clocksource: timer-sp804: Fix an Oops when read_current_timer is called on ARM32 platforms where the SP804 is not registered as the sched_clock.
PATCH 1/1 clocksource: timer-sp804: Fix an Oops when read_current_timer is called on ARM32 platforms where the SP804 is not registered as the sched_clock.
On SP804, the delay timer shares the same clkevt instance with sched_clock.
On some platforms, when sp804_clocksource_and_sched_clock_init is called with use_sched_clock not set to 1, sched_clkevt is not properly initialized. However, sp804_register_delay_timer is invoked unconditionally, and read_current_timer() subsequently calls sp804_read on an uninitialized sched_clkevt, leading to a kernel Oops when accessing sched_clkevt->value.
Declare a dedicated clkevt instance exclusively for delay timer, instead of sharing the same clkevt with sched_clock. This ensures that read_current_timer continues to work correctly regardless of whether SP804 is selected as the sched_clock.
--- drivers/clocksource/timer-sp804.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)
drivers/clocksource/timer-sp804.c +9 -5
@@ -106,21 +106,25 @@ static u64 notrace sp804_read(void)return ~readl_relaxed (sched_clkevt->value); } +/* Register delay timer backed by the hardware counter */ #ifdef CONFIG_ARM static struct delay_timer delay; +struct sp804_clkevt *delay_clkevt; +static unsigned long sp804_read_delay_timer_read (void ) { -return sp804_read (); +return ~readl_relaxed (delay_clkevt->value); } -static void sp804_register_delay_timer (int freq) +static void sp804_register_delay_timer (struct sp804_clkevt *clk,int freq) { + delay_clkevt = clk; delay.freq = freq; delay.read_current_timer = sp804_read_delay_timer_read;register_current_timer_delay (&delay); }#else -static inline void sp804_register_delay_timer (int freq) {} +static inline void sp804_register_delay_timer (struct sp804_clkevt *clk,int freq) {}#endif static int __init sp804_clocksource_and_sched_clock_init(void __iomem *base,
@@ -135,8 +139,6 @@ static int __init sp804_clocksource_and_sched_clock_init(void __iomem *base,if (rate <0 )return -EINVAL ; -sp804_register_delay_timer (rate); - clkevt =sp804_clkevt_get (base);writel (0 , clkevt->ctrl);
@@ -152,6 +154,8 @@ static int __init sp804_clocksource_and_sched_clock_init(void __iomem *base,clocksource_mmio_init (clkevt->value, name, rate,200 ,32 , clocksource_mmio_readl_down); +sp804_register_delay_timer (clkevt, rate); +if (use_sched_clock) { sched_clkevt = clkevt;sched_clock_register (sp804_read,32 , rate);
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251217-fix_timersp804-7910e1c471d4
Best regards,
Signature · 1 line
Stephen Eta Zhou <[email protected]>
kernel test robot
build botkernel test robot noticed the following build warnings:
Hi Stephen,
kernel test robot noticed the following build warnings:
[auto build test WARNING on 8f0b4cce4481fb22653697cced8d0d04027cb1e8]
url: https://github.com/intel-lab-lkp/linux/commits/Stephen-Eta-Zhou/clocksource-timer-sp804-Fix-an-Oops-when-read_current_timer-is-called-on-ARM32-platforms-where-the-SP804-is-not-register/20251219-130527 base: 8f0b4cce4481fb22653697cced8d0d04027cb1e8 patch link: https://lore.kernel.org/r/20251219-fix_timersp804-v1-1-020e3cde7cf5%40gmail.com patch subject: [PATCH] clocksource: timer-sp804: Fix an Oops when read_current_timer is called on ARM32 platforms where the SP804 is not registered as the sched_clock. config: arm-randconfig-r134-20251224 (https://download.01.org/0day-ci/archive/20251225/[email protected]/config) compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 4ef602d446057dabf5f61fb221669ecbeda49279) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251225/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
sparse warnings: (new ones prefixed by >>)
>> drivers/clocksource/timer-sp804.c:112:21: sparse: sparse: symbol 'delay_clkevt' was not declared. Should it be static?
vim +/delay_clkevt +112 drivers/clocksource/timer-sp804.c
108
109 /* Register delay timer backed by the hardware counter */
110 #ifdef CONFIG_ARM
111 static struct delay_timer delay;
> 112 struct sp804_clkevt *delay_clkevt;
113
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