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 465772071EE; Fri, 4 Oct 2024 18:26:00 +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=1728066361; cv=none; b=CZNYI/Giaqg2w498bW1NU7IHWVQqf/E09rOrK4TAqkSdFh3pV2JicD7jIe0Nw2W2O4Y9EaHxeKN8TsHcpSBH4KxVcCJO51Arw5qsKzogaWEy0Sh8LNXau3jWcgepLU084LTyXWljDmOoEpT/NCIkYCvWT4so3WwbAMRA73gloMg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066361; c=relaxed/simple; bh=KEHGx5ZxOwmv3mqRRP4gulTwHNAd9PJT3vm70lAVmY4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ARygTQmK2Ea1GT6zw6wdr6GdvsYtcEKaqKYj+i3LUZmmOoKlcaFfL23BjRkYdgbXho/vWmT9KLoJajYi8yCc9zLTe4c/IhXwjvVRuwIwOMAp7dclMgY7T9uqNW+Hbdvs/mKJuEpTuHAovWIeXS85d+FS5ddvlOEd0eunSyVITBw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GMhwOui6; 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="GMhwOui6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 288A7C4CECC; Fri, 4 Oct 2024 18:25:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728066360; bh=KEHGx5ZxOwmv3mqRRP4gulTwHNAd9PJT3vm70lAVmY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GMhwOui6NifvV0XMnaswzCogywNQ3ugAmVOhFFYu19hf2Da/RyF6pVYdUOqniqVs8 wsaC0GjhyE0JQzKY+BqE5dzv2nVK++UZgYbbbMVuc38HMgS/uu60Djcv2Yxl1iNSvX ReVrBu6ZUHgOXWcK46C3XkrC40mcACe3RoRH3FAaydjHTM8z4lKCa3QnMq5gogPRGv KBG8IIxkTLWvlDpFLB10CksvOjSByYhaShfirlZ7FzFtCWRbpdJlIIIZ5sqEYw0dQ5 DweFebealMUilmhzrk0XVQS+9iRKGDImPA7jDMGyWOYoZRyZrTTLYI7e052jmIJPkh Z8EomJy/lpF7w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jisheng Zhang , Cyril Bur , Palmer Dabbelt , Sasha Levin , paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, samitolvanen@google.com, cleger@rivosinc.com, guoren@kernel.org, antonb@tenstorrent.com, debug@rivosinc.com, andy.chiu@sifive.com, linux-riscv@lists.infradead.org Subject: [PATCH AUTOSEL 6.6 32/58] riscv: avoid Imbalance in RAS Date: Fri, 4 Oct 2024 14:24:05 -0400 Message-ID: <20241004182503.3672477-32-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241004182503.3672477-1-sashal@kernel.org> References: <20241004182503.3672477-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.54 Content-Transfer-Encoding: 8bit From: Jisheng Zhang [ Upstream commit 8f1534e7440382d118c3d655d3a6014128b2086d ] Inspired by[1], modify the code to remove the code of modifying ra to avoid imbalance RAS (return address stack) which may lead to incorret predictions on return. Link: https://lore.kernel.org/linux-riscv/20240607061335.2197383-1-cyrilbur@tenstorrent.com/ [1] Signed-off-by: Jisheng Zhang Reviewed-by: Cyril Bur Link: https://lore.kernel.org/r/20240720170659.1522-1-jszhang@kernel.org Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin --- arch/riscv/kernel/entry.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index ed7baf2cf7e87..1f90fee24a8ba 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -219,8 +219,8 @@ SYM_CODE_START(ret_from_fork) jalr s0 1: move a0, sp /* pt_regs */ - la ra, ret_from_exception - tail syscall_exit_to_user_mode + call syscall_exit_to_user_mode + j ret_from_exception SYM_CODE_END(ret_from_fork) /* -- 2.43.0