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LoongArch: Add VDSO and VSYSCALL support
Add VDSO and VSYSCALL support (sigreturn, gettimeofday and its friends) for LoongArch. Reviewed-by: WANG Xuerui <[email protected]> Reviewed-by: Jiaxun Yang <[email protected]> Signed-off-by: Huacai Chen <[email protected]>
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‎arch/loongarch/include/asm/vdso.h

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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Author: Huacai Chen <[email protected]>
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*/
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#ifndef __ASM_VDSO_H
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#define __ASM_VDSO_H
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#include <linux/mm_types.h>
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#include <vdso/datapage.h>
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#include <asm/barrier.h>
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/*
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* struct loongarch_vdso_info - Details of a VDSO image.
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* @vdso: Pointer to VDSO image (page-aligned).
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* @size: Size of the VDSO image (page-aligned).
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* @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
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* @code_mapping: Special mapping structure for vdso code.
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* @code_mapping: Special mapping structure for vdso data.
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*
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* This structure contains details of a VDSO image, including the image data
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* and offsets of certain symbols required by the kernel. It is generated as
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* part of the VDSO build process, aside from the mapping page array, which is
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* populated at runtime.
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*/
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struct loongarch_vdso_info {
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void *vdso;
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unsigned long size;
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unsigned long offset_sigreturn;
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struct vm_special_mapping code_mapping;
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struct vm_special_mapping data_mapping;
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};
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extern struct loongarch_vdso_info vdso_info;
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#endif /* __ASM_VDSO_H */

‎arch/loongarch/include/asm/vdso/clocksource.h

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/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef __ASM_VDSOCLOCKSOURCE_H
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#define __ASM_VDSOCLOCKSOURCE_H
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#define VDSO_ARCH_CLOCKMODES \
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VDSO_CLOCKMODE_CPU
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#endif /* __ASM_VDSOCLOCKSOURCE_H */

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

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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Author: Huacai Chen <[email protected]>
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*
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*/
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#ifndef __ASM_VDSO_GETTIMEOFDAY_H
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#define __ASM_VDSO_GETTIMEOFDAY_H
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#ifndef __ASSEMBLY__
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#include <asm/unistd.h>
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#include <asm/vdso/vdso.h>
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#define VDSO_HAS_CLOCK_GETRES 1
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static __always_inline long gettimeofday_fallback(
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struct __kernel_old_timeval *_tv,
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struct timezone *_tz)
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{
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register struct __kernel_old_timeval *tv asm("a0") = _tv;
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register struct timezone *tz asm("a1") = _tz;
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register long nr asm("a7") = __NR_gettimeofday;
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register long ret asm("a0");
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asm volatile(
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" syscall 0\n"
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: "+r" (ret)
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: "r" (nr), "r" (tv), "r" (tz)
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: "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7",
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"$t8", "memory");
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return ret;
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}
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static __always_inline long clock_gettime_fallback(
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clockid_t _clkid,
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struct __kernel_timespec *_ts)
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{
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register clockid_t clkid asm("a0") = _clkid;
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register struct __kernel_timespec *ts asm("a1") = _ts;
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register long nr asm("a7") = __NR_clock_gettime;
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register long ret asm("a0");
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asm volatile(
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" syscall 0\n"
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: "+r" (ret)
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: "r" (nr), "r" (clkid), "r" (ts)
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: "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7",
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"$t8", "memory");
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return ret;
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}
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static __always_inline int clock_getres_fallback(
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clockid_t _clkid,
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struct __kernel_timespec *_ts)
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{
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register clockid_t clkid asm("a0") = _clkid;
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register struct __kernel_timespec *ts asm("a1") = _ts;
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register long nr asm("a7") = __NR_clock_getres;
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register long ret asm("a0");
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asm volatile(
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" syscall 0\n"
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: "+r" (ret)
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: "r" (nr), "r" (clkid), "r" (ts)
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: "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7",
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"$t8", "memory");
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return ret;
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}
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static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
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const struct vdso_data *vd)
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{
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uint64_t count;
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__asm__ __volatile__(
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" rdtime.d %0, $zero\n"
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: "=r" (count));
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return count;
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}
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static inline bool loongarch_vdso_hres_capable(void)
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{
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return true;
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}
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#define __arch_vdso_hres_capable loongarch_vdso_hres_capable
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static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
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{
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return get_vdso_data();
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_VDSO_GETTIMEOFDAY_H */

‎arch/loongarch/include/asm/vdso/processor.h

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/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*/
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#ifndef __ASM_VDSO_PROCESSOR_H
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#define __ASM_VDSO_PROCESSOR_H
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#ifndef __ASSEMBLY__
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#define cpu_relax() barrier()
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_VDSO_PROCESSOR_H */

‎arch/loongarch/include/asm/vdso/vdso.h

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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Author: Huacai Chen <[email protected]>
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*/
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#ifndef __ASSEMBLY__
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#include <asm/asm.h>
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#include <asm/page.h>
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static inline unsigned long get_vdso_base(void)
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{
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unsigned long addr;
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__asm__(
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" la.pcrel %0, _start\n"
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: "=r" (addr)
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:
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:);
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return addr;
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}
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static inline const struct vdso_data *get_vdso_data(void)
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{
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return (const struct vdso_data *)(get_vdso_base() - PAGE_SIZE);
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}
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#endif /* __ASSEMBLY__ */

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

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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_VDSO_VSYSCALL_H
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#define __ASM_VDSO_VSYSCALL_H
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#ifndef __ASSEMBLY__
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#include <linux/timekeeper_internal.h>
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#include <vdso/datapage.h>
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extern struct vdso_data *vdso_data;
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/*
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* Update the vDSO data page to keep in sync with kernel timekeeping.
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*/
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static __always_inline
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struct vdso_data *__loongarch_get_k_vdso_data(void)
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{
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return vdso_data;
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}
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#define __arch_get_k_vdso_data __loongarch_get_k_vdso_data
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/* The asm-generic header needs to be included after the definitions above */
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#include <asm-generic/vdso/vsyscall.h>
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_VDSO_VSYSCALL_H */

‎arch/loongarch/kernel/time.c

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@@ -183,6 +183,7 @@ static struct clocksource clocksource_const = {
183183
.read = read_const_counter,
184184
.mask = CLOCKSOURCE_MASK(64),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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.vdso_clock_mode = VDSO_CLOCKMODE_CPU,
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};
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188189
int __init constant_clocksource_init(void)

‎arch/loongarch/kernel/vdso.c

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// SPDX-License-Identifier: GPL-2.0
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/*
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* Author: Huacai Chen <[email protected]>
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*/
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#include <linux/binfmts.h>
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#include <linux/elf.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/ioport.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/random.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/timekeeper_internal.h>
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#include <asm/page.h>
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#include <asm/vdso.h>
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#include <vdso/helpers.h>
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#include <vdso/vsyscall.h>
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#include <generated/vdso-offsets.h>
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extern char vdso_start[], vdso_end[];
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/* Kernel-provided data used by the VDSO. */
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static union loongarch_vdso_data {
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u8 page[PAGE_SIZE];
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struct vdso_data data[CS_BASES];
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} loongarch_vdso_data __page_aligned_data;
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struct vdso_data *vdso_data = loongarch_vdso_data.data;
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static struct page *vdso_pages[] = { NULL };
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static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
36+
{
37+
current->mm->context.vdso = (void *)(new_vma->vm_start);
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return 0;
40+
}
41+
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struct loongarch_vdso_info vdso_info = {
43+
.vdso = vdso_start,
44+
.size = PAGE_SIZE,
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.code_mapping = {
46+
.name = "[vdso]",
47+
.pages = vdso_pages,
48+
.mremap = vdso_mremap,
49+
},
50+
.data_mapping = {
51+
.name = "[vvar]",
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},
53+
.offset_sigreturn = vdso_offset_sigreturn,
54+
};
55+
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static int __init init_vdso(void)
57+
{
58+
unsigned long i, pfn;
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60+
BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
61+
BUG_ON(!PAGE_ALIGNED(vdso_info.size));
62+
63+
pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso));
64+
for (i = 0; i < vdso_info.size / PAGE_SIZE; i++)
65+
vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i);
66+
67+
return 0;
68+
}
69+
subsys_initcall(init_vdso);
70+
71+
static unsigned long vdso_base(void)
72+
{
73+
unsigned long base = STACK_TOP;
74+
75+
if (current->flags & PF_RANDOMIZE) {
76+
base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1);
77+
base = PAGE_ALIGN(base);
78+
}
79+
80+
return base;
81+
}
82+
83+
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
84+
{
85+
int ret;
86+
unsigned long vvar_size, size, data_addr, vdso_addr;
87+
struct mm_struct *mm = current->mm;
88+
struct vm_area_struct *vma;
89+
struct loongarch_vdso_info *info = current->thread.vdso;
90+
91+
if (mmap_write_lock_killable(mm))
92+
return -EINTR;
93+
94+
/*
95+
* Determine total area size. This includes the VDSO data itself
96+
* and the data page.
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*/
98+
vvar_size = PAGE_SIZE;
99+
size = vvar_size + info->size;
100+
101+
data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
102+
if (IS_ERR_VALUE(data_addr)) {
103+
ret = data_addr;
104+
goto out;
105+
}
106+
vdso_addr = data_addr + PAGE_SIZE;
107+
108+
vma = _install_special_mapping(mm, data_addr, vvar_size,
109+
VM_READ | VM_MAYREAD,
110+
&info->data_mapping);
111+
if (IS_ERR(vma)) {
112+
ret = PTR_ERR(vma);
113+
goto out;
114+
}
115+
116+
/* Map VDSO data page. */
117+
ret = remap_pfn_range(vma, data_addr,
118+
virt_to_phys(vdso_data) >> PAGE_SHIFT,
119+
PAGE_SIZE, PAGE_READONLY);
120+
if (ret)
121+
goto out;
122+
123+
/* Map VDSO code page. */
124+
vma = _install_special_mapping(mm, vdso_addr, info->size,
125+
VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
126+
&info->code_mapping);
127+
if (IS_ERR(vma)) {
128+
ret = PTR_ERR(vma);
129+
goto out;
130+
}
131+
132+
mm->context.vdso = (void *)vdso_addr;
133+
ret = 0;
134+
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out:
136+
mmap_write_unlock(mm);
137+
return ret;
138+
}

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