On Mon, 26 Jan 2026 10:44:07 +0000 Vincent Donnefort <[email protected]> wrote:
> The simple_ring_buffer implementation must remain simple enough to be > used by the pKVM hypervisor. Prevent the object build if unresolved > symbols are found. > > Signed-off-by: Vincent Donnefort <[email protected]> Reviewed-by: Steven Rostedt (Google) <[email protected]> -- Steve > > diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile > index 9e86c43bf320..9f675d5d27c7 100644 > --- a/kernel/trace/Makefile > +++ b/kernel/trace/Makefile > @@ -131,4 +131,20 @@ obj-$(CONFIG_TRACE_REMOTE) += trace_remote.o > obj-$(CONFIG_SIMPLE_RING_BUFFER) += simple_ring_buffer.o > obj-$(CONFIG_TRACE_REMOTE_TEST) += remote_test.o > > +# > +# simple_ring_buffer is used by the pKVM hypervisor which does not have > access > +# to all kernel symbols. Fail the build if forbidden symbols are found. > +# > +UNDEFINED_ALLOWLIST := memset alt_cb_patch_nops __x86 __ubsan __asan __kasan > __gcov __aeabi_unwind > +UNDEFINED_ALLOWLIST += __stack_chk_fail stackleak_track_stack __ref_stack > __sanitizer > +UNDEFINED_ALLOWLIST := $(addprefix -e , $(UNDEFINED_ALLOWLIST)) > + > +quiet_cmd_check_undefined = NM $< > + cmd_check_undefined = test -z "`$(NM) -u $< | grep -v > $(UNDEFINED_ALLOWLIST)`" > + > +$(obj)/%.o.checked: $(obj)/%.o FORCE > + $(call if_changed,check_undefined) > + > +always-$(CONFIG_SIMPLE_RING_BUFFER) += simple_ring_buffer.o.checked > + > libftrace-y := ftrace.o
