support for the Ethernet switch clocks
dt-bindings: clock: vf610: Add definitions for MTIP L2 switch
dt-bindings: clock: vf610: Drop VF610_CLK_END define
clk: vf610: Move VF610_CLK_END define to clk-vf610 driver
clk: imx: imx8-acm: fix flags for acm clocks
clk: imx: imx6q: Fix device node reference leak in of_assigned_ldb_sels()
clk: imx: imx6q: Fix device node reference leak in pll6_bypassed()
clk: imx: fracn-gppll: Add 477.4MHz support
clk: imx: fracn-gppll: Add 333.333333 MHz support
clk: imx: pll14xx: Use unsigned format specifier
dt-bindings: clock: imx6q[ul]-clock: add optional clock enet[1]_ref_pad
* clk-allwinner:
clk: sunxi-ng: sun55i-a523-r: Add missing r-spi module clock
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