util.c

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#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/security.h>
#include <asm/uaccess.h>

#include "internal.h"

#define CREATE_TRACE_POINTS
#include <trace/events/kmem.h>

char *kstrdup(const char *s, gfp_t gfp)
{
    size_t len;
    char *buf;

    if (!s)
        return NULL;

    len = strlen(s) + 1;
    buf = kmalloc_track_caller(len, gfp);
    if (buf)
        memcpy(buf, s, len);
    return buf;
}
EXPORT_SYMBOL(kstrdup);

char *kstrndup(const char *s, size_t max, gfp_t gfp)
{
    size_t len;
    char *buf;

    if (!s)
        return NULL;

    len = strnlen(s, max);
    buf = kmalloc_track_caller(len+1, gfp);
    if (buf) {
        memcpy(buf, s, len);
        buf[len] = '\0';
    }
    return buf;
}
EXPORT_SYMBOL(kstrndup);

void *kmemdup(const void *src, size_t len, gfp_t gfp)
{
    void *p;

    p = kmalloc_track_caller(len, gfp);
    if (p)
        memcpy(p, src, len);
    return p;
}
EXPORT_SYMBOL(kmemdup);

void *memdup_user(const void __user *src, size_t len)
{
    void *p;

    /*
     * Always use GFP_KERNEL, since copy_from_user() can sleep and
     * cause pagefault, which makes it pointless to use GFP_NOFS
     * or GFP_ATOMIC.
     */
    p = kmalloc_track_caller(len, GFP_KERNEL);
    if (!p)
        return ERR_PTR(-ENOMEM);

    if (copy_from_user(p, src, len)) {
        kfree(p);
        return ERR_PTR(-EFAULT);
    }

    return p;
}
EXPORT_SYMBOL(memdup_user);

static __always_inline void *__do_krealloc(const void *p, size_t new_size,
                       gfp_t flags)
{
    void *ret;
    size_t ks = 0;

    if (p)
        ks = ksize(p);

    if (ks >= new_size)
        return (void *)p;

    ret = kmalloc_track_caller(new_size, flags);
    if (ret && p)
        memcpy(ret, p, ks);

    return ret;
}

void *__krealloc(const void *p, size_t new_size, gfp_t flags)
{
    if (unlikely(!new_size))
        return ZERO_SIZE_PTR;

    return __do_krealloc(p, new_size, flags);

}
EXPORT_SYMBOL(__krealloc);

void *krealloc(const void *p, size_t new_size, gfp_t flags)
{
    void *ret;

    if (unlikely(!new_size)) {
        kfree(p);
        return ZERO_SIZE_PTR;
    }

    ret = __do_krealloc(p, new_size, flags);
    if (ret && p != ret)
        kfree(p);

    return ret;
}
EXPORT_SYMBOL(krealloc);

void kzfree(const void *p)
{
    size_t ks;
    void *mem = (void *)p;

    if (unlikely(ZERO_OR_NULL_PTR(mem)))
        return;
    ks = ksize(mem);
    memset(mem, 0, ks);
    kfree(mem);
}
EXPORT_SYMBOL(kzfree);

/*
 * strndup_user - duplicate an existing string from user space
 * @s: The string to duplicate
 * @n: Maximum number of bytes to copy, including the trailing NUL.
 */
char *strndup_user(const char __user *s, long n)
{
    char *p;
    long length;

    length = strnlen_user(s, n);

    if (!length)
        return ERR_PTR(-EFAULT);

    if (length > n)
        return ERR_PTR(-EINVAL);

    p = memdup_user(s, length);

    if (IS_ERR(p))
        return p;

    p[length - 1] = '\0';

    return p;
}
EXPORT_SYMBOL(strndup_user);

void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
        struct vm_area_struct *prev, struct rb_node *rb_parent)
{
    struct vm_area_struct *next;

    vma->vm_prev = prev;
    if (prev) {
        next = prev->vm_next;
        prev->vm_next = vma;
    } else {
        mm->mmap = vma;
        if (rb_parent)
            next = rb_entry(rb_parent,
                    struct vm_area_struct, vm_rb);
        else
            next = NULL;
    }
    vma->vm_next = next;
    if (next)
        next->vm_prev = vma;
}

/* Check if the vma is being used as a stack by this task */
static int vm_is_stack_for_task(struct task_struct *t,
                struct vm_area_struct *vma)
{
    return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
}

/*
 * Check if the vma is being used as a stack.
 * If is_group is non-zero, check in the entire thread group or else
 * just check in the current task. Returns the pid of the task that
 * the vma is stack for.
 */
pid_t vm_is_stack(struct task_struct *task,
          struct vm_area_struct *vma, int in_group)
{
    pid_t ret = 0;

    if (vm_is_stack_for_task(task, vma))
        return task->pid;

    if (in_group) {
        struct task_struct *t;
        rcu_read_lock();
        if (!pid_alive(task))
            goto done;

        t = task;
        do {
            if (vm_is_stack_for_task(t, vma)) {
                ret = t->pid;
                goto done;
            }
        } while_each_thread(task, t);
done:
        rcu_read_unlock();
    }

    return ret;
}

#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
void arch_pick_mmap_layout(struct mm_struct *mm)
{
    mm->mmap_base = TASK_UNMAPPED_BASE;
    mm->get_unmapped_area = arch_get_unmapped_area;
    mm->unmap_area = arch_unmap_area;
}
#endif

/*
 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
 * back to the regular GUP.
 * If the architecture not support this function, simply return with no
 * page pinned
 */
int __attribute__((weak)) __get_user_pages_fast(unsigned long start,
                 int nr_pages, int write, struct page **pages)
{
    return 0;
}
EXPORT_SYMBOL_GPL(__get_user_pages_fast);

int __attribute__((weak)) get_user_pages_fast(unsigned long start,
                int nr_pages, int write, struct page **pages)
{
    struct mm_struct *mm = current->mm;
    int ret;

    down_read(&mm->mmap_sem);
    ret = get_user_pages(current, mm, start, nr_pages,
                    write, 0, pages, NULL);
    up_read(&mm->mmap_sem);

    return ret;
}
EXPORT_SYMBOL_GPL(get_user_pages_fast);

unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
    unsigned long len, unsigned long prot,
    unsigned long flag, unsigned long pgoff)
{
    unsigned long ret;
    struct mm_struct *mm = current->mm;

    ret = security_mmap_file(file, prot, flag);
    if (!ret) {
        down_write(&mm->mmap_sem);
        ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff);
        up_write(&mm->mmap_sem);
    }
    return ret;
}

unsigned long vm_mmap(struct file *file, unsigned long addr,
    unsigned long len, unsigned long prot,
    unsigned long flag, unsigned long offset)
{
    if (unlikely(offset + PAGE_ALIGN(len) < offset))
        return -EINVAL;
    if (unlikely(offset & ~PAGE_MASK))
        return -EINVAL;

    return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
}
EXPORT_SYMBOL(vm_mmap);

/* Tracepoints definitions. */
EXPORT_TRACEPOINT_SYMBOL(kmalloc);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
EXPORT_TRACEPOINT_SYMBOL(kfree);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);