Unverified Commit dffe11e2 authored by Tong Tiangen's avatar Tong Tiangen Committed by Palmer Dabbelt
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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: default avatarTong Tiangen <tongtiangen@huawei.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent 8edab023

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/riscv/include/asm/page.h

+2 −0
Original line number Diff line number Diff line
@@ -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))

arch/riscv/include/asm/vdso.h

+1 −1
Original line number Diff line number Diff line
@@ -22,7 +22,7 @@ 
 */

#ifdef CONFIG_MMU



#define __VVAR_PAGES    1

#define __VVAR_PAGES    2



#ifndef __ASSEMBLY__

#include <generated/vdso-offsets.h>

arch/riscv/include/asm/vdso/gettimeofday.h

+7 −0
Original line number Diff line number Diff line
@@ -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 */

arch/riscv/kernel/vdso.c

+197 −53
Original line number Diff line number Diff line
@@ -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)

{

	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_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");

	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);

}



	for (i = 0; i < vdso_pages; i++) {

		struct page *pg;

/*

 * 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;



		pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));

		vdso_pagelist[i] = pg;

		if (vma_is_special_mapping(vma, vdso_info.dm))

			zap_page_range(vma, vma->vm_start, size);

	}

	vdso_pagelist[i] = virt_to_page(vdso_data);



	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,

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;



	if (mmap_write_lock_killable(mm))

		return -EINTR;



	vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);

	vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);

	if (IS_ERR_VALUE(vdso_base)) {

		ret = vdso_base;

		goto end;

		ret = ERR_PTR(vdso_base);

		goto up_fail;

	}



	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,

		(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 + VVAR_SIZE,

		vdso_pages << PAGE_SHIFT,

	   _install_special_mapping(mm, vdso_base, vdso_text_len,

		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),

		vdso_pagelist);

		vdso_info.cm);



	if (unlikely(ret))

		goto end;

	if (IS_ERR(ret))

		goto up_fail;



	/*

	 * 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;

	return 0;



end:

	mmap_write_unlock(mm);

	return ret;

up_fail:

	mm->context.vdso = NULL;

	return PTR_ERR(ret);

}



const char *arch_vma_name(struct vm_area_struct *vma)

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)

{

	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;

	struct mm_struct *mm = current->mm;

	int ret;



	if (mmap_write_lock_killable(mm))

		return -EINTR;



	ret = __setup_additional_pages(mm, bprm, uses_interp);

	mmap_write_unlock(mm);



	return ret;

}