![Will Deacon](/assets/img/avatar_default.png)
This patch is an arm64 version of ce73ec6db4
("powerpc/vdso: Remove
redundant locking in update_vsyscall_tz()").
Timezone data is not protected, so the sequence counter is not required
to ensure consistency. Furthermore, having multiple paths updating the
counter leads to a race between update_vsyscall and update_vsyscall_tz,
so remove the timezone sequence counting from both the kernel and the
vdso.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
258 lines
6.2 KiB
C
258 lines
6.2 KiB
C
/*
|
|
* 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->tz_minuteswest = sys_tz.tz_minuteswest;
|
|
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
|
|
}
|