Thread (28 messages) 28 messages, 5 authors, 2025-02-22
STALE464d LANDED: 2 (2M)

[PATCH v3 12/18] s390/vdso: Switch to generic storage implementation

From: Thomas Weißschuh <hidden>
Date: 2025-02-04 12:06:15
Also in: linux-arch, linux-arm-kernel, linux-mips, linux-riscv, linux-s390, lkml, loongarch
Subsystem: s390 architecture, the rest · Maintainers: Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds

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 <redacted>
Signed-off-by: Nam Cao <redacted>
Signed-off-by: Thomas Weißschuh <redacted>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/Kconfig                         |  1 +
 arch/s390/include/asm/vdso.h              |  4 +-
 arch/s390/include/asm/vdso/getrandom.h    | 12 ----
 arch/s390/include/asm/vdso/gettimeofday.h | 15 +----
 arch/s390/include/asm/vdso/vsyscall.h     | 20 -------
 arch/s390/kernel/time.c                   |  6 +-
 arch/s390/kernel/vdso.c                   | 97 ++-----------------------------
 arch/s390/kernel/vdso32/vdso32.lds.S      |  7 +--
 arch/s390/kernel/vdso64/vdso64.lds.S      |  8 +--
 9 files changed, 17 insertions(+), 153 deletions(-)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 9c9ec08d78c71b4d227beeafab1b82d6434cb5c7..7ed6f229250cf6c26efd4ce30e23123cdb030b2c 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -166,6 +166,7 @@ config S390
 	select GENERIC_PTDUMP
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
+	select GENERIC_VDSO_DATA_STORE
 	select GENERIC_VDSO_TIME_NS
 	select GENERIC_IOREMAP if PCI
 	select HAVE_ALIGNED_STRUCT_PAGE
diff --git a/arch/s390/include/asm/vdso.h b/arch/s390/include/asm/vdso.h
index 92c73e4d97a93a90cb640d44fca9856f93e0be14..420a073fdde5db92cfe84bb1f17a549f333f94e0 100644
--- a/arch/s390/include/asm/vdso.h
+++ b/arch/s390/include/asm/vdso.h
@@ -6,13 +6,11 @@
 
 #ifndef __ASSEMBLY__
 
-extern struct vdso_data *vdso_data;
-
 int vdso_getcpu_init(void);
 
 #endif /* __ASSEMBLY__ */
 
-#define __VVAR_PAGES	2
+#define __VDSO_PAGES	4
 
 #define VDSO_VERSION_STRING	LINUX_2.6.29
 
diff --git a/arch/s390/include/asm/vdso/getrandom.h b/arch/s390/include/asm/vdso/getrandom.h
index 36355af7160bee4f04f5177cfa21283699bee006..f8713ce39bb2f2081c3bb5a42eddccc3cddc40c8 100644
--- a/arch/s390/include/asm/vdso/getrandom.h
+++ b/arch/s390/include/asm/vdso/getrandom.h
@@ -23,18 +23,6 @@ static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsig
 	return syscall3(__NR_getrandom, (long)buffer, (long)len, (long)flags);
 }
 
-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 * PAGE_SIZE;
-	return &_vdso_rng_data;
-}
-
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_VDSO_GETRANDOM_H */
diff --git a/arch/s390/include/asm/vdso/gettimeofday.h b/arch/s390/include/asm/vdso/gettimeofday.h
index 7937765ccfa5b222931591cc5388827e5f75d1b5..fb4564308e9d77a40f8d5059503519e9f5961f14 100644
--- a/arch/s390/include/asm/vdso/gettimeofday.h
+++ b/arch/s390/include/asm/vdso/gettimeofday.h
@@ -14,12 +14,7 @@
 #include <linux/compiler.h>
 
 
-static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
-{
-	return _vdso_data;
-}
-
-static inline u64 __arch_get_hw_counter(s32 clock_mode, const struct vdso_data *vd)
+static inline u64 __arch_get_hw_counter(s32 clock_mode, const struct vdso_time_data *vd)
 {
 	u64 adj, now;
 
@@ -49,12 +44,4 @@ long clock_getres_fallback(clockid_t clkid, struct __kernel_timespec *ts)
 	return syscall2(__NR_clock_getres, (long)clkid, (long)ts);
 }
 
-#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
diff --git a/arch/s390/include/asm/vdso/vsyscall.h b/arch/s390/include/asm/vdso/vsyscall.h
index 3eb576ecd3bd998daf9372a52befa8b76d52f2bf..d346ebe513015e767405452cd69495ae497c91ee 100644
--- a/arch/s390/include/asm/vdso/vsyscall.h
+++ b/arch/s390/include/asm/vdso/vsyscall.h
@@ -2,32 +2,12 @@
 #ifndef __ASM_VDSO_VSYSCALL_H
 #define __ASM_VDSO_VSYSCALL_H
 
-#define __VDSO_RND_DATA_OFFSET	768
-
 #ifndef __ASSEMBLY__
 
 #include <linux/hrtimer.h>
 #include <vdso/datapage.h>
 #include <asm/vdso.h>
 
-enum vvar_pages {
-	VVAR_DATA_PAGE_OFFSET,
-	VVAR_TIMENS_PAGE_OFFSET,
-	VVAR_NR_PAGES
-};
-
-static __always_inline struct vdso_data *__s390_get_k_vdso_data(void)
-{
-	return vdso_data;
-}
-#define __arch_get_k_vdso_data __s390_get_k_vdso_data
-
-static __always_inline struct vdso_rng_data *__s390_get_k_vdso_rnd_data(void)
-{
-	return (void *)vdso_data + __VDSO_RND_DATA_OFFSET;
-}
-#define __arch_get_k_vdso_rng_data __s390_get_k_vdso_rnd_data
-
 /* The asm-generic header needs to be included after the definitions above */
 #include <asm-generic/vdso/vsyscall.h>
 
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index e9f47c3a61978a45c72aee23bc44dcb128113c8c..41ca3586b19f6cac3753b52f0b99be62a33e1cb1 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -84,7 +84,7 @@ void __init time_early_init(void)
 	/* Initialize TOD steering parameters */
 	tod_steering_end = tod_clock_base.tod;
 	for (cs = 0; cs < CS_BASES; cs++)
-		vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
+		vdso_k_time_data[cs].arch_data.tod_steering_end = tod_steering_end;
 
 	if (!test_facility(28))
 		return;
@@ -390,8 +390,8 @@ static void clock_sync_global(long delta)
 		      tod_steering_delta);
 	tod_steering_end = now + (abs(tod_steering_delta) << 15);
 	for (cs = 0; cs < CS_BASES; cs++) {
-		vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
-		vdso_data[cs].arch_data.tod_steering_delta = tod_steering_delta;
+		vdso_k_time_data[cs].arch_data.tod_steering_end = tod_steering_end;
+		vdso_k_time_data[cs].arch_data.tod_steering_delta = tod_steering_delta;
 	}
 
 	/* Update LPAR offset. */
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 598b512cde012b1857c748042ceeea65b54cb92f..70c8f9ad13cde96f0f307213bacb671b818f628b 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -16,8 +16,8 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/smp.h>
-#include <linux/time_namespace.h>
 #include <linux/random.h>
+#include <linux/vdso_datastore.h>
 #include <vdso/datapage.h>
 #include <asm/vdso/vsyscall.h>
 #include <asm/alternative.h>
@@ -26,85 +26,6 @@
 extern char vdso64_start[], vdso64_end[];
 extern char vdso32_start[], vdso32_end[];
 
-static struct vm_special_mapping vvar_mapping;
-
-static union vdso_data_store vdso_data_store __page_aligned_data;
-
-struct vdso_data *vdso_data = vdso_data_store.data;
-
-#ifdef CONFIG_TIME_NS
-struct vdso_data *arch_get_vdso_data(void *vvar_page)
-{
-	return (struct vdso_data *)(vvar_page);
-}
-
-/*
- * The VVAR page layout depends on whether a task belongs to the root or
- * non-root time namespace. Whenever a task changes its namespace, the VVAR
- * page tables are cleared and then they will be re-faulted with a
- * corresponding layout.
- * See also the comment near timens_setup_vdso_data() for details.
- */
-int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
-{
-	struct mm_struct *mm = task->mm;
-	VMA_ITERATOR(vmi, mm, 0);
-	struct vm_area_struct *vma;
-
-	mmap_read_lock(mm);
-	for_each_vma(vmi, vma) {
-		if (!vma_is_special_mapping(vma, &vvar_mapping))
-			continue;
-		zap_vma_pages(vma);
-		break;
-	}
-	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 addr, pfn;
-	vm_fault_t err;
-
-	switch (vmf->pgoff) {
-	case VVAR_DATA_PAGE_OFFSET:
-		pfn = virt_to_pfn(vdso_data);
-		if (timens_page) {
-			/*
-			 * Fault in VVAR page too, since it will be accessed
-			 * to get clock data anyway.
-			 */
-			addr = vmf->address + VVAR_TIMENS_PAGE_OFFSET * PAGE_SIZE;
-			err = vmf_insert_pfn(vma, addr, pfn);
-			if (unlikely(err & VM_FAULT_ERROR))
-				return err;
-			pfn = page_to_pfn(timens_page);
-		}
-		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 = virt_to_pfn(vdso_data);
-		break;
-#endif /* CONFIG_TIME_NS */
-	default:
-		return VM_FAULT_SIGBUS;
-	}
-	return vmf_insert_pfn(vma, vmf->address, pfn);
-}
-
 static int vdso_mremap(const struct vm_special_mapping *sm,
 		       struct vm_area_struct *vma)
 {
@@ -112,11 +33,6 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
-static struct vm_special_mapping vvar_mapping = {
-	.name = "[vvar]",
-	.fault = vvar_fault,
-};
-
 static struct vm_special_mapping vdso64_mapping = {
 	.name = "[vdso]",
 	.mremap = vdso_mremap,
@@ -142,7 +58,7 @@ static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
 	struct vm_area_struct *vma;
 	int rc;
 
-	BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
+	BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES);
 	if (mmap_write_lock_killable(mm))
 		return -EINTR;
 
@@ -157,14 +73,11 @@ static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
 	rc = vvar_start;
 	if (IS_ERR_VALUE(vvar_start))
 		goto out;
-	vma = _install_special_mapping(mm, vvar_start, VVAR_NR_PAGES*PAGE_SIZE,
-				       VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
-				       VM_PFNMAP,
-				       &vvar_mapping);
+	vma = vdso_install_vvar_mapping(mm, vvar_start);
 	rc = PTR_ERR(vma);
 	if (IS_ERR(vma))
 		goto out;
-	vdso_text_start = vvar_start + VVAR_NR_PAGES * PAGE_SIZE;
+	vdso_text_start = vvar_start + VDSO_NR_PAGES * PAGE_SIZE;
 	/* VM_MAYWRITE for COW so gdb can set breakpoints */
 	vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
 				       VM_READ|VM_EXEC|
@@ -220,7 +133,7 @@ unsigned long vdso_text_size(void)
 
 unsigned long vdso_size(void)
 {
-	return vdso_text_size() + VVAR_NR_PAGES * PAGE_SIZE;
+	return vdso_text_size() + VDSO_NR_PAGES * PAGE_SIZE;
 }
 
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
diff --git a/arch/s390/kernel/vdso32/vdso32.lds.S b/arch/s390/kernel/vdso32/vdso32.lds.S
index c916c4f73f766ebcc9328b189e46015e67393b0d..9630d58c20806b51f3a2f3b59a53409ad6d3508f 100644
--- a/arch/s390/kernel/vdso32/vdso32.lds.S
+++ b/arch/s390/kernel/vdso32/vdso32.lds.S
@@ -6,16 +6,15 @@
 
 #include <asm/page.h>
 #include <asm/vdso.h>
+#include <vdso/datapage.h>
 
 OUTPUT_FORMAT("elf32-s390", "elf32-s390", "elf32-s390")
 OUTPUT_ARCH(s390:31-bit)
 
 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
diff --git a/arch/s390/kernel/vdso64/vdso64.lds.S b/arch/s390/kernel/vdso64/vdso64.lds.S
index ec42b7d9cb53094b783c6b0492962af7e5027831..e4f6551ae898881baff6d37701a9d8d9188a52cc 100644
--- a/arch/s390/kernel/vdso64/vdso64.lds.S
+++ b/arch/s390/kernel/vdso64/vdso64.lds.S
@@ -7,17 +7,15 @@
 #include <asm/vdso/vsyscall.h>
 #include <asm/page.h>
 #include <asm/vdso.h>
+#include <vdso/datapage.h>
 
 OUTPUT_FORMAT("elf64-s390", "elf64-s390", "elf64-s390")
 OUTPUT_ARCH(s390:64-bit)
 
 SECTIONS
 {
-	PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE);
-	PROVIDE(_vdso_rng_data = _vdso_data + __VDSO_RND_DATA_OFFSET);
-#ifdef CONFIG_TIME_NS
-	PROVIDE(_timens_data = _vdso_data + PAGE_SIZE);
-#endif
+	VDSO_VVAR_SYMS
+
 	. = SIZEOF_HEADERS;
 
 	.hash		: { *(.hash) }			:text
-- 
2.48.1

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