cregit-Linux how code gets into the kernel

Release 4.18 arch/riscv/kernel/vdso.c

/*
 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
 *                    <benh@kernel.crashing.org>
 * Copyright (C) 2012 ARM Limited
 * Copyright (C) 2015 Regents of the University of California
 *
 * 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/>.
 */

#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/err.h>

#include <asm/vdso.h>

extern char vdso_start[], vdso_end[];


static unsigned int 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;


static int __init vdso_init(void) { unsigned int i; vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; vdso_pagelist = kcalloc(vdso_pages + 1, 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)); ClearPageReserved(pg); vdso_pagelist[i] = pg; } vdso_pagelist[i] = virt_to_page(vdso_data); return 0; }

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Palmer Dabbelt119100.00%1100.00%
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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_len; int ret; vdso_len = (vdso_pages + 1) << PAGE_SHIFT; down_write(&mm->mmap_sem); vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0); if (IS_ERR_VALUE(vdso_base)) { ret = vdso_base; 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; ret = install_special_mapping(mm, vdso_base, vdso_len, (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), vdso_pagelist); if (unlikely(ret)) mm->context.vdso = NULL; end: up_write(&mm->mmap_sem); return ret; }

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Palmer Dabbelt146100.00%1100.00%
Total146100.00%1100.00%


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]"; return NULL; }

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Palmer Dabbelt41100.00%1100.00%
Total41100.00%1100.00%

/* * Function stubs to prevent linker errors when AT_SYSINFO_EHDR is defined */
int in_gate_area_no_mm(unsigned long addr) { return 0; }

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Palmer Dabbelt12100.00%1100.00%
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int in_gate_area(struct mm_struct *mm, unsigned long addr) { return 0; }

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Palmer Dabbelt17100.00%1100.00%
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struct vm_area_struct *get_gate_vma(struct mm_struct *mm) { return NULL; }

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Palmer Dabbelt15100.00%1100.00%
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Palmer Dabbelt420100.00%1100.00%
Tobias Klauser0.00%00.00%
Total420100.00%1100.00%
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