Merge tag 'timers-vdso-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull VDSO infrastructure updates from Thomas Gleixner:

 - Consolidate the VDSO storage

   The VDSO data storage and data layout has been largely architecture
   specific for historical reasons. That increases the maintenance
   effort and causes inconsistencies over and over.

   There is no real technical reason for architecture specific layouts
   and implementations. The architecture specific details can easily be
   integrated into a generic layout, which also reduces the amount of
   duplicated code for managing the mappings.

   Convert all architectures over to a unified layout and common mapping
   infrastructure. This splits the VDSO data layout into subsystem
   specific blocks, timekeeping, random and architecture parts, which
   provides a better structure and allows to improve and update the
   functionalities without conflict and interaction.

 - Rework the timekeeping data storage

   The current implementation is designed for exposing system
   timekeeping accessors, which was good enough at the time when it was
   designed.

   PTP and Time Sensitive Networking (TSN) change that as there are
   requirements to expose independent PTP clocks, which are not related
   to system timekeeping.

   Replace the monolithic data storage by a structured layout, which
   allows to add support for independent PTP clocks on top while reusing
   both the data structures and the time accessor implementations.

* tag 'timers-vdso-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits)
  sparc/vdso: Always reject undefined references during linking
  x86/vdso: Always reject undefined references during linking
  vdso: Rework struct vdso_time_data and introduce struct vdso_clock
  vdso: Move architecture related data before basetime data
  powerpc/vdso: Prepare introduction of struct vdso_clock
  arm64/vdso: Prepare introduction of struct vdso_clock
  x86/vdso: Prepare introduction of struct vdso_clock
  time/namespace: Prepare introduction of struct vdso_clock
  vdso/namespace: Rename timens_setup_vdso_data() to reflect new vdso_clock struct
  vdso/vsyscall: Prepare introduction of struct vdso_clock
  vdso/gettimeofday: Prepare helper functions for introduction of struct vdso_clock
  vdso/gettimeofday: Prepare do_coarse_timens() for introduction of struct vdso_clock
  vdso/gettimeofday: Prepare do_coarse() for introduction of struct vdso_clock
  vdso/gettimeofday: Prepare do_hres_timens() for introduction of struct vdso_clock
  vdso/gettimeofday: Prepare do_hres() for introduction of struct vdso_clock
  vdso/gettimeofday: Prepare introduction of struct vdso_clock
  vdso/helpers: Prepare introduction of struct vdso_clock
  vdso/datapage: Define vdso_clock to prepare for multiple PTP clocks
  vdso: Make vdso_time_data cacheline aligned
  arm64: Make asm/cache.h compatible with vDSO
  ...

Author: torvalds

MAINTAINERS

@@ -9792,6 +9792,7 @@ F:	include/asm-generic/vdso/vsyscall.h
 F:	include/vdso/
 F:	kernel/time/vsyscall.c
 F:	lib/vdso/
+F:	tools/testing/selftests/vDSO/
 
 GENWQE (IBM Generic Workqueue Card)
 M:	Frank Haverkamp <haver@linux.ibm.com>

arch/Kconfig

@@ -1584,6 +1584,10 @@ config HAVE_SPARSE_SYSCALL_NR
 	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
 	  related optimizations for a given architecture.
 
+config ARCH_HAS_VDSO_ARCH_DATA
+	depends on GENERIC_VDSO_DATA_STORE
+	bool
+
 config ARCH_HAS_VDSO_TIME_DATA
 	bool
 

arch/arm/include/asm/vdso.h

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

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

@@ -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 */

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

@@ -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>

arch/arm/kernel/asm-offsets.c

@@ -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));

arch/arm/kernel/vdso.c

@@ -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,

arch/arm/mm/Kconfig

@@ -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

arch/arm/vdso/Makefile

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
 # Include the generic Makefile to check the built vdso.
-include $(srctree)/lib/vdso/Makefile
+include $(srctree)/lib/vdso/Makefile.include
 
 hostprogs := vdsomunge
 

arch/arm/vdso/vdso.lds.S

@@ -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;