From patchwork Mon Dec 18 16:10:43 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Richard Fitzgerald X-Patchwork-Id: 756710 Received: from mx0b-001ae601.pphosted.com (mx0a-001ae601.pphosted.com [67.231.149.25]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5365542386; Mon, 18 Dec 2023 16:11:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=opensource.cirrus.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=opensource.cirrus.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=cirrus.com header.i=@cirrus.com header.b="Gt1cwHPw" Received: from pps.filterd (m0077473.ppops.net [127.0.0.1]) by mx0a-001ae601.pphosted.com (8.17.1.24/8.17.1.24) with ESMTP id 3BI6fl3a012777; Mon, 18 Dec 2023 10:10:49 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cirrus.com; h= from:to:cc:subject:date:message-id:mime-version:content-type :content-transfer-encoding; s=PODMain02222019; bh=UjG2FX1pYQgdsa d8oZ3msOCc5wPjlvgk283e8XXjitk=; b=Gt1cwHPw0m8gzvlZnMusZlonkCVBrd dexXLx7+WNx+dZDH716tyRPjDCM0cfNRRLcUcbdaELky+tBHaFg/klkiLbkNyz2Z TeAixobK6KnuxlKiQ4shUMxxuaWgoFJxNyQunXIn5Ks6pcRs7JQ4K0SE773UB+xH OayeHEmebcCIfjitjdlRw6HmjL1VM7tNv4yo78qndWZSoTiaNldTbpPOCgopwnjP Xuv7aWsXwzvdZtgRVvrCH9gnNsE1qyUOVJjXn/3uqIFnT+FjtuwtfKwasH1MJMxn 8WkZqrvfGqJGClroTiyrnj2euVX4axIl9CJQhX0eYFuk88ehpoVHA92g== Received: from ediex01.ad.cirrus.com ([84.19.233.68]) by mx0a-001ae601.pphosted.com (PPS) with ESMTPS id 3v1a622x3c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 18 Dec 2023 10:10:49 -0600 (CST) Received: from ediex02.ad.cirrus.com (198.61.84.81) by ediex01.ad.cirrus.com (198.61.84.80) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Mon, 18 Dec 2023 16:10:47 +0000 Received: from ediswmail.ad.cirrus.com (198.61.86.93) by anon-ediex02.ad.cirrus.com (198.61.84.81) with Microsoft SMTP Server id 15.2.1118.40 via Frontend Transport; Mon, 18 Dec 2023 16:10:47 +0000 Received: from work-debian.ad.cirrus.com (EDINJ39Q8D3.ad.cirrus.com [198.61.65.115]) by ediswmail.ad.cirrus.com (Postfix) with ESMTP id DDDF615A0; Mon, 18 Dec 2023 16:10:46 +0000 (UTC) From: Richard Fitzgerald To: , , CC: , , , , "Richard Fitzgerald" Subject: [PATCH 1/2] kunit: Allow passing function pointer to kunit_activate_static_stub() Date: Mon, 18 Dec 2023 16:10:43 +0000 Message-ID: <20231218161044.215640-1-rf@opensource.cirrus.com> X-Mailer: git-send-email 2.30.2 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-GUID: 8MoppAXG9dsU7CBuucIKj2cMnzATIQJ_ X-Proofpoint-ORIG-GUID: 8MoppAXG9dsU7CBuucIKj2cMnzATIQJ_ X-Proofpoint-Spam-Reason: safe Swap the arguments to typecheck_fn() in kunit_activate_static_stub() so that real_fn_addr can be either the function itself or a pointer to that function. This is useful to simplify redirecting static functions in a module. Having to pass the actual function meant that it must be exported from the module. Either making the 'static' and EXPORT_SYMBOL*() conditional (which makes the code messy), or change it to always exported (which increases the export namespace and prevents the compiler inlining a trivial stub function in non-test builds). With the original definition of kunit_activate_static_stub() the address of real_fn_addr was passed to typecheck_fn() as the type to be passed. This meant that if real_fn_addr was a pointer-to-function it would resolve to a ** instead of a *, giving an error like this: error: initialization of ‘int (**)(int)’ from incompatible pointer type ‘int (*)(int)’ [-Werror=incompatible-pointer-types] kunit_activate_static_stub(test, add_one_fn_ptr, subtract_one); | ^~~~~~~~~~~~ ./include/linux/typecheck.h:21:25: note: in definition of macro ‘typecheck_fn’ 21 | ({ typeof(type) __tmp = function; \ Swapping the arguments to typecheck_fn makes it take the type of a pointer to the replacement function. Either a function or a pointer to function can be assigned to that. For example: static int some_function(int x) { /* whatever */ } int (* some_function_ptr)(int) = some_function; static int replacement(int x) { /* whatever */ } Then: kunit_activate_static_stub(test, some_function, replacement); yields: typecheck_fn(typeof(&replacement), some_function); and: kunit_activate_static_stub(test, some_function_ptr, replacement); yields: typecheck_fn(typeof(&replacement), some_function_ptr); The two typecheck_fn() then resolve to: int (*__tmp)(int) = some_function; and int (*__tmp)(int) = some_function_ptr; Both of these are valid. In the first case the compiler inserts an implicit '&' to take the address of the supplied function, and in the second case the RHS is already a pointer to the same type. Signed-off-by: Richard Fitzgerald Reviewed-by: Rae Moar --- include/kunit/static_stub.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/kunit/static_stub.h b/include/kunit/static_stub.h index 85315c80b303..bf940322dfc0 100644 --- a/include/kunit/static_stub.h +++ b/include/kunit/static_stub.h @@ -93,7 +93,7 @@ void __kunit_activate_static_stub(struct kunit *test, * The redirection can be disabled again with kunit_deactivate_static_stub(). */ #define kunit_activate_static_stub(test, real_fn_addr, replacement_addr) do { \ - typecheck_fn(typeof(&real_fn_addr), replacement_addr); \ + typecheck_fn(typeof(&replacement_addr), real_fn_addr); \ __kunit_activate_static_stub(test, real_fn_addr, replacement_addr); \ } while (0)