Merge tag 'timers-vdso-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull vdso data page handling updates from Thomas Gleixner:
 "First steps of consolidating the VDSO data page handling.

  The VDSO data page handling is architecture specific for historical
  reasons, but there is no real technical reason to do so.

  Aside of that VDSO data has become a dump ground for various
  mechanisms and fail to provide a clear separation of the
  functionalities.

  Clean this up by:

   - consolidating the VDSO page data by getting rid of architecture
     specific warts especially in x86 and PowerPC.

   - removing the last includes of header files which are pulling in
     other headers outside of the VDSO namespace.

   - seperating timekeeping and other VDSO data accordingly.

  Further consolidation of the VDSO page handling is done in subsequent
  changes scheduled for the next merge window.

  This also lays the ground for expanding the VDSO time getters for
  independent PTP clocks in a generic way without making every
  architecture add support seperately"

* tag 'timers-vdso-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (42 commits)
  x86/vdso: Add missing brackets in switch case
  vdso: Rename struct arch_vdso_data to arch_vdso_time_data
  powerpc: Split systemcfg struct definitions out from vdso
  powerpc: Split systemcfg data out of vdso data page
  powerpc: Add kconfig option for the systemcfg page
  powerpc/pseries/lparcfg: Use num_possible_cpus() for potential processors
  powerpc/pseries/lparcfg: Fix printing of system_active_processors
  powerpc/procfs: Propagate error of remap_pfn_range()
  powerpc/vdso: Remove offset comment from 32bit vdso_arch_data
  x86/vdso: Split virtual clock pages into dedicated mapping
  x86/vdso: Delete vvar.h
  x86/vdso: Access vdso data without vvar.h
  x86/vdso: Move the rng offset to vsyscall.h
  x86/vdso: Access rng vdso data without vvar.h
  x86/vdso: Access timens vdso data without vvar.h
  x86/vdso: Allocate vvar page from C code
  x86/vdso: Access rng data from kernel without vvar
  x86/vdso: Place vdso_data at beginning of vvar page
  x86/vdso: Use __arch_get_vdso_data() to access vdso data
  x86/mm/mmap: Remove arch_vma_name()
  ...

2 files changed, 70 insertions, 42 deletions

diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index bafa73f09e92..872947c1004c 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <asm/vdso.h>
+#include <asm/vdso/vsyscall.h>
 
 /*
  * Linker script for vDSO.  This is an ELF shared object prelinked to
@@ -16,23 +17,16 @@ SECTIONS
 	 * segment.
 	 */
 
-	vvar_start = . - 4 * PAGE_SIZE;
+	vvar_start = . - __VVAR_PAGES * PAGE_SIZE;
 	vvar_page  = vvar_start;
 
-	/* Place all vvars at the offsets in asm/vvar.h. */
-#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
-#include <asm/vvar.h>
-#undef EMIT_VVAR
+	vdso_rng_data = vvar_page + __VDSO_RND_DATA_OFFSET;
 
-	pvclock_page = vvar_start + PAGE_SIZE;
-	hvclock_page = vvar_start + 2 * PAGE_SIZE;
-	timens_page  = vvar_start + 3 * PAGE_SIZE;
+	timens_page  = vvar_start + PAGE_SIZE;
 
-#undef _ASM_X86_VVAR_H
-	/* Place all vvars in timens too at the offsets in asm/vvar.h. */
-#define EMIT_VVAR(name, offset) timens_ ## name = timens_page + offset;
-#include <asm/vvar.h>
-#undef EMIT_VVAR
+	vclock_pages = vvar_start + VDSO_NR_VCLOCK_PAGES * PAGE_SIZE;
+	pvclock_page = vclock_pages + VDSO_PAGE_PVCLOCK_OFFSET * PAGE_SIZE;
+	hvclock_page = vclock_pages + VDSO_PAGE_HVCLOCK_OFFSET * PAGE_SIZE;
 
 	. = SIZEOF_HEADERS;
 
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index b8fed8b8b9cc..bfc7cabf4017 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -20,26 +20,20 @@
 #include <asm/vgtod.h>
 #include <asm/proto.h>
 #include <asm/vdso.h>
-#include <asm/vvar.h>
 #include <asm/tlb.h>
 #include <asm/page.h>
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
+#include <asm/vdso/vsyscall.h>
 #include <clocksource/hyperv_timer.h>
 
-#undef _ASM_X86_VVAR_H
-#define EMIT_VVAR(name, offset)	\
-	const size_t name ## _offset = offset;
-#include <asm/vvar.h>
-
 struct vdso_data *arch_get_vdso_data(void *vvar_page)
 {
-	return (struct vdso_data *)(vvar_page + _vdso_data_offset);
+	return (struct vdso_data *)vvar_page;
 }
-#undef EMIT_VVAR
 
-DEFINE_VVAR(struct vdso_data, _vdso_data);
-DEFINE_VVAR_SINGLE(struct vdso_rng_data, _vdso_rng_data);
+static union vdso_data_store vdso_data_store __page_aligned_data;
+struct vdso_data *vdso_data = vdso_data_store.data;
 
 unsigned int vclocks_used __read_mostly;
 
@@ -154,7 +148,7 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 	if (sym_offset == image->sym_vvar_page) {
 		struct page *timens_page = find_timens_vvar_page(vma);
 
-		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+		pfn = __pa_symbol(vdso_data) >> PAGE_SHIFT;
 
 		/*
 		 * If a task belongs to a time namespace then a namespace
@@ -182,32 +176,52 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		}
 
 		return vmf_insert_pfn(vma, vmf->address, pfn);
-	} else if (sym_offset == image->sym_pvclock_page) {
-		struct pvclock_vsyscall_time_info *pvti =
-			pvclock_get_pvti_cpu0_va();
-		if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK)) {
-			return vmf_insert_pfn_prot(vma, vmf->address,
-					__pa(pvti) >> PAGE_SHIFT,
-					pgprot_decrypted(vma->vm_page_prot));
-		}
-	} else if (sym_offset == image->sym_hvclock_page) {
-		pfn = hv_get_tsc_pfn();
 
-		if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
-			return vmf_insert_pfn(vma, vmf->address, pfn);
 	} else if (sym_offset == image->sym_timens_page) {
 		struct page *timens_page = find_timens_vvar_page(vma);
 
 		if (!timens_page)
 			return VM_FAULT_SIGBUS;
 
-		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+		pfn = __pa_symbol(vdso_data) >> PAGE_SHIFT;
 		return vmf_insert_pfn(vma, vmf->address, pfn);
 	}
 
 	return VM_FAULT_SIGBUS;
 }
 
+static vm_fault_t vvar_vclock_fault(const struct vm_special_mapping *sm,
+				    struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	switch (vmf->pgoff) {
+#ifdef CONFIG_PARAVIRT_CLOCK
+	case VDSO_PAGE_PVCLOCK_OFFSET:
+	{
+		struct pvclock_vsyscall_time_info *pvti =
+			pvclock_get_pvti_cpu0_va();
+
+		if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK))
+			return vmf_insert_pfn_prot(vma, vmf->address,
+					__pa(pvti) >> PAGE_SHIFT,
+					pgprot_decrypted(vma->vm_page_prot));
+		break;
+	}
+#endif /* CONFIG_PARAVIRT_CLOCK */
+#ifdef CONFIG_HYPERV_TIMER
+	case VDSO_PAGE_HVCLOCK_OFFSET:
+	{
+		unsigned long pfn = hv_get_tsc_pfn();
+
+		if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
+			return vmf_insert_pfn(vma, vmf->address, pfn);
+		break;
+	}
+#endif /* CONFIG_HYPERV_TIMER */
+	}
+
+	return VM_FAULT_SIGBUS;
+}
+
 static const struct vm_special_mapping vdso_mapping = {
 	.name = "[vdso]",
 	.fault = vdso_fault,
@@ -217,6 +231,10 @@ static const struct vm_special_mapping vvar_mapping = {
 	.name = "[vvar]",
 	.fault = vvar_fault,
 };
+static const struct vm_special_mapping vvar_vclock_mapping = {
+	.name = "[vvar_vclock]",
+	.fault = vvar_vclock_fault,
+};
 
 /*
  * Add vdso and vvar mappings to current process.
@@ -259,7 +277,7 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
 
 	vma = _install_special_mapping(mm,
 				       addr,
-				       -image->sym_vvar_start,
+				       (__VVAR_PAGES - VDSO_NR_VCLOCK_PAGES) * PAGE_SIZE,
 				       VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
 				       VM_PFNMAP,
 				       &vvar_mapping);
@@ -267,11 +285,26 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
 	if (IS_ERR(vma)) {
 		ret = PTR_ERR(vma);
 		do_munmap(mm, text_start, image->size, NULL);
-	} else {
-		current->mm->context.vdso = (void __user *)text_start;
-		current->mm->context.vdso_image = image;
+		goto up_fail;
 	}
 
+	vma = _install_special_mapping(mm,
+				       addr + (__VVAR_PAGES - VDSO_NR_VCLOCK_PAGES) * PAGE_SIZE,
+				       VDSO_NR_VCLOCK_PAGES * PAGE_SIZE,
+				       VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
+				       VM_PFNMAP,
+				       &vvar_vclock_mapping);
+
+	if (IS_ERR(vma)) {
+		ret = PTR_ERR(vma);
+		do_munmap(mm, text_start, image->size, NULL);
+		do_munmap(mm, addr, image->size, NULL);
+		goto up_fail;
+	}
+
+	current->mm->context.vdso = (void __user *)text_start;
+	current->mm->context.vdso_image = image;
+
 up_fail:
 	mmap_write_unlock(mm);
 	return ret;
@@ -293,7 +326,8 @@ int map_vdso_once(const struct vdso_image *image, unsigned long addr)
 	 */
 	for_each_vma(vmi, vma) {
 		if (vma_is_special_mapping(vma, &vdso_mapping) ||
-				vma_is_special_mapping(vma, &vvar_mapping)) {
+				vma_is_special_mapping(vma, &vvar_mapping) ||
+				vma_is_special_mapping(vma, &vvar_vclock_mapping)) {
 			mmap_write_unlock(mm);
 			return -EEXIST;
 		}