From 45f8dffc0714c3ef49c83e5bba4c56a4499bd5fc Mon Sep 17 00:00:00 2001 From: Karl Mehltretter Date: Wed, 22 Jul 2026 08:21:41 +0200 Subject: [PATCH 1/2] tick: Include ktime.h and jiffies.h in linux/tick.h The !CONFIG_NO_HZ_COMMON stubs use ktime_add(), ktime_get() and TICK_NSEC, but tick.h includes neither nor . Most configurations build only because those declarations arrive transitively. Commit 6440966067dc ("cpuset: Remove cpuset_cpu_is_isolated()") removed from . The include chain had been satisfying these declarations before was parsed. Commit 8aa76aa41589 ("ring-buffer: Use a housekeeping CPU to wake up waiters") then added to ring_buffer.c ahead of any header which provides them. Neither change is wrong on its own: the failure requires both and appeared in v7.0. ARM rpc_defconfig + CONFIG_FUNCTION_TRACER fails to build: $ make ARCH=arm rpc_defconfig $ ./scripts/config -e FTRACE -e FUNCTION_TRACER $ make ARCH=arm olddefconfig $ make ARCH=arm kernel/trace/ring_buffer.o In file included from include/linux/sched/isolation.h:6, from kernel/trace/ring_buffer.c:8: include/linux/tick.h: In function 'tick_nohz_get_next_hrtimer': include/linux/tick.h:156:9: error: implicit declaration of function 'ktime_add'; did you mean 'size_add'? include/linux/tick.h:156:19: error: implicit declaration of function 'ktime_get'; did you mean 'time_init'? include/linux/tick.h:156:32: error: 'TICK_NSEC' undeclared Include the headers the file actually uses. Fixes: 8aa76aa41589 ("ring-buffer: Use a housekeeping CPU to wake up waiters") Signed-off-by: Karl Mehltretter Signed-off-by: Thomas Gleixner Assisted-by: Codex:gpt-5.6-sol Link: https://patch.msgid.link/20260722062141.19671-1-kmehltretter@gmail.com --- include/linux/tick.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 1cf4651f09ad..47750ccd1314 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -7,6 +7,8 @@ #include #include +#include +#include #include #include #include From 94f39e4c017e66130e476268bdaa0bf61e914fa2 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 10 Jul 2026 09:09:58 +0100 Subject: [PATCH 2/2] clocksource/drivers/arm_arch_timer: Workaround bcm2712 broken EL2 virtual timer It appears that the bcm2712 SoC found in the relatively popular RPi5 has a broken EL2 virtual timer. Tthe reason why the timer isn't working is unknown (the timer is ticking, but the interrupt never fires), and the SoC vendor doesn't communicate on the reason why this isn't working, leaving users and maintainers in the dark. Paper over the issue by detecting the broken HW, falling back to the physical timer instead, and let the user know about it. Also taint the kernel as the machine is definitely not compliant with the spec, and it's unknown what else is wrong with it. Reported-by: John Reported-by: Daniel Drake Reported-by: Marek Szyprowski Signed-off-by: Marc Zyngier Signed-off-by: Thomas Gleixner Tested-by: Gary Guo Acked-by: Florian Fainelli Cc: Daniel Lezcano Link: https://patch.msgid.link/20260710080958.491620-1-maz@kernel.org --- drivers/clocksource/arm_arch_timer.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 4adf756423de..7b4a98df6962 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -1090,6 +1090,27 @@ static int __init arch_timer_common_init(void) return arch_timer_arch_init(); } +static bool __init has_broken_el2_vtimer(void) +{ + /* + * SoCs described here have been found to be broken, though no + * explanation has been volunteered by the vendor. Let the user know + * we're papering over the vendor's lack of communication. + */ + static const char * const broken_el2_vtimer[] __initconst = { + "brcm,bcm2712", + NULL + }; + + if (of_machine_compatible_match(broken_el2_vtimer)) { + add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK); + pr_warn_once(HW_ERR "Known broken EL2 virtual timer, ignoring it\n"); + return true; + } + + return false; +} + /** * arch_timer_select_ppi() - Select suitable PPI for the current system. * @@ -1115,7 +1136,8 @@ static int __init arch_timer_common_init(void) static enum arch_timer_ppi_nr __init arch_timer_select_ppi(void) { if (is_kernel_in_hyp_mode()) { - if (arch_timer_ppi[ARCH_TIMER_HYP_VIRT_PPI]) + if (arch_timer_ppi[ARCH_TIMER_HYP_VIRT_PPI] && + !has_broken_el2_vtimer()) return ARCH_TIMER_HYP_VIRT_PPI; pr_warn_once(FW_BUG "VHE-capable CPU without EL2 virtual timer interrupt\n");