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riscv/vdso: Add support for time namespaces 

Implement generic vdso time namespace support which also enables time
namespaces for riscv. This is quite similar to what arm64 does.

selftest/timens test result:
  1..10
  ok 1 Passed for CLOCK_BOOTTIME (syscall)
  ok 2 Passed for CLOCK_BOOTTIME (vdso)
  ok 3 # SKIP CLOCK_BOOTTIME_ALARM isn't supported
  ok 4 # SKIP CLOCK_BOOTTIME_ALARM isn't supported
  ok 5 Passed for CLOCK_MONOTONIC (syscall)
  ok 6 Passed for CLOCK_MONOTONIC (vdso)
  ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall)
  ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso)
  ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall)
  ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso)
  # Totals: pass:8 fail:0 xfail:0 xpass:0 skip:2 error:0

Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Tong Tiangen 2021-09-01 03:20:25 +00:00 committed by Palmer Dabbelt
parent 8edab02386
commit dffe11e280
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
6 changed files with 224 additions and 67 deletions
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1
arch/riscv/Kconfig
View File

@ -62,6 +62,7 @@ config RISCV
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_TIME_VSYSCALL if MMU && 64BIT
select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
select HANDLE_DOMAIN_IRQ
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL

2
arch/riscv/include/asm/page.h
View File

@ -157,6 +157,8 @@ extern phys_addr_t __phys_addr_symbol(unsigned long x);
#define page_to_bus(page) (page_to_phys(page))
#define phys_to_page(paddr) (pfn_to_page(phys_to_pfn(paddr)))
#define sym_to_pfn(x) __phys_to_pfn(__pa_symbol(x))
#ifdef CONFIG_FLATMEM
#define pfn_valid(pfn) \
(((pfn) >= ARCH_PFN_OFFSET) && (((pfn) - ARCH_PFN_OFFSET) < max_mapnr))

2
arch/riscv/include/asm/vdso.h
View File

@ -22,7 +22,7 @@
*/
#ifdef CONFIG_MMU
#define __VVAR_PAGES 1
#define __VVAR_PAGES 2
#ifndef __ASSEMBLY__
#include <generated/vdso-offsets.h>

7
arch/riscv/include/asm/vdso/gettimeofday.h
View File

@ -76,6 +76,13 @@ static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
return _vdso_data;
}
#ifdef CONFIG_TIME_NS
static __always_inline
const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
{
return _timens_data;
}
#endif
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_VDSO_GETTIMEOFDAY_H */

276
arch/riscv/kernel/vdso.c
View File

@ -13,6 +13,7 @@
#include <linux/err.h>
#include <asm/page.h>
#include <asm/vdso.h>
#include <linux/time_namespace.h>
#ifdef CONFIG_GENERIC_TIME_VSYSCALL
#include <vdso/datapage.h>
@ -25,14 +26,12 @@ extern char vdso_start[], vdso_end[];
enum vvar_pages {
VVAR_DATA_PAGE_OFFSET,
VVAR_TIMENS_PAGE_OFFSET,
VVAR_NR_PAGES,
};
#define VVAR_SIZE (VVAR_NR_PAGES << PAGE_SHIFT)
static unsigned int vdso_pages __ro_after_init;
static struct page **vdso_pagelist __ro_after_init;
/*
* The vDSO data page.
*/
@ -42,83 +41,228 @@ static union {
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = &vdso_data_store.data;
static int __init vdso_init(void)
struct __vdso_info {
const char *name;
const char *vdso_code_start;
const char *vdso_code_end;
unsigned long vdso_pages;
/* Data Mapping */
struct vm_special_mapping *dm;
/* Code Mapping */
struct vm_special_mapping *cm;
};
static struct __vdso_info vdso_info __ro_after_init = {
.name = "vdso",
.vdso_code_start = vdso_start,
.vdso_code_end = vdso_end,
};
static int vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *new_vma)
{
unsigned int i;
vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
vdso_pagelist =
kcalloc(vdso_pages + VVAR_NR_PAGES, sizeof(struct page *), GFP_KERNEL);
if (unlikely(vdso_pagelist == NULL)) {
pr_err("vdso: pagelist allocation failed\n");
return -ENOMEM;
}
for (i = 0; i < vdso_pages; i++) {
struct page *pg;
pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
vdso_pagelist[i] = pg;
}
vdso_pagelist[i] = virt_to_page(vdso_data);
current->mm->context.vdso = (void *)new_vma->vm_start;
return 0;
}
static int __init __vdso_init(void)
{
unsigned int i;
struct page **vdso_pagelist;
unsigned long pfn;
if (memcmp(vdso_info.vdso_code_start, "\177ELF", 4)) {
pr_err("vDSO is not a valid ELF object!\n");
return -EINVAL;
}
vdso_info.vdso_pages = (
vdso_info.vdso_code_end -
vdso_info.vdso_code_start) >>
PAGE_SHIFT;
vdso_pagelist = kcalloc(vdso_info.vdso_pages,
sizeof(struct page *),
GFP_KERNEL);
if (vdso_pagelist == NULL)
return -ENOMEM;
/* Grab the vDSO code pages. */
pfn = sym_to_pfn(vdso_info.vdso_code_start);
for (i = 0; i < vdso_info.vdso_pages; i++)
vdso_pagelist[i] = pfn_to_page(pfn + i);
vdso_info.cm->pages = vdso_pagelist;
return 0;
}
#ifdef CONFIG_TIME_NS
struct vdso_data *arch_get_vdso_data(void *vvar_page)
{
return (struct vdso_data *)(vvar_page);
}
/*
* The vvar mapping contains data for a specific time namespace, so when a task
* changes namespace we must unmap its vvar data for the old namespace.
* Subsequent faults will map in data for the new namespace.
*
* For more details see timens_setup_vdso_data().
*/
int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
{
struct mm_struct *mm = task->mm;
struct vm_area_struct *vma;
mmap_read_lock(mm);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
unsigned long size = vma->vm_end - vma->vm_start;
if (vma_is_special_mapping(vma, vdso_info.dm))
zap_page_range(vma, vma->vm_start, size);
}
mmap_read_unlock(mm);
return 0;
}
static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
{
if (likely(vma->vm_mm == current->mm))
return current->nsproxy->time_ns->vvar_page;
/*
* VM_PFNMAP | VM_IO protect .fault() handler from being called
* through interfaces like /proc/$pid/mem or
* process_vm_{readv,writev}() as long as there's no .access()
* in special_mapping_vmops.
* For more details check_vma_flags() and __access_remote_vm()
*/
WARN(1, "vvar_page accessed remotely");
return NULL;
}
#else
static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
{
return NULL;
}
#endif
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *timens_page = find_timens_vvar_page(vma);
unsigned long pfn;
switch (vmf->pgoff) {
case VVAR_DATA_PAGE_OFFSET:
if (timens_page)
pfn = page_to_pfn(timens_page);
else
pfn = sym_to_pfn(vdso_data);
break;
#ifdef CONFIG_TIME_NS
case VVAR_TIMENS_PAGE_OFFSET:
/*
* If a task belongs to a time namespace then a namespace
* specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
* the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
* offset.
* See also the comment near timens_setup_vdso_data().
*/
if (!timens_page)
return VM_FAULT_SIGBUS;
pfn = sym_to_pfn(vdso_data);
break;
#endif /* CONFIG_TIME_NS */
default:
return VM_FAULT_SIGBUS;
}
return vmf_insert_pfn(vma, vmf->address, pfn);
}
enum rv_vdso_map {
RV_VDSO_MAP_VVAR,
RV_VDSO_MAP_VDSO,
};
static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
[RV_VDSO_MAP_VVAR] = {
.name = "[vvar]",
.fault = vvar_fault,
},
[RV_VDSO_MAP_VDSO] = {
.name = "[vdso]",
.mremap = vdso_mremap,
},
};
static int __init vdso_init(void)
{
vdso_info.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR];
vdso_info.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO];
return __vdso_init();
}
arch_initcall(vdso_init);
int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
static int __setup_additional_pages(struct mm_struct *mm,
struct linux_binprm *bprm,
int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long vdso_base, vdso_len;
int ret;
unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
void *ret;
BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
vdso_len = (vdso_pages + VVAR_NR_PAGES) << PAGE_SHIFT;
vdso_text_len = vdso_info.vdso_pages << PAGE_SHIFT;
/* Be sure to map the data page */
vdso_mapping_len = vdso_text_len + VVAR_SIZE;
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, VVAR_SIZE,
(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info.dm);
if (IS_ERR(ret))
goto up_fail;
vdso_base += VVAR_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_info.cm);
if (IS_ERR(ret))
goto up_fail;
return 0;
up_fail:
mm->context.vdso = NULL;
return PTR_ERR(ret);
}
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
int ret;
if (mmap_write_lock_killable(mm))
return -EINTR;
vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
ret = vdso_base;
goto end;
}
mm->context.vdso = NULL;
ret = install_special_mapping(mm, vdso_base, VVAR_SIZE,
(VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
if (unlikely(ret))
goto end;
ret =
install_special_mapping(mm, vdso_base + VVAR_SIZE,
vdso_pages << PAGE_SHIFT,
(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
vdso_pagelist);
if (unlikely(ret))
goto end;
/*
* Put vDSO base into mm struct. We need to do this before calling
* install_special_mapping or the perf counter mmap tracking code
* will fail to recognise it as a vDSO (since arch_vma_name fails).
*/
mm->context.vdso = (void *)vdso_base + VVAR_SIZE;
end:
ret = __setup_additional_pages(mm, bprm, uses_interp);
mmap_write_unlock(mm);
return ret;
}
const char *arch_vma_name(struct vm_area_struct *vma)
{
if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
return "[vdso]";
if (vma->vm_mm && (vma->vm_start ==
(long)vma->vm_mm->context.vdso - VVAR_SIZE))
return "[vdso_data]";
return NULL;
}

3
arch/riscv/kernel/vdso/vdso.lds.S
View File

@ -10,6 +10,9 @@ OUTPUT_ARCH(riscv)
SECTIONS
{
PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE);
#ifdef CONFIG_TIME_NS
PROVIDE(_timens_data = _vdso_data + PAGE_SIZE);
#endif
. = SIZEOF_HEADERS;
.hash : { *(.hash) } :text