Compiler and tooling-generated symbols are difficult to maintain across all supported architectures. Make the allowlist more robust by replacing the harcoded list with a mechanism that automatically detects these symbols.
This mechanism generates a C function designed to trigger common compiler-inserted symbols. Signed-off-by: Vincent Donnefort <[email protected]> --- Changes in v2: - Use filechk (Nathan) - Removed deprecated extra-y (Nathan) - Added simple_ring_buffer in allowlist (Nathan) - Added memcpy() to generate more symbols (Nathan) - Added __sancov diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index beb15936829d..96627a909ecc 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -136,17 +136,42 @@ 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 llvm_gcda llvm_gcov -UNDEFINED_ALLOWLIST += .TOC\. __clear_pages_unrolled __memmove copy_page warn_slowpath_fmt -UNDEFINED_ALLOWLIST += ftrace_likely_update __hwasan_load __hwasan_store __hwasan_tag_memory -UNDEFINED_ALLOWLIST += warn_bogus_irq_restore __stack_chk_guard -UNDEFINED_ALLOWLIST := $(addprefix -e , $(UNDEFINED_ALLOWLIST)) +# undefsyms_base generates a set of compiler and tooling-generated symbols that can +# safely be ignored for simple_ring_buffer. +# +filechk_undefsyms_base = \ + echo '$(pound)include <linux/atomic.h>'; \ + echo '$(pound)include <linux/string.h>'; \ + echo '$(pound)include <asm/page.h>'; \ + echo 'static char page[PAGE_SIZE] __aligned(PAGE_SIZE);'; \ + echo 'void undefsyms_base(void *p, int n);'; \ + echo 'void undefsyms_base(void *p, int n) {'; \ + echo ' char buffer[256] = { 0 };'; \ + echo ' u32 u = 0;'; \ + echo ' memset((char * volatile)page, 8, PAGE_SIZE);'; \ + echo ' memset((char * volatile)buffer, 8, sizeof(buffer));'; \ + echo ' memcpy((void * volatile)p, buffer, sizeof(buffer));'; \ + echo ' cmpxchg((u32 * volatile)&u, 0, 8);'; \ + echo ' WARN_ON(n == 0xdeadbeef);'; \ + echo '}' + +$(obj)/undefsyms_base.c: FORCE + $(call filechk,undefsyms_base) + +clean-files += undefsyms_base.c + +$(obj)/undefsyms_base.o: $(obj)/undefsyms_base.c + +targets += undefsyms_base.o + +UNDEFINED_ALLOWLIST = __asan __gcov __kasan __kcsan __hwasan __sancov __sanitizer __tsan __ubsan __x86_indirect_thunk \ + simple_ring_buffer \ + $(shell $(NM) -u $(obj)/undefsyms_base.o 2>/dev/null | awk '{print $$2}') quiet_cmd_check_undefined = NM $< - cmd_check_undefined = test -z "`$(NM) -u $< | grep -v $(UNDEFINED_ALLOWLIST)`" + cmd_check_undefined = test -z "`$(NM) -u $< | grep -v $(addprefix -e , $(UNDEFINED_ALLOWLIST))`" -$(obj)/%.o.checked: $(obj)/%.o FORCE +$(obj)/%.o.checked: $(obj)/%.o $(obj)/undefsyms_base.o FORCE $(call if_changed,check_undefined) always-$(CONFIG_SIMPLE_RING_BUFFER) += simple_ring_buffer.o.checked base-commit: 33f2e266515717c4b2df585dadefa0525557726c -- 2.53.0.851.ga537e3e6e9-goog
