- 02 Jul, 2020 4 commits
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Steven Rostedt (VMware) authored
After tweaking the ring buffer to be a bit faster, a warning is triggering on one of my machines, and causing my tests to fail. This warning is caused when the delta (current time stamp minus previous time stamp), is larger than the max time held by the ring buffer (59 bits). If the clock were to go backwards slightly, this would then easily trigger this warning. The machine that it triggered on, the clock did go backwards by around 450 nanoseconds, and this happened after a recalibration of the TSC clock. Now that the ring buffer is faster, it detects this, and the delta that is used larger than the max, the warning is triggered and my test fails. To handle the clock going backwards, look at the saved before and after time stamps. If they are the same, it means that the current event did not interrupt another event, and that those timestamp are of a previous event that was recorded. If the max delta is triggered, look at those time stamps, make sure they are the same, then use them to compare with the current timestamp. If the current timestamp is less than the before/after time stamps, then that means the clock being used went backward. Print out a message that this has happened, but do not warn about it (and only print the message once). Still do the warning if the delta is indeed larger than what can be used. Also remove the unneeded KERN_WARNING from the WARN_ONCE() print. Signed-off-by:Steven Rostedt (VMware) <rostedt@goodmis.org>
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Steven Rostedt (VMware) authored
After doing some benchmarks and examining the code, I found that the ring buffer clock calls were quite expensive, and noticed that it uses retpolines. This is because the ring buffer clock is programmable, and can be set. But in most cases it simply uses the fastest ns unit clock which is the trace_clock_local(). For RETPOLINE builds, checking if the ring buffer clock is set to trace_clock_local() and then calling it directly has brought the time of an event on my i7 box from an average of 93 nanoseconds an event down to 83 nanoseconds an event, and the minimum time from 81 nanoseconds to 68 nanoseconds! Suggested-by:
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by:
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Steven Rostedt (VMware) authored
Make a helper function rb_add_timestamp() that moves the adding of the extended time stamps into its own function. Also, remove the noinline and inline for the functions it calls, as recent benchmarks appear they do not make a difference (just let gcc decide). Signed-off-by: -
Steven Rostedt (VMware) authored
Reorganize a little the logic to handle adding the absolute time stamp, extended and forced time stamps, in such a way to remove a branch or two. This is just a micro optimization. Also add before and after time stamps to the rb_event_info structure to display those values in the rb_check_timestamps() code, if something were to go wrong. Suggested-by:
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- 30 Jun, 2020 10 commits
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Steven Rostedt (VMware) authored
It is the uncommon case where an event crosses a sub buffer boundary (page) mark that check at the end of reserving an event as unlikely. Suggested-by:
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Nicholas Piggin authored
On a 144 thread system, `perf ftrace` takes about 20 seconds to start up, due to calling synchronize_rcu() for each CPU. cat /proc/108560/stack 0xc0003e7eb336f470 __switch_to+0x2e0/0x480 __wait_rcu_gp+0x20c/0x220 synchronize_rcu+0x9c/0xc0 ring_buffer_reset_cpu+0x88/0x2e0 tracing_reset_online_cpus+0x84/0xe0 tracing_open+0x1d4/0x1f0 On a system with 10x more threads, it starts to become an annoyance. Batch these up so we disable all the per-cpu buffers first, then synchronize_rcu() once, then reset each of the buffers. This brings the time down to about 0.5s. Link: https://lkml.kernel.org/r/20200625053403.2386972-1-npiggin@gmail.comTested-by:Anton Blanchard <anton@ozlabs.org> Acked-by:
Paul E. McKenney <paulmck@kernel.org> Signed-off-by:
Nicholas Piggin <npiggin@gmail.com> Signed-off-by:
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Steven Rostedt (VMware) authored
After a discussion with the new time algorithm to have nested events still have proper time keeping but required using local64_t atomic operations. Mathieu was concerned about the performance this would have on 32 bit machines, as in most cases, atomic 64 bit operations on them can be expensive. As the ring buffer's timing needs do not require full features of local64_t, a wrapper is made to implement a new rb_time_t operation that uses two longs on 32 bit machines but still uses the local64_t operations on 64 bit machines. There's a switch that can be made in the file to force 64 bit to use the 32 bit version just for testing purposes. All reads do not need to succeed if a read happened while the stamp being read is in the process of being updated. The requirement is that all reads must succed that were done by an interrupting event (where this event was interrupted by another event that did the write). Or if the event itself did the write first. That is: rb_time_set(t, x) followed by rb_time_read(t) will always succeed (even if it gets interrupted by another event that writes to t. The result of the read will be either the previous set, or a set performed by an interrupting event. If the read is done by an event that interrupted another event that was in the process of setting the time stamp, and no other event came along to write to that time stamp, it will fail and the rb_time_read() will return that it failed (the value to read will be undefined). A set will always write to the time stamp and return with a valid time stamp, such that any read after it will be valid. A cmpxchg may fail if it interrupted an event that was in the process of updating the time stamp just like the reads do. Other than that, it will act like a normal cmpxchg. The way this works is that the rb_time_t is made of of three fields. A cnt, that gets updated atomically everyting a modification is made. A top that represents the most significant 30 bits of the time, and a bottom to represent the least significant 30 bits of the time. Notice, that the time values is only 60 bits long (where the ring buffer only uses 59 bits, which gives us 18 years of nanoseconds!). The top two bits of both the top and bottom is a 2 bit counter that gets set by the value of the least two significant bits of the cnt. A read of the top and the bottom where both the top and bottom have the same most significant top 2 bits, are considered a match and a valid 60 bit number can be created from it. If they do not match, then the number is considered invalid, and this must only happen if an event interrupted another event in the midst of updating the time stamp. This is only used for 32 bits machines as 64 bit machines can get better performance out of the local64_t. This has been tested heavily by forcing 64 bit to use this logic. Link: https://lore.kernel.org/r/20200625225345.18cf5881@oasis.local.home Link: http://lkml.kernel.org/r/20200629025259.309232719@goodmis.orgInspired-by:
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Steven Rostedt (VMware) authored
Instead of calling out the absolute test for each time to check if the ring buffer wants absolute time stamps for all its recording, incorporate it with the add_timestamp field and turn it into flags for faster processing between wanting a absolute tag and needing to force one. Link: http://lkml.kernel.org/r/20200629025259.154892368@goodmis.orgSigned-off-by:
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Steven Rostedt (VMware) authored
Up until now, if an event is interrupted while it is recorded by an interrupt, and that interrupt records events, the time of those events will all be the same. This is because events only record the delta of the time since the previous event (or beginning of a page), and to handle updating the time keeping for that of nested events is extremely racy. After years of thinking about this and several failed attempts, I finally have a solution to solve this puzzle. The problem is that you need to atomically calculate the delta and then update the time stamp you made the delta from, as well as then record it into the buffer, all this while at any time an interrupt can come in and do the same thing. This is easy to solve with heavy weight atomics, but that would be detrimental to the performance of the ring buffer. The current state of affairs sacrificed the time deltas for nested events for performance. The reason for previous failed attempts at solving this puzzle was because I was trying to completely avoid slow atomic operations like cmpxchg. I final came to the conclusion to always avoid cmpxchg is not possible, which is why those previous attempts always failed. But it is possible to pick one path (the most common case) and avoid cmpxchg in that path, which is the "fast path". The most common case is that an event will not be interrupted and have other events added into it. An event can detect if it has interrupted another event, and for these cases we can make it the slow path and use the heavy operations like cmpxchg. One more player was added to the game that made this possible, and that is the "absolute timestamp" (by Tom Zanussi) that allows us to inject a full 59 bit time stamp. (Of course this breaks if a machine is running for more than 18 years without a reboot!). There's barrier() placements around for being paranoid, even when they are not needed because of other atomic functions near by. But those should not hurt, as if they are not needed, they basically become a nop. Note, this also makes the race window much smaller, which means there are less slow paths to slow down the performance. The basic idea is that there's two main paths taken. 1) Not being interrupted between time stamps and reserving buffer space. In this case, the time stamps taken are true to the location in the buffer. 2) Was interrupted by another path between taking time stamps and reserving buffer space. The objective is to know what the delta is from the last reserved location in the buffer. As it is possible to detect if an event is interrupting another event before reserving data, space is added to the length to be reserved to inject a full time stamp along with the event being reserved. When an event is not interrupted, the write stamp is always the time of the last event written to the buffer. In path 1, there's two sub paths we care about: a) The event did not interrupt another event. b) The event interrupted another event. In case a, as the write stamp was read and known to be correct, the delta between the current time stamp and the write stamp is the delta between the current event and the previously recorded event. In case b, extra space was reserved to just put the full time stamp into the buffer. Which is done, as stated, in this path the time stamp taken is known to match the location in the buffer. In path 2, there's also two sub paths we care about: a) The event was not interrupted by another event since it reserved space on the buffer and re-reading the write stamp. b) The event was interrupted by another event. In case a, the write stamp is that of the last event that interrupted this event between taking the time stamps and reserving. As no event came in after re-reading the write stamp, that event is known to be the time of the event directly before this event and the delta can be the new time stamp and the write stamp. In case b, one or more events came in between reserving the event and re-reading he write stamp. Since this event's buffer reservation is between other events at this path, there's no way to know what the delta is. But because an event interrupted this event after it started, its fine to just give a zero delta, and take the same time stamp as the events that happened within the event being recorded. Here's the implementation of the design of this solution: All this is per cpu, and only needs to worry about nested events (not parallel events). The players: write_tail: The index in the buffer where new events can be written to. It is incremented via local_add() to reserve space for a new event. before_stamp: A time stamp set by all events before reserving space. write_stamp: A time stamp updated by events after it has successfully reserved space. /* Save the current position of write */ [A] w = local_read(write_tail); barrier(); /* Read both before and write stamps before touching anything */ before = local_read(before_stamp); after = local_read(write_stamp); barrier(); /* * If before and after are the same, then this event is not * interrupting a time update. If it is, then reserve space for adding * a full time stamp (this can turn into a time extend which is * just an extended time delta but fill up the extra space). */ if (after != before) abs = true; ts = clock(); /* Now update the before_stamp (everyone does this!) */ [B] local_set(before_stamp, ts); /* Now reserve space on the buffer */ [C] write = local_add_return(len, write_tail); /* Set tail to be were this event's data is */ tail = write - len; if (w == tail) { /* Nothing interrupted this between A and C */ [D] local_set(write_stamp, ts); barrier(); [E] save_before = local_read(before_stamp); if (!abs) { /* This did not interrupt a time update */ delta = ts - after; } else { delta = ts; /* The full time stamp will be in use */ } if (ts != save_before) { /* slow path - Was interrupted between C and E */ /* The update to write_stamp could have overwritten the update to * it by the interrupting event, but before and after should be * the same for all completed top events */ after = local_read(write_stamp); if (save_before > after) local_cmpxchg(write_stamp, after, save_before); } } else { /* slow path - Interrupted between A and C */ after = local_read(write_stamp); temp_ts = clock(); barrier(); [F] if (write == local_read(write_tail) && after < temp_ts) { /* This was not interrupted since C and F * The last write_stamp is still valid for the previous event * in the buffer. */ delta = temp_ts - after; /* OK to keep this new time stamp */ ts = temp_ts; } else { /* Interrupted between C and F * Well, there's no use to try to know what the time stamp * is for the previous event. Just set delta to zero and * be the same time as that event that interrupted us before * the reservation of the buffer. */ delta = 0; } /* No need to use full timestamps here */ abs = 0; } Link: https://lkml.kernel.org/r/20200625094454.732790f7@oasis.local.home Link: https://lore.kernel.org/r/20200627010041.517736087@goodmis.org Link: http://lkml.kernel.org/r/20200629025258.957440797@goodmis.orgReviewed-by:Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by:
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Steven Rostedt (VMware) authored
If a process has the trace_pipe open on a trace_array, the current tracer for that trace array should not be changed. This was original enforced by a global lock, but when instances were introduced, it was moved to the current_trace. But this structure is shared by all instances, and a trace_pipe is for a single instance. There's no reason that a process that has trace_pipe open on one instance should prevent another instance from changing its current tracer. Move the reference counter to the trace_array instead. This is marked as "Fixes" but is more of a clean up than a true fix. Backport if you want, but its not critical. Fixes: cf6ab6d9 ("tracing: Add ref count to tracer for when they are being read by pipe") Signed-off-by:
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Wei Yang authored
After the previous cleanup, DEFINE_EVENT_PRINT's definition has no relationship with DEFINE_EVENT. So After we re-define DEFINE_EVENT, it is not necessary to define DEFINE_EVENT_PRINT to be empty again. Link: http://lkml.kernel.org/r/20200612092844.56107-5-richard.weiyang@linux.alibaba.comSigned-off-by:
Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by:
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Wei Yang authored
Current definition define DEFINE_EVENT_PRINT to be DEFINE_EVENT. Actually, at this point DEFINE_EVENT is already an empty macro. Let's cut the relationship between DEFINE_EVENT_PRINT and DEFINE_EVENT. Link: http://lkml.kernel.org/r/20200612092844.56107-4-richard.weiyang@linux.alibaba.comSigned-off-by:
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Wei Yang authored
The definition of DEFINE_EVENT_PRINT is not changed after previous one, so not necessary to re-define is as the same form. Link: http://lkml.kernel.org/r/20200612092844.56107-3-richard.weiyang@linux.alibaba.comSigned-off-by:
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Wei Yang authored
After un-define DEFINE_EVENT in Stage 2, DEFINE_EVENT is not defined to a specific form. It is not necessary to un-define it again. Let's skip this. Link: http://lkml.kernel.org/r/20200612092844.56107-2-richard.weiyang@linux.alibaba.comSigned-off-by:
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- 29 Jun, 2020 4 commits
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Steven Rostedt (VMware) authored
When creating a trampoline based on the ftrace_regs_caller code, nop out the jnz test that would jmup to the code that would return to a direct caller (stored in the ORIG_RAX field) and not back to the function that called it. Link: http://lkml.kernel.org/r/20200422162750.638839749@goodmis.org Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by:
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Steven Rostedt (VMware) authored
If a direct hook is attached to a function that ftrace also has a function attached to it, then it is required that the ftrace_ops_list_func() is used to iterate over the registered ftrace callbacks. This will also include the direct ftrace_ops helper, that tells ftrace_regs_caller where to return to (the direct callback and not the function that called it). As this direct helper is only to handle the case of ftrace callbacks attached to the same function as the direct callback, the ftrace callback allocated trampolines (used to only call them), should never be used to return back to a direct callback. Only copy the portion of the ftrace_regs_caller that will return back to what called it, and not the portion that returns back to the direct caller. The direct ftrace_ops must then pick the ftrace_regs_caller builtin function as its own trampoline to ensure that it will never have one allocated for it (which would not include the handling of direct callbacks). Link: http://lkml.kernel.org/r/20200422162750.495903799@goodmis.org Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by:
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Steven Rostedt (VMware) authored
If a direct function is hooked along with one of the ftrace registered functions, then the ftrace_regs_caller is attached to the function that shares the direct hook as well as the ftrace hook. The ftrace_regs_caller will call ftrace_ops_list_func() that iterates through all the registered ftrace callbacks, and if there's a direct callback attached to that function, the direct ftrace_ops callback is called to notify that ftrace_regs_caller to return to the direct caller instead of going back to the function that called it. But this is a very uncommon case. Currently, the code has it as the default case. Modify ftrace_regs_caller to make the default case (the non jump) to just return normally, and have the jump to the handling of the direct caller. Link: http://lkml.kernel.org/r/20200422162750.350373278@goodmis.org Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by:
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Steven Rostedt (VMware) authored
To prevent default "trace_printks()" from spamming the top level tracing ring buffer, only allow trace instances to use trace_array_printk() (which can be used without the trace_printk() start up warning). Signed-off-by:
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- 28 Jun, 2020 22 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/soc/socLinus Torvalds authored
Pull ARM OMAP fixes from Arnd Bergmann: "The OMAP developers are particularly active at hunting down regressions, so this is a separate branch with OMAP specific fixes for v5.8: As Tony explains "The recent display subsystem (DSS) related platform data changes caused display related regressions for suspend and resume. Looks like I only tested suspend and resume before dropping the legacy platform data, and forgot to test it after dropping it. Turns out the main issue was that we no longer have platform code calling pm_runtime_suspend for DSS like we did for the legacy platform data case, and that fix is still being discussed on the dri-devel list and will get merged separately. The DSS related testing exposed a pile other other display related issues that also need fixing though": - Fix ti-sysc optional clock handling and reset status checks for devices that reset automatically in idle like DSS - Ignore ti-sysc clockactivity bit unless separately requested to avoid unexpected performance issues - Init ti-sysc framedonetv_irq to true and disable for am4 - Avoid duplicate DSS reset for legacy mode with dts data - Remove LCD timings for am4 as they cause warnings now that we're using generic panels Other OMAP changes from Tony include: - Fix omap_prm reset deassert as we still have drivers setting the pm_runtime_irq_safe() flag - Flush posted write for ti-sysc enable and disable - Fix droid4 spi related errors with spi flags - Fix am335x USB range and a typo for softreset - Fix dra7 timer nodes for clocks for IPU and DSP - Drop duplicate mailboxes after mismerge for dra7 - Prevent pocketgeagle header line signal from accidentally setting micro-SD write protection signal by removing the default mux - Fix NFSroot flakeyness after resume for duover by switching the smsc911x gpio interrupt to back to level sensitive - Fix regression for omap4 clockevent source after recent system timer changes - Yet another ethernet regression fix for the "rgmii" vs "rgmii-rxid" phy-mode - One patch to convert am3/am4 DT files to use the regular sdhci-omap driver instead of the old hsmmc driver, this was meant for the merge window but got lost in the process" * tag 'arm-omap-fixes-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (21 commits) ARM: dts: am5729: beaglebone-ai: fix rgmii phy-mode ARM: dts: Fix omap4 system timer source clocks ARM: dts: Fix duovero smsc interrupt for suspend ARM: dts: am335x-pocketbeagle: Fix mmc0 Write Protect Revert "bus: ti-sysc: Increase max softreset wait" ARM: dts: am437x-epos-evm: remove lcd timings ARM: dts: am437x-gp-evm: remove lcd timings ARM: dts: am437x-sk-evm: remove lcd timings ARM: dts: dra7-evm-common: Fix duplicate mailbox nodes ARM: dts: dra7: Fix timer nodes properly for timer_sys_ck clocks ARM: dts: Fix am33xx.dtsi ti,sysc-mask wrong softreset flag ARM: dts: Fix am33xx.dtsi USB ranges length bus: ti-sysc: Increase max softreset wait ARM: OMAP2+: Fix legacy mode dss_reset bus: ti-sysc: Fix uninitialized framedonetv_irq bus: ti-sysc: Ignore clockactivity unless specified as a quirk bus: ti-sysc: Use optional clocks on for enable and wait for softreset bit ARM: dts: omap4-droid4: Fix spi configuration and increase rate bus: ti-sysc: Flush posted write on enable and disable soc: ti: omap-prm: use atomic iopoll instead of sleeping one ... -
git://git.kernel.org/pub/scm/linux/kernel/git/soc/socLinus Torvalds authored
Pull ARM SoC fixes from Arnd Bergmann: "Here are a couple of bug fixes, mostly for devicetree files NXP i.MX: - Use correct voltage on some i.MX8M board device trees to avoid hardware damage - Code fixes for a compiler warning and incorrect reference counting, both harmless. - Fix the i.MX8M SoC driver to correctly identify imx8mp - Fix watchdog configuration in imx6ul-kontron device tree. Broadcom: - A small regression fix for the Raspberry-Pi firmware driver - A Kconfig change to use the correct timer driver on Northstar - A DT fix for the Luxul XWC-2000 machine - Two more DT fixes for NSP SoCs STmicroelectronics STI - Revert one broken patch for L2 cache configuration ARM Versatile Express: - Fix a regression by reverting a broken DT cleanup TEE drivers: - MAINTAINERS: change tee mailing list" * tag 'arm-fixes-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: Revert "ARM: sti: Implement dummy L2 cache's write_sec" soc: imx8m: fix build warning ARM: imx6: add missing put_device() call in imx6q_suspend_init() ARM: imx5: add missing put_device() call in imx_suspend_alloc_ocram() soc: imx8m: Correct i.MX8MP UID fuse offset ARM: dts: imx6ul-kontron: Change WDOG_ANY signal from push-pull to open-drain ARM: dts: imx6ul-kontron: Move watchdog from Kontron i.MX6UL/ULL board to SoM arm64: dts: imx8mm-beacon: Fix voltages on LDO1 and LDO2 arm64: dts: imx8mn-ddr4-evk: correct ldo1/ldo2 voltage range arm64: dts: imx8mm-evk: correct ldo1/ldo2 voltage range ARM: dts: NSP: Correct FA2 mailbox node ARM: bcm2835: Fix integer overflow in rpi_firmware_print_firmware_revision() MAINTAINERS: change tee mailing list ARM: dts: NSP: Disable PL330 by default, add dma-coherent property ARM: bcm: Select ARM_TIMER_SP804 for ARCH_BCM_NSP ARM: dts: BCM5301X: Add missing memory "device_type" for Luxul XWC-2000 arm: dts: vexpress: Move mcc node back into motherboard node -
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull timer fix from Ingo Molnar: "A single DocBook fix" * tag 'timers-urgent-2020-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timekeeping: Fix kerneldoc system_device_crosststamp & al
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull perf fix from Ingo Molnar: "A single Kbuild dependency fix" * tag 'perf-urgent-2020-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/x86/rapl: Fix RAPL config variable bug
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull EFI fixes from Ingo Molnar: - Fix build regression on v4.8 and older - Robustness fix for TPM log parsing code - kobject refcount fix for the ESRT parsing code - Two efivarfs fixes to make it behave more like an ordinary file system - Style fixup for zero length arrays - Fix a regression in path separator handling in the initrd loader - Fix a missing prototype warning - Add some kerneldoc headers for newly introduced stub routines - Allow support for SSDT overrides via EFI variables to be disabled - Report CPU mode and MMU state upon entry for 32-bit ARM - Use the correct stack pointer alignment when entering from mixed mode * tag 'efi-urgent-2020-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: efi/libstub: arm: Print CPU boot mode and MMU state at boot efi/libstub: arm: Omit arch specific config table matching array on arm64 efi/x86: Setup stack correctly for efi_pe_entry efi: Make it possible to disable efivar_ssdt entirely efi/libstub: Descriptions for stub helper functions efi/libstub: Fix path separator regression efi/libstub: Fix missing-prototype warning for skip_spaces() efi: Replace zero-length array and use struct_size() helper efivarfs: Don't return -EINTR when rate-limiting reads efivarfs: Update inode modification time for successful writes efi/esrt: Fix reference count leak in esre_create_sysfs_entry. efi/tpm: Verify event log header before parsing efi/x86: Fix build with gcc 4
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull scheduler fixes from Borislav Petkov: "The most anticipated fix in this pull request is probably the horrible build fix for the RANDSTRUCT fail that didn't make -rc2. Also included is the cleanup that removes those BUILD_BUG_ON()s and replaces it with ugly unions. Also included is the try_to_wake_up() race fix that was first triggered by Paul's RCU-torture runs, but was independently hit by Dave Chinner's fstest runs as well" * tag 'sched_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/cfs: change initial value of runnable_avg smp, irq_work: Continue smp_call_function*() and irq_work*() integration sched/core: s/WF_ON_RQ/WQ_ON_CPU/ sched/core: Fix ttwu() race sched/core: Fix PI boosting between RT and DEADLINE tasks sched/deadline: Initialize ->dl_boosted sched/core: Check cpus_mask, not cpus_ptr in __set_cpus_allowed_ptr(), to fix mask corruption sched/core: Fix CONFIG_GCC_PLUGIN_RANDSTRUCT build fail
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 fixes from Borislav Petkov: - AMD Memory bandwidth counter width fix, by Babu Moger. - Use the proper length type in the 32-bit truncate() syscall variant, by Jiri Slaby. - Reinit IA32_FEAT_CTL during wakeup to fix the case where after resume, VMXON would #GP due to VMX not being properly enabled, by Sean Christopherson. - Fix a static checker warning in the resctrl code, by Dan Carpenter. - Add a CR4 pinning mask for bits which cannot change after boot, by Kees Cook. - Align the start of the loop of __clear_user() to 16 bytes, to improve performance on AMD zen1 and zen2 microarchitectures, by Matt Fleming. * tag 'x86_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/asm/64: Align start of __clear_user() loop to 16-bytes x86/cpu: Use pinning mask for CR4 bits needing to be 0 x86/resctrl: Fix a NULL vs IS_ERR() static checker warning in rdt_cdp_peer_get() x86/cpu: Reinitialize IA32_FEAT_CTL MSR on BSP during wakeup syscalls: Fix offset type of ksys_ftruncate() x86/resctrl: Fix memory bandwidth counter width for AMD
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull RCU-vs-KCSAN fixes from Borislav Petkov: "A single commit that uses "arch_" atomic operations to avoid the instrumentation that comes with the non-"arch_" versions. In preparation for that commit, it also has another commit that makes these "arch_" atomic operations available to generic code. Without these commits, KCSAN uses can see pointless errors" * tag 'rcu_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcu: Fixup noinstr warnings locking/atomics: Provide the arch_atomic_ interface to generic code
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull objtool fixes from Borislav Petkov: "Three fixes from Peter Zijlstra suppressing KCOV instrumentation in noinstr sections. Peter Zijlstra says: "Address KCOV vs noinstr. There is no function attribute to selectively suppress KCOV instrumentation, instead teach objtool to NOP out the calls in noinstr functions" This cures a bunch of KCOV crashes (as used by syzcaller)" * tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Fix noinstr vs KCOV objtool: Provide elf_write_{insn,reloc}() objtool: Clean up elf_write() condition -
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 entry fixes from Borislav Petkov: "This is the x86/entry urgent pile which has accumulated since the merge window. It is not the smallest but considering the almost complete entry core rewrite, the amount of fixes to follow is somewhat higher than usual, which is to be expected. Peter Zijlstra says: 'These patches address a number of instrumentation issues that were found after the x86/entry overhaul. When combined with rcu/urgent and objtool/urgent, these patches make UBSAN/KASAN/KCSAN happy again. Part of making this all work is bumping the minimum GCC version for KASAN builds to gcc-8.3, the reason for this is that the __no_sanitize_address function attribute is broken in GCC releases before that. No known GCC version has a working __no_sanitize_undefined, however because the only noinstr violation that results from this happens when an UB is found, we treat it like WARN. That is, we allow it to violate the noinstr rules in order to get the warning out'" * tag 'x86_entry_for_5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/entry: Fix #UD vs WARN more x86/entry: Increase entry_stack size to a full page x86/entry: Fixup bad_iret vs noinstr objtool: Don't consider vmlinux a C-file kasan: Fix required compiler version compiler_attributes.h: Support no_sanitize_undefined check with GCC 4 x86/entry, bug: Comment the instrumentation_begin() usage for WARN() x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*() x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline() compiler_types.h: Add __no_sanitize_{address,undefined} to noinstr kasan: Bump required compiler version x86, kcsan: Add __no_kcsan to noinstr kcsan: Remove __no_kcsan_or_inline x86, kcsan: Remove __no_kcsan_or_inline usage -
Vincent Guittot authored
Some performance regression on reaim benchmark have been raised with commit 070f5e86 ("sched/fair: Take into account runnable_avg to classify group") The problem comes from the init value of runnable_avg which is initialized with max value. This can be a problem if the newly forked task is finally a short task because the group of CPUs is wrongly set to overloaded and tasks are pulled less agressively. Set initial value of runnable_avg equals to util_avg to reflect that there is no waiting time so far. Fixes: 070f5e86 ("sched/fair: Take into account runnable_avg to classify group") Reported-by:
kernel test robot <rong.a.chen@intel.com> Signed-off-by:
Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200624154422.29166-1-vincent.guittot@linaro.org
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Peter Zijlstra authored
Instead of relying on BUG_ON() to ensure the various data structures line up, use a bunch of horrible unions to make it all automatic. Much of the union magic is to ensure irq_work and smp_call_function do not (yet) see the members of their respective data structures change name. Suggested-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Ingo Molnar <mingo@kernel.org> Reviewed-by:
Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20200622100825.844455025@infradead.org
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Peter Zijlstra authored
Use a better name for this poorly named flag, to avoid confusion... Signed-off-by:
Mel Gorman <mgorman@suse.de> Link: https://lkml.kernel.org/r/20200622100825.785115830@infradead.org
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Peter Zijlstra authored
Paul reported rcutorture occasionally hitting a NULL deref: sched_ttwu_pending() ttwu_do_wakeup() check_preempt_curr() := check_preempt_wakeup() find_matching_se() is_same_group() if (se->cfs_rq == pse->cfs_rq) <-- *BOOM* Debugging showed that this only appears to happen when we take the new code-path from commit: 2ebb1771 ("sched/core: Offload wakee task activation if it the wakee is descheduling") and only when @cpu == smp_processor_id(). Something which should not be possible, because p->on_cpu can only be true for remote tasks. Similarly, without the new code-path from commit: c6e7bd7a ("sched/core: Optimize ttwu() spinning on p->on_cpu") this would've unconditionally hit: smp_cond_load_acquire(&p->on_cpu, !VAL); and if: 'cpu == smp_processor_id() && p->on_cpu' is possible, this would result in an instant live-lock (with IRQs disabled), something that hasn't been reported. The NULL deref can be explained however if the task_cpu(p) load at the beginning of try_to_wake_up() returns an old value, and this old value happens to be smp_processor_id(). Further assume that the p->on_cpu load accurately returns 1, it really is still running, just not here. Then, when we enqueue the task locally, we can crash in exactly the observed manner because p->se.cfs_rq != rq->cfs_rq, because p's cfs_rq is from the wrong CPU, therefore we'll iterate into the non-existant parents and NULL deref. The closest semi-plausible scenario I've managed to contrive is somewhat elaborate (then again, actual reproduction takes many CPU hours of rcutorture, so it can't be anything obvious): X->cpu = 1 rq(1)->curr = X CPU0 CPU1 CPU2 // switch away from X LOCK rq(1)->lock smp_mb__after_spinlock dequeue_task(X) X->on_rq = 9 switch_to(Z) X->on_cpu = 0 UNLOCK rq(1)->lock // migrate X to cpu 0 LOCK rq(1)->lock dequeue_task(X) set_task_cpu(X, 0) X->cpu = 0 UNLOCK rq(1)->lock LOCK rq(0)->lock enqueue_task(X) X->on_rq = 1 UNLOCK rq(0)->lock // switch to X LOCK rq(0)->lock smp_mb__after_spinlock switch_to(X) X->on_cpu = 1 UNLOCK rq(0)->lock // X goes sleep X->state = TASK_UNINTERRUPTIBLE smp_mb(); // wake X ttwu() LOCK X->pi_lock smp_mb__after_spinlock if (p->state) cpu = X->cpu; // =? 1 smp_rmb() // X calls schedule() LOCK rq(0)->lock smp_mb__after_spinlock dequeue_task(X) X->on_rq = 0 if (p->on_rq) smp_rmb(); if (p->on_cpu && ttwu_queue_wakelist(..)) [*] smp_cond_load_acquire(&p->on_cpu, !VAL) cpu = select_task_rq(X, X->wake_cpu, ...) if (X->cpu != cpu) switch_to(Y) X->on_cpu = 0 UNLOCK rq(0)->lock However I'm having trouble convincing myself that's actually possible on x86_64 -- after all, every LOCK implies an smp_mb() there, so if ttwu observes ->state != RUNNING, it must also observe ->cpu != 1. (Most of the previous ttwu() races were found on very large PowerPC) Nevertheless, this fully explains the observed failure case. Fix it by ordering the task_cpu(p) load after the p->on_cpu load, which is easy since nothing actually uses @cpu before this. Fixes: c6e7bd7a ("sched/core: Optimize ttwu() spinning on p->on_cpu") Reported-by: -
Juri Lelli authored
syzbot reported the following warning: WARNING: CPU: 1 PID: 6351 at kernel/sched/deadline.c:628 enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 At deadline.c:628 we have: 623 static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) 624 { 625 struct dl_rq *dl_rq = dl_rq_of_se(dl_se); 626 struct rq *rq = rq_of_dl_rq(dl_rq); 627 628 WARN_ON(dl_se->dl_boosted); 629 WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline)); [...] } Which means that setup_new_dl_entity() has been called on a task currently boosted. This shouldn't happen though, as setup_new_dl_entity() is only called when the 'dynamic' deadline of the new entity is in the past w.r.t. rq_clock and boosted tasks shouldn't verify this condition. Digging through the PI code I noticed that what above might in fact happen if an RT tasks blocks on an rt_mutex hold by a DEADLINE task. In the first branch of boosting conditions we check only if a pi_task 'dynamic' deadline is earlier than mutex holder's and in this case we set mutex holder to be dl_boosted. However, since RT 'dynamic' deadlines are only initialized if such tasks get boosted at some point (or if they become DEADLINE of course), in general RT 'dynamic' deadlines are usually equal to 0 and this verifies the aforementioned condition. Fix it by checking that the potential donor task is actually (even if temporary because in turn boosted) running at DEADLINE priority before using its 'dynamic' deadline value. Fixes: 2d3d891d ("sched/deadline: Add SCHED_DEADLINE inheritance logic") Reported-by: syzbot+119ba87189432ead09b4@syzkaller.appspotmail.com Signed-off-by:Juri Lelli <juri.lelli@redhat.com> Signed-off-by:
Daniel Bristot de Oliveira <bristot@redhat.com> Tested-by:
Daniel Wagner <dwagner@suse.de> Link: https://lkml.kernel.org/r/20181119153201.GB2119@localhost.localdomain
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Juri Lelli authored
syzbot reported the following warning triggered via SYSC_sched_setattr(): WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 setup_new_dl_entity /kernel/sched/deadline.c:594 [inline] WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 enqueue_dl_entity /kernel/sched/deadline.c:1370 [inline] WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 enqueue_task_dl+0x1c17/0x2ba0 /kernel/sched/deadline.c:1441 This happens because the ->dl_boosted flag is currently not initialized by __dl_clear_params() (unlike the other flags) and setup_new_dl_entity() rightfully complains about it. Initialize dl_boosted to 0. Fixes: 2d3d891d ("sched/deadline: Add SCHED_DEADLINE inheritance logic") Reported-by: syzbot+5ac8bac25f95e8b221e7@syzkaller.appspotmail.com Signed-off-by:
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Scott Wood authored
This function is concerned with the long-term CPU mask, not the transitory mask the task might have while migrate disabled. Before this patch, if a task was migrate-disabled at the time __set_cpus_allowed_ptr() was called, and the new mask happened to be equal to the CPU that the task was running on, then the mask update would be lost. Signed-off-by:
Scott Wood <swood@redhat.com> Signed-off-by:
Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by:
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Peter Zijlstra authored
As a temporary build fix, the proper cleanup needs more work. Reported-by:
Guenter Roeck <linux@roeck-us.net> Reported-by:
Eric Biggers <ebiggers@kernel.org> Suggested-by:
Kees Cook <keescook@chromium.org> Fixes: a1488664 ("sched: Replace rq::wake_list") Signed-off-by:
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Arnd Bergmann authored
Merge tag 'imx-fixes-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux into arm/fixes i.MX fixes for 5.8: - Fix LDO1 and LDO2 voltage range for a couple of i.MX8M board device trees. - Fix i.MX8MP UID fuse offset in i.MX8M SoC driver. - Fix watchdog configuration in imx6ul-kontron device tree. - Fix one build warning seen on building soc-imx8m driver with x86_64-randconfig. - Add missing put_device() call for a couple of mach-imx PM functions. * tag 'imx-fixes-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux: soc: imx8m: fix build warning ARM: imx6: add missing put_device() call in imx6q_suspend_init() ARM: imx5: add missing put_device() call in imx_suspend_alloc_ocram() soc: imx8m: Correct i.MX8MP UID fuse offset ARM: dts: imx6ul-kontron: Change WDOG_ANY signal from push-pull to open-drain ARM: dts: imx6ul-kontron: Move watchdog from Kontron i.MX6UL/ULL board to SoM arm64: dts: imx8mm-beacon: Fix voltages on LDO1 and LDO2 arm64: dts: imx8mn-ddr4-evk: correct ldo1/ldo2 voltage range arm64: dts: imx8mm-evk: correct ldo1/ldo2 voltage range Link: https://lore.kernel.org/r/20200624111725.GA24312@dragonSigned-off-by:
Arnd Bergmann <arnd@arndb.de>
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https://github.com/Broadcom/stblinuxArnd Bergmann authored
This pull request contains Broadcom ARM/ARM64/MIPS SoCs drivers fixes for 5.8, please pull the following: - Andy provides a fix for the Raspberry Pi firmware driver to print the correct time upon boot. This is a fallout from a converstion to use the ptT format * tag 'arm-soc/for-5.8/drivers-fixes' of https://github.com/Broadcom/stblinux: ARM: bcm2835: Fix integer overflow in rpi_firmware_print_firmware_revision() Link: https://lore.kernel.org/r/20200619202250.19029-2-f.fainelli@gmail.comSigned-off-by:
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https://github.com/Broadcom/stblinuxArnd Bergmann authored
This pull request contains Broadcom ARM-based SoCs machine/Kconfig fixes for 5.8, please pull the following: - Matthew adds a missing select to permit the use of the standard ARM SP804 timers on Norsthstar Plus (NSP) * tag 'arm-soc/for-5.8/soc-fixes' of https://github.com/Broadcom/stblinux: ARM: bcm: Select ARM_TIMER_SP804 for ARCH_BCM_NSP Link: https://lore.kernel.org/r/20200619202250.19029-3-f.fainelli@gmail.comSigned-off-by:
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