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mips: Add support for generic vDSO

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

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

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
[paul.burton@mips.com: Prepend $(src) to config-n32-o32-env.c path.]
Signed-off-by: Paul Burton <paul.burton@mips.com>
This commit is contained in:
Vincenzo Frascino
2019-06-21 10:52:46 +01:00
committed by Paul Burton
parent c2aeaaea17
commit 24640f233b
11 changed files with 296 additions and 115 deletions
Download Patch File Download Diff File Expand all files Collapse all files

78
arch/mips/include/asm/vdso.h
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@@ -8,6 +8,7 @@
#define __ASM_VDSO_H
#include <linux/mm_types.h>
#include <vdso/datapage.h>
#include <asm/barrier.h>
@@ -49,84 +50,9 @@ extern struct mips_vdso_image vdso_image_o32;
extern struct mips_vdso_image vdso_image_n32;
#endif
/**
* 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. 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;
u64 wall_to_mono_sec;
u64 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;
};
struct vdso_data data[CS_BASES];
u8 page[PAGE_SIZE];
};
static inline u32 vdso_data_read_begin(const union mips_vdso_data *data)
{
u32 seq;
while (true) {
seq = READ_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 */

151
arch/mips/include/asm/vdso/gettimeofday.h Normal file
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@@ -0,0 +1,151 @@
/*
* Copyright (C) 2018 ARM Limited
* 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_VDSO_GETTIMEOFDAY_H
#define __ASM_VDSO_GETTIMEOFDAY_H
#ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <linux/time.h>
#include <asm/vdso/vdso.h>
#include <asm/clocksource.h>
#include <asm/io.h>
#include <asm/unistd.h>
#include <asm/vdso.h>
#ifdef CONFIG_MIPS_CLOCK_VSYSCALL
static __always_inline long gettimeofday_fallback(
struct __kernel_old_timeval *_tv,
struct timezone *_tz)
{
register struct timezone *tz asm("a1") = _tz;
register struct __kernel_old_timeval *tv asm("a0") = _tv;
register long ret asm("v0");
register long nr asm("v0") = __NR_gettimeofday;
register long error asm("a3");
asm volatile(
" syscall\n"
: "=r" (ret), "=r" (error)
: "r" (tv), "r" (tz), "r" (nr)
: "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13",
"$14", "$15", "$24", "$25", "hi", "lo", "memory");
return error ? -ret : ret;
}
#else
static __always_inline long gettimeofday_fallback(
struct __kernel_old_timeval *_tv,
struct timezone *_tz)
{
return -1;
}
#endif
static __always_inline long clock_gettime_fallback(
clockid_t _clkid,
struct __kernel_timespec *_ts)
{
register struct __kernel_timespec *ts asm("a1") = _ts;
register clockid_t clkid asm("a0") = _clkid;
register long ret asm("v0");
#if _MIPS_SIM == _MIPS_SIM_ABI64
register long nr asm("v0") = __NR_clock_gettime;
#else
register long nr asm("v0") = __NR_clock_gettime64;
#endif
register long error asm("a3");
asm volatile(
" syscall\n"
: "=r" (ret), "=r" (error)
: "r" (clkid), "r" (ts), "r" (nr)
: "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13",
"$14", "$15", "$24", "$25", "hi", "lo", "memory");
return error ? -ret : ret;
}
#ifdef CONFIG_CSRC_R4K
static __always_inline u64 read_r4k_count(void)
{
unsigned int count;
__asm__ __volatile__(
" .set push\n"
" .set mips32r2\n"
" rdhwr %0, $2\n"
" .set pop\n"
: "=r" (count));
return count;
}
#endif
#ifdef CONFIG_CLKSRC_MIPS_GIC
static __always_inline u64 read_gic_count(const struct vdso_data *data)
{
void __iomem *gic = get_gic(data);
u32 hi, hi2, lo;
do {
hi = __raw_readl(gic + sizeof(lo));
lo = __raw_readl(gic);
hi2 = __raw_readl(gic + sizeof(lo));
} while (hi2 != hi);
return (((u64)hi) << 32) + lo;
}
#endif
static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
{
#ifdef CONFIG_CLKSRC_MIPS_GIC
const struct vdso_data *data = get_vdso_data();
#endif
u64 cycle_now;
switch (clock_mode) {
#ifdef CONFIG_CSRC_R4K
case VDSO_CLOCK_R4K:
cycle_now = read_r4k_count();
break;
#endif
#ifdef CONFIG_CLKSRC_MIPS_GIC
case VDSO_CLOCK_GIC:
cycle_now = read_gic_count(data);
break;
#endif
default:
cycle_now = 0;
break;
}
return cycle_now;
}
static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
{
return get_vdso_data();
}
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_VDSO_GETTIMEOFDAY_H */

85
arch/mips/include/asm/vdso/vdso.h Normal file
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@@ -0,0 +1,85 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright (C) 2015 Imagination Technologies
* Author: Alex Smith <alex.smith@imgtec.com>
*/
#include <asm/sgidefs.h>
#if _MIPS_SIM != _MIPS_SIM_ABI64 && defined(CONFIG_64BIT)
/* Building 32-bit VDSO for the 64-bit kernel. Fake a 32-bit Kconfig. */
#undef CONFIG_64BIT
#define CONFIG_32BIT 1
#ifndef __ASSEMBLY__
#include <asm-generic/atomic64.h>
#endif
#endif
#ifndef __ASSEMBLY__
#include <asm/asm.h>
#include <asm/page.h>
#include <asm/vdso.h>
static inline unsigned long get_vdso_base(void)
{
unsigned long addr;
/*
* We can't use cpu_has_mips_r6 since it needs the cpu_data[]
* kernel symbol.
*/
#ifdef CONFIG_CPU_MIPSR6
/*
* lapc <symbol> is an alias to addiupc reg, <symbol> - .
*
* We can't use addiupc because there is no label-label
* support for the addiupc reloc
*/
__asm__("lapc %0, _start \n"
: "=r" (addr) : :);
#else
/*
* Get the base load address of the VDSO. We have to avoid generating
* relocations and references to the GOT because ld.so does not peform
* relocations on the VDSO. We use the current offset from the VDSO base
* and perform a PC-relative branch which gives the absolute address in
* ra, and take the difference. The assembler chokes on
* "li %0, _start - .", so embed the offset as a word and branch over
* it.
*
*/
__asm__(
" .set push \n"
" .set noreorder \n"
" bal 1f \n"
" nop \n"
" .word _start - . \n"
"1: lw %0, 0($31) \n"
" " STR(PTR_ADDU) " %0, $31, %0 \n"
" .set pop \n"
: "=r" (addr)
:
: "$31");
#endif /* CONFIG_CPU_MIPSR6 */
return addr;
}
static inline const struct vdso_data *get_vdso_data(void)
{
return (const struct vdso_data *)(get_vdso_base() - PAGE_SIZE);
}
#ifdef CONFIG_CLKSRC_MIPS_GIC
static inline void __iomem *get_gic(const struct vdso_data *data)
{
return (void __iomem *)data - PAGE_SIZE;
}
#endif /* CONFIG_CLKSRC_MIPS_GIC */
#endif /* __ASSEMBLY__ */

43
arch/mips/include/asm/vdso/vsyscall.h Normal file
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@@ -0,0 +1,43 @@
/* 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>
extern struct vdso_data *vdso_data;
/*
* Update the vDSO data page to keep in sync with kernel timekeeping.
*/
static __always_inline
struct vdso_data *__mips_get_k_vdso_data(void)
{
return vdso_data;
}
#define __arch_get_k_vdso_data __mips_get_k_vdso_data
static __always_inline
int __mips_get_clock_mode(struct timekeeper *tk)
{
u32 clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode;
return clock_mode;
}
#define __arch_get_clock_mode __mips_get_clock_mode
static __always_inline
int __mips_use_vsyscall(struct vdso_data *vdata)
{
return (vdata[CS_HRES_COARSE].clock_mode != VDSO_CLOCK_NONE);
}
#define __arch_use_vsyscall __mips_use_vsyscall
/* 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 */