Allow printk time stamps/sched_clock() to be available from the early boot.
Signed-off-by: Pavel Tatashin <[email protected]> --- arch/arm64/kernel/setup.c | 25 +++++++++++++++++++++++++ drivers/clocksource/arm_arch_timer.c | 8 ++++---- include/clocksource/arm_arch_timer.h | 3 +++ 3 files changed, 32 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index f4fc1e0544b7..7a43e63b737b 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -40,6 +40,7 @@ #include <linux/efi.h> #include <linux/psci.h> #include <linux/sched/task.h> +#include <linux/sched_clock.h> #include <linux/mm.h> #include <asm/acpi.h> @@ -279,8 +280,32 @@ arch_initcall(reserve_memblock_reserved_regions); u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID }; +/* + * Get time stamps available early in boot, useful to identify boot time issues + * from the early boot. + */ +static __init void sched_clock_early_init(void) +{ + u64 freq = arch_timer_get_cntfrq(); + + /* + * The arm64 boot protocol mandates that CNTFRQ_EL0 reflects + * the timer frequency. To avoid breakage on misconfigured + * systems, do not register the early sched_clock if the + * programmed value if zero. Other random values will just + * result in random output. + */ + if (!freq) + return; + + arch_timer_read_counter = arch_counter_get_cntvct; + sched_clock_register(arch_timer_read_counter, ARCH_TIMER_NBITS, freq); +} + void __init setup_arch(char **cmdline_p) { + sched_clock_early_init(); + init_mm.start_code = (unsigned long) _text; init_mm.end_code = (unsigned long) _etext; init_mm.end_data = (unsigned long) _edata; diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 9a7d4dc00b6e..e4843ad48bd3 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -175,13 +175,13 @@ static struct clocksource clocksource_counter = { .name = "arch_sys_counter", .rating = 400, .read = arch_counter_read, - .mask = CLOCKSOURCE_MASK(56), + .mask = CLOCKSOURCE_MASK(ARCH_TIMER_NBITS), .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; static struct cyclecounter cyclecounter __ro_after_init = { .read = arch_counter_read_cc, - .mask = CLOCKSOURCE_MASK(56), + .mask = CLOCKSOURCE_MASK(ARCH_TIMER_NBITS), }; struct ate_acpi_oem_info { @@ -963,8 +963,8 @@ static void __init arch_counter_register(unsigned type) timecounter_init(&arch_timer_kvm_info.timecounter, &cyclecounter, start_count); - /* 56 bits minimum, so we assume worst case rollover */ - sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate); + sched_clock_register(arch_timer_read_counter, ARCH_TIMER_NBITS, + arch_timer_rate); } static void arch_timer_stop(struct clock_event_device *clk) diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h index 349e5957c949..c485512e1d01 100644 --- a/include/clocksource/arm_arch_timer.h +++ b/include/clocksource/arm_arch_timer.h @@ -71,6 +71,9 @@ enum arch_timer_spi_nr { #define ARCH_TIMER_EVT_STREAM_FREQ \ (USEC_PER_SEC / ARCH_TIMER_EVT_STREAM_PERIOD_US) +/* 56 bits minimum, so we assume worst case rollover */ +#define ARCH_TIMER_NBITS 56 + struct arch_timer_kvm_info { struct timecounter timecounter; int virtual_irq; -- 2.19.1
