Commit 20e2fc42 authored by Vincenzo Frascino's avatar Vincenzo Frascino Committed by Russell King
Browse files

ARM: 8930/1: Add support for generic vDSO 



The arm vDSO library requires some adaptations to take advantage of
the newly introduced generic vDSO library.

Introduce the following changes:
 - Modification vdso.c to be compliant with the common vdso datapage
 - Use of lib/vdso for gettimeofday
 - Implementation of elf note

Signed-off-by: default avatarVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 9f1984c6

arch/arm/include/asm/vdso/gettimeofday.h

0 → 100644
+74 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Copyright (C) 2018 ARM Limited

 */

#ifndef __ASM_VDSO_GETTIMEOFDAY_H

#define __ASM_VDSO_GETTIMEOFDAY_H



#ifndef __ASSEMBLY__



#include <asm/barrier.h>

#include <asm/cp15.h>

#include <asm/unistd.h>

#include <uapi/linux/time.h>



extern struct vdso_data *__get_datapage(void);



static __always_inline int gettimeofday_fallback(

				struct __kernel_old_timeval *_tv,

				struct timezone *_tz)

{

	register struct timezone *tz asm("r1") = _tz;

	register struct __kernel_old_timeval *tv asm("r0") = _tv;

	register long ret asm ("r0");

	register long nr asm("r7") = __NR_gettimeofday;



	asm volatile(

	"	swi #0\n"

	: "=r" (ret)

	: "r" (tv), "r" (tz), "r" (nr)

	: "memory");



	return ret;

}



static __always_inline long clock_gettime_fallback(

					clockid_t _clkid,

					struct __kernel_timespec *_ts)

{

	register struct __kernel_timespec *ts asm("r1") = _ts;

	register clockid_t clkid asm("r0") = _clkid;

	register long ret asm ("r0");

	register long nr asm("r7") = __NR_clock_gettime64;



	asm volatile(

	"	swi #0\n"

	: "=r" (ret)

	: "r" (clkid), "r" (ts), "r" (nr)

	: "memory");



	return ret;

}



static __always_inline u64 __arch_get_hw_counter(int clock_mode)

{

#ifdef CONFIG_ARM_ARCH_TIMER

	u64 cycle_now;



	isb();

	cycle_now = read_sysreg(CNTVCT);



	return cycle_now;

#else

	return -EINVAL; /* use fallback */

#endif

}



static __always_inline const struct vdso_data *__arch_get_vdso_data(void)

{

	return __get_datapage();

}



#endif /* !__ASSEMBLY__ */



#endif /* __ASM_VDSO_GETTIMEOFDAY_H */

arch/arm/include/asm/vdso/vsyscall.h

0 → 100644
+71 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __ASM_VDSO_VSYSCALL_H

#define __ASM_VDSO_VSYSCALL_H



#ifndef __ASSEMBLY__



#include <linux/timekeeper_internal.h>

#include <vdso/datapage.h>

#include <asm/cacheflush.h>



extern struct vdso_data *vdso_data;

extern bool cntvct_ok;



static __always_inline

bool tk_is_cntvct(const struct timekeeper *tk)

{

	if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))

		return false;



	if (!tk->tkr_mono.clock->archdata.vdso_direct)

		return false;



	return true;

}



/*

 * Update the vDSO data page to keep in sync with kernel timekeeping.

 */

static __always_inline

struct vdso_data *__arm_get_k_vdso_data(void)

{

	return vdso_data;

}

#define __arch_get_k_vdso_data __arm_get_k_vdso_data



static __always_inline

int __arm_update_vdso_data(void)

{

	return !cntvct_ok;

}

#define __arch_update_vdso_data __arm_update_vdso_data



static __always_inline

int __arm_get_clock_mode(struct timekeeper *tk)

{

	u32 __tk_is_cntvct = tk_is_cntvct(tk);



	return __tk_is_cntvct;

}

#define __arch_get_clock_mode __arm_get_clock_mode



static __always_inline

int __arm_use_vsyscall(struct vdso_data *vdata)

{

	return vdata[CS_HRES_COARSE].clock_mode;

}

#define __arch_use_vsyscall __arm_use_vsyscall



static __always_inline

void __arm_sync_vdso_data(struct vdso_data *vdata)

{

	flush_dcache_page(virt_to_page(vdata));

}

#define __arch_sync_vdso_data __arm_sync_vdso_data



/* The asm-generic header needs to be included after the definitions above */

#include <asm-generic/vdso/vsyscall.h>



#endif /* !__ASSEMBLY__ */



#endif /* __ASM_VDSO_VSYSCALL_H */

arch/arm/include/asm/vdso_datapage.h

+3 −26
Original line number Diff line number Diff line
@@ -11,34 +11,11 @@ 


#ifndef __ASSEMBLY__



#include <vdso/datapage.h>

#include <asm/page.h>



/* Try to be cache-friendly on systems that don't implement the

 * generic timer: fit the unconditionally updated fields in the first

 * 32 bytes.

 */

struct vdso_data {

	u32 seq_count;		/* sequence count - odd during updates */

	u16 tk_is_cntvct;	/* fall back to syscall if false */

	u16 cs_shift;		/* clocksource shift */

	u32 xtime_coarse_sec;	/* coarse time */

	u32 xtime_coarse_nsec;



	u32 wtm_clock_sec;	/* wall to monotonic offset */

	u32 wtm_clock_nsec;

	u32 xtime_clock_sec;	/* CLOCK_REALTIME - seconds */

	u32 cs_mult;		/* clocksource multiplier */



	u64 cs_cycle_last;	/* last cycle value */

	u64 cs_mask;		/* clocksource mask */



	u64 xtime_clock_snsec;	/* CLOCK_REALTIME sub-ns base */

	u32 tz_minuteswest;	/* timezone info for gettimeofday(2) */

	u32 tz_dsttime;

};



union vdso_data_store {

	struct vdso_data data;

	struct vdso_data	data[CS_BASES];

	u8			page[PAGE_SIZE];

};

arch/arm/kernel/vdso.c

+4 −83
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
#include <asm/vdso.h>

#include <asm/vdso_datapage.h>

#include <clocksource/arm_arch_timer.h>

#include <vdso/helpers.h>

#include <vdso/vsyscall.h>



#define MAX_SYMNAME	64
@@ -37,7 +39,7 @@ unsigned int vdso_total_pages __ro_after_init; 
 * The VDSO data page.

 */

static union vdso_data_store vdso_data_store __page_aligned_data;

static struct vdso_data *vdso_data = &vdso_data_store.data;

struct vdso_data *vdso_data = vdso_data_store.data;



static struct page *vdso_data_page __ro_after_init;

static const struct vm_special_mapping vdso_data_mapping = {
@@ -77,7 +79,7 @@ struct elfinfo { 
/* Cached result of boot-time check for whether the arch timer exists,

 * and if so, whether the virtual counter is useable.

 */

static bool cntvct_ok __ro_after_init;

bool cntvct_ok __ro_after_init;



static bool __init cntvct_functional(void)

{
@@ -262,84 +264,3 @@ void arm_install_vdso(struct mm_struct *mm, unsigned long addr) 
		mm->context.vdso = addr;

}

static void vdso_write_begin(struct vdso_data *vdata)

{

	++vdso_data->seq_count;

	smp_wmb(); /* Pairs with smp_rmb in vdso_read_retry */

}



static void vdso_write_end(struct vdso_data *vdata)

{

	smp_wmb(); /* Pairs with smp_rmb in vdso_read_begin */

	++vdso_data->seq_count;

}



static bool tk_is_cntvct(const struct timekeeper *tk)

{

	if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))

		return false;



	if (!tk->tkr_mono.clock->archdata.vdso_direct)

		return false;



	return true;

}



/**

 * update_vsyscall - update the vdso data page

 *

 * Increment the sequence counter, making it odd, indicating to

 * userspace that an update is in progress.  Update the fields used

 * for coarse clocks and, if the architected system timer is in use,

 * the fields used for high precision clocks.  Increment the sequence

 * counter again, making it even, indicating to userspace that the

 * update is finished.

 *

 * Userspace is expected to sample seq_count before reading any other

 * fields from the data page.  If seq_count is odd, userspace is

 * expected to wait until it becomes even.  After copying data from

 * the page, userspace must sample seq_count again; if it has changed

 * from its previous value, userspace must retry the whole sequence.

 *

 * Calls to update_vsyscall are serialized by the timekeeping core.

 */

void update_vsyscall(struct timekeeper *tk)

{

	struct timespec64 *wtm = &tk->wall_to_monotonic;



	if (!cntvct_ok) {

		/* The entry points have been zeroed, so there is no

		 * point in updating the data page.

		 */

		return;

	}



	vdso_write_begin(vdso_data);



	vdso_data->tk_is_cntvct			= tk_is_cntvct(tk);

	vdso_data->xtime_coarse_sec		= tk->xtime_sec;

	vdso_data->xtime_coarse_nsec		= (u32)(tk->tkr_mono.xtime_nsec >>

							tk->tkr_mono.shift);

	vdso_data->wtm_clock_sec		= wtm->tv_sec;

	vdso_data->wtm_clock_nsec		= wtm->tv_nsec;



	if (vdso_data->tk_is_cntvct) {

		vdso_data->cs_cycle_last	= tk->tkr_mono.cycle_last;

		vdso_data->xtime_clock_sec	= tk->xtime_sec;

		vdso_data->xtime_clock_snsec	= tk->tkr_mono.xtime_nsec;

		vdso_data->cs_mult		= tk->tkr_mono.mult;

		vdso_data->cs_shift		= tk->tkr_mono.shift;

		vdso_data->cs_mask		= tk->tkr_mono.mask;

	}



	vdso_write_end(vdso_data);



	flush_dcache_page(virt_to_page(vdso_data));

}



void update_vsyscall_tz(void)

{

	vdso_data->tz_minuteswest	= sys_tz.tz_minuteswest;

	vdso_data->tz_dsttime		= sys_tz.tz_dsttime;

	flush_dcache_page(virt_to_page(vdso_data));

}

arch/arm/mm/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -896,7 +896,10 @@ config VDSO 
	bool "Enable VDSO for acceleration of some system calls"

	depends on AEABI && MMU && CPU_V7

	default y if ARM_ARCH_TIMER

	select HAVE_GENERIC_VDSO

	select GENERIC_TIME_VSYSCALL

	select GENERIC_VDSO_32

	select GENERIC_GETTIMEOFDAY

	help

	  Place in the process address space an ELF shared object

	  providing fast implementations of gettimeofday and