lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 04 Nov 2022 21:16:19 +0100 From: "Arnd Bergmann" <arnd@...db.de> To: "Giulio Benetti" <giulio.benetti@...ettiengineering.com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Cc: "Russell King" <linux@...linux.org.uk>, "Anshuman Khandual" <anshuman.khandual@....com>, "Andrew Morton" <akpm@...ux-foundation.org>, "Kefeng Wang" <wangkefeng.wang@...wei.com>, "Russell King" <rmk+kernel@...linux.org.uk>, "Will Deacon" <will@...nel.org> Subject: Re: [PATCH v2 1/2] ARM: mm: fix no-MMU ZERO_PAGE() implementation On Wed, Oct 19, 2022, at 00:25, Giulio Benetti wrote: > Actually in no-MMU SoCs(i.e. i.MXRT) ZERO_PAGE(vaddr) expands to > ``` > virt_to_page(0) > ``` > that in order expands to: > ``` > pfn_to_page(virt_to_pfn(0)) > ``` > and then virt_to_pfn(0) to: > ``` > #define virt_to_pfn(0) \ > ((((unsigned long)(0) - PAGE_OFFSET) >> PAGE_SHIFT) + \ > PHYS_PFN_OFFSET) > ``` > where PAGE_OFFSET and PHYS_PFN_OFFSET are the DRAM offset(0x80000000) and > PAGE_SHIFT is 12. This way we obtain 16MB(0x01000000) summed to the base of > DRAM(0x80000000). > When ZERO_PAGE(0) is then used, for example in bio_add_page(), the page > gets an address that is out of DRAM bounds. > So instead of using fake virtual page 0 let's allocate a dedicated > zero_page during paging_init() and assign it to a global 'struct page * > empty_zero_page' the same way mmu.c does and it's the same approach used > in m68k with commit dc068f462179 as discussed here[0]. Then let's move > ZERO_PAGE() definition to the top of pgtable.h to be in common between > mmu.c and nommu.c. > > [0]: > https://lore.kernel.org/linux-m68k/2a462b23-5b8e-bbf4-ec7d-778434a3b9d7@google.com/T/#m1266ceb63ad140743174d6b3070364d3c9a5179b > > Signed-off-by: Giulio Benetti <giulio.benetti@...ettiengineering.com> Reviewed-by: Arnd Bergmann <arnd@...db.de>
Powered by blists - more mailing lists