[PATCH v3 09/18] riscv: vdso: Switch to generic storage implementation

Thomas Weißschuh
2025-02-04T12:06:12Z

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 <namcao@linutronix.de>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
arch/riscv/Kconfig | 3 +-
arch/riscv/include/asm/vdso.h | 2 +-
.../include/asm/vdso/{time_data.h => arch_data.h} | 8 +-
arch/riscv/include/asm/vdso/gettimeofday.h | 14 +---
arch/riscv/include/asm/vdso/vsyscall.h | 9 ---
arch/riscv/kernel/sys_hwprobe.c | 3 +-
arch/riscv/kernel/vdso.c | 90 +---------------------
arch/riscv/kernel/vdso/hwprobe.c | 6 +-
arch/riscv/kernel/vdso/vdso.lds.S | 7 +-
9 files changed, 18 insertions(+), 124 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 7612c52e9b1e35607f1dd4603a596416d3357a71..aa8ea53186c04ad68582255f74b09a0605fe8368 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -53,7 +53,7 @@ config RISCV
select ARCH_HAS_SYSCALL_WRAPPER
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UBSAN
- select ARCH_HAS_VDSO_TIME_DATA
+ select ARCH_HAS_VDSO_ARCH_DATA if GENERIC_VDSO_DATA_STORE
select ARCH_KEEP_MEMBLOCK if ACPI
select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE if 64BIT && MMU
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
@@ -116,6 +116,7 @@ config RISCV
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_TIME_VSYSCALL if MMU && 64BIT
+ select GENERIC_VDSO_DATA_STORE if MMU
select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
select HARDIRQS_SW_RESEND
select HAS_IOPORT if MMU
diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h
index f891478829a52c41e06240f67611694cc28197d9..c130d8100232cbe50e52e35eb418e354bd114cb7 100644
--- a/arch/riscv/include/asm/vdso.h
+++ b/arch/riscv/include/asm/vdso.h
@@ -14,7 +14,7 @@
*/
#ifdef CONFIG_MMU

-#define __VVAR_PAGES 2
+#define __VDSO_PAGES 4

#ifndef __ASSEMBLY__
#include <generated/vdso-offsets.h>
diff --git a/arch/riscv/include/asm/vdso/time_data.h b/arch/riscv/include/asm/vdso/arch_data.h
similarity index 71%
rename from arch/riscv/include/asm/vdso/time_data.h
rename to arch/riscv/include/asm/vdso/arch_data.h
index dfa65228999bed41dfd6c5e36cb678e1e055eec8..da57a3786f7a53c866fc00948826b4a2d839940f 100644
--- a/arch/riscv/include/asm/vdso/time_data.h
+++ b/arch/riscv/include/asm/vdso/arch_data.h
@@ -1,12 +1,12 @@
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __RISCV_ASM_VDSO_TIME_DATA_H
-#define __RISCV_ASM_VDSO_TIME_DATA_H
+#ifndef __RISCV_ASM_VDSO_ARCH_DATA_H
+#define __RISCV_ASM_VDSO_ARCH_DATA_H

#include <linux/types.h>
#include <vdso/datapage.h>
#include <asm/hwprobe.h>

-struct arch_vdso_time_data {
+struct vdso_arch_data {
/* Stash static answers to the hwprobe queries when all CPUs are selected. */
__u64 all_cpu_hwprobe_values[RISCV_HWPROBE_MAX_KEY + 1];

@@ -14,4 +14,4 @@ struct arch_vdso_time_data {
__u8 homogeneous_cpus;
};

-#endif /* __RISCV_ASM_VDSO_TIME_DATA_H */
+#endif /* __RISCV_ASM_VDSO_ARCH_DATA_H */
diff --git a/arch/riscv/include/asm/vdso/gettimeofday.h b/arch/riscv/include/asm/vdso/gettimeofday.h
index ba3283cf7accaa93a38512d2c17eda0eefde0612..29164f84f93cec6e28251e6a0adfbc341ac88241 100644
--- a/arch/riscv/include/asm/vdso/gettimeofday.h
+++ b/arch/riscv/include/asm/vdso/gettimeofday.h
@@ -69,7 +69,7 @@ int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
#endif /* CONFIG_GENERIC_TIME_VSYSCALL */

static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
- const struct vdso_data *vd)
+ const struct vdso_time_data *vd)
{
/*
* The purpose of csr_read(CSR_TIME) is to trap the system into
@@ -79,18 +79,6 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
return csr_read(CSR_TIME);
}

-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 */
diff --git a/arch/riscv/include/asm/vdso/vsyscall.h b/arch/riscv/include/asm/vdso/vsyscall.h
index e8a9c4b53c0c9f4744196eed800b21f3918d1040..1140b54b4bc8278d7a322036cd9f84f71258f246 100644
--- a/arch/riscv/include/asm/vdso/vsyscall.h
+++ b/arch/riscv/include/asm/vdso/vsyscall.h
@@ -6,15 +6,6 @@

#include <vdso/datapage.h>

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

diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
index bcd3b816306c22df62f60ad044f4ae58f7dad4d1..04a4e549551284bb3340673eb76a2e7bd457025e 100644
--- a/arch/riscv/kernel/sys_hwprobe.c
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -450,8 +450,7 @@ static int do_riscv_hwprobe(struct riscv_hwprobe __user *pairs,

static int __init init_hwprobe_vdso_data(void)
{
- struct vdso_data *vd = __arch_get_k_vdso_data();
- struct arch_vdso_time_data *avd = &vd->arch_data;
+ struct vdso_arch_data *avd = vdso_k_arch_data;
u64 id_bitsmash = 0;
struct riscv_hwprobe pair;
int key;
diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index 3ca3ae4277e187e790a8bf513a9e80d8b6290bb2..cc2895d1fbc2fe752b3edc94f4e28a6a8fca7a3b 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c
@@ -13,20 +13,11 @@
#include <linux/err.h>
#include <asm/page.h>
#include <asm/vdso.h>
-#include <linux/time_namespace.h>
+#include <linux/vdso_datastore.h>
#include <vdso/datapage.h>
#include <vdso/vsyscall.h>

-enum vvar_pages {
- VVAR_DATA_PAGE_OFFSET,
- VVAR_TIMENS_PAGE_OFFSET,
- VVAR_NR_PAGES,
-};
-
-#define VVAR_SIZE (VVAR_NR_PAGES << PAGE_SHIFT)
-
-static union vdso_data_store vdso_data_store __page_aligned_data;
-struct vdso_data *vdso_data = vdso_data_store.data;
+#define VVAR_SIZE (VDSO_NR_PAGES << PAGE_SHIFT)

struct __vdso_info {
const char *name;
@@ -79,78 +70,6 @@ static void __init __vdso_init(struct __vdso_info *vdso_info)
vdso_info->cm->pages = vdso_pagelist;
}

-#ifdef CONFIG_TIME_NS
-struct vdso_data *arch_get_vdso_data(void *vvar_page)
-{
- return (struct vdso_data *)(vvar_page);
-}
-
-static const struct vm_special_mapping rv_vvar_map;
-
-/*
- * 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, &rv_vvar_map))
- zap_vma_pages(vma);
- }
-
- mmap_read_unlock(mm);
- return 0;
-}
-#endif
-
-static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
- struct vm_area_struct *vma, struct vm_fault *vmf)
-{
- struct page *timens_page = find_timens_vvar_page(vma);
- unsigned long pfn;
-
- switch (vmf->pgoff) {
- case VVAR_DATA_PAGE_OFFSET:
- if (timens_page)
- pfn = page_to_pfn(timens_page);
- else
- pfn = sym_to_pfn(vdso_data);
- 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_DATA_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;
- pfn = sym_to_pfn(vdso_data);
- break;
-#endif /* CONFIG_TIME_NS */
- default:
- return VM_FAULT_SIGBUS;
- }
-
- return vmf_insert_pfn(vma, vmf->address, pfn);
-}
-
-static const struct vm_special_mapping rv_vvar_map = {
- .name = "[vvar]",
- .fault = vvar_fault,
-};
-
static struct vm_special_mapping rv_vdso_map __ro_after_init = {
.name = "[vdso]",
.mremap = vdso_mremap,
@@ -196,7 +115,7 @@ static int __setup_additional_pages(struct mm_struct *mm,
unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
void *ret;

- BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
+ BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES);

vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
/* Be sure to map the data page */
@@ -208,8 +127,7 @@ static int __setup_additional_pages(struct mm_struct *mm,
goto up_fail;
}

- ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
- (VM_READ | VM_MAYREAD | VM_PFNMAP), &rv_vvar_map);
+ ret = vdso_install_vvar_mapping(mm, vdso_base);
if (IS_ERR(ret))
goto up_fail;

diff --git a/arch/riscv/kernel/vdso/hwprobe.c b/arch/riscv/kernel/vdso/hwprobe.c
index a158c029344f60c022e7565757ff44df7e3d89e5..2ddeba6c68dda09b0249117fd06a5d249f3b0abd 100644
--- a/arch/riscv/kernel/vdso/hwprobe.c
+++ b/arch/riscv/kernel/vdso/hwprobe.c
@@ -16,8 +16,7 @@ static int riscv_vdso_get_values(struct riscv_hwprobe *pairs, size_t pair_count,
size_t cpusetsize, unsigned long *cpus,
unsigned int flags)
{
- const struct vdso_data *vd = __arch_get_vdso_data();
- const struct arch_vdso_time_data *avd = &vd->arch_data;
+ const struct vdso_arch_data *avd = &vdso_u_arch_data;
bool all_cpus = !cpusetsize && !cpus;
struct riscv_hwprobe *p = pairs;
struct riscv_hwprobe *end = pairs + pair_count;
@@ -51,8 +50,7 @@ static int riscv_vdso_get_cpus(struct riscv_hwprobe *pairs, size_t pair_count,
size_t cpusetsize, unsigned long *cpus,
unsigned int flags)
{
- const struct vdso_data *vd = __arch_get_vdso_data();
- const struct arch_vdso_time_data *avd = &vd->arch_data;
+ const struct vdso_arch_data *avd = &vdso_u_arch_data;
struct riscv_hwprobe *p = pairs;
struct riscv_hwprobe *end = pairs + pair_count;
unsigned char *c = (unsigned char *)cpus;
diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S
index cbe2a179331d2511a8b4a26c06383e46131661b1..8e86965a8aae4d7c5a36d0f26026cd1c8680b339 100644
--- a/arch/riscv/kernel/vdso/vdso.lds.S
+++ b/arch/riscv/kernel/vdso/vdso.lds.S
@@ -4,15 +4,14 @@
*/
#include <asm/page.h>
#include <asm/vdso.h>
+#include <vdso/datapage.h>

OUTPUT_ARCH(riscv)

SECTIONS
{
- PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE);
-#ifdef CONFIG_TIME_NS
- PROVIDE(_timens_data = _vdso_data + PAGE_SIZE);
-#endif
+ VDSO_VVAR_SYMS
+
. = SIZEOF_HEADERS;

.hash : { *(.hash) } :text

--
2.48.1