/*
* Copyright 2007 Andi Kleen, SUSE Labs.
* Subject to the GPL, v.2
*
* This contains most of the x86 vDSO kernel-side code.
*/
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/elf.h>
#include <linux/cpu.h>
#include <asm/vgtod.h>
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/vvar.h>
#include <asm/page.h>
#include <asm/hpet.h>
#include <asm/desc.h>
#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso64_enabled = 1;
#endif
void __init init_vdso_image(const struct vdso_image *image)
{
int i;
int npages = (image->size) / PAGE_SIZE;
BUG_ON(image->size % PAGE_SIZE != 0);
for (i = 0; i < npages; i++)
image->text_mapping.pages[i] =
virt_to_page(image->data + i*PAGE_SIZE);
apply_alternatives((struct alt_instr *)(image->data + image->alt),
(struct alt_instr *)(image->data + image->alt +
image->alt_len));
}
struct linux_binprm;
/*
* Put the vdso above the (randomized) stack with another randomized
* offset. This way there is no hole in the middle of address space.
* To save memory make sure it is still in the same PTE as the stack
* top. This doesn't give that many random bits.
*
* Note that this algorithm is imperfect: the distribution of the vdso
* start address within a PMD is biased toward the end.
*
* Only used for the 64-bit and x32 vdsos.
*/
static unsigned long vdso_addr(unsigned long start, unsigned len)
{
#ifdef CONFIG_X86_32
return 0;
#else
unsigned long addr, end;
unsigned 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 >= TASK_SIZE_MAX)
end = TASK_SIZE_MAX;
end -= len;
if (end > start) {
offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
addr = start + (offset << PAGE_SHIFT);
} else {
addr = start;
}
/*
* Forcibly align the final address in case we have a hardware
* issue that requires alignment for performance reasons.
*/
addr = align_vdso_addr(addr);
return addr;
#endif
}
static int map_vdso(const struct vdso_image *image, bool calculate_addr)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long addr, text_start;
int ret = 0;
static struct page *no_pages[] = {NULL};
static struct vm_special_mapping vvar_mapping = {
.name = "[vvar]",
.pages = no_pages,
};
if (calculate_addr) {
addr = vdso_addr(current->mm->start_stack,
image->size - image->sym_vvar_start);
} else {
addr = 0;
}
down_write(&mm->mmap_sem);
addr = get_unmapped_area(NULL, addr,
image->size - image->sym_vvar_start, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
text_start = addr - image->sym_vvar_start;
current->mm->context.vdso = (void __user *)text_start;
/*
* MAYWRITE to allow gdb to COW and set breakpoints
*/
vma = _install_special_mapping(mm,
text_start,
image->size,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
&image->text_mapping);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto up_fail;
}
vma = _install_special_mapping(mm,
addr,
-image->sym_vvar_start,
VM_READ|VM_MAYREAD,
&vvar_mapping);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto up_fail;
}
if (image->sym_vvar_page)
ret = remap_pfn_range(vma,
text_start + image->sym_vvar_page,
__pa_symbol(&__vvar_page) >> PAGE_SHIFT,
PAGE_SIZE,
PAGE_READONLY);
if (ret)
goto up_fail;
#ifdef CONFIG_HPET_TIMER
if (hpet_address && image->sym_hpet_page) {
ret = io_remap_pfn_range(vma,
text_start + image->sym_hpet_page,
hpet_address >> PAGE_SHIFT,
PAGE_SIZE,
pgprot_noncached(PAGE_READONLY));
if (ret)
goto up_fail;
}
#endif
up_fail:
if (ret)
current->mm->context.vdso = NULL;
up_write(&mm->mmap_sem);
return ret;
}
#if defined(CONFIG_X86_32) || defined(CONFIG_COMPAT)
static int load_vdso32(void)
{
int ret;
if (vdso32_enabled != 1) /* Other values all mean "disabled" */
return 0;
ret = map_vdso(selected_vdso32, false);
if (ret)
return ret;
if (selected_vdso32->sym_VDSO32_SYSENTER_RETURN)
current_thread_info()->sysenter_return =
current->mm->context.vdso +
selected_vdso32->sym_VDSO32_SYSENTER_RETURN;
return 0;
}
#endif
#ifdef CONFIG_X86_64
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
if (!vdso64_enabled)
return 0;
return map_vdso(&vdso_image_64, true);
}
#ifdef CONFIG_COMPAT
int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
#ifdef CONFIG_X86_X32_ABI
if (test_thread_flag(TIF_X32)) {
if (!vdso64_enabled)
return 0;
return map_vdso(&vdso_image_x32, true);
}
#endif
return load_vdso32();
}
#endif
#else
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
return load_vdso32();
}
#endif
#ifdef CONFIG_X86_64
static __init int vdso_setup(char *s)
{
vdso64_enabled = simple_strtoul(s, NULL, 0);
return 0;
}
__setup("vdso=", vdso_setup);
#endif
#ifdef CONFIG_X86_64
static void vgetcpu_cpu_init(void *arg)
{
int cpu = smp_processor_id();
struct desc_struct d = { };
unsigned long node = 0;
#ifdef CONFIG_NUMA
node = cpu_to_node(cpu);
#endif
if (cpu_has(&cpu_data(cpu), X86_FEATURE_RDTSCP))
write_rdtscp_aux((node << 12) | cpu);
/*
* Store cpu number in limit so that it can be loaded
* quickly in user space in vgetcpu. (12 bits for the CPU
* and 8 bits for the node)
*/
d.limit0 = cpu | ((node & 0xf) << 12);
d.limit = node >> 4;
d.type = 5; /* RO data, expand down, accessed */
d.dpl = 3; /* Visible to user code */
d.s = 1; /* Not a system segment */
d.p = 1; /* Present */
d.d = 1; /* 32-bit */
write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
}
static int
vgetcpu_cpu_notifier(struct notifier_block *n, unsigned long action, void *arg)
{
long cpu = (long)arg;
if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
smp_call_function_single(cpu, vgetcpu_cpu_init, NULL, 1);
return NOTIFY_DONE;
}
static int __init init_vdso(void)
{
init_vdso_image(&vdso_image_64);
#ifdef CONFIG_X86_X32_ABI
init_vdso_image(&vdso_image_x32);
#endif
cpu_notifier_register_begin();
on_each_cpu(vgetcpu_cpu_init, NULL, 1);
/* notifier priority > KVM */
__hotcpu_notifier(vgetcpu_cpu_notifier, 30);
cpu_notifier_register_done();
return 0;
}
subsys_initcall(init_vdso);
#endif /* CONFIG_X86_64 */
