From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/s390/kernel/vdso.c | 280 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 280 insertions(+) create mode 100644 arch/s390/kernel/vdso.c (limited to 'arch/s390/kernel/vdso.c') diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c new file mode 100644 index 000000000..3105ca5bd --- /dev/null +++ b/arch/s390/kernel/vdso.c @@ -0,0 +1,280 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * vdso setup for s390 + * + * Copyright IBM Corp. 2008 + * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +extern char vdso64_start[], vdso64_end[]; +extern char vdso32_start[], vdso32_end[]; + +static struct vm_special_mapping vvar_mapping; + +static union { + struct vdso_data data[CS_BASES]; + u8 page[PAGE_SIZE]; +} vdso_data_store __page_aligned_data; + +struct vdso_data *vdso_data = vdso_data_store.data; + +enum vvar_pages { + VVAR_DATA_PAGE_OFFSET, + VVAR_TIMENS_PAGE_OFFSET, + VVAR_NR_PAGES, +}; + +#ifdef CONFIG_TIME_NS +struct vdso_data *arch_get_vdso_data(void *vvar_page) +{ + return (struct vdso_data *)(vvar_page); +} + +static struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + if (likely(vma->vm_mm == current->mm)) + return current->nsproxy->time_ns->vvar_page; + /* + * VM_PFNMAP | VM_IO protect .fault() handler from being called + * through interfaces like /proc/$pid/mem or + * process_vm_{readv,writev}() as long as there's no .access() + * in special_mapping_vmops(). + * For more details check_vma_flags() and __access_remote_vm() + */ + WARN(1, "vvar_page accessed remotely"); + return NULL; +} + +/* + * 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) { + unsigned long size = vma->vm_end - vma->vm_start; + + if (!vma_is_special_mapping(vma, &vvar_mapping)) + continue; + zap_page_range(vma, vma->vm_start, size); + break; + } + mmap_read_unlock(mm); + return 0; +} +#else +static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + return NULL; +} +#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) +{ + current->mm->context.vdso_base = vma->vm_start; + 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, +}; + +static struct vm_special_mapping vdso32_mapping = { + .name = "[vdso]", + .mremap = vdso_mremap, +}; + +int vdso_getcpu_init(void) +{ + set_tod_programmable_field(smp_processor_id()); + return 0; +} +early_initcall(vdso_getcpu_init); /* Must be called before SMP init */ + +static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len) +{ + unsigned long vvar_start, vdso_text_start, vdso_text_len; + struct vm_special_mapping *vdso_mapping; + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + int rc; + + BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); + if (mmap_write_lock_killable(mm)) + return -EINTR; + + if (is_compat_task()) { + vdso_text_len = vdso32_end - vdso32_start; + vdso_mapping = &vdso32_mapping; + } else { + vdso_text_len = vdso64_end - vdso64_start; + vdso_mapping = &vdso64_mapping; + } + vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0); + 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); + rc = PTR_ERR(vma); + if (IS_ERR(vma)) + goto out; + vdso_text_start = vvar_start + VVAR_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| + VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, + vdso_mapping); + if (IS_ERR(vma)) { + do_munmap(mm, vvar_start, PAGE_SIZE, NULL); + rc = PTR_ERR(vma); + } else { + current->mm->context.vdso_base = vdso_text_start; + rc = 0; + } +out: + mmap_write_unlock(mm); + return rc; +} + +static unsigned long vdso_addr(unsigned long start, unsigned long len) +{ + unsigned long addr, end, offset; + + /* + * Round up the start address. It can start out unaligned as a result + * of stack start randomization. + */ + start = PAGE_ALIGN(start); + + /* Round the lowest possible end address up to a PMD boundary. */ + end = (start + len + PMD_SIZE - 1) & PMD_MASK; + if (end >= VDSO_BASE) + end = VDSO_BASE; + end -= len; + + if (end > start) { + offset = prandom_u32_max(((end - start) >> PAGE_SHIFT) + 1); + addr = start + (offset << PAGE_SHIFT); + } else { + addr = start; + } + return addr; +} + +unsigned long vdso_size(void) +{ + unsigned long size = VVAR_NR_PAGES * PAGE_SIZE; + + if (is_compat_task()) + size += vdso32_end - vdso32_start; + else + size += vdso64_end - vdso64_start; + return PAGE_ALIGN(size); +} + +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +{ + unsigned long addr = VDSO_BASE; + unsigned long size = vdso_size(); + + if (current->flags & PF_RANDOMIZE) + addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size); + return map_vdso(addr, size); +} + +static struct page ** __init vdso_setup_pages(void *start, void *end) +{ + int pages = (end - start) >> PAGE_SHIFT; + struct page **pagelist; + int i; + + pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL); + if (!pagelist) + panic("%s: Cannot allocate page list for VDSO", __func__); + for (i = 0; i < pages; i++) + pagelist[i] = virt_to_page(start + i * PAGE_SIZE); + return pagelist; +} + +static int __init vdso_init(void) +{ + vdso64_mapping.pages = vdso_setup_pages(vdso64_start, vdso64_end); + if (IS_ENABLED(CONFIG_COMPAT)) + vdso32_mapping.pages = vdso_setup_pages(vdso32_start, vdso32_end); + return 0; +} +arch_initcall(vdso_init); -- cgit v1.2.3