From patchwork series 436945

https://patchwork.ozlabs.org//project/linuxppc-dev/list/?series=436945

Author: Fox Snowpatch

MAINTAINERS

@@ -9679,6 +9679,7 @@ F:	include/asm-generic/vdso/vsyscall.h
 F:	include/vdso/
 F:	kernel/time/vsyscall.c
 F:	lib/vdso/
+F:	lib/vdso_kernel/
 
 GENWQE (IBM Generic Workqueue Card)
 M:	Frank Haverkamp <[email protected]>

arch/Kconfig

@@ -1576,6 +1576,10 @@ 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 HAVE_GENERIC_VDSO
+	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 __arm_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 __arm_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/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;
 

arch/arm64/include/asm/vdso.h

@@ -5,7 +5,7 @@
 #ifndef __ASM_VDSO_H
 #define __ASM_VDSO_H
 
-#define __VVAR_PAGES    2
+#define __VDSO_PAGES    4
 
 #ifndef __ASSEMBLY__
 

arch/arm64/include/asm/vdso/compat_gettimeofday.h

@@ -104,7 +104,7 @@ int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
 }
 
 static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
-						 const struct vdso_data *vd)
+						 const struct vdso_time_data *vd)
 {
 	u64 res;
 
@@ -131,43 +131,45 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
 	return res;
 }
 
-static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
+static __always_inline const struct vdso_time_data *__aarch64_get_vdso_u_time_data(void)
 {
-	const struct vdso_data *ret;
+	const struct vdso_time_data *ret;
 
 	/*
-	 * This simply puts &_vdso_data into ret. The reason why we don't use
-	 * `ret = _vdso_data` is that the compiler tends to optimise this in a
-	 * very suboptimal way: instead of keeping &_vdso_data in a register,
-	 * it goes through a relocation almost every time _vdso_data must be
+	 * This simply puts &_vdso_time_data into ret. The reason why we don't use
+	 * `ret = _vdso_time_data` is that the compiler tends to optimise this in a
+	 * very suboptimal way: instead of keeping &_vdso_time_data in a register,
+	 * it goes through a relocation almost every time _vdso_time_data must be
 	 * accessed (even in subfunctions). This is both time and space
 	 * consuming: each relocation uses a word in the code section, and it
 	 * has to be loaded at runtime.
 	 *
 	 * This trick hides the assignment from the compiler. Since it cannot
 	 * track where the pointer comes from, it will only use one relocation
-	 * where __arch_get_vdso_data() is called, and then keep the result in
-	 * a register.
+	 * where __aarch64_get_vdso_u_time_data() is called, and then keep the
+	 * result in a register.
 	 */
-	asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
+	asm volatile("mov %0, %1" : "=r"(ret) : "r"(vdso_u_time_data));
 
 	return ret;
 }
+#define __arch_get_vdso_u_time_data __aarch64_get_vdso_u_time_data
 
 #ifdef CONFIG_TIME_NS
 static __always_inline
-const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
+const struct vdso_time_data *__aarch64_get_vdso_u_timens_data(void)
 {
-	const struct vdso_data *ret;
+	const struct vdso_time_data *ret;
 
-	/* See __arch_get_vdso_data(). */
-	asm volatile("mov %0, %1" : "=r"(ret) : "r"(_timens_data));
+	/* See __aarch64_get_vdso_u_time_data(). */
+	asm volatile("mov %0, %1" : "=r"(ret) : "r"(vdso_u_timens_data));
 
 	return ret;
 }
+#define __arch_get_vdso_u_timens_data __aarch64_get_vdso_u_timens_data
 #endif
 
-static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
+static inline bool vdso_clocksource_ok(const struct vdso_time_data *vd)
 {
 	return vd->clock_mode == VDSO_CLOCKMODE_ARCHTIMER;
 }

arch/arm64/include/asm/vdso/getrandom.h

@@ -33,18 +33,6 @@ static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, uns
 	return ret;
 }
 
-static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
-{
-	/*
-	 * The RNG data is in the real VVAR data page, but if a task belongs to a time namespace
-	 * then VVAR_DATA_PAGE_OFFSET points to the namespace-specific VVAR page and VVAR_TIMENS_
-	 * PAGE_OFFSET points to the real VVAR page.
-	 */
-	if (IS_ENABLED(CONFIG_TIME_NS) && _vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS)
-		return (void *)&_vdso_rng_data + VVAR_TIMENS_PAGE_OFFSET * (1UL << CONFIG_PAGE_SHIFT);
-	return &_vdso_rng_data;
-}
-
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_VDSO_GETRANDOM_H */

arch/arm64/include/asm/vdso/gettimeofday.h

@@ -67,7 +67,7 @@ int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
 }
 
 static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
-						 const struct vdso_data *vd)
+						 const struct vdso_time_data *vd)
 {
 	u64 res;
 
@@ -99,20 +99,6 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
 	return res;
 }
 
-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/arm64/include/asm/vdso/vsyscall.h

@@ -2,41 +2,18 @@
 #ifndef __ASM_VDSO_VSYSCALL_H
 #define __ASM_VDSO_VSYSCALL_H
 
-#define __VDSO_RND_DATA_OFFSET  480
-
 #ifndef __ASSEMBLY__
 
 #include <vdso/datapage.h>
 
-enum vvar_pages {
-	VVAR_DATA_PAGE_OFFSET,
-	VVAR_TIMENS_PAGE_OFFSET,
-	VVAR_NR_PAGES,
-};
-
 #define VDSO_PRECISION_MASK	~(0xFF00ULL<<48)
 
-extern struct vdso_data *vdso_data;
 
 /*
  * Update the vDSO data page to keep in sync with kernel timekeeping.
  */
 static __always_inline
-struct vdso_data *__arm64_get_k_vdso_data(void)
-{
-	return vdso_data;
-}
-#define __arch_get_k_vdso_data __arm64_get_k_vdso_data
-
-static __always_inline
-struct vdso_rng_data *__arm64_get_k_vdso_rnd_data(void)
-{
-	return (void *)vdso_data + __VDSO_RND_DATA_OFFSET;
-}
-#define __arch_get_k_vdso_rng_data __arm64_get_k_vdso_rnd_data
-
-static __always_inline
-void __arm64_update_vsyscall(struct vdso_data *vdata)
+void __arm64_update_vsyscall(struct vdso_time_data *vdata)
 {
 	vdata[CS_HRES_COARSE].mask	= VDSO_PRECISION_MASK;
 	vdata[CS_RAW].mask		= VDSO_PRECISION_MASK;