Revision tags: v6.6.67, v6.6.66, v6.6.65, v6.6.64, v6.6.63, v6.6.62, v6.6.61, v6.6.60, v6.6.59, v6.6.58, v6.6.57, v6.6.56, v6.6.55, v6.6.54, v6.6.53, v6.6.52, v6.6.51, v6.6.50, v6.6.49, v6.6.48, v6.6.47, v6.6.46, v6.6.45, v6.6.44, v6.6.43, v6.6.42, v6.6.41, v6.6.40, v6.6.39, v6.6.38, v6.6.37, v6.6.36, v6.6.35, v6.6.34, v6.6.33, v6.6.32, v6.6.31, v6.6.30, v6.6.29, v6.6.28, v6.6.27, v6.6.26, v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14, v6.6.13, v6.6.12, v6.6.11, v6.6.10, v6.6.9, v6.6.8, v6.6.7, v6.6.6, v6.6.5, v6.6.4, v6.6.3, v6.6.2, v6.5.11, v6.6.1, v6.5.10, v6.6, v6.5.9, v6.5.8, v6.5.7, v6.5.6, v6.5.5, v6.5.4, v6.5.3, v6.5.2, v6.1.51, v6.5.1, v6.1.50, v6.5, v6.1.49, v6.1.48, v6.1.46, v6.1.45, v6.1.44 |
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2612e3bb |
| 07-Aug-2023 |
Rodrigo Vivi <rodrigo.vivi@intel.com> |
Merge drm/drm-next into drm-intel-next
Catching-up with drm-next and drm-intel-gt-next. It will unblock a code refactor around the platform definitions (names vs acronyms).
Signed-off-by: Rodrigo V
Merge drm/drm-next into drm-intel-next
Catching-up with drm-next and drm-intel-gt-next. It will unblock a code refactor around the platform definitions (names vs acronyms).
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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9f771739 |
| 07-Aug-2023 |
Joonas Lahtinen <joonas.lahtinen@linux.intel.com> |
Merge drm/drm-next into drm-intel-gt-next
Need to pull in b3e4aae612ec ("drm/i915/hdcp: Modify hdcp_gsc_message msg sending mechanism") as a dependency for https://patchwork.freedesktop.org/series/1
Merge drm/drm-next into drm-intel-gt-next
Need to pull in b3e4aae612ec ("drm/i915/hdcp: Modify hdcp_gsc_message msg sending mechanism") as a dependency for https://patchwork.freedesktop.org/series/121735/
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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Revision tags: v6.1.43, v6.1.42, v6.1.41 |
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61b73694 |
| 24-Jul-2023 |
Thomas Zimmermann <tzimmermann@suse.de> |
Merge drm/drm-next into drm-misc-next
Backmerging to get v6.5-rc2.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
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Revision tags: v6.1.40, v6.1.39 |
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0791faeb |
| 17-Jul-2023 |
Mark Brown <broonie@kernel.org> |
ASoC: Merge v6.5-rc2
Get a similar baseline to my other branches, and fixes for people using the branch.
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2f98e686 |
| 11-Jul-2023 |
Maxime Ripard <mripard@kernel.org> |
Merge v6.5-rc1 into drm-misc-fixes
Boris needs 6.5-rc1 in drm-misc-fixes to prevent a conflict.
Signed-off-by: Maxime Ripard <mripard@kernel.org>
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Revision tags: v6.1.38, v6.1.37 |
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44f10dbe |
| 30-Jun-2023 |
Andrew Morton <akpm@linux-foundation.org> |
Merge branch 'master' into mm-hotfixes-stable
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77b1a7f7 |
| 28-Jun-2023 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-mm updates from Andrew Morton:
- Arnd Bergmann has fixed a bunch of -Wmissing-prototy
Merge tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-mm updates from Andrew Morton:
- Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in top-level directories
- Douglas Anderson has added a new "buddy" mode to the hardlockup detector. It permits the detector to work on architectures which cannot provide the required interrupts, by having CPUs periodically perform checks on other CPUs
- Zhen Lei has enhanced kexec's ability to support two crash regions
- Petr Mladek has done a lot of cleanup on the hard lockup detector's Kconfig entries
- And the usual bunch of singleton patches in various places
* tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (72 commits) kernel/time/posix-stubs.c: remove duplicated include ocfs2: remove redundant assignment to variable bit_off watchdog/hardlockup: fix typo in config HARDLOCKUP_DETECTOR_PREFER_BUDDY powerpc: move arch_trigger_cpumask_backtrace from nmi.h to irq.h devres: show which resource was invalid in __devm_ioremap_resource() watchdog/hardlockup: define HARDLOCKUP_DETECTOR_ARCH watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64 watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific watchdog/hardlockup: declare arch_touch_nmi_watchdog() only in linux/nmi.h watchdog/hardlockup: make the config checks more straightforward watchdog/hardlockup: sort hardlockup detector related config values a logical way watchdog/hardlockup: move SMP barriers from common code to buddy code watchdog/buddy: simplify the dependency for HARDLOCKUP_DETECTOR_PREFER_BUDDY watchdog/buddy: don't copy the cpumask in watchdog_next_cpu() watchdog/buddy: cleanup how watchdog_buddy_check_hardlockup() is called watchdog/hardlockup: remove softlockup comment in touch_nmi_watchdog() watchdog/hardlockup: in watchdog_hardlockup_check() use cpumask_copy() watchdog/hardlockup: don't use raw_cpu_ptr() in watchdog_hardlockup_kick() watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe() watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails ...
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Revision tags: v6.1.36 |
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9244724f |
| 26-Jun-2023 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge tag 'smp-core-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull SMP updates from Thomas Gleixner: "A large update for SMP management:
- Parallel CPU bringup
Merge tag 'smp-core-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull SMP updates from Thomas Gleixner: "A large update for SMP management:
- Parallel CPU bringup
The reason why people are interested in parallel bringup is to shorten the (kexec) reboot time of cloud servers to reduce the downtime of the VM tenants.
The current fully serialized bringup does the following per AP:
1) Prepare callbacks (allocate, intialize, create threads) 2) Kick the AP alive (e.g. INIT/SIPI on x86) 3) Wait for the AP to report alive state 4) Let the AP continue through the atomic bringup 5) Let the AP run the threaded bringup to full online state
There are two significant delays:
#3 The time for an AP to report alive state in start_secondary() on x86 has been measured in the range between 350us and 3.5ms depending on vendor and CPU type, BIOS microcode size etc.
#4 The atomic bringup does the microcode update. This has been measured to take up to ~8ms on the primary threads depending on the microcode patch size to apply.
On a two socket SKL server with 56 cores (112 threads) the boot CPU spends on current mainline about 800ms busy waiting for the APs to come up and apply microcode. That's more than 80% of the actual onlining procedure.
This can be reduced significantly by splitting the bringup mechanism into two parts:
1) Run the prepare callbacks and kick the AP alive for each AP which needs to be brought up.
The APs wake up, do their firmware initialization and run the low level kernel startup code including microcode loading in parallel up to the first synchronization point. (#1 and #2 above)
2) Run the rest of the bringup code strictly serialized per CPU (#3 - #5 above) as it's done today.
Parallelizing that stage of the CPU bringup might be possible in theory, but it's questionable whether required surgery would be justified for a pretty small gain.
If the system is large enough the first AP is already waiting at the first synchronization point when the boot CPU finished the wake-up of the last AP. That reduces the AP bringup time on that SKL from ~800ms to ~80ms, i.e. by a factor ~10x.
The actual gain varies wildly depending on the system, CPU, microcode patch size and other factors. There are some opportunities to reduce the overhead further, but that needs some deep surgery in the x86 CPU bringup code.
For now this is only enabled on x86, but the core functionality obviously works for all SMP capable architectures.
- Enhancements for SMP function call tracing so it is possible to locate the scheduling and the actual execution points. That allows to measure IPI delivery time precisely"
* tag 'smp-core-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits) trace,smp: Add tracepoints for scheduling remotelly called functions trace,smp: Add tracepoints around remotelly called functions MAINTAINERS: Add CPU HOTPLUG entry x86/smpboot: Fix the parallel bringup decision x86/realmode: Make stack lock work in trampoline_compat() x86/smp: Initialize cpu_primary_thread_mask late cpu/hotplug: Fix off by one in cpuhp_bringup_mask() x86/apic: Fix use of X{,2}APIC_ENABLE in asm with older binutils x86/smpboot/64: Implement arch_cpuhp_init_parallel_bringup() and enable it x86/smpboot: Support parallel startup of secondary CPUs x86/smpboot: Implement a bit spinlock to protect the realmode stack x86/apic: Save the APIC virtual base address cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_KICK_AP_STATE x86/apic: Provide cpu_primary_thread mask x86/smpboot: Enable split CPU startup cpu/hotplug: Provide a split up CPUHP_BRINGUP mechanism cpu/hotplug: Reset task stack state in _cpu_up() cpu/hotplug: Remove unused state functions riscv: Switch to hotplug core state synchronization parisc: Switch to hotplug core state synchronization ...
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Revision tags: v6.4, v6.1.35, v6.1.34, v6.1.33, v6.1.32, v6.1.31, v6.1.30 |
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ad1a4830 |
| 17-May-2023 |
Arnd Bergmann <arnd@arndb.de> |
init: consolidate prototypes in linux/init.h
The init/main.c file contains some extern declarations for functions defined in architecture code, and it defines some other functions that are called fr
init: consolidate prototypes in linux/init.h
The init/main.c file contains some extern declarations for functions defined in architecture code, and it defines some other functions that are called from architecture code with a custom prototype. Both of those result in warnings with 'make W=1':
init/calibrate.c:261:37: error: no previous prototype for 'calibrate_delay_is_known' [-Werror=missing-prototypes] init/main.c:790:20: error: no previous prototype for 'mem_encrypt_init' [-Werror=missing-prototypes] init/main.c:792:20: error: no previous prototype for 'poking_init' [-Werror=missing-prototypes] arch/arm64/kernel/irq.c:122:13: error: no previous prototype for 'init_IRQ' [-Werror=missing-prototypes] arch/arm64/kernel/time.c:55:13: error: no previous prototype for 'time_init' [-Werror=missing-prototypes] arch/x86/kernel/process.c:935:13: error: no previous prototype for 'arch_post_acpi_subsys_init' [-Werror=missing-prototypes] init/calibrate.c:261:37: error: no previous prototype for 'calibrate_delay_is_known' [-Werror=missing-prototypes] kernel/fork.c:991:20: error: no previous prototype for 'arch_task_cache_init' [-Werror=missing-prototypes]
Add prototypes for all of these in include/linux/init.h or another appropriate header, and remove the duplicate declarations from architecture specific code.
[sfr@canb.auug.org.au: declare time_init_early()] Link: https://lkml.kernel.org/r/20230519124311.5167221c@canb.auug.org.au Link: https://lkml.kernel.org/r/20230517131102.934196-12-arnd@kernel.org Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Eric Paris <eparis@redhat.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Moore <paul@paul-moore.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v6.1.29 |
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9d349d47 |
| 12-May-2023 |
Thomas Gleixner <tglx@linutronix.de> |
x86/smpboot: Make TSC synchronization function call based
Spin-waiting on the control CPU until the AP reaches the TSC synchronization is just a waste especially in the case that there is no synchro
x86/smpboot: Make TSC synchronization function call based
Spin-waiting on the control CPU until the AP reaches the TSC synchronization is just a waste especially in the case that there is no synchronization required.
As the synchronization has to run with interrupts disabled the control CPU part can just be done from a SMP function call. The upcoming AP issues that call async only in the case that synchronization is required.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Tested-by: Helge Deller <deller@gmx.de> # parisc Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck Link: https://lore.kernel.org/r/20230512205256.148255496@linutronix.de
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Revision tags: v6.1.28, v6.1.27, v6.1.26, v6.3, v6.1.25, v6.1.24, v6.1.23, v6.1.22, v6.1.21, v6.1.20, v6.1.19, v6.1.18, v6.1.17, v6.1.16, v6.1.15, v6.1.14, v6.1.13, v6.2, v6.1.12, v6.1.11, v6.1.10, v6.1.9, v6.1.8, v6.1.7, v6.1.6, v6.1.5, v6.0.19, v6.0.18, v6.1.4, v6.1.3, v6.0.17, v6.1.2, v6.0.16, v6.1.1, v6.0.15, v6.0.14, v6.0.13 |
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4f2c0a4a |
| 13-Dec-2022 |
Nick Terrell <terrelln@fb.com> |
Merge branch 'main' into zstd-linus
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Revision tags: v6.1, v6.0.12, v6.0.11, v6.0.10, v5.15.80, v6.0.9, v5.15.79, v6.0.8, v5.15.78, v6.0.7, v5.15.77, v5.15.76, v6.0.6, v6.0.5, v5.15.75, v6.0.4 |
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14e77332 |
| 21-Oct-2022 |
Nick Terrell <terrelln@fb.com> |
Merge branch 'main' into zstd-next
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Revision tags: v6.0.3, v6.0.2, v5.15.74, v5.15.73, v6.0.1, v5.15.72 |
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97acb6a8 |
| 03-Oct-2022 |
Tvrtko Ursulin <tvrtko.ursulin@intel.com> |
Merge drm/drm-next into drm-intel-gt-next
Daniele needs 84d4333c1e28 ("misc/mei: Add NULL check to component match callback functions") in order to merge the DG2 HuC patches.
Signed-off-by: Tvrtko
Merge drm/drm-next into drm-intel-gt-next
Daniele needs 84d4333c1e28 ("misc/mei: Add NULL check to component match callback functions") in order to merge the DG2 HuC patches.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
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Revision tags: v6.0, v5.15.71, v5.15.70, v5.15.69, v5.15.68, v5.15.67, v5.15.66, v5.15.65, v5.15.64, v5.15.63, v5.15.62, v5.15.61, v5.15.60 |
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fc30eea1 |
| 04-Aug-2022 |
Rodrigo Vivi <rodrigo.vivi@intel.com> |
Merge drm/drm-next into drm-intel-next
Sync up. In special to get the drm-intel-gt-next stuff.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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Revision tags: v5.15.59 |
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8bb5e7f4 |
| 02-Aug-2022 |
Dmitry Torokhov <dmitry.torokhov@gmail.com> |
Merge branch 'next' into for-linus
Prepare input updates for 5.20 (or 6.0) merge window.
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Revision tags: v5.19, v5.15.58, v5.15.57, v5.15.56, v5.15.55 |
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f83d9396 |
| 14-Jul-2022 |
Thomas Zimmermann <tzimmermann@suse.de> |
Merge drm/drm-next into drm-misc-next-fixes
Backmerging from drm/drm-next for the final fixes that will go into v5.20.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
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Revision tags: v5.15.54 |
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a63f7778 |
| 08-Jul-2022 |
Dmitry Torokhov <dmitry.torokhov@gmail.com> |
Merge tag 'v5.19-rc5' into next
Merge with mainline to bring up the latest definition from MFD subsystem needed for Mediatek keypad driver.
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Revision tags: v5.15.53 |
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dd84cfff |
| 04-Jul-2022 |
Takashi Iwai <tiwai@suse.de> |
Merge tag 'asoc-fix-v5.19-rc3' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus
ASoC: Fixes for v5.19
A collection of fixes for v5.19, quite large but nothing major -
Merge tag 'asoc-fix-v5.19-rc3' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus
ASoC: Fixes for v5.19
A collection of fixes for v5.19, quite large but nothing major - a good chunk of it is more stuff that was identified by mixer-test regarding event generation.
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Revision tags: v5.15.52, v5.15.51, v5.15.50, v5.15.49 |
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2b1333b8 |
| 20-Jun-2022 |
Thomas Zimmermann <tzimmermann@suse.de> |
Merge drm/drm-next into drm-misc-next
Backmerging to get new regmap APIs of v5.19-rc1.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
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Revision tags: v5.15.48 |
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f777316e |
| 15-Jun-2022 |
Takashi Iwai <tiwai@suse.de> |
Merge branch 'topic/ctl-enhancements' into for-next
Pull ALSA control enhancement patches. One is the faster lookup of control elements, and another is to introduce the input data validation.
Signe
Merge branch 'topic/ctl-enhancements' into for-next
Pull ALSA control enhancement patches. One is the faster lookup of control elements, and another is to introduce the input data validation.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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Revision tags: v5.15.47 |
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66da6500 |
| 09-Jun-2022 |
Paolo Bonzini <pbonzini@redhat.com> |
Merge tag 'kvm-riscv-fixes-5.19-1' of https://github.com/kvm-riscv/linux into HEAD
KVM/riscv fixes for 5.19, take #1
- Typo fix in arch/riscv/kvm/vmid.c
- Remove broken reference pattern from MAIN
Merge tag 'kvm-riscv-fixes-5.19-1' of https://github.com/kvm-riscv/linux into HEAD
KVM/riscv fixes for 5.19, take #1
- Typo fix in arch/riscv/kvm/vmid.c
- Remove broken reference pattern from MAINTAINERS entry
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Revision tags: v5.15.46 |
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6e2b347d |
| 08-Jun-2022 |
Maxime Ripard <maxime@cerno.tech> |
Merge v5.19-rc1 into drm-misc-fixes
Let's kick-off the start of the 5.19 fix cycle
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
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073350da |
| 07-Jun-2022 |
Mark Brown <broonie@kernel.org> |
Merge tag 'v5.19-rc1' into asoc-5.19
Linux 5.19-rc1
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Revision tags: v5.15.45, v5.15.44, v5.15.43, v5.15.42 |
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ac2ab990 |
| 24-May-2022 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge tag 'random-5.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld: "These updates continue to refine the w
Merge tag 'random-5.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld: "These updates continue to refine the work began in 5.17 and 5.18 of modernizing the RNG's crypto and streamlining and documenting its code.
New for 5.19, the updates aim to improve entropy collection methods and make some initial decisions regarding the "premature next" problem and our threat model. The cloc utility now reports that random.c is 931 lines of code and 466 lines of comments, not that basic metrics like that mean all that much, but at the very least it tells you that this is very much a manageable driver now.
Here's a summary of the various updates:
- The random_get_entropy() function now always returns something at least minimally useful. This is the primary entropy source in most collectors, which in the best case expands to something like RDTSC, but prior to this change, in the worst case it would just return 0, contributing nothing. For 5.19, additional architectures are wired up, and architectures that are entirely missing a cycle counter now have a generic fallback path, which uses the highest resolution clock available from the timekeeping subsystem.
Some of those clocks can actually be quite good, despite the CPU not having a cycle counter of its own, and going off-core for a stamp is generally thought to increase jitter, something positive from the perspective of entropy gathering. Done very early on in the development cycle, this has been sitting in next getting some testing for a while now and has relevant acks from the archs, so it should be pretty well tested and fine, but is nonetheless the thing I'll be keeping my eye on most closely.
- Of particular note with the random_get_entropy() improvements is MIPS, which, on CPUs that lack the c0 count register, will now combine the high-speed but short-cycle c0 random register with the lower-speed but long-cycle generic fallback path.
- With random_get_entropy() now always returning something useful, the interrupt handler now collects entropy in a consistent construction.
- Rather than comparing two samples of random_get_entropy() for the jitter dance, the algorithm now tests many samples, and uses the amount of differing ones to determine whether or not jitter entropy is usable and how laborious it must be. The problem with comparing only two samples was that if the cycle counter was extremely slow, but just so happened to be on the cusp of a change, the slowness wouldn't be detected. Taking many samples fixes that to some degree.
This, combined with the other improvements to random_get_entropy(), should make future unification of /dev/random and /dev/urandom maybe more possible. At the very least, were we to attempt it again today (we're not), it wouldn't break any of Guenter's test rigs that broke when we tried it with 5.18. So, not today, but perhaps down the road, that's something we can revisit.
- We attempt to reseed the RNG immediately upon waking up from system suspend or hibernation, making use of the various timestamps about suspend time and such available, as well as the usual inputs such as RDRAND when available.
- Batched randomness now falls back to ordinary randomness before the RNG is initialized. This provides more consistent guarantees to the types of random numbers being returned by the various accessors.
- The "pre-init injection" code is now gone for good. I suspect you in particular will be happy to read that, as I recall you expressing your distaste for it a few months ago. Instead, to avoid a "premature first" issue, while still allowing for maximal amount of entropy availability during system boot, the first 128 bits of estimated entropy are used immediately as it arrives, with the next 128 bits being buffered. And, as before, after the RNG has been fully initialized, it winds up reseeding anyway a few seconds later in most cases. This resulted in a pretty big simplification of the initialization code and let us remove various ad-hoc mechanisms like the ugly crng_pre_init_inject().
- The RNG no longer pretends to handle the "premature next" security model, something that various academics and other RNG designs have tried to care about in the past. After an interesting mailing list thread, these issues are thought to be a) mainly academic and not practical at all, and b) actively harming the real security of the RNG by delaying new entropy additions after a potential compromise, making a potentially bad situation even worse. As well, in the first place, our RNG never even properly handled the premature next issue, so removing an incomplete solution to a fake problem was particularly nice.
This allowed for numerous other simplifications in the code, which is a lot cleaner as a consequence. If you didn't see it before, https://lore.kernel.org/lkml/YmlMGx6+uigkGiZ0@zx2c4.com/ may be a thread worth skimming through.
- While the interrupt handler received a separate code path years ago that avoids locks by using per-cpu data structures and a faster mixing algorithm, in order to reduce interrupt latency, input and disk events that are triggered in hardirq handlers were still hitting locks and more expensive algorithms. Those are now redirected to use the faster per-cpu data structures.
- Rather than having the fake-crypto almost-siphash-based random32 implementation be used right and left, and in many places where cryptographically secure randomness is desirable, the batched entropy code is now fast enough to replace that.
- As usual, numerous code quality and documentation cleanups. For example, the initialization state machine now uses enum symbolic constants instead of just hard coding numbers everywhere.
- Since the RNG initializes once, and then is always initialized thereafter, a pretty heavy amount of code used during that initialization is never used again. It is now completely cordoned off using static branches and it winds up in the .text.unlikely section so that it doesn't reduce cache compactness after the RNG is ready.
- A variety of functions meant for waiting on the RNG to be initialized were only used by vsprintf, and in not a particularly optimal way. Replacing that usage with a more ordinary setup made it possible to remove those functions.
- A cleanup of how we warn userspace about the use of uninitialized /dev/urandom and uninitialized get_random_bytes() usage. Interestingly, with the change you merged for 5.18 that attempts to use jitter (but does not block if it can't), the majority of users should never see those warnings for /dev/urandom at all now, and the one for in-kernel usage is mainly a debug thing.
- The file_operations struct for /dev/[u]random now implements .read_iter and .write_iter instead of .read and .write, allowing it to also implement .splice_read and .splice_write, which makes splice(2) work again after it was broken here (and in many other places in the tree) during the set_fs() removal. This was a bit of a last minute arrival from Jens that hasn't had as much time to bake, so I'll be keeping my eye on this as well, but it seems fairly ordinary. Unfortunately, read_iter() is around 3% slower than read() in my tests, which I'm not thrilled about. But Jens and Al, spurred by this observation, seem to be making progress in removing the bottlenecks on the iter paths in the VFS layer in general, which should remove the performance gap for all drivers.
- Assorted other bug fixes, cleanups, and optimizations.
- A small SipHash cleanup"
* tag 'random-5.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (49 commits) random: check for signals after page of pool writes random: wire up fops->splice_{read,write}_iter() random: convert to using fops->write_iter() random: convert to using fops->read_iter() random: unify batched entropy implementations random: move randomize_page() into mm where it belongs random: remove mostly unused async readiness notifier random: remove get_random_bytes_arch() and add rng_has_arch_random() random: move initialization functions out of hot pages random: make consistent use of buf and len random: use proper return types on get_random_{int,long}_wait() random: remove extern from functions in header random: use static branch for crng_ready() random: credit architectural init the exact amount random: handle latent entropy and command line from random_init() random: use proper jiffies comparison macro random: remove ratelimiting for in-kernel unseeded randomness random: move initialization out of reseeding hot path random: avoid initializing twice in credit race random: use symbolic constants for crng_init states ...
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Revision tags: v5.18, v5.15.41, v5.15.40, v5.15.39, v5.15.38, v5.15.37, v5.15.36, v5.15.35, v5.15.34 |
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3bd4abc0 |
| 08-Apr-2022 |
Jason A. Donenfeld <Jason@zx2c4.com> |
x86/tsc: Use fallback for random_get_entropy() instead of zero
In the event that random_get_entropy() can't access a cycle counter or similar, falling back to returning 0 is suboptimal. Instead, fal
x86/tsc: Use fallback for random_get_entropy() instead of zero
In the event that random_get_entropy() can't access a cycle counter or similar, falling back to returning 0 is suboptimal. Instead, fallback to calling random_get_entropy_fallback(), which isn't extremely high precision or guaranteed to be entropic, but is certainly better than returning zero all the time.
If CONFIG_X86_TSC=n, then it's possible for the kernel to run on systems without RDTSC, such as 486 and certain 586, so the fallback code is only required for that case.
As well, fix up both the new function and the get_cycles() function from which it was derived to use cpu_feature_enabled() rather than boot_cpu_has(), and use !IS_ENABLED() instead of #ifndef.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: x86@kernel.org
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