arch/s390/kernel/vdso.c

Source file repositories/reference/linux-study-clean/arch/s390/kernel/vdso.c

File Facts

System
Linux kernel
Corpus path
arch/s390/kernel/vdso.c
Extension
.c
Size
4106 bytes
Lines
166
Domain
Architecture Layer
Bucket
arch/s390
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * vdso setup for s390
 *
 *  Copyright IBM Corp. 2008
 *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#include <linux/binfmts.h>
#include <linux/elf.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/random.h>
#include <linux/vdso_datastore.h>
#include <vdso/datapage.h>
#include <asm/vdso/vsyscall.h>
#include <asm/alternative.h>
#include <asm/vdso.h>

extern char vdso_start[], vdso_end[];

static int vdso_mremap(const struct vm_special_mapping *sm,
		       struct vm_area_struct *vma)
{
	current->mm->context.vdso_base = vma->vm_start;
	return 0;
}

static struct vm_special_mapping vdso_mapping = {
	.name = "[vdso]",
	.mremap = vdso_mremap,
};

int vdso_getcpu_init(void)
{
	set_tod_programmable_field(smp_processor_id());
	return 0;
}
early_initcall(vdso_getcpu_init); /* Must be called before SMP init */

static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
{
	unsigned long vvar_start, vdso_text_start, vdso_text_len;
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	int rc;

	BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES);
	if (mmap_write_lock_killable(mm))
		return -EINTR;

	vdso_text_len = vdso_end - vdso_start;
	vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
	rc = vvar_start;
	if (IS_ERR_VALUE(vvar_start))
		goto out;
	vma = vdso_install_vvar_mapping(mm, vvar_start);
	rc = PTR_ERR(vma);
	if (IS_ERR(vma))
		goto out;
	vdso_text_start = vvar_start + VDSO_NR_PAGES * PAGE_SIZE;
	/* VM_MAYWRITE for COW so gdb can set breakpoints */
	vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
				       VM_READ|VM_EXEC|VM_SEALED_SYSMAP|
				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
				       &vdso_mapping);
	if (IS_ERR(vma)) {
		do_munmap(mm, vvar_start, PAGE_SIZE, NULL);
		rc = PTR_ERR(vma);
	} else {
		current->mm->context.vdso_base = vdso_text_start;
		rc = 0;
	}
out:
	mmap_write_unlock(mm);
	return rc;
}

static unsigned long vdso_addr(unsigned long start, unsigned long len)
{
	unsigned long addr, end, offset;

	/*
	 * Round up the start address. It can start out unaligned as a result
	 * of stack start randomization.

Annotation

Implementation Notes