tjh.dev
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Pull turbostat updates from Len Brown:
- Add initial DMR support, which required smarter RAPL probe
- Fix AMD MSR RAPL energy reporting
- Add RAPL power limit configuration output
- Minor fixes
* tag 'turbostat-2025.06.08' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux:
tools/power turbostat: version 2025.06.08
tools/power turbostat: Add initial support for BartlettLake
tools/power turbostat: Add initial support for DMR
tools/power turbostat: Dump RAPL sysfs info
tools/power turbostat: Avoid probing the same perf counters
tools/power turbostat: Allow probing RAPL with platform_features->rapl_msrs cleared
tools/power turbostat: Clean up add perf/msr counter logic
tools/power turbostat: Introduce add_msr_counter()
tools/power turbostat: Remove add_msr_perf_counter_()
tools/power turbostat: Remove add_cstate_perf_counter_()
tools/power turbostat: Remove add_rapl_perf_counter_()
tools/power turbostat: Quit early for unsupported RAPL counters
tools/power turbostat: Always check rapl_joules flag
tools/power turbostat: Fix AMD package-energy reporting
tools/power turbostat: Fix RAPL_GFX_ALL typo
tools/power turbostat: Add Android support for MSR device handling
tools/power turbostat.8: pm_domain wording fix
tools/power turbostat.8: fix typo: idle_pct should be pct_idle
Pull timer cleanup from Thomas Gleixner:
"The delayed from_timer() API cleanup:
The renaming to the timer_*() namespace was delayed due massive
conflicts against Linux-next. Now that everything is upstream finish
the conversion"
* tag 'timers-cleanups-2025-06-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
treewide, timers: Rename from_timer() to timer_container_of()
Add initial DMR support, which required smarter RAPL probe
Fix AMD MSR RAPL energy reporting
Add RAPL power limit configuration output
Minor fixes
Signed-off-by: Len Brown <len.brown@intel.com>
Pull x86 fixes from Thomas Gleixner:
"A small set of x86 fixes:
- Cure IO bitmap inconsistencies
A failed fork cleans up all resources of the newly created thread
via exit_thread(). exit_thread() invokes io_bitmap_exit() which
does the IO bitmap cleanups, which unfortunately assume that the
cleanup is related to the current task, which is obviously bogus.
Make it work correctly
- A lockdep fix in the resctrl code removed the clearing of the
command buffer in two places, which keeps stale error messages
around. Bring them back.
- Remove unused trace events"
* tag 'x86-urgent-2025-06-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
fs/resctrl: Restore the rdt_last_cmd_clear() calls after acquiring rdtgroup_mutex
x86/iopl: Cure TIF_IO_BITMAP inconsistencies
x86/fpu: Remove unused trace events
Move this API to the canonical timer_*() namespace.
[ tglx: Redone against pre rc1 ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com
Add initial support for BartlettLake.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Pull timer fix from Thomas Gleixner:
"Add the missing seq_file forward declaration in the timer namespace
header"
* tag 'timers-urgent-2025-06-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timens: Add struct seq_file forward declaration
A lockdep fix removed two rdt_last_cmd_clear() calls that were used to
clear the last_cmd_status buffer but called without holding the required
rdtgroup_mutex.
The impacted resctrl commands are writing to the cpus or cpus_list files
and creating a new monitor or control group. With stale data in the
last_cmd_status buffer the impacted resctrl commands report the stale error
on success, or append its own failure message to the stale error on
failure.
Consequently, restore the rdt_last_cmd_clear() calls after acquiring
rdtgroup_mutex.
Fixes: c8eafe149530 ("x86/resctrl: Fix potential lockdep warning")
Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/all/20250603125828.1590067-1-zengheng4@huawei.com
Pull Kbuild updates from Masahiro Yamada:
- Add support for the EXPORT_SYMBOL_GPL_FOR_MODULES() macro, which
exports a symbol only to specified modules
- Improve ABI handling in gendwarfksyms
- Forcibly link lib-y objects to vmlinux even if CONFIG_MODULES=n
- Add checkers for redundant or missing <linux/export.h> inclusion
- Deprecate the extra-y syntax
- Fix a genksyms bug when including enum constants from *.symref files
* tag 'kbuild-v6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (28 commits)
genksyms: Fix enum consts from a reference affecting new values
arch: use always-$(KBUILD_BUILTIN) for vmlinux.lds
kbuild: set y instead of 1 to KBUILD_{BUILTIN,MODULES}
efi/libstub: use 'targets' instead of extra-y in Makefile
module: make __mod_device_table__* symbols static
scripts/misc-check: check unnecessary #include <linux/export.h> when W=1
scripts/misc-check: check missing #include <linux/export.h> when W=1
scripts/misc-check: add double-quotes to satisfy shellcheck
kbuild: move W=1 check for scripts/misc-check to top-level Makefile
scripts/tags.sh: allow to use alternative ctags implementation
kconfig: introduce menu type enum
docs: symbol-namespaces: fix reST warning with literal block
kbuild: link lib-y objects to vmlinux forcibly even when CONFIG_MODULES=n
tinyconfig: enable CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
docs/core-api/symbol-namespaces: drop table of contents and section numbering
modpost: check forbidden MODULE_IMPORT_NS("module:") at compile time
kbuild: move kbuild syntax processing to scripts/Makefile.build
Makefile: remove dependency on archscripts for header installation
Documentation/kbuild: Add new gendwarfksyms kABI rules
Documentation/kbuild: Drop section numbers
...
Add initial support for DMR.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Pull x86 perf fix from Thomas Gleixner:
"A single fix for the x86 performance counters on Intel CPUs:
The MSR offset calculations for fixed performance counters are stored
at the wrong index in the configuration array causing the general
purpose counter MSR offset to be overwritten, so both the general
purpose and the fixed counters offsets are incorrect.
Correct the array index calculation to fix that"
* tag 'perf-urgent-2025-06-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel: Fix incorrect MSR index calculations in intel_pmu_config_acr()
Add forward declaration of struct seq_file before using it in a
function prototype.
Fixes: 04a8682a71be ("fs/proc: Introduce /proc/pid/timens_offsets")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andrei Vagin <avagin@gmail.com>
Link: https://lore.kernel.org/all/aDlskzKIAULMlwPj@gondor.apana.org.au
io_bitmap_exit() is invoked from exit_thread() when a task exists or
when a fork fails. In the latter case the exit_thread() cleans up
resources which were allocated during fork().
io_bitmap_exit() invokes task_update_io_bitmap(), which in turn ends up
in tss_update_io_bitmap(). tss_update_io_bitmap() operates on the
current task. If current has TIF_IO_BITMAP set, but no bitmap installed,
tss_update_io_bitmap() crashes with a NULL pointer dereference.
There are two issues, which lead to that problem:
1) io_bitmap_exit() should not invoke task_update_io_bitmap() when
the task, which is cleaned up, is not the current task. That's a
clear indicator for a cleanup after a failed fork().
2) A task should not have TIF_IO_BITMAP set and neither a bitmap
installed nor IOPL emulation level 3 activated.
This happens when a kernel thread is created in the context of
a user space thread, which has TIF_IO_BITMAP set as the thread
flags are copied and the IO bitmap pointer is cleared.
Other than in the failed fork() case this has no impact because
kernel threads including IO workers never return to user space and
therefore never invoke tss_update_io_bitmap().
Cure this by adding the missing cleanups and checks:
1) Prevent io_bitmap_exit() to invoke task_update_io_bitmap() if
the to be cleaned up task is not the current task.
2) Clear TIF_IO_BITMAP in copy_thread() unconditionally. For user
space forks it is set later, when the IO bitmap is inherited in
io_bitmap_share().
For paranoia sake, add a warning into tss_update_io_bitmap() to catch
the case, when that code is invoked with inconsistent state.
Fixes: ea5f1cd7ab49 ("x86/ioperm: Remove bitmap if all permissions dropped")
Reported-by: syzbot+e2b1803445d236442e54@syzkaller.appspotmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/87wmdceom2.ffs@tglx
Pull sh updates from John Paul Adrian Glaubitz:
- replace the __ASSEMBLY__ with __ASSEMBLER__ macro in all headers
since the latter is now defined automatically by both GCC and Clang
when compiling assembly code (Thomas Huth)
- set the default SPI mode for the ecovec24 board which became
necessary after a new mode member as added to the sh_msiof_spi_info
struct in cf9e4784f3bd ("spi: sh-msiof: Add slave mode support")
(Geert Uytterhoeven)
- remove unused variables in the kprobes code in
kprobe_exceptions_notify() (Mike Rapoport)
* tag 'sh-for-v6.16-tag1' of git://git.kernel.org/pub/scm/linux/kernel/git/glaubitz/sh-linux:
sh: kprobes: Remove unused variables in kprobe_exceptions_notify()
sh: ecovec24: Make SPI mode explicit
sh: Replace __ASSEMBLY__ with __ASSEMBLER__ in all headers
Enumeration constants read from a symbol reference file can incorrectly
affect new enumeration constants parsed from an actual input file.
Example:
$ cat test.c
enum { E_A, E_B, E_MAX };
struct bar { int mem[E_MAX]; };
int foo(struct bar *a) {}
__GENKSYMS_EXPORT_SYMBOL(foo);
$ cat test.c | ./scripts/genksyms/genksyms -T test.0.symtypes
#SYMVER foo 0x070d854d
$ cat test.0.symtypes
E#E_MAX 2
s#bar struct bar { int mem [ E#E_MAX ] ; }
foo int foo ( s#bar * )
$ cat test.c | ./scripts/genksyms/genksyms -T test.1.symtypes -r test.0.symtypes
<stdin>:4: warning: foo: modversion changed because of changes in enum constant E_MAX
#SYMVER foo 0x9c9dfd81
$ cat test.1.symtypes
E#E_MAX ( 2 ) + 3
s#bar struct bar { int mem [ E#E_MAX ] ; }
foo int foo ( s#bar * )
The __add_symbol() function includes logic to handle the incrementation of
enumeration values, but this code is also invoked when reading a reference
file. As a result, the variables last_enum_expr and enum_counter might be
incorrectly set after reading the reference file, which later affects
parsing of the actual input.
Fix the problem by splitting the logic for the incrementation of
enumeration values into a separate function process_enum() and call it from
__add_symbol() only when processing non-reference data.
Fixes: e37ddb825003 ("genksyms: Track changes to enum constants")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
for example:
intel-rapl:1: psys 28.0s:100W 976.0us:100W
intel-rapl:0: package-0 28.0s:57W,max:15W 2.4ms:57W
intel-rapl:0/intel-rapl:0:0: core disabled
intel-rapl:0/intel-rapl:0:1: uncore disabled
intel-rapl-mmio:0: package-0 28.0s:28W,max:15W 2.4ms:57W
[lenb: simplified format]
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
squish me
Signed-off-by: Len Brown <len.brown@intel.com>
README