From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) (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 9F94A3B789 for ; Fri, 10 Nov 2023 20:08:39 +0000 (UTC) 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--davidgow.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="OG/X/TJ6" Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-d9ab7badadeso3131268276.1 for ; Fri, 10 Nov 2023 12:08:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1699646918; x=1700251718; darn=lists.linux.dev; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=4YunHZgtb5nkD4PkAgnIRkW9gO+ZcmaQMUyBJXXvNgg=; b=OG/X/TJ6CHjDCuPNPUUPP/nc5W8Z879X5f60t73aRi+VnsXETL2hAo8aWv4vayL3wx /ajeqpmX+rRI1ttQuMeSyS0wP1D8d4234uhXzRSagiu2lYK8ZEORrcGPFs924dt9vF90 mQUu3ssZq9SKpHBfgj9RrNKDwjEY7pDnJZCqoNixgbBhAuGqHdnPO/HiPmiIvApyBQ8k RuYSdvNRTBYU/kZAxQCO8RQIN0lJoqcCJKXnpIdb1iV+8KEPvDAXfU68+4z5g2SuCEwb 3anUzR1Ug0U9nuI3DLA05yl6FSXEcUnIR14H9COaZ46yaZmziZpezOp0IIfs0rNoSXm5 nhnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699646918; x=1700251718; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=4YunHZgtb5nkD4PkAgnIRkW9gO+ZcmaQMUyBJXXvNgg=; b=BPITekdA0Mif5AmG/YaHywtjMhr3hY3ifEKU1zabHgzdhPdCANMjPkCTxI7ijfm1CD YqJ4IMSkSmSN6DdseGpX8sDsGt7sDzC71EJp/Q4B8SXuhWljlsuZNhEW2eOz5GaOL/KW Ya51W0KnIuwVwEdwE5Ig2AtVLx4zs8GibczL2O5Vk0q9yl+qYBnGCtR7ZxL41er8cp4p 55F5Lj4m798d3R4MA+jx/xNr+wEdUgMv4NbvpdNWhDcmvivcpXBNue55+0vYwg4sLE8+ W5gyJNYJMe5KMybe2gvCHGXO9Zs3laMmqnAEl6g1/J0bLY5CSG0rbo4NEbR2B+y2vyaY yzTA== X-Gm-Message-State: AOJu0Yw4IoqUO8uTe6Yx7Wfuw3EkEBf3o8dzhR9HANKh2RxtGZduCJ6Q 4c9lwsIkT0XpC6skJ7VKexqVSCwTpJpfQg== X-Google-Smtp-Source: AGHT+IHpA8elPSDmxOHqJghOs6XywJyufpnZHYdeTgE8gm6TvPMzYUyvszmAZYiKI4lKiyHTNGpdXhSKe/S/Cw== X-Received: from slicestar.c.googlers.com ([fda3:e722:ac3:cc00:4f:4b78:c0a8:20a1]) (user=davidgow job=sendgmr) by 2002:a25:d849:0:b0:d9a:f3dc:7d18 with SMTP id p70-20020a25d849000000b00d9af3dc7d18mr3271ybg.13.1699646918475; Fri, 10 Nov 2023 12:08:38 -0800 (PST) Date: Sat, 11 Nov 2023 04:08:26 +0800 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.869.gea05f2083d-goog Message-ID: <20231110200830.1832556-1-davidgow@google.com> Subject: [PATCH 1/3] kunit: Add a macro to wrap a deferred action function From: David Gow To: Nathan Chancellor , Kees Cook , Brendan Higgins , Rae Moar , dlatypov@google.com, Maxime Ripard , Arthur Grillo , Shuah Khan Cc: David Gow , "=?UTF-8?q?Ma=C3=ADra=20Canal?=" , Sami Tolvanen , kunit-dev@googlegroups.com, llvm@lists.linux.dev, linux-hardening@vger.kernel.org, linux-kselftest@vger.kernel.org, Benjamin Berg , Richard Fitzgerald , linux-kernel@vger.kernel.org, Maarten Lankhorst , Thomas Zimmermann , Emma Anholt , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org Content-Type: text/plain; charset="UTF-8" KUnit's deferred action API accepts a void(*)(void *) function pointer which is called when the test is exited. However, we very frequently want to use existing functions which accept a single pointer, but which may not be of type void*. While this is probably dodgy enough to be on the wrong side of the C standard, it's been often used for similar callbacks, and gcc's -Wcast-function-type seems to ignore cases where the only difference is the type of the argument, assuming it's compatible (i.e., they're both pointers to data). However, clang 16 has introduced -Wcast-function-type-strict, which no longer permits any deviation in function pointer type. This seems to be because it'd break CFI, which validates the type of function calls. This rather ruins our attempts to cast functions to defer them, and leaves us with a few options. The one we've chosen is to implement a macro which will generate a wrapper function which accepts a void*, and casts the argument to the appropriate type. For example, if you were trying to wrap: void foo_close(struct foo *handle); you could use: KUNIT_DEFINE_ACTION_WRAPPER(kunit_action_foo_close, foo_close, struct foo *); This would create a new kunit_action_foo_close() function, of type kunit_action_t, which could be passed into kunit_add_action() and similar functions. In addition to defining this macro, update KUnit and its tests to use it. Link: https://github.com/ClangBuiltLinux/linux/issues/1750 Signed-off-by: David Gow --- This is a follow-up to the RFC here: https://lore.kernel.org/linux-kselftest/20230915050125.3609689-1-davidgow@google.com/ There's no difference in the macro implementation, just an update to the KUnit tests to use it. This version is intended to complement: https://lore.kernel.org/all/20231106172557.2963-1-rf@opensource.cirrus.com/ There are also two follow-up patches in the series to use this macro in various DRM tests. Hopefully this will solve any CFI issues that show up with KUnit. Thanks, -- David --- include/kunit/resource.h | 9 +++++++++ lib/kunit/kunit-test.c | 5 +---- lib/kunit/test.c | 6 ++++-- 3 files changed, 14 insertions(+), 6 deletions(-) diff --git a/include/kunit/resource.h b/include/kunit/resource.h index c7383e90f5c9..4110e13970dc 100644 --- a/include/kunit/resource.h +++ b/include/kunit/resource.h @@ -390,6 +390,15 @@ void kunit_remove_resource(struct kunit *test, struct kunit_resource *res); /* A 'deferred action' function to be used with kunit_add_action. */ typedef void (kunit_action_t)(void *); +/* We can't cast function pointers to kunit_action_t if CFI is enabled. */ +#define KUNIT_DEFINE_ACTION_WRAPPER(wrapper, orig, arg_type) \ + static void wrapper(void *in) \ + { \ + arg_type arg = (arg_type)in; \ + orig(arg); \ + } + + /** * kunit_add_action() - Call a function when the test ends. * @test: Test case to associate the action with. diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c index de2113a58fa0..ee6927c60979 100644 --- a/lib/kunit/kunit-test.c +++ b/lib/kunit/kunit-test.c @@ -538,10 +538,7 @@ static struct kunit_suite kunit_resource_test_suite = { #if IS_BUILTIN(CONFIG_KUNIT_TEST) /* This avoids a cast warning if kfree() is passed direct to kunit_add_action(). */ -static void kfree_wrapper(void *p) -{ - kfree(p); -} +KUNIT_DEFINE_ACTION_WRAPPER(kfree_wrapper, kfree, const void *); static void kunit_log_test(struct kunit *test) { diff --git a/lib/kunit/test.c b/lib/kunit/test.c index f2eb71f1a66c..0308865194bb 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -772,6 +772,8 @@ static struct notifier_block kunit_mod_nb = { }; #endif +KUNIT_DEFINE_ACTION_WRAPPER(kfree_action_wrapper, kfree, const void *) + void *kunit_kmalloc_array(struct kunit *test, size_t n, size_t size, gfp_t gfp) { void *data; @@ -781,7 +783,7 @@ void *kunit_kmalloc_array(struct kunit *test, size_t n, size_t size, gfp_t gfp) if (!data) return NULL; - if (kunit_add_action_or_reset(test, (kunit_action_t *)kfree, data) != 0) + if (kunit_add_action_or_reset(test, kfree_action_wrapper, data) != 0) return NULL; return data; @@ -793,7 +795,7 @@ void kunit_kfree(struct kunit *test, const void *ptr) if (!ptr) return; - kunit_release_action(test, (kunit_action_t *)kfree, (void *)ptr); + kunit_release_action(test, kfree_action_wrapper, (void *)ptr); } EXPORT_SYMBOL_GPL(kunit_kfree); -- 2.42.0.869.gea05f2083d-goog