LoongArch: Add VDSO and VSYSCALL support

Add VDSO and VSYSCALL support (sigreturn, gettimeofday and its friends)
for LoongArch.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

6 files changed, 216 insertions, 0 deletions

diff --git a/arch/loongarch/include/asm/vdso.h b/arch/loongarch/include/asm/vdso.h
new file mode 100644
index 000000000000..8f8a0f9a4953
--- /dev/null
+++ b/arch/loongarch/include/asm/vdso.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Author: Huacai Chen <chenhuacai@loongson.cn>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef __ASM_VDSO_H
+#define __ASM_VDSO_H
+
+#include <linux/mm_types.h>
+#include <vdso/datapage.h>
+
+#include <asm/barrier.h>
+
+/*
+ * struct loongarch_vdso_info - Details of a VDSO image.
+ * @vdso: Pointer to VDSO image (page-aligned).
+ * @size: Size of the VDSO image (page-aligned).
+ * @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
+ * @code_mapping: Special mapping structure for vdso code.
+ * @code_mapping: Special mapping structure for vdso data.
+ *
+ * This structure contains details of a VDSO image, including the image data
+ * and offsets of certain symbols required by the kernel. It is generated as
+ * part of the VDSO build process, aside from the mapping page array, which is
+ * populated at runtime.
+ */
+struct loongarch_vdso_info {
+	void *vdso;
+	unsigned long size;
+	unsigned long offset_sigreturn;
+	struct vm_special_mapping code_mapping;
+	struct vm_special_mapping data_mapping;
+};
+
+extern struct loongarch_vdso_info vdso_info;
+
+#endif /* __ASM_VDSO_H */
diff --git a/arch/loongarch/include/asm/vdso/clocksource.h b/arch/loongarch/include/asm/vdso/clocksource.h
new file mode 100644
index 000000000000..13cd580d406d
--- /dev/null
+++ b/arch/loongarch/include/asm/vdso/clocksource.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __ASM_VDSOCLOCKSOURCE_H
+#define __ASM_VDSOCLOCKSOURCE_H
+
+#define VDSO_ARCH_CLOCKMODES	\
+	VDSO_CLOCKMODE_CPU
+
+#endif /* __ASM_VDSOCLOCKSOURCE_H */
diff --git a/arch/loongarch/include/asm/vdso/gettimeofday.h b/arch/loongarch/include/asm/vdso/gettimeofday.h
new file mode 100644
index 000000000000..7b2cd37641e2
--- /dev/null
+++ b/arch/loongarch/include/asm/vdso/gettimeofday.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Author: Huacai Chen <chenhuacai@loongson.cn>
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef __ASM_VDSO_GETTIMEOFDAY_H
+#define __ASM_VDSO_GETTIMEOFDAY_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/unistd.h>
+#include <asm/vdso/vdso.h>
+
+#define VDSO_HAS_CLOCK_GETRES		1
+
+static __always_inline long gettimeofday_fallback(
+				struct __kernel_old_timeval *_tv,
+				struct timezone *_tz)
+{
+	register struct __kernel_old_timeval *tv asm("a0") = _tv;
+	register struct timezone *tz asm("a1") = _tz;
+	register long nr asm("a7") = __NR_gettimeofday;
+	register long ret asm("a0");
+
+	asm volatile(
+	"       syscall 0\n"
+	: "+r" (ret)
+	: "r" (nr), "r" (tv), "r" (tz)
+	: "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7",
+	  "$t8", "memory");
+
+	return ret;
+}
+
+static __always_inline long clock_gettime_fallback(
+					clockid_t _clkid,
+					struct __kernel_timespec *_ts)
+{
+	register clockid_t clkid asm("a0") = _clkid;
+	register struct __kernel_timespec *ts asm("a1") = _ts;
+	register long nr asm("a7") = __NR_clock_gettime;
+	register long ret asm("a0");
+
+	asm volatile(
+	"       syscall 0\n"
+	: "+r" (ret)
+	: "r" (nr), "r" (clkid), "r" (ts)
+	: "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7",
+	  "$t8", "memory");
+
+	return ret;
+}
+
+static __always_inline int clock_getres_fallback(
+					clockid_t _clkid,
+					struct __kernel_timespec *_ts)
+{
+	register clockid_t clkid asm("a0") = _clkid;
+	register struct __kernel_timespec *ts asm("a1") = _ts;
+	register long nr asm("a7") = __NR_clock_getres;
+	register long ret asm("a0");
+
+	asm volatile(
+	"       syscall 0\n"
+	: "+r" (ret)
+	: "r" (nr), "r" (clkid), "r" (ts)
+	: "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7",
+	  "$t8", "memory");
+
+	return ret;
+}
+
+static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
+						 const struct vdso_data *vd)
+{
+	uint64_t count;
+
+	__asm__ __volatile__(
+	"	rdtime.d %0, $zero\n"
+	: "=r" (count));
+
+	return count;
+}
+
+static inline bool loongarch_vdso_hres_capable(void)
+{
+	return true;
+}
+#define __arch_vdso_hres_capable loongarch_vdso_hres_capable
+
+static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
+{
+	return get_vdso_data();
+}
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
diff --git a/arch/loongarch/include/asm/vdso/processor.h b/arch/loongarch/include/asm/vdso/processor.h
new file mode 100644
index 000000000000..ef5770b343a0
--- /dev/null
+++ b/arch/loongarch/include/asm/vdso/processor.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef __ASM_VDSO_PROCESSOR_H
+#define __ASM_VDSO_PROCESSOR_H
+
+#ifndef __ASSEMBLY__
+
+#define cpu_relax()	barrier()
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_VDSO_PROCESSOR_H */
diff --git a/arch/loongarch/include/asm/vdso/vdso.h b/arch/loongarch/include/asm/vdso/vdso.h
new file mode 100644
index 000000000000..5a01643a65b3
--- /dev/null
+++ b/arch/loongarch/include/asm/vdso/vdso.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Author: Huacai Chen <chenhuacai@loongson.cn>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef __ASSEMBLY__
+
+#include <asm/asm.h>
+#include <asm/page.h>
+
+static inline unsigned long get_vdso_base(void)
+{
+	unsigned long addr;
+
+	__asm__(
+	" la.pcrel %0, _start\n"
+	: "=r" (addr)
+	:
+	:);
+
+	return addr;
+}
+
+static inline const struct vdso_data *get_vdso_data(void)
+{
+	return (const struct vdso_data *)(get_vdso_base() - PAGE_SIZE);
+}
+
+#endif /* __ASSEMBLY__ */
diff --git a/arch/loongarch/include/asm/vdso/vsyscall.h b/arch/loongarch/include/asm/vdso/vsyscall.h
new file mode 100644
index 000000000000..5de615383a22
--- /dev/null
+++ b/arch/loongarch/include/asm/vdso/vsyscall.h
@@ -0,0 +1,27 @@
+/* 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 *__loongarch_get_k_vdso_data(void)
+{
+	return vdso_data;
+}
+#define __arch_get_k_vdso_data __loongarch_get_k_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 */