GCC emits GOT indirections for weak symbol references on AArch64 #547
Description
Since the GCC 12.1 release (Zephyr SDK 0.15.0), GCC emits the "GOT indirections" for weak symbol references on AArch64, even when compiling with -fno-pic and -fno-pie.
Building the following code:
extern __weak void
pm_state_exit_post_ops(enum pm_state state, uint8_t substate_id);
if (pm_state_exit_post_ops != NULL) {The pm_state_exit_post_ops, a weak symbol, is referenced as follows:
GCC 10.3 (Zephyr SDK 0.14.2)
adrp x0, .LC0
ldr x0, [x0, #:lo12:.LC0]
...
.LC0:
.xword pm_state_exit_post_ops
GCC 12.1 (Zephyr SDK 0.15.0)
adrp x0, :got:pm_state_exit_post_ops
ldr x0, [x0, :got_lo12:pm_state_exit_post_ops]
Note that the code emitted by GCC 12.1 makes use of :got:, which references the Global Offset Table (GOT). This effectively requires the .got section to be included in the final image (these are currently discarded by the AArch64 linker script).
The Global Offset Table (GOT) should not be used when not compiling position independent code (PIC).
This issue was introduced by the GCC commit gcc-mirror/gcc@fb0746f.
p.s. when the weak symbol is actually defined, the linker does populate the corresponding GOT entry with the address of the symbol at the default linking address (though, the "default" linking address does not really apply to the static executables ...).
Raw listing output: https://gist.github.com/stephanosio/a7fa3cbbf285794b4b1f3520c9376e7b