From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (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 C0C1035E4F4 for ; Fri, 5 Sep 2025 14:30:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757082612; cv=none; b=qVHCdTQqgdiU4/P1Pp2bV2JAzmX3BMqxRelI/yN/nu4vr7KwRTDC8NaLpUPNxGOxJqRU72OfWKKcyzZJtkDAD+hxgJIcmKrascAWRUT4nZgfWDPg6xI8esHiV2TwTIOvZsuXODHi+uknkjKlEs1VjtEw77lVWS2PV7JfTyiwRl4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757082612; c=relaxed/simple; bh=8za7Led7D4aJfemB4PVED3Zs6Yn9ydiPIUGtGx6Zjn8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WkxNSd19ebNDPeT1yeNqTacIrj9Q4VUgg10NoAsRekE5s6S920VqE+cLADxQz4wU0vUERRlHJldPgEfqmcSrPfTwYvbZgFEh4QmANLWF35L7Y+fg5dADcC6SxGPKvpwpw6XKa/ROFaN5ySGUffvavSlcqOx11/qoQCQlUVDKAto= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=wh9iY/Qv; arc=none smtp.client-ip=80.241.56.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="wh9iY/Qv" Received: from smtp202.mailbox.org (smtp202.mailbox.org [IPv6:2001:67c:2050:b231:465::202]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4cJJf56Q90z9sTl; Fri, 5 Sep 2025 16:30:05 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1757082605; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ev4jgj8g0fTNZJltLUp+cJJPga8rWwR8rDlO94sZYmI=; b=wh9iY/QvbGvwg28pN/htEhvEiWKV2zp9ojU3BF39AiKc1X+fq9ANWtEHWntHkW4PY78st2 vFbr3XsShutGe/ye/N/o0Ml/ynD+GZ53HefAP/7Py6wG/25KSrNK8wno1k3ss8ADPaEQHA itTsE27PiSnMDJtkkcqvIHLuLk+JdgJ6Xn2PEiB/Zum+sz2Icx8XZlNdknxu5K7OdFeuJf iv/2/U7zg7y7wcKEF2cRkJ4zckjRug7O5ftGKw1Bj1LfXjn2/RbEJDg7SaiUy5UKCGk8OZ ifUjqKIetJzWHMIXaCUGT7Q81iUxsqV9rrmbO0BHKMPMPLwtNQZ5vCKQKt9IEA== Message-ID: <8918c4b9-5156-4b9a-83cb-d1d4856ae48d@mailbox.org> Date: Fri, 5 Sep 2025 16:30:02 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] powerpc/32: Remove PAGE_KERNEL_TEXT to fix startup failure To: Christophe Leroy , Andrew Donnellan , Michael Ellerman , Nicholas Piggin , Madhavan Srinivasan Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <342b4120-911c-4723-82ec-d8c9b03a8aef@mailbox.org> <4b5e6eb281d7b1ea77619bee17095f905a125168.1757003584.git.christophe.leroy@csgroup.eu> Content-Language: en-US, de-DE From: Erhard Furtner In-Reply-To: <4b5e6eb281d7b1ea77619bee17095f905a125168.1757003584.git.christophe.leroy@csgroup.eu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-MBO-RS-META: 1ysqxpzg7idqdqmdink5xg9ag6hqs4sn X-MBO-RS-ID: c4f9d3b81d940f5d21c On 9/4/25 18:33, Christophe Leroy wrote: > PAGE_KERNEL_TEXT is an old macro that is used to tell kernel whether > kernel text has to be mapped read-only or read-write based on build > time options. > > But nowadays, with functionnalities like jump_labels, static links, > etc ... more only less all kernels need to be read-write at some > point, and some combinations of configs failed to work due to > innacurate setting of PAGE_KERNEL_TEXT. On the other hand, today > we have CONFIG_STRICT_KERNEL_RWX which implements a more controlled > access to kernel modifications. > > Instead of trying to keep PAGE_KERNEL_TEXT accurate with all > possible options that may imply kernel text modification, always > set kernel text read-write at startup and rely on > CONFIG_STRICT_KERNEL_RWX to provide accurate protection. I can confirm your patch fixes the startup failure for my G4 .config. Thanks! Regards, Erhard > Reported-by: Erhard Furtner > Closes: https://lore.kernel.org/all/342b4120-911c-4723-82ec-d8c9b03a8aef@mailbox.org/ > Signed-off-by: Christophe Leroy > --- > arch/powerpc/include/asm/pgtable.h | 12 ------------ > arch/powerpc/mm/book3s32/mmu.c | 4 ++-- > arch/powerpc/mm/pgtable_32.c | 2 +- > 3 files changed, 3 insertions(+), 15 deletions(-) > > diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h > index 93d77ad5a92f..d8f944a5a037 100644 > --- a/arch/powerpc/include/asm/pgtable.h > +++ b/arch/powerpc/include/asm/pgtable.h > @@ -20,18 +20,6 @@ struct mm_struct; > #include > #endif /* !CONFIG_PPC_BOOK3S */ > > -/* > - * Protection used for kernel text. We want the debuggers to be able to > - * set breakpoints anywhere, so don't write protect the kernel text > - * on platforms where such control is possible. > - */ > -#if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) || \ > - defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE) > -#define PAGE_KERNEL_TEXT PAGE_KERNEL_X > -#else > -#define PAGE_KERNEL_TEXT PAGE_KERNEL_ROX > -#endif > - > /* Make modules code happy. We don't set RO yet */ > #define PAGE_KERNEL_EXEC PAGE_KERNEL_X > > diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c > index be9c4106e22f..c42ecdf94e48 100644 > --- a/arch/powerpc/mm/book3s32/mmu.c > +++ b/arch/powerpc/mm/book3s32/mmu.c > @@ -204,7 +204,7 @@ int mmu_mark_initmem_nx(void) > > for (i = 0; i < nb - 1 && base < top;) { > size = bat_block_size(base, top); > - setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT); > + setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_X); > base += size; > } > if (base < top) { > @@ -215,7 +215,7 @@ int mmu_mark_initmem_nx(void) > pr_warn("Some RW data is getting mapped X. " > "Adjust CONFIG_DATA_SHIFT to avoid that.\n"); > } > - setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT); > + setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_X); > base += size; > } > for (; i < nb; i++) > diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c > index 15276068f657..0c9ef705803e 100644 > --- a/arch/powerpc/mm/pgtable_32.c > +++ b/arch/powerpc/mm/pgtable_32.c > @@ -104,7 +104,7 @@ static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top) > p = memstart_addr + s; > for (; s < top; s += PAGE_SIZE) { > ktext = core_kernel_text(v); > - map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL); > + map_kernel_page(v, p, ktext ? PAGE_KERNEL_X : PAGE_KERNEL); > v += PAGE_SIZE; > p += PAGE_SIZE; > }