LoongArch: vDSO: Switch to generic storage implementation

The generic storage implementation provides the same features as the
custom one. However it can be shared between architectures, making
maintenance easier.

Co-developed-by: Nam Cao <[e-mail]>
Signed-off-by: Nam Cao <[e-mail]>
Signed-off-by: Thomas Weißschuh <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]

arch/loongarch/Kconfig

···
 	select ARCH_HAS_SET_MEMORY
 	select ARCH_HAS_SET_DIRECT_MAP
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
+	select ARCH_HAS_VDSO_ARCH_DATA
 	select ARCH_INLINE_READ_LOCK if !PREEMPTION
 	select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
 	select ARCH_INLINE_READ_LOCK_IRQ if !PREEMPTION
···
 	select GENERIC_SCHED_CLOCK
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
+	select GENERIC_VDSO_DATA_STORE
 	select GENERIC_VDSO_TIME_NS
 	select GPIOLIB
 	select HAS_IOPORT

arch/loongarch/include/asm/vdso.h

···
 	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;

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

···
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Author: Huacai Chen <[e-mail]>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef _VDSO_ARCH_DATA_H
+#define _VDSO_ARCH_DATA_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/asm.h>
+#include <asm/vdso.h>
+
+struct vdso_pcpu_data {
+	u32 node;
+} ____cacheline_aligned_in_smp;
+
+struct vdso_arch_data {
+	struct vdso_pcpu_data pdata[NR_CPUS];
+};
+
+#endif /* __ASSEMBLY__ */
+
+#endif

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

···
 	return ret;
 }
 
-static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
-{
-	return &_loongarch_data.rng_data;
-}
-
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_VDSO_GETRANDOM_H */

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

···
 }
 
 static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
-						 const struct vdso_data *vd)
+						 const struct vdso_time_data *vd)
 {
 	uint64_t count;
 
···
 }
 #define __arch_vdso_hres_capable loongarch_vdso_hres_capable
 
-static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
-{
-	return _vdso_data;
-}
-
-#ifdef CONFIG_TIME_NS
-static __always_inline
-const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
-{
-	return _timens_data;
-}
-#endif
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_VDSO_GETTIMEOFDAY_H */

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

···
 #include <asm/asm.h>
 #include <asm/page.h>
 #include <asm/vdso.h>
+#include <vdso/datapage.h>
 
-struct vdso_pcpu_data {
-	u32 node;
-} ____cacheline_aligned_in_smp;
-
-struct loongarch_vdso_data {
-	struct vdso_pcpu_data pdata[NR_CPUS];
-	struct vdso_rng_data rng_data;
-};
-
-/*
- * The layout of vvar:
- *
- *                      high
- * +---------------------+--------------------------+
- * | loongarch vdso data | LOONGARCH_VDSO_DATA_SIZE |
- * +---------------------+--------------------------+
- * |  time-ns vdso data  |        PAGE_SIZE         |
- * +---------------------+--------------------------+
- * |  generic vdso data  |        PAGE_SIZE         |
- * +---------------------+--------------------------+
- *                      low
- */
-#define LOONGARCH_VDSO_DATA_SIZE PAGE_ALIGN(sizeof(struct loongarch_vdso_data))
-#define LOONGARCH_VDSO_DATA_PAGES (LOONGARCH_VDSO_DATA_SIZE >> PAGE_SHIFT)
-
-enum vvar_pages {
-	VVAR_GENERIC_PAGE_OFFSET,
-	VVAR_TIMENS_PAGE_OFFSET,
-	VVAR_LOONGARCH_PAGES_START,
-	VVAR_LOONGARCH_PAGES_END = VVAR_LOONGARCH_PAGES_START + LOONGARCH_VDSO_DATA_PAGES - 1,
-	VVAR_NR_PAGES,
-};
-
-#define VVAR_SIZE (VVAR_NR_PAGES << PAGE_SHIFT)
-
-extern struct loongarch_vdso_data _loongarch_data __attribute__((visibility("hidden")));
+#define VVAR_SIZE (VDSO_NR_PAGES << PAGE_SHIFT)
 
 #endif /* __ASSEMBLY__ */
 

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

···
 
 #include <vdso/datapage.h>
 
-extern struct vdso_data *vdso_data;
-extern struct vdso_rng_data *vdso_rng_data;
-
-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
-
-static __always_inline
-struct vdso_rng_data *__loongarch_get_k_vdso_rng_data(void)
-{
-	return vdso_rng_data;
-}
-#define __arch_get_k_vdso_rng_data __loongarch_get_k_vdso_rng_data
-
 /* The asm-generic header needs to be included after the definitions above */
 #include <asm-generic/vdso/vsyscall.h>
 

arch/loongarch/kernel/asm-offsets.c

···
 {
 	COMMENT("LoongArch vDSO offsets.");
 
-	DEFINE(__VVAR_PAGES, VVAR_NR_PAGES);
+	DEFINE(__VDSO_PAGES, VDSO_NR_PAGES);
 	BLANK();
 }

arch/loongarch/kernel/vdso.c

···
 #include <linux/random.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
-#include <linux/time_namespace.h>
+#include <linux/vdso_datastore.h>
 
 #include <asm/page.h>
 #include <asm/vdso.h>
···
 
 extern char vdso_start[], vdso_end[];
 
-/* Kernel-provided data used by the VDSO. */
-static union vdso_data_store generic_vdso_data __page_aligned_data;
-
-static union {
-	u8 page[LOONGARCH_VDSO_DATA_SIZE];
-	struct loongarch_vdso_data vdata;
-} loongarch_vdso_data __page_aligned_data;
-
-struct vdso_data *vdso_data = generic_vdso_data.data;
-struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata;
-struct vdso_rng_data *vdso_rng_data = &loongarch_vdso_data.vdata.rng_data;
-
 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
 {
 	current->mm->context.vdso = (void *)(new_vma->vm_start);
···
 	return 0;
 }
 
-static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
-			     struct vm_area_struct *vma, struct vm_fault *vmf)
-{
-	unsigned long pfn;
-	struct page *timens_page = find_timens_vvar_page(vma);
-
-	switch (vmf->pgoff) {
-	case VVAR_GENERIC_PAGE_OFFSET:
-		if (!timens_page)
-			pfn = sym_to_pfn(vdso_data);
-		else
-			pfn = page_to_pfn(timens_page);
-		break;
-#ifdef CONFIG_TIME_NS
-	case VVAR_TIMENS_PAGE_OFFSET:
-		/*
-		 * If a task belongs to a time namespace then a namespace specific
-		 * VVAR is mapped with the VVAR_GENERIC_PAGE_OFFSET and the real
-		 * VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET offset.
-		 * See also the comment near timens_setup_vdso_data().
-		 */
-		if (!timens_page)
-			return VM_FAULT_SIGBUS;
-		else
-			pfn = sym_to_pfn(vdso_data);
-		break;
-#endif /* CONFIG_TIME_NS */
-	case VVAR_LOONGARCH_PAGES_START ... VVAR_LOONGARCH_PAGES_END:
-		pfn = sym_to_pfn(&loongarch_vdso_data) + vmf->pgoff - VVAR_LOONGARCH_PAGES_START;
-		break;
-	default:
-		return VM_FAULT_SIGBUS;
-	}
-
-	return vmf_insert_pfn(vma, vmf->address, pfn);
-}
-
 struct loongarch_vdso_info vdso_info = {
 	.vdso = vdso_start,
 	.code_mapping = {
 		.name = "[vdso]",
 		.mremap = vdso_mremap,
-	},
-	.data_mapping = {
-		.name = "[vvar]",
-		.fault = vvar_fault,
 	},
 	.offset_sigreturn = vdso_offset_sigreturn,
 };
···
 	BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
 
 	for_each_possible_cpu(cpu)
-		vdso_pdata[cpu].node = cpu_to_node(cpu);
+		vdso_k_arch_data->pdata[cpu].node = cpu_to_node(cpu);
 
 	vdso_info.size = PAGE_ALIGN(vdso_end - vdso_start);
 	vdso_info.code_mapping.pages =
···
 	return 0;
 }
 subsys_initcall(init_vdso);
-
-#ifdef CONFIG_TIME_NS
-struct vdso_data *arch_get_vdso_data(void *vvar_page)
-{
-	return (struct vdso_data *)(vvar_page);
-}
-
-/*
- * The vvar mapping contains data for a specific time namespace, so when a
- * task changes namespace we must unmap its vvar data for the old namespace.
- * Subsequent faults will map in data for the new namespace.
- *
- * For more details see timens_setup_vdso_data().
- */
-int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
-{
-	struct mm_struct *mm = task->mm;
-	struct vm_area_struct *vma;
-
-	VMA_ITERATOR(vmi, mm, 0);
-
-	mmap_read_lock(mm);
-	for_each_vma(vmi, vma) {
-		if (vma_is_special_mapping(vma, &vdso_info.data_mapping))
-			zap_vma_pages(vma);
-	}
-	mmap_read_unlock(mm);
-
-	return 0;
-}
-#endif
 
 static unsigned long vdso_base(void)
 {
···
 		goto out;
 	}
 
-	vma = _install_special_mapping(mm, data_addr, VVAR_SIZE,
-				       VM_READ | VM_MAYREAD | VM_PFNMAP,
-				       &info->data_mapping);
+	vma = vdso_install_vvar_mapping(mm, data_addr);
 	if (IS_ERR(vma)) {
 		ret = PTR_ERR(vma);
 		goto out;

arch/loongarch/vdso/vdso.lds.S

···
  */
 #include <asm/page.h>
 #include <generated/asm-offsets.h>
+#include <vdso/datapage.h>
 
 OUTPUT_FORMAT("elf64-loongarch", "elf64-loongarch", "elf64-loongarch")
 
···
 
 SECTIONS
 {
-	PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE);
-#ifdef CONFIG_TIME_NS
-	PROVIDE(_timens_data = _vdso_data + PAGE_SIZE);
-#endif
-	PROVIDE(_loongarch_data = _vdso_data + 2 * PAGE_SIZE);
+	VDSO_VVAR_SYMS
+
 	. = SIZEOF_HEADERS;
 
 	.hash		: { *(.hash) }			:text

arch/loongarch/vdso/vgetcpu.c

···
 	return cpu_id;
 }
 
-static __always_inline const struct vdso_pcpu_data *get_pcpu_data(void)
-{
-	return _loongarch_data.pdata;
-}
-
 extern
 int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
 int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
 {
 	int cpu_id;
-	const struct vdso_pcpu_data *data;
 
 	cpu_id = read_cpu_id();
 
 	if (cpu)
 		*cpu = cpu_id;
 
-	if (node) {
-		data = get_pcpu_data();
-		*node = data[cpu_id].node;
-	}
+	if (node)
+		*node = vdso_u_arch_data.pdata[cpu_id].node;
 
 	return 0;
 }