// SPDX-License-Identifier: GPL-2.0
/*
* vdso setup for s390
*
* Copyright IBM Corp. 2008
* Author(s): Martin Schwidefsky ([email protected])
*/
#include <linux/binfmts.h>
#include <linux/compat.h>
#include <linux/elf.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/time_namespace.h>
#include <linux/random.h>
#include <vdso/datapage.h>
#include <asm/vdso.h>
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;
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);
}
/*
* 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)
{
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 = get_random_u32_below(((end - start) >> PAGE_SHIFT) + 1);
addr = start + (offset << PAGE_SHIFT);
} else {
addr = start;
}
return addr;
}
unsigned long vdso_text_size(void)
{
unsigned long size;
if (is_compat_task())
size = vdso32_end - vdso32_start;
else
size = vdso64_end - vdso64_start;
return PAGE_ALIGN(size);
}
unsigned long vdso_size(void)
{
return vdso_text_size() + VVAR_NR_PAGES * PAGE_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);
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