Linux kernel source tree
Go to file
Wentao Guan 8dfa2f8780 LoongArch: Fix potential ADE in loongson_gpu_fixup_dma_hang()
The switch case in loongson_gpu_fixup_dma_hang() may not DC2 or DC3, and
readl(crtc_reg) will access with random address, because the "device" is
from "base+PCI_DEVICE_ID", "base" is from "pdev->devfn+1". This is wrong
when my platform inserts a discrete GPU:

lspci -tv
-[0000:00]-+-00.0  Loongson Technology LLC Hyper Transport Bridge Controller
...
           +-06.0  Loongson Technology LLC LG100 GPU
           +-06.2  Loongson Technology LLC Device 7a37
...

Add a default switch case to fix the panic as below:

 Kernel ade access[#1]:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.6.136-loong64-desktop-hwe+ #4
 pc 90000000017e5534 ra 90000000017e54c0 tp 90000001002f8000 sp 90000001002fb6c0
 a0 80000efe00003100 a1 0000000000003100 a2 0000000000000000 a3 0000000000000002
 a4 90000001002fb6b4 a5 900000087cdb58fd a6 90000000027af000 a7 0000000000000001
 t0 00000000000085b9 t1 000000000000ffff t2 0000000000000000 t3 0000000000000000
 t4 fffffffffffffffd t5 00000000fffb6d9c t6 0000000000083b00 t7 00000000000070c0
 t8 900000087cdb4d94 u0 900000087cdb58fd s9 90000001002fb826 s0 90000000031c12c8
 s1 7fffffffffffff00 s2 90000000031c12d0 s3 0000000000002710 s4 0000000000000000
 s5 0000000000000000 s6 9000000100053000 s7 7fffffffffffff00 s8 90000000030d4000
    ra: 90000000017e54c0 loongson_gpu_fixup_dma_hang+0x40/0x210
   ERA: 90000000017e5534 loongson_gpu_fixup_dma_hang+0xb4/0x210
  CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)
  PRMD: 00000004 (PPLV0 +PIE -PWE)
  EUEN: 00000000 (-FPE -SXE -ASXE -BTE)
  ECFG: 00071c1d (LIE=0,2-4,10-12 VS=7)
 ESTAT: 00480000 [ADEM] (IS= ECode=8 EsubCode=1)
  BADV: 7fffffffffffff00
  PRID: 0014d000 (Loongson-64bit, Loongson-3A6000-HV)
 Modules linked in:
 Process swapper/0 (pid: 1, threadinfo=(____ptrval____), task=(____ptrval____))
 Stack : 0000000000000006 90000001002fb778 90000001002fb704 0000000000000007
         0000000016a65700 90000000017e5690 000000000000ffff ffffffffffffffff
         900000000209f7c0 9000000100053000 900000000209f7a8 9000000000eebc08
         0000000000000000 0000000000000000 0000000000000006 90000001002fb778
         90000001000530b8 90000000027af000 0000000000000000 9000000100054000
         9000000100053000 9000000000ebb70c 9000000100004c00 9000000004000001
         90000001002fb7e4 bae765461f31cb12 0000000000000000 0000000000000000
         0000000000000006 90000000027af000 0000000000000030 90000000027af000
         900000087cd6f800 9000000100053000 0000000000000000 9000000000ebc560
         7a2500147cdaf720 bae765461f31cb12 0000000000000001 0000000000000030
         ...
 Call Trace:
 [<90000000017e5534>] loongson_gpu_fixup_dma_hang+0xb4/0x210
 [<9000000000eebc08>] pci_fixup_device+0x108/0x280
 [<9000000000ebb70c>] pci_setup_device+0x24c/0x690
 [<9000000000ebc560>] pci_scan_single_device+0xe0/0x140
 [<9000000000ebc684>] pci_scan_slot+0xc4/0x280
 [<9000000000ebdd00>] pci_scan_child_bus_extend+0x60/0x3f0
 [<9000000000f5bc94>] acpi_pci_root_create+0x2b4/0x420
 [<90000000017e5e74>] pci_acpi_scan_root+0x2d4/0x440
 [<9000000000f5b02c>] acpi_pci_root_add+0x21c/0x3a0
 [<9000000000f4ee54>] acpi_bus_attach+0x1a4/0x3c0
 [<90000000010e200c>] device_for_each_child+0x6c/0xe0
 [<9000000000f4bbf4>] acpi_dev_for_each_child+0x44/0x70
 [<9000000000f4ef40>] acpi_bus_attach+0x290/0x3c0
 [<90000000010e200c>] device_for_each_child+0x6c/0xe0
 [<9000000000f4bbf4>] acpi_dev_for_each_child+0x44/0x70
 [<9000000000f4ef40>] acpi_bus_attach+0x290/0x3c0
 [<9000000000f5211c>] acpi_bus_scan+0x6c/0x280
 [<900000000189c028>] acpi_scan_init+0x194/0x310
 [<900000000189bc6c>] acpi_init+0xcc/0x140
 [<9000000000220cdc>] do_one_initcall+0x4c/0x310
 [<90000000018618fc>] kernel_init_freeable+0x258/0x2d4
 [<900000000184326c>] kernel_init+0x28/0x13c
 [<9000000000222008>] ret_from_kernel_thread+0xc/0xa4

Cc: stable@vger.kernel.org
Fixes: 95db0c9f52 ("LoongArch: Workaround LS2K/LS7A GPU DMA hang bug")
Link: https://gist.github.com/opsiff/ebf2dac51b4013d22462f2124c55f807
Link: https://gist.github.com/opsiff/a62f2a73db0492b3c49bf223a339b133
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2026-05-04 09:00:20 +08:00
arch LoongArch: Fix potential ADE in loongson_gpu_fixup_dma_hang() 2026-05-04 09:00:20 +08:00
block block: only restrict bio allocation gfp mask asked to block 2026-04-21 11:42:12 -06:00
certs Clang build fixes for 7.1 2026-04-24 09:29:51 -07:00
crypto This push contains the following changes: 2026-05-02 12:31:43 -07:00
Documentation Including fixes from netfilter. 2026-04-30 08:45:43 -07:00
drivers drm fixes for 7.1-rc2 2026-05-01 16:56:08 -07:00
fs Description for this pull request: 2026-05-02 12:25:57 -07:00
include drm fixes for 7.1-rc2 2026-05-01 16:56:08 -07:00
init memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
io_uring io_uring-7.1-20260430 2026-05-01 11:01:31 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel Fix lockup in requeue-PI during signal/timeout wakeups, 2026-05-03 08:17:09 -07:00
lib 20 hotfixes. All are for MM (and for MMish maintainers). 9 are cc:stable 2026-05-01 08:45:23 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm slab fixes for 7.1-rc1 2026-05-03 08:19:57 -07:00
net net/sched: cls_flower: revert unintended changes 2026-04-30 13:47:01 +02:00
rust Char/Misc/IIO/and others driver updates for 7.1-rc1 2026-04-24 13:23:50 -07:00
samples soc: drivers for 7.1 2026-04-16 20:34:34 -07:00
scripts First round of Kbuild fixes for 7.1 2026-04-25 17:04:15 -07:00
security selinux: fix avdcache auditing 2026-04-28 18:13:58 -04:00
sound ALSA: hda/tas2781: Fix incorrect bit update for non-book-zero or book 0 pages >1 2026-04-29 07:51:17 +02:00
tools Assorted arm64, ACPI and kselftest fixes for 7.1-rc2: 2026-05-01 16:32:42 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt Arm: 2026-04-17 07:18:03 -07:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes
.gitignore kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap drm fixes for 7.1-rc2 2026-05-01 16:56:08 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml
COPYING
CREDITS Delete some obsolete networking code 2026-04-24 09:41:58 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS drm fixes for 7.1-rc2 2026-05-01 16:56:08 -07:00
Makefile Linux 7.1-rc2 2026-05-03 14:21:25 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

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