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OpenCloudOS-Kernel/arch/arm64/kernel/vdso.c

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/*
* VDSO implementations.
*
* 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/cache.h>
#include <linux/clocksource.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/kernel.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 __ro_after_init;
/*
* 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.
*/
#define C_VECTORS 0
#define C_SIGPAGE 1
#define C_PAGES (C_SIGPAGE + 1)
static struct page *aarch32_vdso_pages[C_PAGES] __ro_after_init;
static const struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
{
.name = "[vectors]", /* ABI */
.pages = &aarch32_vdso_pages[C_VECTORS],
},
{
.name = "[sigpage]", /* ABI */
.pages = &aarch32_vdso_pages[C_SIGPAGE],
},
};
static int aarch32_alloc_kuser_vdso_page(void)
{
extern char __kuser_helper_start[], __kuser_helper_end[];
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
unsigned long vdso_page;
if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
return 0;
vdso_page = get_zeroed_page(GFP_ATOMIC);
if (!vdso_page)
return -ENOMEM;
memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start,
kuser_sz);
aarch32_vdso_pages[C_VECTORS] = virt_to_page(vdso_page);
flush_dcache_page(aarch32_vdso_pages[C_VECTORS]);
return 0;
}
static int __init aarch32_alloc_vdso_pages(void)
{
extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
unsigned long sigpage;
int ret;
sigpage = get_zeroed_page(GFP_ATOMIC);
if (!sigpage)
return -ENOMEM;
memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz);
aarch32_vdso_pages[C_SIGPAGE] = virt_to_page(sigpage);
flush_dcache_page(aarch32_vdso_pages[C_SIGPAGE]);
ret = aarch32_alloc_kuser_vdso_page();
if (ret)
free_page(sigpage);
return ret;
}
arch_initcall(aarch32_alloc_vdso_pages);
static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
{
void *ret;
if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
return 0;
/*
* Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's
* not safe to CoW the page containing the CPU exception vectors.
*/
ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE,
VM_READ | VM_EXEC |
VM_MAYREAD | VM_MAYEXEC,
&aarch32_vdso_spec[C_VECTORS]);
return PTR_ERR_OR_ZERO(ret);
}
static int aarch32_sigreturn_setup(struct mm_struct *mm)
{
unsigned long addr;
void *ret;
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = ERR_PTR(addr);
goto out;
}
/*
* VM_MAYWRITE is required to allow gdb to Copy-on-Write and
* set breakpoints.
*/
ret = _install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_EXEC | VM_MAYREAD |
VM_MAYWRITE | VM_MAYEXEC,
&aarch32_vdso_spec[C_SIGPAGE]);
if (IS_ERR(ret))
goto out;
mm->context.vdso = (void *)addr;
out:
return PTR_ERR_OR_ZERO(ret);
}
int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
int ret;
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
ret = aarch32_kuser_helpers_setup(mm);
if (ret)
goto out;
ret = aarch32_sigreturn_setup(mm);
out:
up_write(&mm->mmap_sem);
return ret;
}
#endif /* CONFIG_COMPAT */
static int vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *new_vma)
{
unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
unsigned long vdso_size = vdso_end - vdso_start;
if (vdso_size != new_size)
return -EINVAL;
current->mm->context.vdso = (void *)new_vma->vm_start;
return 0;
}
static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
{
.name = "[vvar]",
},
{
.name = "[vdso]",
.mremap = vdso_mremap,
},
};
static int __init vdso_init(void)
{
int i;
struct page **vdso_pagelist;
unsigned long pfn;
if (memcmp(vdso_start, "\177ELF", 4)) {
pr_err("vDSO is not a valid ELF object!\n");
return -EINVAL;
}
vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
/* Allocate the vDSO pagelist, plus a page for the data. */
vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
GFP_KERNEL);
if (vdso_pagelist == NULL)
return -ENOMEM;
/* Grab the vDSO data page. */
vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
/* Grab the vDSO code pages. */
pfn = sym_to_pfn(vdso_start);
for (i = 0; i < vdso_pages; i++)
vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
vdso_spec[0].pages = &vdso_pagelist[0];
vdso_spec[1].pages = &vdso_pagelist[1];
return 0;
}
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_text_len, vdso_mapping_len;
void *ret;
vdso_text_len = vdso_pages << PAGE_SHIFT;
/* Be sure to map the data page */
vdso_mapping_len = vdso_text_len + PAGE_SIZE;
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
ret = ERR_PTR(vdso_base);
goto up_fail;
}
ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
VM_READ|VM_MAYREAD,
&vdso_spec[0]);
if (IS_ERR(ret))
goto up_fail;
vdso_base += PAGE_SIZE;
mm->context.vdso = (void *)vdso_base;
ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
&vdso_spec[1]);
if (IS_ERR(ret))
goto up_fail;
up_write(&mm->mmap_sem);
return 0;
up_fail:
mm->context.vdso = NULL;
up_write(&mm->mmap_sem);
return PTR_ERR(ret);
}
/*
* Update the vDSO data page to keep in sync with kernel timekeeping.
*/
void update_vsyscall(struct timekeeper *tk)
{
u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct;
++vdso_data->tb_seq_count;
smp_wmb();
vdso_data->use_syscall = use_syscall;
vdso_data->xtime_coarse_sec = tk->xtime_sec;
vdso_data->xtime_coarse_nsec = tk->tkr_mono.xtime_nsec >>
tk->tkr_mono.shift;
vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec;
vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec;
/* Read without the seqlock held by clock_getres() */
WRITE_ONCE(vdso_data->hrtimer_res, hrtimer_resolution);
if (!use_syscall) {
/* tkr_mono.cycle_last == tkr_raw.cycle_last */
vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
vdso_data->raw_time_sec = tk->raw_sec;
vdso_data->raw_time_nsec = tk->tkr_raw.xtime_nsec;
vdso_data->xtime_clock_sec = tk->xtime_sec;
vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec;
vdso_data->cs_mono_mult = tk->tkr_mono.mult;
vdso_data->cs_raw_mult = tk->tkr_raw.mult;
/* tkr_mono.shift == tkr_raw.shift */
vdso_data->cs_shift = tk->tkr_mono.shift;
}
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;
}
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