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arm: vdso: Switch to generic storage implementation

Browse source 
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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-11-13a4669dfc8c@linutronix.de
This commit is contained in:
Thomas Weißschuh 2025-02-04 13:05:43 +01:00 • committed by Thomas Gleixner
parent d2862bb9d9
commit 31e9fa2ba9
7 changed files with 15 additions and 49 deletions
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2
arch/arm/include/asm/vdso.h
View file

@ -4,6 +4,8 @@
#ifdef __KERNEL__
#define __VDSO_PAGES 4
#ifndef __ASSEMBLY__
struct mm_struct;

7
arch/arm/include/asm/vdso/gettimeofday.h
View file

@ -112,7 +112,7 @@ static inline bool arm_vdso_hres_capable(void)
#define __arch_vdso_hres_capable arm_vdso_hres_capable
static __always_inline u64 __arch_get_hw_counter(int clock_mode,
const struct vdso_data *vd)
const struct vdso_time_data *vd)
{
#ifdef CONFIG_ARM_ARCH_TIMER
u64 cycle_now;
@ -135,11 +135,6 @@ static __always_inline u64 __arch_get_hw_counter(int clock_mode,
#endif
}
static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
{
return _vdso_data;
}
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_VDSO_GETTIMEOFDAY_H */

12
arch/arm/include/asm/vdso/vsyscall.h
View file

@ -7,22 +7,14 @@
#include <vdso/datapage.h>
#include <asm/cacheflush.h>
extern struct vdso_data *vdso_data;
extern bool cntvct_ok;
static __always_inline
struct vdso_data *__arm_get_k_vdso_data(void)
{
return vdso_data;
}
#define __arch_get_k_vdso_data __arm_get_k_vdso_data
static __always_inline
void __arm_sync_vdso_data(struct vdso_data *vdata)
void __arch_sync_vdso_time_data(struct vdso_time_data *vdata)
{
flush_dcache_page(virt_to_page(vdata));
}
#define __arch_sync_vdso_data __arm_sync_vdso_data
#define __arch_sync_vdso_time_data __arch_sync_vdso_time_data
/* The asm-generic header needs to be included after the definitions above */
#include <asm-generic/vdso/vsyscall.h>

4
arch/arm/kernel/asm-offsets.c
View file

@ -153,10 +153,6 @@ int main(void)
DEFINE(CACHE_WRITEBACK_ORDER, __CACHE_WRITEBACK_ORDER);
DEFINE(CACHE_WRITEBACK_GRANULE, __CACHE_WRITEBACK_GRANULE);
BLANK();
#ifdef CONFIG_VDSO
DEFINE(VDSO_DATA_SIZE, sizeof(union vdso_data_store));
#endif
BLANK();
#ifdef CONFIG_ARM_MPU
DEFINE(MPU_RNG_INFO_RNGS, offsetof(struct mpu_rgn_info, rgns));
DEFINE(MPU_RNG_INFO_USED, offsetof(struct mpu_rgn_info, used));

34
arch/arm/kernel/vdso.c
View file

@ -7,6 +7,7 @@
*/
#include <linux/cache.h>
#include <linux/vdso_datastore.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/kernel.h>
@ -33,15 +34,6 @@ extern char vdso_start[], vdso_end[];
/* Total number of pages needed for the data and text portions of the VDSO. */
unsigned int vdso_total_pages __ro_after_init;
static union vdso_data_store vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = vdso_data_store.data;
static struct page *vdso_data_page __ro_after_init;
static const struct vm_special_mapping vdso_data_mapping = {
.name = "[vvar]",
.pages = &vdso_data_page,
};
static int vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *new_vma)
{
@ -192,9 +184,6 @@ static int __init vdso_init(void)
if (vdso_text_pagelist == NULL)
return -ENOMEM;
/* Grab the VDSO data page. */
vdso_data_page = virt_to_page(vdso_data);
/* Grab the VDSO text pages. */
for (i = 0; i < text_pages; i++) {
struct page *page;
@ -205,7 +194,7 @@ static int __init vdso_init(void)
vdso_text_mapping.pages = vdso_text_pagelist;
vdso_total_pages = 1; /* for the data/vvar page */
vdso_total_pages = VDSO_NR_PAGES; /* for the data/vvar pages */
vdso_total_pages += text_pages;
cntvct_ok = cntvct_functional();
@ -216,16 +205,7 @@ static int __init vdso_init(void)
}
arch_initcall(vdso_init);
static int install_vvar(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma;
vma = _install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_MAYREAD,
&vdso_data_mapping);
return PTR_ERR_OR_ZERO(vma);
}
static_assert(__VDSO_PAGES == VDSO_NR_PAGES);
/* assumes mmap_lock is write-locked */
void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
@ -238,12 +218,12 @@ void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
if (vdso_text_pagelist == NULL)
return;
if (install_vvar(mm, addr))
if (IS_ERR(vdso_install_vvar_mapping(mm, addr)))
return;
/* Account for vvar page. */
addr += PAGE_SIZE;
len = (vdso_total_pages - 1) << PAGE_SHIFT;
/* Account for vvar pages. */
addr += VDSO_NR_PAGES * PAGE_SIZE;
len = (vdso_total_pages - VDSO_NR_PAGES) << PAGE_SHIFT;
vma = _install_special_mapping(mm, addr, len,
VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,

1
arch/arm/mm/Kconfig
View file

@ -928,6 +928,7 @@ config VDSO
select GENERIC_TIME_VSYSCALL
select GENERIC_VDSO_32
select GENERIC_GETTIMEOFDAY
select GENERIC_VDSO_DATA_STORE
help
Place in the process address space an ELF shared object
providing fast implementations of gettimeofday and

4
arch/arm/vdso/vdso.lds.S
View file

@ -11,16 +11,16 @@
*/
#include <linux/const.h>
#include <asm/asm-offsets.h>
#include <asm/page.h>
#include <asm/vdso.h>
#include <vdso/datapage.h>
OUTPUT_FORMAT("elf32-littlearm", "elf32-bigarm", "elf32-littlearm")
OUTPUT_ARCH(arm)
SECTIONS
{
PROVIDE(_vdso_data = . - VDSO_DATA_SIZE);
VDSO_VVAR_SYMS
. = SIZEOF_HEADERS;