From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 3FFC12D94B5; Tue, 13 Oct 2026 12:44:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791895467; cv=none; b=JYBnsHWaMIURl0ouxLtNuhYNFLKqdR45ZkuFKKoQ1EdIm+HOttAhNnS1LgVa7PpgPv9k7+c06Yd7rog/x7mhnMTEdxpq4+pDqH8GaIfoaB6TAKzI6tCezBlQjyoAJJw+IQU6fg9RgTyv17l7SdKfXFFm6M0Lxbof0vC5WJ6aQFg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791895467; c=relaxed/simple; bh=dfZc9mNszvoGDlqdhPP62S4GO+QhzAJBA24z49dTHG4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QpTodFyewyZRlPcAFvA0++Z4x2aywi+qMDRi7vjKv2EcAsQewfKIW5PIidxGe9X3OLxYLNdP+WFNlb0hijXE9DpbqcxrklQ11EfV6ycQQ+O4/C3qLUQEfON41fjmkpmP8c2Tr4f/4TqANKi8Jp3A0gav9zPi2Xd3n/HVx9uAxOk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gGfRlLhp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gGfRlLhp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BFF61F000FF; Tue, 13 Oct 2026 12:44:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791895465; bh=1bj5hVunOU3EYUwtaPKaouQZvNogTZNTx6LJd4NvKkU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gGfRlLhpl5arxxE9KSBy47kEU5wgM3QEFT4rrDt9Z3RifAzoCoRimYbQxe6WoXZnR jNACwO5Aj1xJYPViSi/Mf6oKX1eKXuduGbvJrMv2kVwO4vjQttXOEynxYpS8KY3aef qWuwJFase4t2SY5vU4uoAdWr3kcH9DzrJCWWGjM0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Will Deacon , Mark Rutland , Catalin Marinas , Marc Zyngier , Mark Brown , Sasha Levin Subject: [PATCH 6.12 285/497] arm64/fpsimd: signal: Consistently read FPSIMD context Date: Tue, 13 Oct 2026 13:37:32 +0200 Message-ID: <20261013112914.660106209@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112907.864180619@linuxfoundation.org> References: <20261013112907.864180619@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Rutland [ Upstream commit be625d803c3bbfa9652697eb57589fe6f2f24b89 ] For historical reasons, restore_sve_fpsimd_context() has an open-coded copy of the logic from read_fpsimd_context(), which is used to either restore an FPSIMD-only context, or to merge FPSIMD state into an SVE state when restoring an SVE+FPSIMD context. The logic is *almost* identical. Refactor the logic to avoid duplication and make this clearer. This comes with two functional changes that I do not believe will be problematic in practice: * The user_fpsimd_state::size field will be checked in all restore paths that consume it user_fpsimd_state. The kernel always populates this field when delivering a signal, and so this should contain the expected value unless it has been corrupted. * If a read of user_fpsimd_state fails, we will return early without modifying TIF_SVE, the saved SVCR, or the save fp_type. This will leave the task in a consistent state, without potentially resurrecting stale FPSIMD state. A read of user_fpsimd_state should never fail unless the structure has been corrupted or the stack has been unmapped. Suggested-by: Will Deacon Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Marc Zyngier Cc: Mark Brown Cc: Will Deacon Link: https://lore.kernel.org/r/20250508132644.1395904-5-mark.rutland@arm.com [will: Ensure read_fpsimd_context() returns negative error code or zero] Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/signal.c | 57 +++++++++++++++++++------------------- 1 file changed, 29 insertions(+), 28 deletions(-) diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index fc817154e8990..02ec2aa171453 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -262,30 +262,40 @@ static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) return err ? -EFAULT : 0; } -static int restore_fpsimd_context(struct user_ctxs *user) +static int read_fpsimd_context(struct user_fpsimd_state *fpsimd, + struct user_ctxs *user) { - struct user_fpsimd_state fpsimd; - int err = 0; + int err; /* check the size information */ if (user->fpsimd_size != sizeof(struct fpsimd_context)) return -EINVAL; /* copy the FP and status/control registers */ - err = __copy_from_user(fpsimd.vregs, &(user->fpsimd->vregs), - sizeof(fpsimd.vregs)); - __get_user_error(fpsimd.fpsr, &(user->fpsimd->fpsr), err); - __get_user_error(fpsimd.fpcr, &(user->fpsimd->fpcr), err); + err = __copy_from_user(fpsimd->vregs, &(user->fpsimd->vregs), + sizeof(fpsimd->vregs)); + __get_user_error(fpsimd->fpsr, &(user->fpsimd->fpsr), err); + __get_user_error(fpsimd->fpcr, &(user->fpsimd->fpcr), err); + + return err ? -EFAULT : 0; +} + +static int restore_fpsimd_context(struct user_ctxs *user) +{ + struct user_fpsimd_state fpsimd; + int err; + + err = read_fpsimd_context(&fpsimd, user); + if (err) + return err; clear_thread_flag(TIF_SVE); current->thread.svcr &= ~SVCR_SM_MASK; current->thread.fp_type = FP_STATE_FPSIMD; /* load the hardware registers from the fpsimd_state structure */ - if (!err) - fpsimd_update_current_state(&fpsimd); - - return err ? -EFAULT : 0; + fpsimd_update_current_state(&fpsimd); + return 0; } static int preserve_fpmr_context(struct fpmr_context __user *ctx) @@ -432,12 +442,8 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user) * consistency and robustness, reject restoring streaming SVE state * without an SVE payload. */ - if (!sm && user->sve_size == sizeof(*user->sve)) { - clear_thread_flag(TIF_SVE); - current->thread.svcr &= ~SVCR_SM_MASK; - current->thread.fp_type = FP_STATE_FPSIMD; - goto fpsimd_only; - } + if (!sm && user->sve_size == sizeof(*user->sve)) + return restore_fpsimd_context(user); vq = sve_vq_from_vl(vl); @@ -473,19 +479,14 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user) set_thread_flag(TIF_SVE); current->thread.fp_type = FP_STATE_SVE; -fpsimd_only: - /* copy the FP and status/control registers */ - /* restore_sigframe() already checked that user->fpsimd != NULL. */ - err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs, - sizeof(fpsimd.vregs)); - __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err); - __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err); + err = read_fpsimd_context(&fpsimd, user); + if (err) + return err; - /* load the hardware registers from the fpsimd_state structure */ - if (!err) - fpsimd_update_current_state(&fpsimd); + /* Merge the FPSIMD registers into the SVE state */ + fpsimd_update_current_state(&fpsimd); - return err ? -EFAULT : 0; + return 0; } #else /* ! CONFIG_ARM64_SVE */ -- 2.53.0