Commit 365841e1 authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Thomas Gleixner
Browse files

vdso: Add generic architecture-specific data storage 



Some architectures need to expose architecture-specific data to the vDSO.

Enable the generic vDSO storage mechanism to both store and map this
data. Some architectures require more than a single page, like LoongArch,
so prepare for that usecase, too.

Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-7-13a4669dfc8c@linutronix.de
parent 51d6ca37

arch/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -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

include/vdso/datapage.h

+25 −0
Original line number Diff line number Diff line
@@ -9,11 +9,13 @@ 
#include <uapi/linux/types.h>

#include <uapi/asm-generic/errno-base.h>



#include <vdso/align.h>

#include <vdso/bits.h>

#include <vdso/clocksource.h>

#include <vdso/ktime.h>

#include <vdso/limits.h>

#include <vdso/math64.h>

#include <vdso/page.h>

#include <vdso/processor.h>

#include <vdso/time.h>

#include <vdso/time32.h>
@@ -25,6 +27,15 @@ 
struct arch_vdso_time_data {};

#endif



#if defined(CONFIG_ARCH_HAS_VDSO_ARCH_DATA)

#include <asm/vdso/arch_data.h>

#elif defined(CONFIG_GENERIC_VDSO_DATA_STORE)

struct vdso_arch_data {

	/* Needed for the generic code, never actually used at runtime */

	char __unused;

};

#endif



#define VDSO_BASES	(CLOCK_TAI + 1)

#define VDSO_HRES	(BIT(CLOCK_REALTIME)		| \

			 BIT(CLOCK_MONOTONIC)		| \
@@ -145,9 +156,11 @@ extern struct vdso_rng_data _vdso_rng_data __attribute__((visibility("hidden"))) 
#else

extern struct vdso_time_data vdso_u_time_data[CS_BASES] __attribute__((visibility("hidden")));

extern struct vdso_rng_data vdso_u_rng_data __attribute__((visibility("hidden")));

extern struct vdso_arch_data vdso_u_arch_data __attribute__((visibility("hidden")));



extern struct vdso_time_data *vdso_k_time_data;

extern struct vdso_rng_data *vdso_k_rng_data;

extern struct vdso_arch_data *vdso_k_arch_data;

#endif



/**
@@ -160,10 +173,15 @@ union vdso_data_store { 


#ifdef CONFIG_GENERIC_VDSO_DATA_STORE



#define VDSO_ARCH_DATA_SIZE ALIGN(sizeof(struct vdso_arch_data), PAGE_SIZE)

#define VDSO_ARCH_DATA_PAGES (VDSO_ARCH_DATA_SIZE >> PAGE_SHIFT)



enum vdso_pages {

	VDSO_TIME_PAGE_OFFSET,

	VDSO_TIMENS_PAGE_OFFSET,

	VDSO_RNG_PAGE_OFFSET,

	VDSO_ARCH_PAGES_START,

	VDSO_ARCH_PAGES_END = VDSO_ARCH_PAGES_START + VDSO_ARCH_DATA_PAGES - 1,

	VDSO_NR_PAGES

};
@@ -193,10 +211,17 @@ enum vdso_pages { 
#define __vdso_u_rng_data

#endif



#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA

#define __vdso_u_arch_data	PROVIDE(vdso_u_arch_data = vdso_u_data + 3 * PAGE_SIZE);

#else

#define __vdso_u_arch_data

#endif



#define VDSO_VVAR_SYMS						\

	PROVIDE(vdso_u_data = . - __VDSO_PAGES * PAGE_SIZE);	\

	PROVIDE(vdso_u_time_data = vdso_u_data);		\

	__vdso_u_rng_data					\

	__vdso_u_arch_data					\





#endif /* !__ASSEMBLY__ */

lib/vdso/datastore.c

+14 −0
Original line number Diff line number Diff line
@@ -26,6 +26,14 @@ struct vdso_rng_data *vdso_k_rng_data = &vdso_rng_data_store.data; 
static_assert(sizeof(vdso_rng_data_store) == PAGE_SIZE);

#endif /* CONFIG_VDSO_GETRANDOM */



#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA

static union {

	struct vdso_arch_data	data;

	u8			page[VDSO_ARCH_DATA_SIZE];

} vdso_arch_data_store __page_aligned_data;

struct vdso_arch_data *vdso_k_arch_data = &vdso_arch_data_store.data;

#endif /* CONFIG_ARCH_HAS_VDSO_ARCH_DATA */



static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,

			     struct vm_area_struct *vma, struct vm_fault *vmf)

{
@@ -67,6 +75,12 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, 
			return VM_FAULT_SIGBUS;

		pfn = __phys_to_pfn(__pa_symbol(vdso_k_rng_data));

		break;

	case VDSO_ARCH_PAGES_START ... VDSO_ARCH_PAGES_END:

		if (!IS_ENABLED(CONFIG_ARCH_HAS_VDSO_ARCH_DATA))

			return VM_FAULT_SIGBUS;

		pfn = __phys_to_pfn(__pa_symbol(vdso_k_arch_data)) +

			vmf->pgoff - VDSO_ARCH_PAGES_START;

		break;

	default:

		return VM_FAULT_SIGBUS;

	}