MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()

	select SYSCTL_EXCEPTION_TRACE

	select HAVE_VIRT_CPU_ACCOUNTING_GEN

	select HAVE_IRQ_TIME_ACCOUNTING

	select GENERIC_TIME_VSYSCALL

	select ARCH_CLOCKSOURCE_DATA

menu "Machine selection"

config CSRC_SB1250

	bool

config MIPS_CLOCK_VSYSCALL

	def_bool CSRC_R4K || CLKSRC_MIPS_GIC

config GPIO_TXX9

	select ARCH_REQUIRE_GPIOLIB

	bool

/*

 * Copyright (C) 2015 Imagination Technologies

 * Author: Alex Smith <alex.smith@imgtec.com>

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the

 * Free Software Foundation;  either version 2 of the  License, or (at your

 * option) any later version.

 */

#ifndef __ASM_CLOCKSOURCE_H

#define __ASM_CLOCKSOURCE_H

#include <linux/types.h>

/* VDSO clocksources. */

#define VDSO_CLOCK_NONE		0	/* No suitable clocksource. */

#define VDSO_CLOCK_R4K		1	/* Use the coprocessor 0 count. */

#define VDSO_CLOCK_GIC		2	/* Use the GIC. */

/**

 * struct arch_clocksource_data - Architecture-specific clocksource information.

 * @vdso_clock_mode: Method the VDSO should use to access the clocksource.

 */

struct arch_clocksource_data {

	u8 vdso_clock_mode;

};

#endif /* __ASM_CLOCKSOURCE_H */

#include <linux/mm_types.h>

#include <asm/barrier.h>

/**

 * struct mips_vdso_image - Details of a VDSO image.

 * @data: Pointer to VDSO image data (page-aligned).

/**

 * union mips_vdso_data - Data provided by the kernel for the VDSO.

 * @xtime_sec:		Current real time (seconds part).

 * @xtime_nsec:		Current real time (nanoseconds part, shifted).

 * @wall_to_mono_sec:	Wall-to-monotonic offset (seconds part).

 * @wall_to_mono_nsec:	Wall-to-monotonic offset (nanoseconds part).

 * @seq_count:		Counter to synchronise updates (odd = updating).

 * @cs_shift:		Clocksource shift value.

 * @clock_mode:		Clocksource to use for time functions.

 * @cs_mult:		Clocksource multiplier value.

 * @cs_cycle_last:	Clock cycle value at last update.

 * @cs_mask:		Clocksource mask value.

 * @tz_minuteswest:	Minutes west of Greenwich (from timezone).

 * @tz_dsttime:		Type of DST correction (from timezone).

 *

 * This structure contains data needed by functions within the VDSO. It is

 * populated by the kernel and mapped read-only into user memory.

 * populated by the kernel and mapped read-only into user memory. The time

 * fields are mirrors of internal data from the timekeeping infrastructure.

 *

 * Note: Care should be taken when modifying as the layout must remain the same

 * for both 64- and 32-bit (for 32-bit userland on 64-bit kernel).

 */

union mips_vdso_data {

	struct {

		u64 xtime_sec;

		u64 xtime_nsec;

		u32 wall_to_mono_sec;

		u32 wall_to_mono_nsec;

		u32 seq_count;

		u32 cs_shift;

		u8 clock_mode;

		u32 cs_mult;

		u64 cs_cycle_last;

		u64 cs_mask;

		s32 tz_minuteswest;

		s32 tz_dsttime;

	};

	u8 page[PAGE_SIZE];

};

static inline u32 vdso_data_read_begin(const union mips_vdso_data *data)

{

	u32 seq;

	while (true) {

		seq = ACCESS_ONCE(data->seq_count);

		if (likely(!(seq & 1))) {

			/* Paired with smp_wmb() in vdso_data_write_*(). */

			smp_rmb();

			return seq;

		}

		cpu_relax();

	}

}

static inline bool vdso_data_read_retry(const union mips_vdso_data *data,

					u32 start_seq)

{

	/* Paired with smp_wmb() in vdso_data_write_*(). */

	smp_rmb();

	return unlikely(data->seq_count != start_seq);

}

static inline void vdso_data_write_begin(union mips_vdso_data *data)

{

	++data->seq_count;

	/* Ensure sequence update is written before other data page values. */

	smp_wmb();

}

static inline void vdso_data_write_end(union mips_vdso_data *data)

{

	/* Ensure data values are written before updating sequence again. */

	smp_wmb();

	++data->seq_count;

}

#endif /* __ASM_VDSO_H */

	return read_c0_count();

}

static inline unsigned int rdhwr_count(void)

{

	unsigned int count;

	__asm__ __volatile__(

	"	.set push\n"

	"	.set mips32r2\n"

	"	rdhwr	%0, $2\n"

	"	.set pop\n"

	: "=r" (count));

	return count;

}

static bool rdhwr_count_usable(void)

{

	unsigned int prev, curr, i;

	/*

	 * Older QEMUs have a broken implementation of RDHWR for the CP0 count

	 * which always returns a constant value. Try to identify this and don't

	 * use it in the VDSO if it is broken. This workaround can be removed

	 * once the fix has been in QEMU stable for a reasonable amount of time.

	 */

	for (i = 0, prev = rdhwr_count(); i < 100; i++) {

		curr = rdhwr_count();

		if (curr != prev)

			return true;

		prev = curr;

	}

	pr_warn("Not using R4K clocksource in VDSO due to broken RDHWR\n");

	return false;

}

int __init init_r4k_clocksource(void)

{

	if (!cpu_has_counter || !mips_hpt_frequency)

	/* Calculate a somewhat reasonable rating value */

	clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;

	/*

	 * R2 onwards makes the count accessible to user mode so it can be used

	 * by the VDSO (HWREna is configured by configure_hwrena()).

	 */

	if (cpu_has_mips_r2_r6 && rdhwr_count_usable())

		clocksource_mips.archdata.vdso_clock_mode = VDSO_CLOCK_R4K;

	clocksource_register_hz(&clocksource_mips, mips_hpt_frequency);

	sched_clock_register(r4k_read_sched_clock, 32, mips_hpt_frequency);

#include <linux/elf.h>

#include <linux/err.h>

#include <linux/init.h>

#include <linux/ioport.h>

#include <linux/irqchip/mips-gic.h>

#include <linux/mm.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/timekeeper_internal.h>

#include <asm/abi.h>

#include <asm/vdso.h>

static union mips_vdso_data vdso_data __page_aligned_data;

/*

 * Mapping for the VDSO data pages. The real pages are mapped manually, as

 * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as

 * what we map and where within the area they are mapped is determined at

 * runtime.

 */

}

subsys_initcall(init_vdso);

void update_vsyscall(struct timekeeper *tk)

{

	vdso_data_write_begin(&vdso_data);

	vdso_data.xtime_sec = tk->xtime_sec;

	vdso_data.xtime_nsec = tk->tkr_mono.xtime_nsec;

	vdso_data.wall_to_mono_sec = tk->wall_to_monotonic.tv_sec;

	vdso_data.wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec;

	vdso_data.cs_shift = tk->tkr_mono.shift;

	vdso_data.clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode;

	if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {

		vdso_data.cs_mult = tk->tkr_mono.mult;

		vdso_data.cs_cycle_last = tk->tkr_mono.cycle_last;

		vdso_data.cs_mask = tk->tkr_mono.mask;

	}

	vdso_data_write_end(&vdso_data);

}

void update_vsyscall_tz(void)

{

	if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {

		vdso_data.tz_minuteswest = sys_tz.tz_minuteswest;

		vdso_data.tz_dsttime = sys_tz.tz_dsttime;

	}

}

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)

{

	struct mips_vdso_image *image = current->thread.abi->vdso;

	struct mm_struct *mm = current->mm;

	unsigned long base, vdso_addr;

	unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr;

	struct vm_area_struct *vma;

	struct resource gic_res;

	int ret;

	down_write(&mm->mmap_sem);

	base = get_unmapped_area(NULL, 0, PAGE_SIZE + image->size, 0, 0);

	/*

	 * Determine total area size. This includes the VDSO data itself, the

	 * data page, and the GIC user page if present. Always create a mapping

	 * for the GIC user area if the GIC is present regardless of whether it

	 * is the current clocksource, in case it comes into use later on. We

	 * only map a page even though the total area is 64K, as we only need

	 * the counter registers at the start.

	 */

	gic_size = gic_present ? PAGE_SIZE : 0;

	vvar_size = gic_size + PAGE_SIZE;

	size = vvar_size + image->size;

	base = get_unmapped_area(NULL, 0, size, 0, 0);

	if (IS_ERR_VALUE(base)) {

		ret = base;

		goto out;

	}

	vdso_addr = base + PAGE_SIZE;

	data_addr = base + gic_size;

	vdso_addr = data_addr + PAGE_SIZE;

	vma = _install_special_mapping(mm, base, PAGE_SIZE,

	vma = _install_special_mapping(mm, base, vvar_size,

				       VM_READ | VM_MAYREAD,

				       &vdso_vvar_mapping);

	if (IS_ERR(vma)) {

		goto out;

	}

	/* Map GIC user page. */

	if (gic_size) {

		ret = gic_get_usm_range(&gic_res);

		if (ret)

			goto out;

		ret = io_remap_pfn_range(vma, base,

					 gic_res.start >> PAGE_SHIFT,

					 gic_size,

					 pgprot_noncached(PAGE_READONLY));

		if (ret)

			goto out;

	}

	/* Map data page. */

	ret = remap_pfn_range(vma, base,

	ret = remap_pfn_range(vma, data_addr,

			      virt_to_phys(&vdso_data) >> PAGE_SHIFT,

			      PAGE_SIZE, PAGE_READONLY);

	if (ret)