From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752766AbdLEMlb (ORCPT ); Tue, 5 Dec 2017 07:41:31 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:47420 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752546AbdLEMl3 (ORCPT ); Tue, 5 Dec 2017 07:41:29 -0500 Message-Id: <20171205123820.337227593@infradead.org> User-Agent: quilt/0.63-1 Date: Tue, 05 Dec 2017 13:34:54 +0100 From: Peter Zijlstra To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Linus Torvalds , Andy Lutomirsky , Peter Zijlstra , Dave Hansen , Borislav Petkov , Greg KH , keescook@google.com, hughd@google.com, Brian Gerst , Josh Poimboeuf , Denys Vlasenko , Rik van Riel , Boris Ostrovsky , Juergen Gross , David Laight , Eduardo Valentin , aliguori@amazon.com, Will Deacon , daniel.gruss@iaik.tugraz.at, Dave Hansen , Ingo Molnar , moritz.lipp@iaik.tugraz.at, linux-mm@kvack.org, Borislav Petkov , michael.schwarz@iaik.tugraz.at, richard.fellner@student.tugraz.at Subject: [PATCH 9/9] x86/doc: Remove obvious weirdness References: <20171205123444.990868007@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-mm-doc.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Peter Zijlstra (Intel) --- Documentation/x86/x86_64/mm.txt | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) --- a/Documentation/x86/x86_64/mm.txt +++ b/Documentation/x86/x86_64/mm.txt @@ -1,6 +1,4 @@ - - Virtual memory map with 4 level page tables: 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm @@ -47,8 +45,9 @@ ffffffffffe00000 - ffffffffffffffff (=2 Architecture defines a 64-bit virtual address. Implementations can support less. Currently supported are 48- and 57-bit virtual addresses. Bits 63 -through to the most-significant implemented bit are set to either all ones -or all zero. This causes hole between user space and kernel addresses. +through to the most-significant implemented bit are sign extended. +This causes hole between user space and kernel addresses if you interpret them +as unsigned. The direct mapping covers all memory in the system up to the highest memory address (this means in some cases it can also include PCI memory @@ -58,9 +57,6 @@ vmalloc space is lazily synchronized int the processes using the page fault handler, with init_top_pgt as reference. -Current X86-64 implementations support up to 46 bits of address space (64 TB), -which is our current limit. This expands into MBZ space in the page tables. - We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual memory window (this size is arbitrary, it can be raised later if needed). The mappings are not part of any other kernel PGD and are only available @@ -72,5 +68,3 @@ following fixmap section. Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all physical memory, vmalloc/ioremap space and virtual memory map are randomized. Their order is preserved but their base will be offset early at boot time. - --Andi Kleen, Jul 2004