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 CEA7D40F742 for ; Mon, 12 Oct 2026 10:28:42 +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=1791800930; cv=none; b=hjiHITjvRtIoj/uKC6E/Xl1suW8GGX25rs3NyP298bYUYUoOaOoNr1MCZZmiZmnHHLnuy/pkNWdqyFlGro2vQ1FgEzH8xmfK46EoS2woogIBMFybP27C9m+E6EtnhEW/b5iFCpsQnsq2ZexZ59JkSwC6id3PGf/+ct4EAGrBXfo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791800930; c=relaxed/simple; bh=pO+qG2ZW1LdcFAtcDiFa+a5tDPpp8nUfhYBPsy6rAp0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ZbxvFD8pOPKXaK3ipqFUD2/GqoA3la6nB494o/Z+FSyK72f+a51t/M8aZB8wnXnCawQQV4LC+MOPly0+oCqdmMfj7tR3BovBos2DlelGqvjN8dJP9XwgtcUqHtGz5XiO1xSXArYqPzSLasH7m/U8Ossjo+EliiKpFVzcUM1M8Gg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=K1/3XoFu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="K1/3XoFu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A54D1F0089B; Mon, 12 Oct 2026 10:28:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791800922; bh=9SqsLlEeY8Z7JWwzaLCKZ/Afkt3yxtAt34Q/0TSpfLw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=K1/3XoFuG4eFCz4OgQUA5uvMw5WFNnU7QPlivAAaTatqVPi3cfWD+k64Z4caemYUQ 6iP+1uGhOTfGoAspZ0yAGGysurE2NeOJ5wN6/EHkGksFKdoIM+uwlBCHyYUb4vQl6Z OhASdimiqXso6Xgzsh0CMCMLrSLqqjdSjcJnYJYdeDH1Yelk49tF+ucS16RTNOvZTZ 7fpBuvNP3YxfABcb0X+tOBjhQ9+eaKVdyHibNaedLJi5idk6wxyUPKS8nCf1fLcoF0 uBY1H99GdHtmZaqphKNxl+QzSIWXXDfgm3VT2qELvVg9XmWjkeVJJtRzqTyryR1qV4 P/gDk2LoIF8mQ== Message-ID: Date: Mon, 12 Oct 2026 12:28:37 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] powerpc/Kconfig: limit the PPC_85xx DATA_SHIFT range to STRICT_KERNEL_RWX To: Julian Braha , maddy@linux.ibm.com Cc: mpe@ellerman.id.au, npiggin@gmail.com, ritesh.list@gmail.com, sshegde@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20261011113108.539470-1-julianbraha@gmail.com> Content-Language: fr-FR From: "Christophe Leroy (CS GROUP)" In-Reply-To: <20261011113108.539470-1-julianbraha@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 11/10/2026 à 13:31, Julian Braha a écrit : > On PPC_85xx, enabling DEBUG_PAGEALLOC without STRICT_KERNEL_RWX activates > the DATA_SHIFT range of 20..24, but since the PAGE_SHIFT default is > outside the range (12), kconfig adjusts it to 20, causing 1mb alignment > instead of 4kb. However, the larger alignment is only needed for the > separate kernel permissions provided by STRICT_KERNEL_RWX. > > Since PPC_85xx uses page poisoning for DEBUG_PAGEALLOC and does not > support KFENCE, let's restrict this range to STRICT_KERNEL_RWX. > > This out-of-range default was detected by kconfirm, a static analysis tool > for Kconfig. Looks like with this change I'm now able to set DATA_SHIFT to any value when STRICT_KERNEL_RWX is not set and DEBUG_PAGEALLOC is set. The range used to protect against that. > > Signed-off-by: Julian Braha > --- > arch/powerpc/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index c3b6cd655606..5e2a4799438d 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -896,7 +896,7 @@ config DATA_SHIFT > default 24 if STRICT_KERNEL_RWX && PPC64 > range 17 28 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC || KFENCE) && PPC_BOOK3S_32 > range 14 23 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC || KFENCE) && PPC_8xx > - range 20 24 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC || KFENCE) && PPC_85xx > + range 20 24 if STRICT_KERNEL_RWX && PPC_85xx > default 22 if STRICT_KERNEL_RWX && PPC_BOOK3S_32 > default 18 if (DEBUG_PAGEALLOC || KFENCE) && PPC_BOOK3S_32 > default 23 if (STRICT_KERNEL_RWX || DEBUG_PAGEALLOC || KFENCE) && PPC_8xx && \