Re: kmalloc - Address is not consecutive

Thanks a lot, it worked :)

On Thu, Aug 19, 2021 at 7:00 PM ckim [off-list ref] wrote:

Hi! this one is easy :)
For printing pointer in kernel space, you should use %px  not %p as format
specifier. I heard this is for security reason(?).
Chan Kim

내 Galaxy에서 보냄


-------- 원본 이메일 --------
발신: wuzhouhui [off-list ref]
날짜: 21/8/19 오후 9:17 (GMT+09:00)
받은 사람: Lloyd [off-list ref], kernelnewbies@kernelnewbies.org
제목: Re: kmalloc - Address is not consecutive



On 8/19/21 6:54 PM, Lloyd wrote:

quoted

Hi,

I am trying to print the address of consecutive locations in a
memory allocated using kmalloc. It prints non contiguous addresses! I
tried with kmalloc_array, and  normal array on stack, I got the same
result. May I know the reason? The code fragment for array and result
are given below.

uint8_t MyArray[100]={'0'};
printk(KERN_INFO "\nAddress is-> %p\n",&MyArray[0]);
printk(KERN_INFO "\nAddress is-> %p\n",&MyArray[1]);
printk(KERN_INFO "\nAddress is-> %p\n",&MyArray[2]);


[ 8684.613909]               Address is-> 00000000b3330991
[ 8684.613914]               Address is-> 000000000519068c
[ 8684.613915]               Address is-> 00000000e448ca76

Quoted from Documentation/core-api/printk-formats.rst:

quoted

A raw pointer value may be printed with %p which will hash the address
before printing. The kernel also supports extended specifiers for

printing

quoted

pointers of different types.

So the address printed neither logical nor physical address.

quoted

Thanks a lot,
  Lloyd


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