https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83782
Bug ID: 83782
Summary: Inconsistent address for hidden ifunc in a shared
library
Product: gcc
Version: 7.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: rafael.espindola at gmail dot com
Target Milestone: ---
Created attachment 43092
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43092&action=edit
testcase
If a function with hidden visibility is implemented with an ifunc, different
translation units have different opinions as to what its address is.
The translation unit implementing the function gets its address with
movq foo@GOTPCREL(%rip), %rax
That is, it finds the address of the actual function after it is selected.
Any translation unit will use
leaq foo(%rip), %rax
which the linker translates to the address of the plt.
The net result is that the attached program finds two addresses for the same
function:
$ ./t
0x7fc5f331360a 0x7fc5f3313510
Gives the desire to allow ifuncs to be used by changing just the implementation
(not the declaration), I think the only solution is to use the plt address in
both translation units.
