/*
* VDSO implementation for AArch64 and vector page setup for AArch32.
*
* Copyright (C) 2012 ARM Limited
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Will Deacon <will.deacon@arm.com>
*/
#include <linux/kernel.h>
#include <linux/clocksource.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/timekeeper_internal.h>
#include <linux/vmalloc.h>
#include <asm/cacheflush.h>
#include <asm/signal32.h>
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>
extern char vdso_start, vdso_end;
static unsigned long vdso_pages;
static struct page **vdso_pagelist;
/*
* 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;
#ifdef CONFIG_COMPAT
/*
* Create and map the vectors page for AArch32 tasks.
*/
static struct page *vectors_page[1];
static int alloc_vectors_page(void)
{
extern char __kuser_helper_start[], __kuser_helper_end[];
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
unsigned long vpage;
vpage = get_zeroed_page(GFP_ATOMIC);
if (!vpage)
return -ENOMEM;
/* kuser helpers */
memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start,
kuser_sz);
/* sigreturn code */
memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,
aarch32_sigret_code, sizeof(aarch32_sigret_code));
flush_icache_range(vpage, vpage + PAGE_SIZE);
vectors_page[0] = virt_to_page(vpage);
return 0;
}
arch_initcall(alloc_vectors_page);
int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long addr = AARCH32_VECTORS_BASE;
int ret;
down_write(&mm->mmap_sem);
current->mm->context.vdso = (void *)addr;
/* Map vectors page at the high address. */
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
vectors_page);
up_write(&mm->mmap_sem);
return ret;
}
#endif /* CONFIG_COMPAT */
static int __init vdso_init(void)
{
struct page *pg;
char *vbase;
int i, ret = 0;
vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n",
vdso_pages + 1, vdso_pages, 1L, &vdso_start);
/* Allocate the vDSO pagelist, plus a page for the data. */
vdso_pagelist = kzalloc(sizeof(struct page *) * (vdso_pages + 1),
GFP_KERNEL);
if (vdso_pagelist == NULL) {
pr_err("Failed to allocate vDSO pagelist!\n");
return -ENOMEM;
}
/* Grab the vDSO code pages. */
for (i = 0; i < vdso_pages; i++) {
pg = virt_to_page(&vdso_start + i*PAGE_SIZE);
ClearPageReserved(pg);
get_page(pg);
vdso_pagelist[i] = pg;
}
/* Sanity check the shared object header. */
vbase = vmap(vdso_pagelist, 1, 0, PAGE_KERNEL);
if (vbase == NULL) {
pr_err("Failed to map vDSO pagelist!\n");
return -ENOMEM;
} else if (memcmp(vbase, "\177ELF", 4)) {
pr_err("vDSO is not a valid ELF object!\n");
ret = -EINVAL;
goto unmap;
}
/* Grab the vDSO data page. */
pg = virt_to_page(vdso_data);
get_page(pg);
vdso_pagelist[i] = pg;
unmap:
vunmap(vbase);
return ret;
}
arch_initcall(vdso_init);
int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long vdso_base, vdso_mapping_len;
int ret;
/* Be sure to map the data page */
vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT;
down_write(&mm->mmap_sem);
vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
ret = vdso_base;
goto up_fail;
}
mm->context.vdso = (void *)vdso_base;
ret = install_special_mapping(mm, vdso_base, vdso_mapping_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_pagelist);
if (ret) {
mm->context.vdso = NULL;
goto up_fail;
}
up_fail:
up_write(&mm->mmap_sem);
return ret;
}
const char *arch_vma_name(struct vm_area_struct *vma)
{
/*
* We can re-use the vdso pointer in mm_context_t for identifying
* the vectors page for compat applications. The vDSO will always
* sit above TASK_UNMAPPED_BASE and so we don't need to worry about
* it conflicting with the vectors base.
*/
if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) {
#ifdef CONFIG_COMPAT
if (vma->vm_start == AARCH32_VECTORS_BASE)
return "[vectors]";
#endif
return "[vdso]";
}
return NULL;
}
/*
* We define AT_SYSINFO_EHDR, so we need these function stubs to keep
* Linux happy.
*/
int in_gate_area_no_mm(unsigned long addr)
{
return 0;
}
int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
return 0;
}
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
return NULL;
}
/*
* Update the vDSO data page to keep in sync with kernel timekeeping.
*/
void update_vsyscall(struct timekeeper *tk)
{
struct timespec xtime_coarse;
u32 use_syscall = strcmp(tk->clock->name, "arch_sys_counter");
++vdso_data->tb_seq_count;
smp_wmb();
xtime_coarse = __current_kernel_time();
vdso_data->use_syscall = use_syscall;
vdso_data->xtime_coarse_sec = xtime_coarse.tv_sec;
vdso_data->xtime_coarse_nsec = xtime_coarse.tv_nsec;
if (!use_syscall) {
vdso_data->cs_cycle_last = tk->clock->cycle_last;
vdso_data->xtime_clock_sec = tk->xtime_sec;
vdso_data->xtime_clock_nsec = tk->xtime_nsec;
vdso_data->cs_mult = tk->mult;
vdso_data->cs_shift = tk->shift;
vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec;
vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec;
}
smp_wmb();
++vdso_data->tb_seq_count;
}
void update_vsyscall_tz(void)
{
++vdso_data->tb_seq_count;
smp_wmb();
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
smp_wmb();
++vdso_data->tb_seq_count;
}
