Commit d6e56a2a authored by Tony Luck's avatar Tony Luck
Browse files

[IA64] Fix CONFIG_PRINTK_TIME 



There were two problems with enabling the PRINTK_TIME config
option:
1) The first calls to printk() occur before per-cpu data virtual
address is pinned into the TLB, so sched_clock() can fault.
2) sched_clock() is based on ar.itc, which may not be synchronized
across cpus.

Ken Chen started this patch, Tony Luck tinkered with it, and Jes
Sorensen perfected it.

Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 9d78f43d

arch/ia64/kernel/head.S

+1 −0
Original line number Diff line number Diff line
@@ -352,6 +352,7 @@ start_ap: 
	mov ar.rsc=0		// place RSE in enforced lazy mode

	;;

	loadrs			// clear the dirty partition

	mov IA64_KR(PER_CPU_DATA)=r0	// clear physical per-CPU base

	;;

	mov ar.bspstore=r2	// establish the new RSE stack

	;;

arch/ia64/kernel/setup.c

+4 −0
Original line number Diff line number Diff line
@@ -71,6 +71,8 @@ unsigned long __per_cpu_offset[NR_CPUS]; 
EXPORT_SYMBOL(__per_cpu_offset);

#endif



extern void ia64_setup_printk_clock(void);



DEFINE_PER_CPU(struct cpuinfo_ia64, cpu_info);

DEFINE_PER_CPU(unsigned long, local_per_cpu_offset);

DEFINE_PER_CPU(unsigned long, ia64_phys_stacked_size_p8);
@@ -445,6 +447,8 @@ setup_arch (char **cmdline_p) 
	/* process SAL system table: */

	ia64_sal_init(efi.sal_systab);



	ia64_setup_printk_clock();



#ifdef CONFIG_SMP

	cpu_physical_id(0) = hard_smp_processor_id();

arch/ia64/kernel/time.c

+27 −0
Original line number Diff line number Diff line
@@ -278,3 +278,30 @@ udelay (unsigned long usecs) 
	}

}

EXPORT_SYMBOL(udelay);



static unsigned long long ia64_itc_printk_clock(void)

{

	if (ia64_get_kr(IA64_KR_PER_CPU_DATA))

		return sched_clock();

	return 0;

}



static unsigned long long ia64_default_printk_clock(void)

{

	return (unsigned long long)(jiffies_64 - INITIAL_JIFFIES) *

		(1000000000/HZ);

}



unsigned long long (*ia64_printk_clock)(void) = &ia64_default_printk_clock;



unsigned long long printk_clock(void)

{

	return ia64_printk_clock();

}



void __init

ia64_setup_printk_clock(void)

{

	if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT))

		ia64_printk_clock = ia64_itc_printk_clock;

}

arch/ia64/sn/kernel/setup.c

+27 −13
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ extern unsigned long last_time_offset; 
extern void (*ia64_mark_idle) (int);

extern void snidle(int);

extern unsigned char acpi_kbd_controller_present;

extern unsigned long long (*ia64_printk_clock)(void);



unsigned long sn_rtc_cycles_per_second;

EXPORT_SYMBOL(sn_rtc_cycles_per_second);
@@ -372,6 +373,16 @@ sn_scan_pcdp(void) 
	}

}



static unsigned long sn2_rtc_initial;



static unsigned long long ia64_sn2_printk_clock(void)

{

	unsigned long rtc_now = rtc_time();



	return (rtc_now - sn2_rtc_initial) *

		(1000000000 / sn_rtc_cycles_per_second);

}



/**

 * sn_setup - SN platform setup routine

 * @cmdline_p: kernel command line
@@ -386,6 +397,7 @@ void __init sn_setup(char **cmdline_p) 
	u32 version = sn_sal_rev();

	extern void sn_cpu_init(void);



	sn2_rtc_initial = rtc_time();

	ia64_sn_plat_set_error_handling_features();	// obsolete

	ia64_sn_set_os_feature(OSF_MCA_SLV_TO_OS_INIT_SLV);

	ia64_sn_set_os_feature(OSF_FEAT_LOG_SBES);
@@ -437,19 +449,6 @@ void __init sn_setup(char **cmdline_p) 
	 */

	build_cnode_tables();



	/*

	 * Old PROMs do not provide an ACPI FADT. Disable legacy keyboard

	 * support here so we don't have to listen to failed keyboard probe

	 * messages.

	 */

	if (version <= 0x0209 && acpi_kbd_controller_present) {

		printk(KERN_INFO "Disabling legacy keyboard support as prom "

		       "is too old and doesn't provide FADT\n");

		acpi_kbd_controller_present = 0;

	}



	printk("SGI SAL version %x.%02x\n", version >> 8, version & 0x00FF);



	status =

	    ia64_sal_freq_base(SAL_FREQ_BASE_REALTIME_CLOCK, &ticks_per_sec,

			       &drift);
@@ -463,6 +462,21 @@ void __init sn_setup(char **cmdline_p) 


	platform_intr_list[ACPI_INTERRUPT_CPEI] = IA64_CPE_VECTOR;



	ia64_printk_clock = ia64_sn2_printk_clock;



	/*

	 * Old PROMs do not provide an ACPI FADT. Disable legacy keyboard

	 * support here so we don't have to listen to failed keyboard probe

	 * messages.

	 */

	if (version <= 0x0209 && acpi_kbd_controller_present) {

		printk(KERN_INFO "Disabling legacy keyboard support as prom "

		       "is too old and doesn't provide FADT\n");

		acpi_kbd_controller_present = 0;

	}



	printk("SGI SAL version %x.%02x\n", version >> 8, version & 0x00FF);



	/*

	 * we set the default root device to /dev/hda

	 * to make simulation easy

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