From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9AC09C3ABA5 for ; Tue, 29 Apr 2025 18:22:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Reply-To:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To: References:Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version: Subject:Date:From:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=myVfGyM4QWerr4szyQd4EaWR6WV2JkWhStZMnwWd3T4=; b=10phdzUau9YmBtox1qDQPdR3qU GZ+m5HTrapZUslXWiqjb2XYige5qi3xGhEj/ZG9E/Wdc0s+LFBcwTpwfBklyqadE7Hn7dIBjQtdC3 wRI4CJVwCmA/2na93b8YtEI/S3y9StdBNQsT4df8SwB/Mdcj7BhShOtimUJu+nwj/CuBOTi5Y8LsA p2h9Uszrppt5fxtnFbE2B2ymE2cMZaD2iassIw9sRRP/AhV7G9s8EILDFfI7twql0mUiBuDMICWdE Xdlihkulxwdt8kCIFU2R0es1loupoUK4nnF7Nc5qMTx4Cv2u6087hc+lzmCVhtUtHvnVk7Z5NpvKv cjMZt/Gw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u9pbd-0000000AWBG-1yLb; Tue, 29 Apr 2025 18:22:57 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u9cEd-00000008G4K-03Qi for linux-nvme@lists.infradead.org; Tue, 29 Apr 2025 04:06:21 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 3DF6D4A286; Tue, 29 Apr 2025 04:06:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id 0B92EC113CF; Tue, 29 Apr 2025 04:06:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745899577; bh=3PdF33JBq1nyxsd62zvfFmuPbfAnSnsdpa3r3ouJFOo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=ImSxOhegHftYhReRG8oW+oM6LY5yoKLWrzrGW2V//kVusiY4KJ6C0HKApYqiV/umZ jZDui8NpjNYOGK5MqF5aClgT+4pvtjZWMb3AgQxuqqCOAz00C0Lpow4dLS8fVmD8AE Ew5h7vn3uiwE1AvsN5M2//c/5JyZpQKKbX7Q2uuKJzjHODfOAkvLYlkfv/lDyfol63 jo+QK5Rd1p+0TMQoBTMEsNJWU3r3jcXOzCGrBtNYQaJBhwRFYH8Og+3Yvb56e+MIWk lrqdTOn18f4raKMikcfbZmVYGUzYJPzipTeU+RQml6v6GlEpxvCZhUZyn6fyKdVLbn 3BOR5syl/U+lg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id F4210C369D1; Tue, 29 Apr 2025 04:06:16 +0000 (UTC) From: Chen Linxuan via B4 Relay Date: Tue, 29 Apr 2025 12:06:08 +0800 Subject: [PATCH RFC v3 4/8] tpm: add __always_inline for tpm_is_hwrng_enabled MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250429-noautoinline-v3-4-4c49f28ea5b5@uniontech.com> References: <20250429-noautoinline-v3-0-4c49f28ea5b5@uniontech.com> In-Reply-To: <20250429-noautoinline-v3-0-4c49f28ea5b5@uniontech.com> To: Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , Andrew Morton , Yishai Hadas , Jason Gunthorpe , Shameer Kolothum , Kevin Tian , Alex Williamson , Peter Huewe , Jarkko Sakkinen , Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Mathieu Desnoyers , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Dmitry Vyukov , Andrey Konovalov , Juergen Gross , Boris Ostrovsky , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, virtualization@lists.linux.dev, linux-integrity@vger.kernel.org, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, Winston Wen , kasan-dev@googlegroups.com, xen-devel@lists.xenproject.org, Chen Linxuan , Changbin Du X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3942; i=chenlinxuan@uniontech.com; h=from:subject:message-id; bh=kxFAxUbcgxKFCXw3/ErTxJwPqpRyvp2FJuqCBA7VzuY=; b=owEBbQKS/ZANAwAKAXYe5hQ5ma6LAcsmYgBoEFAxPbGcLXiOi/dV/SoVEXm3HRnbi5/8nSvZh +e82+25uS6JAjMEAAEKAB0WIQTO1VElAk6xdvy0ZVp2HuYUOZmuiwUCaBBQMQAKCRB2HuYUOZmu i+71D/9hbbS4WFdBy9iBvtGFu5uSk9QxvEUgVVEszHz05+5HiG4ksE8wbutqqbHRzodOZ4fTRqw FBgWQudMTfmZ9Fzj2OyQSpBDCrM8FsKFEp555qc9ICcP/+NEGCSsRMIq6JHxaZziOrAUiqsMpl7 PDahCNl1FroL8m5qLyTgyojpMOANxIr1af/VNJ8bPL6C+kt3UbvxE1BQxJaGaFWwu4tuA6W2H6P 99dM27ARBneT1Ci6a8VKJuN083PUS0DxYveGnH1FdDIjWVzoNOuccgzNF0F8v4/nl2tP84KxlLQ oPDVasKXAZJN0tEcMKQIwEAC+r1bcpKYHpMRVEYDYmBa264Q5nFxMISnjvLEJCKf83yqHDECcUe tggtJisUCNA23s3fRH1vFO5aVh1wasktvWFK0rezqWKiiSOynNsUWjQButCpUZofWo4wTHmJihb Ia2GiI8yLBpkdorp4xsf4SL4zvcLOzgirApNORHtHhkb9txKJ20L2WHS1VhiW7xpl3ejCcR9CpP YW9L2nkVmlDG0qngRaNtWv3EZCV/wN9/811wqZzwMQLNekcn/t8lq9fv9RB/bPjq7aCVZESyGER OBAzAGQDg3kym5GaVrbjje99pIap2zj0QwO9eZHif/0av9uHNFusDMAZGbKPHCqaEevUMehhBGq Eom+AMw7eNH7lTQ== X-Developer-Key: i=chenlinxuan@uniontech.com; a=openpgp; fpr=D818ACDD385CAE92D4BAC01A6269794D24791D21 X-Endpoint-Received: by B4 Relay for chenlinxuan@uniontech.com/default with auth_id=380 X-Original-From: Chen Linxuan X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250428_210619_131203_F18CAEEE X-CRM114-Status: GOOD ( 20.08 ) X-Mailman-Approved-At: Tue, 29 Apr 2025 11:22:51 -0700 X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: chenlinxuan@uniontech.com Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org From: Winston Wen Presume that kernel is compiled for x86_64 with gcc version 13.3.0: make defconfig ./scripts/kconfig/merge_config.sh .config <( echo CONFIG_TCG_TPM=y echo CONFIG_HW_RANDOM=m ) make KCFLAGS="-fno-inline-small-functions -fno-inline-functions-called-once" This results a link error: ld: vmlinux.o: in function `tpm_add_hwrng': tpm-chip.c:(.text+0x6c5924): undefined reference to `hwrng_register' ld: vmlinux.o: in function `tpm_chip_unregister': (.text+0x6c5bc9): undefined reference to `hwrng_unregister' ld: vmlinux.o: in function `tpm_chip_register': (.text+0x6c5c9b): undefined reference to `hwrng_unregister' With `CONFIG_TCG_TPM=y` and `CONFIG_HW_RANDOM=m`, the functions `tpm_add_hwrng`, `tpm_chip_unregister`, and `tpm_chip_register` are compiled into `vmlinux.o` and reference the symbols `hwrng_register` and `hwrng_unregister`. These symbols, however, are compiled into `rng-core.ko`, which results in the linking error. I am not sure but I think this weird linking error only arises when auto inlining is disabled because of some dead code elimination. `CONFIG_TCG_TPM=y` and `CONFIG_HW_RANDOM=m` set `CONFIG_HW_RANDOM_TPM=n`. This causes the function `tpm_is_hwrng_enabled` to always return `false`, as shown below: static bool tpm_is_hwrng_enabled(struct tpm_chip *chip) { if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM)) return false; if (tpm_is_firmware_upgrade(chip)) return false; if (chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED) return false; return true; } When `tpm_is_hwrng_enabled` is inlined, dead code elimination optimizations are applied and the reference to the `hwrng_*` functions will been removed. For instance, in the `tpm_chip_unregister` function: void tpm_chip_unregister(struct tpm_chip *chip) { #ifdef CONFIG_TCG_TPM2_HMAC int rc; rc = tpm_try_get_ops(chip); if (!rc) { tpm2_end_auth_session(chip); tpm_put_ops(chip); } #endif tpm_del_legacy_sysfs(chip); if (tpm_is_hwrng_enabled(chip)) hwrng_unregister(&chip->hwrng); tpm_bios_log_teardown(chip); if (chip->flags & TPM_CHIP_FLAG_TPM2 && !tpm_is_firmware_upgrade(chip)) tpm_devs_remove(chip); tpm_del_char_device(chip); } When `tpm_is_hwrng_enabled` is inlined and always returns `false`, the call to `hwrng_unregister` is effectively part of a `if (false)` block, which I guess that will be then optimized out. However, when the `-fno-inline-small-functions` and `-fno-inline-functions-called-once` flags are used, tpm_is_hwrng_enabled is not inline. And this optimization some how cannot occur, leading to the undefined reference errors during linking. Adding the `__always_inline` attribute ensures that `tpm_is_hwrng_enabled` is inlined regardless of the compiler flags. This allows the dead code elimination to proceed as expected, resolving the linking issue. Co-developed-by: Chen Linxuan Signed-off-by: Chen Linxuan Signed-off-by: Winston Wen Reviewed-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-chip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index e25daf2396d37bcaeae8a96267764df0861ad1be..48cc74d84247e258a39f2118e03aa10d0cbb066a 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -534,7 +534,7 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) return tpm_get_random(chip, data, max); } -static bool tpm_is_hwrng_enabled(struct tpm_chip *chip) +static __always_inline bool tpm_is_hwrng_enabled(struct tpm_chip *chip) { if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM)) return false; -- 2.43.0