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Commit 6acc71cc authored by Marc Zyngier's avatar Marc Zyngier
Browse files

arm64: arch_timer: Allows a CPU-specific erratum to only affect a subset of CPUs 



Instead of applying a CPU-specific workaround to all CPUs in the system,
allow it to only affect a subset of them (typical big-little case).

This is done by turning the erratum pointer into a per-CPU variable.

Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 8c64621b

arch/arm64/include/asm/arch_timer.h

+20 −11
Original line number Original line Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/bug.h>

#include <linux/bug.h>

#include <linux/init.h>

#include <linux/init.h>

#include <linux/jump_label.h>

#include <linux/jump_label.h>

#include <linux/smp.h>

#include <linux/types.h>

#include <linux/types.h>





#include <clocksource/arm_arch_timer.h>

#include <clocksource/arm_arch_timer.h>
@@ -55,16 +56,24 @@ struct arch_timer_erratum_workaround { 
	int (*set_next_event_virt)(unsigned long, struct clock_event_device *);

	int (*set_next_event_virt)(unsigned long, struct clock_event_device *);

};

};





extern const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround;

DECLARE_PER_CPU(const struct arch_timer_erratum_workaround *,

		timer_unstable_counter_workaround);





#define arch_timer_reg_read_stable(reg)					\

#define arch_timer_reg_read_stable(reg)					\

({									\

({									\

	u64 _val;							\

	u64 _val;							\

	if (needs_unstable_timer_counter_workaround() &&		\

	if (needs_unstable_timer_counter_workaround()) {		\

	    timer_unstable_counter_workaround->read_##reg)		\

		const struct arch_timer_erratum_workaround *wa;		\

		_val = timer_unstable_counter_workaround->read_##reg();	\

		preempt_disable();					\

		wa = __this_cpu_read(timer_unstable_counter_workaround); \

		if (wa && wa->read_##reg)				\

			_val = wa->read_##reg();			\

		else							\

		else							\

			_val = read_sysreg(reg);			\

			_val = read_sysreg(reg);			\

		preempt_enable();					\

	} else {							\

		_val = read_sysreg(reg);				\

	}								\

	_val;								\

	_val;								\

})

})

drivers/clocksource/arm_arch_timer.c

+30 −12
Original line number Original line Diff line number Diff line
@@ -235,7 +235,8 @@ static u64 notrace hisi_161010101_read_cntvct_el0(void) 
#endif

#endif





#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND

#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND

const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround = NULL;

DEFINE_PER_CPU(const struct arch_timer_erratum_workaround *,

	       timer_unstable_counter_workaround);

EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);

EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);





DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled);

DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled);
@@ -338,9 +339,18 @@ arch_timer_iterate_errata(enum arch_timer_erratum_match_type type, 
}

}





static

static

void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa)

void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa,

				  bool local)

{

{

	timer_unstable_counter_workaround = wa;

	int i;



	if (local) {

		__this_cpu_write(timer_unstable_counter_workaround, wa);

	} else {

		for_each_possible_cpu(i)

			per_cpu(timer_unstable_counter_workaround, i) = wa;

	}



	static_branch_enable(&arch_timer_read_ool_enabled);

	static_branch_enable(&arch_timer_read_ool_enabled);

}

}
@@ -369,14 +379,17 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t 
		return;

		return;





	if (needs_unstable_timer_counter_workaround()) {

	if (needs_unstable_timer_counter_workaround()) {

		if (wa != timer_unstable_counter_workaround)

		const struct arch_timer_erratum_workaround *__wa;

		__wa = __this_cpu_read(timer_unstable_counter_workaround);

		if (__wa && wa != __wa)

			pr_warn("Can't enable workaround for %s (clashes with %s\n)",

			pr_warn("Can't enable workaround for %s (clashes with %s\n)",

				wa->desc,

				wa->desc, __wa->desc);

				timer_unstable_counter_workaround->desc);



		if (__wa)

			return;

			return;

	}

	}





	arch_timer_enable_workaround(wa);

	arch_timer_enable_workaround(wa, local);

	pr_info("Enabling %s workaround for %s\n",

	pr_info("Enabling %s workaround for %s\n",

		local ? "local" : "global", wa->desc);

		local ? "local" : "global", wa->desc);

}

}
@@ -384,13 +397,18 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t 
#define erratum_handler(fn, r, ...)					\

#define erratum_handler(fn, r, ...)					\

({									\

({									\

	bool __val;							\

	bool __val;							\

	if (needs_unstable_timer_counter_workaround() &&		\

	if (needs_unstable_timer_counter_workaround()) {		\

	    timer_unstable_counter_workaround->fn) {			\

		const struct arch_timer_erratum_workaround *__wa;	\

		r = timer_unstable_counter_workaround->fn(__VA_ARGS__);	\

		__wa = __this_cpu_read(timer_unstable_counter_workaround); \

		if (__wa && __wa->fn) {					\

			r = __wa->fn(__VA_ARGS__);			\

			__val = true;					\

			__val = true;					\

		} else {						\

		} else {						\

			__val = false;					\

			__val = false;					\

		}							\

		}							\

	} else {							\

		__val = false;						\

	}								\

	__val;								\

	__val;								\

})

})