[PATCH v8 18/28] tracing: Check for undefined symbols in simple_ring_buffer
From: Vincent Donnefort <hidden>
Date: 2025-11-07 09:39:07
Also in:
kvmarm, linux-arm-kernel, lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
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 <redacted>
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 53534447e70b..38523ea2e19b 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile@@ -114,4 +114,20 @@ 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
--
2.51.2.1041.gc1ab5b90ca-goog