From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 351AD38A713 for ; Fri, 13 Mar 2026 10:58:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773399515; cv=none; b=Hq37SEL+4V6tHD2lVVRh3NVkylMaTH9R46Rp380cPP95+uT6N40GwUwEGWv18viiLE3XT7P7w5/OXaw5MccPglK/H4MFO30GImsUM816+fO/wD/kD5DT/ceaPtt/Irr4FtOu73a1a9Pj5iqDRYPyzJE2vmdUly66vNqgtaRovD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773399515; c=relaxed/simple; bh=0gg+BXwTZs8y0vwcB8E2pQg8BCz8Cb+Fa+086MaSqfs=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=bYddSeAzdRZKuknxBsVF/V1CxMqEB4ZAnixcWrdxEV0zZWo0tzONpqazlNbEKkqJHKrhGvWHge3dTPFMEtikfTmIjnIL5BaU32uLa7iIjhU5uyNYJry5N5G7W4tJqgoYdFoGMDaECCmspRpFkWtkv1FJdlFuUe0ukexC0g3MboY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=rYGjkEcD; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rYGjkEcD" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-48535f4d5e1so16572775e9.0 for ; Fri, 13 Mar 2026 03:58:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773399511; x=1774004311; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=mrymzRMwHOpggoI9a5WaW3RvaXQ2tcgefwApaR5IFTc=; b=rYGjkEcDMudIuN3AmQxQHIyW5t9W2qf7LIcB9LwPn6OEsUSwRwHIoNpQKcnjiruYO2 FoVnO/awtcZOcERSaSF6yw5M52TBbCguq4fUwjc4xZh82Mv/oyzt9767RBq+MlaJd2Fm x3LrZpsoE2mClD1DdhZohfh8bNdFI0hzaibZWVe6U7AhziAY08Ymmhj4Y/sda8cEkE6A 79v/0FhznxsYlv7pkxOYlLG0Frcsp61nlNAyu0V2uIqZ0OSAN1DVnA3d6QD21njQJmQM DlwfIMVDY9bMGCeO3je6vIUGS/Q677EA+61xfUMgooGEmPxSDdOezwKlp6kU+YAAieN/ 65Aw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773399511; x=1774004311; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=mrymzRMwHOpggoI9a5WaW3RvaXQ2tcgefwApaR5IFTc=; b=DFvs7pONC2OticYe25yQipRntxxFKw4NNkTKzybMZDF/iGuNmsJwqQAuOqm3lxdaPO 1fw/Fi3p0Nnv+RL/oOL1NWAxJguv6LEuP+4YSHiIPkfb89wKfycnzx5eX1HaVaVNTQw1 AeCMCQ3k1t0wbdldmi43P2FcoLfsf/x3ej62bWuBE0m9jo7whdtc/sCktKAjRcfMMnz9 NpW+FZy82cy99Afd95jYqVoBlCPkmdCEJL0AqM9xtt4eHT1NMttrngFGaMNG7mse5Orp lPwWaHEnqUwlUSDgfGRT0r2D1RsLyhpKi5O99LORG+S/5iG5yTZFXHnGt3D0+9euZ+59 grSQ== X-Forwarded-Encrypted: i=1; AJvYcCWiWfaSQWlhVsmmrzrgTtym4Z0Mgrcg2WKALDXYFteUlmk8/qdNviZLp0s01JrMwv4wFsssYbxBJ01kIIexvZ8E7BE=@vger.kernel.org X-Gm-Message-State: AOJu0YwPwQRwiBuSWFXL1AiIXWIqp9GmwPpuS+szkaPriq1K7MUQzkBm I2zELxau5FIfGVJVQE0UEywK46RozOm3pdS03+6fX6UEsrn++WHgTUD1OwBFgzg1p5HHobUcCcc S8NrOq/SVvRKgnZxUfqelUg== X-Received: from wmsk23-n1.prod.google.com ([2002:a05:600d:8497:10b0:485:3ee6:2d4]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:1d24:b0:485:379b:57bb with SMTP id 5b1f17b1804b1-485566c69a5mr39972655e9.3.1773399511375; Fri, 13 Mar 2026 03:58:31 -0700 (PDT) Date: Fri, 13 Mar 2026 10:58:29 +0000 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.851.ga537e3e6e9-goog Message-ID: <20260313105829.1214123-1-vdonnefort@google.com> Subject: [PATCH v2] tracing: Generate undef symbols allowlist for simple_ring_buffer From: Vincent Donnefort To: maz@kernel.org Cc: rostedt@goodmis.org, arnd@arndb.de, nathan@kernel.org, linux-trace-kernel@vger.kernel.org, kvmarm@lists.linux.dev, kernel-team@android.com, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" 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 --- 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 '; \ + echo '$(pound)include '; \ + echo '$(pound)include '; \ + 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