From: Masahiro Yamada masahiroy@kernel.org
[ Upstream commit 245b993d8f6c4e25f19191edfbd8080b645e12b1 ]
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic.
modpost used to detect it, but it has been broken for a decade.
Recently, I fixed modpost so it started to warn it again, then this showed up in linux-next builds.
There are two ways to fix it:
- Remove __init - Remove EXPORT_SYMBOL
I chose the latter for this case because the only in-tree call-site, arch/x86/kernel/cpu/mshyperv.c is never compiled as modular. (CONFIG_HYPERVISOR_GUEST is boolean)
Fixes: dd2cb348613b ("clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic") Reported-by: Stephen Rothwell sfr@canb.auug.org.au Signed-off-by: Masahiro Yamada masahiroy@kernel.org Reviewed-by: Vitaly Kuznetsov vkuznets@redhat.com Reviewed-by: Michael Kelley mikelley@microsoft.com Link: https://lore.kernel.org/r/20220606050238.4162200-1-masahiroy@kernel.org Signed-off-by: Wei Liu wei.liu@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clocksource/hyperv_timer.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c index ff188ab68496..bb47610bbd1c 100644 --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -565,4 +565,3 @@ void __init hv_init_clocksource(void) hv_sched_clock_offset = hv_read_reference_counter(); hv_setup_sched_clock(read_hv_sched_clock_msr); } -EXPORT_SYMBOL_GPL(hv_init_clocksource);