From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (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 769C6146A66 for ; Fri, 3 May 2024 07:56:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=150.107.74.76 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714722995; cv=none; b=MkxY2qO+ivke05HkrPG12+5gbaW6Qinsd5HuQZsWriVkNefwEiBIcLNB//QA8ucJZ7DzxOHdBy3cYkvwH0l7sfZbFrFfnyINmP15F1IkNAw2nGhezerBzUVyftNdtkpeQG9AKcOsKpahulD5VFtdgtrAlE503ZNIWq+UttN7hic= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714722995; c=relaxed/simple; bh=ahhzW9dnhyFxRLPS4I3nFGCbkRfNCSQ4XiAAz1KsG3Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IO9IBIZeRVqGKx+T62queMSSdbTmcrbdcgHNb4S0SNo/HjBazGw43jc0b9DyGBfmlBZRAfMzuIPclSRYFdVeYhMhnbeOy03s1BdQG1BM1uan9VgOa9gj/jbmeIedwe4UNXsorVPiHcBaZsAVqN8SZ+zXEj2PIGvAIbOy0EObQwY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au; spf=pass smtp.mailfrom=ellerman.id.au; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b=r/XIi942; arc=none smtp.client-ip=150.107.74.76 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="r/XIi942" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1714722991; bh=Xb4uZcBO3ovCjGUGsxkoEGWYJ/aNPwvO8oVcR3qqzIw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r/XIi94277McCWwhdAjYT+0VYIGkuxJC1N9kJtqfpmvQk3+SScslZAbQFACFSYeI6 NB3gIgPmNKbphACVaJRlSjMBDJAzBN2S1KPYM97FuN00hnwsU2cBdRYPxhYOj8QELX OWR0SM7hphCpZAF+pG4qLmi3kREc6tWjYwwoGmy+AEgVSvWGJ18xPvG6Qyzcp23c0I u+Ge4fn+FBi0ad4ocsY132MiYDsnz5YfILVXbokV/qmHprZ9GO6zw5S+OantsqnlYs eaotmD5tKFbm01PNj2OrOhQ/doOad++5HFX1LR0MwtCj3P9Gl1Rc7brRubF70gyGRl CTixMm84cHeQA== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (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 mail.ozlabs.org (Postfix) with ESMTPSA id 4VW36765XRz4x0v; Fri, 3 May 2024 17:56:31 +1000 (AEST) From: Michael Ellerman To: Cc: , naresh.kamboju@linaro.org, , Subject: [PATCH v2 2/2] powerpc/64: Set _IO_BASE to POISON_POINTER_DELTA not 0 for CONFIG_PCI=n Date: Fri, 3 May 2024 17:56:19 +1000 Message-ID: <20240503075619.394467-2-mpe@ellerman.id.au> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240503075619.394467-1-mpe@ellerman.id.au> References: <20240503075619.394467-1-mpe@ellerman.id.au> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit There is code that builds with calls to IO accessors even when CONFIG_PCI=n, but the actual calls are guarded by runtime checks. If not those calls would be faulting, because the page at virtual address zero is (usually) not mapped into the kernel. As Arnd pointed out, it is possible a large port value could cause the address to be above mmap_min_addr which would then access userspace, which would be a bug. To avoid any such issues, set _IO_BASE to POISON_POINTER_DELTA. That is a value chosen to point into unmapped space between the kernel and userspace, so any access will always fault. Note that on 32-bit POISON_POINTER_DELTA is 0, so the patch only has an effect on 64-bit. Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/io.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) v2: Patch unchanged, changelog updated to reflect patch 1. diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h index ba2e13bb879d..048e3705af20 100644 --- a/arch/powerpc/include/asm/io.h +++ b/arch/powerpc/include/asm/io.h @@ -37,7 +37,7 @@ extern struct pci_dev *isa_bridge_pcidev; * define properly based on the platform */ #ifndef CONFIG_PCI -#define _IO_BASE 0 +#define _IO_BASE POISON_POINTER_DELTA #define _ISA_MEM_BASE 0 #define PCI_DRAM_OFFSET 0 #elif defined(CONFIG_PPC32) -- 2.44.0