c - Traversing `vm_area_struct`'s of a process -

-

as extension of answer traversing physical pages of process , data here http://www.makelinux.net/ldd3/chp-15-sect-1, had small question. in first answer suggested traverse physical pages of process, 

struct vm_area_struct *vma = 0; unsigned long vpage; if (task->mm && task->mm->mmap)     (vma = task->mm->mmap; vma; vma = vma->vm_next)         (vpage = vma->vm_start; vpage < vma->vm_end; vpage += page_size)             unsigned long phys = virt2phys(task->mm, vpage);

and referring example given in second link under heading "15.1.6. virtual memory areas", 

# cat /proc/1/maps     @ init 08048000-0804e000 r-xp 00000000 03:01 64652      /sbin/init   text 0804e000-0804f000 rw-p 00006000 03:01 64652      /sbin/init   data 0804f000-08053000 rwxp 00000000 00:00 0           zero-mapped bss 40000000-40015000 r-xp 00000000 03:01 96278      /lib/ld-2.3.2.so   text 40015000-40016000 rw-p 00014000 03:01 96278      /lib/ld-2.3.2.so   data

now question is, traverse values of vm_start , vm_end first area 08048000 , 0804e000, or 08048000 , 08053000 (one contiguous chunk of memory). should write program , try myself, using data project, , helpful if understand this. want know that, if 

08048000-0804e000 r-xp 00000000 03:01 64652      /sbin/init   text 0804e000-0804f000 rw-p 00006000 03:01 64652      /sbin/init   data 0804f000-08053000 rwxp 00000000 00:00 0           zero-mapped bss

is 1 "module" belonging process, have 1 or multiple vm_area_struct data structures.

thank you.

it has separate vm_area_struct each map section. if @ code in fs/proc/task_mmu.c, functions m_start() , m_next, you'll see lines in maps pseudo-file created iteratively traversing process vma list. also, note comment on struct vm_area_struct declaration:

/*  * struct defines memory vmm memory area. there 1 of these  * per vm-area/task.  vm area part of process virtual memory  * space has special rule page-fault handlers (ie shared  * library, executable area etc).  */

clearly, text, data , bss sections have different page-fault handling rules: text can't written @ all. data read-on-first-access, copy-on-write. bss zeroed-on-first-access.


Comments

Post a Comment

Popular posts from this blog

python - TypeError: start must be a integer -

-
i trying draw 5 turtles, getting typeerror on line 25. here code: import turtle wn = turtle.screen() redrose = turtle.turtle() color = input("what background color be?") fillcolor_f = input("what color of rose be?") redrose.hideturtle() redrose.speed(30) redrose.penup() redrose.left(180) redrose.forward(175) redrose.right(90) redrose.forward(30) redrose.right(90) redrose.pendown() def drawrose(red): redrose.color("pink") redrose.fillcolor(fillcolor_f) redrose.fill(true) in range(red): redrose.forward(i) redrose.right(49) in range(5): drawrose(redrose) redrose.penup() redrose.forward(350) redrose.right(144) redrose.pendown() redrose.fill(false) drawrose(50) wn.bgcolor(color) i trying draw 5 roses, produces errors. doing in interactivepython.org. you recursively calling drawrose wrong parameter. on line 23 ( for in range(red): ) expect red integer...
Read more

c# - DevExpress RepositoryItemComboBox BackColor property ignored -

-
i have following code almost works properly; private void cbstatus_drawitem(object sender, listboxdrawitemeventargs e) { string item = e.item string; if (item != null) { switch (item) { case "1": e.appearance.forecolor = color.green; e.appearance.backcolor = color.green; break; case "2": e.appearance.forecolor = color.orange; e.appearance.backcolor = color.orange; break; case "3": e.appearance.forecolor = color.red; e.appearance.backcolor = color.red; break; } } } when dropdown shown, items forecolor correct, backcolor remains whatever backcolor of theme is; i.e. if i've got set dark theme, backcolor dark, cells in gridview, rather being green/orange/red. i've tried setting e.appearance.options.usebackcolor trying set e....
Read more

django - Creating multiple model instances in DRF3 -

-
1) create multiple model instances 1 api call, asked here: how create multiple model instances django rest framework? tried solution named in link, no success. i trying upload multiple files in 1 api call. result: files uploaded (only once overwrote perform_create) 1 instance created (if send 2 files, latter created instance). my code: class fileuploadserializer(serializers.modelserializer): def __init__(self, *args, **kwargs): many = kwargs.pop('many', true) super(fileuploadserializer, self).__init__(many=many, *args, **kwargs) class meta: model = fileupload read_only_fields = ('created', 'datafile', 'owner') class fileuploadviewset(viewsets.modelviewset): queryset = fileupload.objects.all() serializer_class = fileuploadserializer parser_classes = (multipartparser, formparser, ) def perform_create(self, serializer): file_list = self.request.data.getlist('file') ...
Read more