// SPDX-License-Identifier: GPL-2.0
/*
* vdso setup for s390
*
* Copyright IBM Corp. 2008
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/security.h>
#include <linux/memblock.h>
#include <linux/compat.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/sections.h>
#include <asm/vdso.h>
#include <asm/facility.h>
#ifdef CONFIG_COMPAT_VDSO
extern char vdso32_start, vdso32_end;
static void *vdso32_kbase = &vdso32_start;
static unsigned int vdso32_pages;
static struct page **vdso32_pagelist;
#endif
extern char vdso64_start, vdso64_end;
static void *vdso64_kbase = &vdso64_start;
static unsigned int vdso64_pages;
static struct page **vdso64_pagelist;
/*
* Should the kernel map a VDSO page into processes and pass its
* address down to glibc upon exec()?
*/
unsigned int __read_mostly vdso_enabled = 1;
static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page **vdso_pagelist;
unsigned long vdso_pages;
vdso_pagelist = vdso64_pagelist;
vdso_pages = vdso64_pages;
#ifdef CONFIG_COMPAT_VDSO
if (vma->vm_mm->context.compat_mm) {
vdso_pagelist = vdso32_pagelist;
vdso_pages = vdso32_pages;
}
#endif
if (vmf->pgoff >= vdso_pages)
return VM_FAULT_SIGBUS;
vmf->page = vdso_pagelist[vmf->pgoff];
get_page(vmf->page);
return 0;
}
static int vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *vma)
{
unsigned long vdso_pages;
vdso_pages = vdso64_pages;
#ifdef CONFIG_COMPAT_VDSO
if (vma->vm_mm->context.compat_mm)
vdso_pages = vdso32_pages;
#endif
if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)
return -EINVAL;
if (WARN_ON_ONCE(current->mm != vma->vm_mm))
return -EFAULT;
current->mm->context.vdso_base = vma->vm_start;
return 0;
}
static const struct vm_special_mapping vdso_mapping = {
.name = "[vdso]",
.fault = vdso_fault,
.mremap = vdso_mremap,
};
static int __init vdso_setup(char *s)
{
unsigned long val;
int rc;
rc = 0;
if (strncmp(s, "on", 3) == 0)
vdso_enabled = 1;
else if (strncmp(s, "off", 4) == 0)
vdso_enabled = 0;
else {
rc = kstrtoul(s, 0, &val);
vdso_enabled = rc ? 0 : !!val;
}
return !rc;
}
__setup("vdso=", vdso_setup);
/*
* The vdso data page
*/
static union {
struct vdso_data data;
u8 page[PAGE_SIZE];
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = &vdso_data_store.data;
/*
* Setup vdso data page.
*/
static void __init vdso_init_data(struct vdso_data *vd)
{
vd->ectg_available = test_facility(31);
}
/*
* Allocate/free per cpu vdso data.
*/
#define SEGMENT_ORDER 2
/*
* The initial vdso_data structure for the boot CPU. Eventually
* it is replaced with a properly allocated structure in vdso_init.
* This is necessary because a valid S390_lowcore.vdso_per_cpu_data
* pointer is required to be able to return from an interrupt or
* program check. See the exit paths in entry.S.
*/
struct vdso_data boot_vdso_data __initdata;
void __init vdso_alloc_boot_cpu(struct lowcore *lowcore)
{
lowcore->vdso_per_cpu_data = (unsigned long) &boot_vdso_data;
}
int vdso_alloc_per_cpu(struct lowcore *lowcore)
{
unsigned long segment_table, page_table, page_frame;
struct vdso_per_cpu_data *vd;
segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
page_table = get_zeroed_page(GFP_KERNEL);
page_frame = get_zeroed_page(GFP_KERNEL);
if (!segment_table || !page_table || !page_frame)
goto out;
arch_set_page_dat(virt_to_page(segment_table), SEGMENT_ORDER);
arch_set_page_dat(virt_to_page(page_table), 0);
/* Initialize per-cpu vdso data page */
vd = (struct vdso_per_cpu_data *) page_frame;
vd->cpu_nr = lowcore->cpu_nr;
vd->node_id = cpu_to_node(vd->cpu_nr);
/* Set up page table for the vdso address space */
memset64((u64 *)segment_table, _SEGMENT_ENTRY_EMPTY, _CRST_ENTRIES);
memset64((u64 *)page_table, _PAGE_INVALID, PTRS_PER_PTE);
*(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
*(unsigned long *) page_table = _PAGE_PROTECT + page_frame;
lowcore->vdso_asce = segment_table +
_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
lowcore->vdso_per_cpu_data = page_frame;
return 0;
out:
free_page(page_frame);
free_page(page_table);
free_pages(segment_table, SEGMENT_ORDER);
return -ENOMEM;
}
void vdso_free_per_cpu(struct lowcore *lowcore)
{
unsigned long segment_table, page_table, page_frame;
segment_table = lowcore->vdso_asce & PAGE_MASK;
page_table = *(unsigned long *) segment_table;
page_frame = *(unsigned long *) page_table;
free_page(page_frame);
free_page(page_table);
free_pages(segment_table, SEGMENT_ORDER);
}
/*
* This is called from binfmt_elf, we create the special vma for the
* vDSO and insert it into the mm struct tree
*/
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long vdso_pages;
unsigned long vdso_base;
int rc;
if (!vdso_enabled)
return 0;
vdso_pages = vdso64_pages;
#ifdef CONFIG_COMPAT_VDSO
mm->context.compat_mm = is_compat_task();
if (mm->context.compat_mm)
vdso_pages = vdso32_pages;
#endif
/*
* vDSO has a problem and was disabled, just don't "enable" it for
* the process
*/
if (vdso_pages == 0)
return 0;
/*
* pick a base address for the vDSO in process space. We try to put
* it at vdso_base which is the "natural" base for it, but we might
* fail and end up putting it elsewhere.
*/
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
rc = vdso_base;
goto out_up;
}
/*
* our vma flags don't have VM_WRITE so by default, the process
* isn't allowed to write those pages.
* gdb can break that with ptrace interface, and thus trigger COW
* on those pages but it's then your responsibility to never do that
* on the "data" page of the vDSO or you'll stop getting kernel
* updates and your nice userland gettimeofday will be totally dead.
* It's fine to use that for setting breakpoints in the vDSO code
* pages though.
*/
vma = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
&vdso_mapping);
if (IS_ERR(vma)) {
rc = PTR_ERR(vma);
goto out_up;
}
current->mm->context.vdso_base = vdso_base;
rc = 0;
out_up:
up_write(&mm->mmap_sem);
return rc;
}
static int __init vdso_init(void)
{
int i;
vdso_init_data(vdso_data);
#ifdef CONFIG_COMPAT_VDSO
/* Calculate the size of the 32 bit vDSO */
vdso32_pages = ((&vdso32_end - &vdso32_start
+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
/* Make sure pages are in the correct state */
vdso32_pagelist = kcalloc(vdso32_pages + 1, sizeof(struct page *),
GFP_KERNEL);
BUG_ON(vdso32_pagelist == NULL);
for (i = 0; i < vdso32_pages - 1; i++) {
struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
get_page(pg);
vdso32_pagelist[i] = pg;
}
vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
vdso32_pagelist[vdso32_pages] = NULL;
#endif
/* Calculate the size of the 64 bit vDSO */
vdso64_pages = ((&vdso64_end - &vdso64_start
+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
/* Make sure pages are in the correct state */
vdso64_pagelist = kcalloc(vdso64_pages + 1, sizeof(struct page *),
GFP_KERNEL);
BUG_ON(vdso64_pagelist == NULL);
for (i = 0; i < vdso64_pages - 1; i++) {
struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
get_page(pg);
vdso64_pagelist[i] = pg;
}
vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
vdso64_pagelist[vdso64_pages] = NULL;
if (vdso_alloc_per_cpu(&S390_lowcore))
BUG();
get_page(virt_to_page(vdso_data));
return 0;
}
early_initcall(vdso_init);
