Messages in this thread | | | Subject | Re: Difference in values of addresses in System.map and /proc/kallsyms | From | Randy Dunlap <> | Date | Tue, 19 May 2020 08:57:04 -0700 |
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Hi--
On 6/22/19 8:28 AM, Ajay Garg wrote: > Hi All. > > My system is > > ajay@latitude-3480:~$ uname -a > Linux latitude-3480 4.13.0-38-generic #43~16.04.1-Ubuntu SMP Wed Mar > 14 17:48:43 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux > > > When I see the address for a symbol, say linux_banner, in > /boot/System.map-4.13.0-38-generic, it shows > ffffffff81e00120 R linux_banner
That's a static (build-time) address.
> > However, when I see it in /proc/kallsyms, it shows > ffffffffa7000120 R linux_banner >
That's where it actually was loaded to at boot time.
> > Also, I note that /proc/kallsyms addresses vary upon reboots, so I am > a little confused as to what the entries in /proc/kallsyms really > mean.
You forgot to provide the kernel config file.
Possibly it has this config item: CONFIG_RANDOMIZE_BASE=y
You can read the help text for that config option in arch/x86/Kconfig.
> So, will be grateful for some pointers from the experts :) > > > Thanks and Regards, > Ajay
If this doesn't explain what you are seeing, then I don't know. Maybe someone else can help.
-- ~Randy
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