lkml.org 
[lkml]   [2012]   [Jun]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] uprobes: install_breakpoint() should fail if is_swbp_insn() == T
On 06/01, Oleg Nesterov wrote:
>
> But. What do you think about the pseudo-code below? Only to illustrate
> the approach, the code is not complete.
>
> In the "likely" case we do vma_prio_tree_foreach() twice, this is
> better than the current quadratic behaviour.

See the "full" version. Untested of course, most probably has bugs,
but hopefully close enough.

What do you think?

Oleg.

struct map_info {
struct map_info *next;
struct mm_struct *mm;
loff_t vaddr;
};
static inline struct map_info *free_map_info(struct map_info *info)
{
struct map_info *next = info->next;
kfree(info);
return next;
}
static struct map_info *
build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
{
unsigned long pgoff = offset >> PAGE_SHIFT;
struct prio_tree_iter iter;
struct vm_area_struct *vma;
struct map_info *curr = NULL;
struct map_info *prev = NULL;
struct map_info *info;
int more = 0;
again:
mutex_lock(&mapping->i_mmap_mutex);
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
if (!valid_vma(vma, is_register))
continue;
if (!prev) {
more++;
continue;
}
if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
continue;
info = prev;
prev = prev->next;
info->next = curr;
curr = info;

info->mm = vma->vm_mm;
info->vaddr = vma_address(vma, offset);
}
mutex_unlock(&mapping->i_mmap_mutex);
if (!more)
goto out;
prev = curr;
while (curr) {
mmput(curr->mm);
curr = curr->next;
}
while (more--) {
info = kmalloc(sizeof(struct map_info), GFP_KERNEL);
if (!info) {
curr = ERR_PTR(-ENOMEM);
goto out;
}
info->next = prev;
prev = info;
}
goto again;
out:
while (prev)
prev = free_map_info(prev);
return curr;
}
static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
{
struct map_info *info;
int err = 0;
info = build_map_info(uprobe->inode->i_mapping,
uprobe->offset, is_register);
if (IS_ERR(info))
return PTR_ERR(info);
while (info) {
struct mm_struct *mm = info->mm;
struct vm_area_struct *vma;
loff_t vaddr;
if (err)
goto free;
down_write(&mm->mmap_sem);
vma = find_vma(mm, (unsigned long)info->vaddr);
if (!vma || !valid_vma(vma, is_register))
goto unlock;
vaddr = vma_address(vma, uprobe->offset);
if (vma->vm_file->f_mapping->host != uprobe->inode ||
vaddr != info->vaddr)
goto unlock;
if (is_register) {
err = install_breakpoint(uprobe, mm, vma, info->vaddr);
if (err == -EEXIST)
err = 0;
} else {
remove_breakpoint(uprobe, mm, info->vaddr);
}
unlock:
up_write(&mm->mmap_sem);
free:
mmput(mm);
info = free_map_info(info);
}
return err;
}


\
 
 \ /
  Last update: 2012-06-01 21:21    [from the cache]
©2003-2011 Jasper Spaans