LinuxQuestions.org - How System.map addresses are translated

- Linux - Kernel (https://www.linuxquestions.org/questions/linux-kernel-70/)

- - How System.map addresses are translated (https://www.linuxquestions.org/questions/linux-kernel-70/how-system-map-addresses-are-translated-4175560481/)

How System.map addresses are translated

I am new to Kernel development and trying to make sense of things. I am running an Ubuntu 14.04 LTS machine that has the following entry in its System.map file

ffffffff81801400 R sys_call_table

Is the address a virtual memory offset or the actual virtual address where the system call table will reside. I've heard conflicting information from TWO experts - one suggests that it is the exact virtual address of the system call table and the other says I would need to add the kernel base virtual address to that virtual address to locate the system call table. Which one of these people are correct as I am now confused?

Let's find out:

Code:

 cat /proc/2269/stack 

[<ffffffff813ab31e>] n_tty_read+0x51e/0xa20

[<ffffffff813a56f7>] tty_read+0xa7/0xf0

[<ffffffff8119e321>] vfs_read+0xb1/0x130

[<ffffffff8119e7af>] SyS_read+0x5f/0xa0

[<ffffffff8160e7f9>] system_call_fastpath+0x16/0x1b

[<ffffffffffffffff>] 0xffffffffffffffff





grep n_tty_read  /boot/System.map-`uname -r`

ffffffff813aae00 t n_tty_read



813aae00 + 51e = 813ab31e

So I guess they are the actual addresses.