Le 29/08/2024 à 20:02, Segher Boessenkool a écrit :

On Thu, Aug 29, 2024 at 07:36:38PM +0200, Christophe Leroy wrote:

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Le 28/08/2024 à 19:25, Segher Boessenkool a écrit :

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Not sure about static binaries, though: do those even use the VDSO?

With "static binary" people usually mean "a binary not using any DSOs",
I think the VDSO is a DSO, also in this respect?  As always, -static
builds are *way* less problematic (and faster and smaller :-) )

AFAIK on powerpc even static binaries use the vDSO, otherwise signals
don't work.

How can that work?  Non-dynamic binaries do not use ld.so (that is the
definition of a dynamic binary, even).  So they cannot link (at runtime)
to any DSO (unless that is done manually?!)

Maybe there is something at a fixed offset in the vDSO, or something
like that?  Is this documented somewhere?

You've got some explanation here : 
https://github.com/torvalds/linux/blob/master/Documentation/ABI/stable/vdso