MIPS: vdso: Switch to generic storage implementation

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-v3-13-13a4669dfc8c@linutronix.de

arch/mips/Kconfig

@@ -51,6 +51,7 @@ config MIPS
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_TIME_VSYSCALL
+	select GENERIC_VDSO_DATA_STORE
 	select GUP_GET_PXX_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
 	select HAS_IOPORT if !NO_IOPORT_MAP || ISA
 	select HAVE_ARCH_COMPILER_H

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

@@ -167,7 +167,7 @@ static __always_inline u64 read_r4k_count(void)
 
 #ifdef CONFIG_CLKSRC_MIPS_GIC
 
-static __always_inline u64 read_gic_count(const struct vdso_data *data)
+static __always_inline u64 read_gic_count(const struct vdso_time_data *data)
 {
 	void __iomem *gic = get_gic(data);
 	u32 hi, hi2, lo;
@@ -184,7 +184,7 @@ static __always_inline u64 read_gic_count(const struct vdso_data *data)
 #endif
 
 static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
-						 const struct vdso_data *vd)
+						 const struct vdso_time_data *vd)
 {
 #ifdef CONFIG_CSRC_R4K
 	if (clock_mode == VDSO_CLOCKMODE_R4K)
@@ -209,10 +209,11 @@ static inline bool mips_vdso_hres_capable(void)
 }
 #define __arch_vdso_hres_capable mips_vdso_hres_capable
 
-static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
+static __always_inline const struct vdso_time_data *__arch_get_vdso_u_time_data(void)
 {
-	return get_vdso_data();
+	return get_vdso_time_data();
 }
+#define __arch_get_vdso_u_time_data __arch_get_vdso_u_time_data
 
 #endif /* !__ASSEMBLY__ */
 

arch/mips/include/asm/vdso/vdso.h

@@ -5,16 +5,18 @@
  */
 
 #include <asm/sgidefs.h>
+#include <vdso/page.h>
+
+#define __VDSO_PAGES 4
 
 #ifndef __ASSEMBLY__
 
 #include <asm/asm.h>
-#include <asm/page.h>
 #include <asm/vdso.h>
 
-static inline unsigned long get_vdso_base(void)
+static inline const struct vdso_time_data *get_vdso_time_data(void)
 {
-	unsigned long addr;
+	const struct vdso_time_data *addr;
 
 	/*
 	 * We can't use cpu_has_mips_r6 since it needs the cpu_data[]
@@ -27,7 +29,7 @@ static inline unsigned long get_vdso_base(void)
 	 * We can't use addiupc because there is no label-label
 	 * support for the addiupc reloc
 	 */
-	__asm__("lapc	%0, _start			\n"
+	__asm__("lapc	%0, vdso_u_time_data		\n"
 		: "=r" (addr) : :);
 #else
 	/*
@@ -46,7 +48,7 @@ static inline unsigned long get_vdso_base(void)
 	"	.set noreorder				\n"
 	"	bal	1f				\n"
 	"	 nop					\n"
-	"	.word	_start - .			\n"
+	"	.word	vdso_u_time_data - .		\n"
 	"1:	lw	%0, 0($31)			\n"
 	"	" STR(PTR_ADDU) " %0, $31, %0		\n"
 	"	.set pop				\n"
@@ -58,14 +60,9 @@ static inline unsigned long get_vdso_base(void)
 	return addr;
 }
 
-static inline const struct vdso_data *get_vdso_data(void)
-{
-	return (const struct vdso_data *)(get_vdso_base() - PAGE_SIZE);
-}
-
 #ifdef CONFIG_CLKSRC_MIPS_GIC
 
-static inline void __iomem *get_gic(const struct vdso_data *data)
+static inline void __iomem *get_gic(const struct vdso_time_data *data)
 {
 	return (void __iomem *)((unsigned long)data & PAGE_MASK) - PAGE_SIZE;
 }

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

@@ -2,22 +2,12 @@
 #ifndef __ASM_VDSO_VSYSCALL_H
 #define __ASM_VDSO_VSYSCALL_H
 
+#include <asm/page.h>
+
 #ifndef __ASSEMBLY__
 
 #include <vdso/datapage.h>
 
-extern struct vdso_data *vdso_data;
-
-/*
- * Update the vDSO data page to keep in sync with kernel timekeeping.
- */
-static __always_inline
-struct vdso_data *__mips_get_k_vdso_data(void)
-{
-	return vdso_data;
-}
-#define __arch_get_k_vdso_data __mips_get_k_vdso_data
-
 /* The asm-generic header needs to be included after the definitions above */
 #include <asm-generic/vdso/vsyscall.h>
 

arch/mips/kernel/vdso.c

@@ -15,6 +15,7 @@
 #include <linux/random.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
+#include <linux/vdso_datastore.h>
 
 #include <asm/abi.h>
 #include <asm/mips-cps.h>
@@ -23,20 +24,7 @@
 #include <vdso/helpers.h>
 #include <vdso/vsyscall.h>
 
-/* Kernel-provided data used by the VDSO. */
+static_assert(VDSO_NR_PAGES == __VDSO_PAGES);
-static union vdso_data_store mips_vdso_data __page_aligned_data;
-struct vdso_data *vdso_data = mips_vdso_data.data;
-
-/*
- * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as
- * what we map and where within the area they are mapped is determined at
- * runtime.
- */
-static struct page *no_pages[] = { NULL };
-static struct vm_special_mapping vdso_vvar_mapping = {
-	.name = "[vvar]",
-	.pages = no_pages,
-};
 
 static void __init init_vdso_image(struct mips_vdso_image *image)
 {
@@ -90,7 +78,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
 	struct mips_vdso_image *image = current->thread.abi->vdso;
 	struct mm_struct *mm = current->mm;
-	unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base;
+	unsigned long gic_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base;
 	struct vm_area_struct *vma;
 	int ret;
 
@@ -119,8 +107,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	 * the counter registers at the start.
 	 */
 	gic_size = mips_gic_present() ? PAGE_SIZE : 0;
-	vvar_size = gic_size + PAGE_SIZE;
+	size = gic_size + VDSO_NR_PAGES * PAGE_SIZE + image->size;
-	size = vvar_size + image->size;
 
 	/*
 	 * Find a region that's large enough for us to perform the
@@ -143,15 +130,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	 */
 	if (cpu_has_dc_aliases) {
 		base = __ALIGN_MASK(base, shm_align_mask);
-		base += ((unsigned long)vdso_data - gic_size) & shm_align_mask;
+		base += ((unsigned long)vdso_k_time_data - gic_size) & shm_align_mask;
 	}
 
 	data_addr = base + gic_size;
-	vdso_addr = data_addr + PAGE_SIZE;
+	vdso_addr = data_addr + VDSO_NR_PAGES * PAGE_SIZE;
 
-	vma = _install_special_mapping(mm, base, vvar_size,
+	vma = vdso_install_vvar_mapping(mm, data_addr);
-				       VM_READ | VM_MAYREAD,
-				       &vdso_vvar_mapping);
 	if (IS_ERR(vma)) {
 		ret = PTR_ERR(vma);
 		goto out;
@@ -161,6 +146,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	if (gic_size) {
 		gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS;
 		gic_pfn = PFN_DOWN(__pa(gic_base));
+		static const struct vm_special_mapping gic_mapping = {
+			.name	= "[gic]",
+			.pages	= (struct page **) { NULL },
+		};
+
+		vma = _install_special_mapping(mm, base, gic_size, VM_READ | VM_MAYREAD,
+					       &gic_mapping);
+		if (IS_ERR(vma)) {
+			ret = PTR_ERR(vma);
+			goto out;
+		}
 
 		ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
 					 pgprot_noncached(vma->vm_page_prot));
@@ -168,13 +164,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 			goto out;
 	}
 
-	/* Map data page. */
-	ret = remap_pfn_range(vma, data_addr,
-			      virt_to_phys(vdso_data) >> PAGE_SHIFT,
-			      PAGE_SIZE, vma->vm_page_prot);
-	if (ret)
-		goto out;
-
 	/* Map VDSO image. */
 	vma = _install_special_mapping(mm, vdso_addr, image->size,
 				       VM_READ | VM_EXEC |

arch/mips/vdso/vdso.lds.S

@@ -5,6 +5,8 @@
  */
 
 #include <asm/sgidefs.h>
+#include <asm/vdso/vdso.h>
+#include <vdso/datapage.h>
 
 #if _MIPS_SIM == _MIPS_SIM_ABI64
 OUTPUT_FORMAT("elf64-tradlittlemips", "elf64-tradbigmips", "elf64-tradlittlemips")
@@ -18,7 +20,8 @@ OUTPUT_ARCH(mips)
 
 SECTIONS
 {
-	PROVIDE(_start = .);
+	VDSO_VVAR_SYMS
+
 	. = SIZEOF_HEADERS;
 
 	/*