Revision b90d72a6bfdb5e5c62cd223a8cdf4045bfbcb94d authored by Will Deacon on 12 January 2021, 22:18:55 UTC, committed by Catalin Marinas on 13 January 2021, 15:08:41 UTC
This reverts commit 367c820ef08082e68df8a3bc12e62393af21e4b5. lockup_detector_init() makes heavy use of per-cpu variables and must be called with preemption disabled. Usually, it's handled early during boot in kernel_init_freeable(), before SMP has been initialised. Since we do not know whether or not our PMU interrupt can be signalled as an NMI until considerably later in the boot process, the Arm PMU driver attempts to re-initialise the lockup detector off the back of a device_initcall(). Unfortunately, this is called from preemptible context and results in the following splat: | BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 | caller is debug_smp_processor_id+0x20/0x2c | CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.10.0+ #276 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x3c0 | show_stack+0x20/0x6c | dump_stack+0x2f0/0x42c | check_preemption_disabled+0x1cc/0x1dc | debug_smp_processor_id+0x20/0x2c | hardlockup_detector_event_create+0x34/0x18c | hardlockup_detector_perf_init+0x2c/0x134 | watchdog_nmi_probe+0x18/0x24 | lockup_detector_init+0x44/0xa8 | armv8_pmu_driver_init+0x54/0x78 | do_one_initcall+0x184/0x43c | kernel_init_freeable+0x368/0x380 | kernel_init+0x1c/0x1cc | ret_from_fork+0x10/0x30 Rather than bodge this with raw_smp_processor_id() or randomly disabling preemption, simply revert the culprit for now until we figure out how to do this properly. Reported-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Will Deacon <will@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Alexandru Elisei <alexandru.elisei@arm.com> Link: https://lore.kernel.org/r/20201221162249.3119-1-lecopzer.chen@mediatek.com Link: https://lore.kernel.org/r/20210112221855.10666-1-will@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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videomode.h
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>
*
* generic videomode description
*/
#ifndef __LINUX_VIDEOMODE_H
#define __LINUX_VIDEOMODE_H
#include <linux/types.h>
#include <video/display_timing.h>
/*
* Subsystem independent description of a videomode.
* Can be generated from struct display_timing.
*/
struct videomode {
unsigned long pixelclock; /* pixelclock in Hz */
u32 hactive;
u32 hfront_porch;
u32 hback_porch;
u32 hsync_len;
u32 vactive;
u32 vfront_porch;
u32 vback_porch;
u32 vsync_len;
enum display_flags flags; /* display flags */
};
/**
* videomode_from_timing - convert display timing to videomode
* @dt: display_timing structure
* @vm: return value
*
* DESCRIPTION:
* This function converts a struct display_timing to a struct videomode.
*/
void videomode_from_timing(const struct display_timing *dt,
struct videomode *vm);
/**
* videomode_from_timings - convert one display timings entry to videomode
* @disp: structure with all possible timing entries
* @vm: return value
* @index: index into the list of display timings in devicetree
*
* DESCRIPTION:
* This function converts one struct display_timing entry to a struct videomode.
*/
int videomode_from_timings(const struct display_timings *disp,
struct videomode *vm, unsigned int index);
#endif
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