From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A2CDF270EAF; Tue, 29 Apr 2025 04:06:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745899577; cv=none; b=F7I9BfC8eFgmq2qjxKKEzpzT6q89K/BVVEn9+1g6KGfMPHPxt+M+LyxUMnXZV4oN5gzt9y9FKkMA71iQMKn22qBAX+A80KSjoV9Rbmi2M9yYfTAB7V0GcOjUSruVgmN5FVjmWyG/xjHjj6nZMlmrBKM6saOevCRsaCKGm1wtDvs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745899577; c=relaxed/simple; bh=3PdF33JBq1nyxsd62zvfFmuPbfAnSnsdpa3r3ouJFOo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=tv7Nbvw519jroQ0WkJLA4Z1CGpkLtnDTGTDEGbjcugf3RAjkbnAcduA6YD21XB1+/Q7XQN6O9QbdSVn9+d90RdY4p6B23dmoxXbq9+Es8QkP4Ko1ghc7wAyPPRfXTLNzsNdc8mIV0ylW3ImHD2NQkqxraIpB1oEN6NBWFKhTQqk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ImSxOheg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ImSxOheg" 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 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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 Reply-To: chenlinxuan@uniontech.com 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