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Message-ID: <56157F60.1000503@sr71.net> Date: Wed, 7 Oct 2015 13:24:00 -0700 From: Dave Hansen <dave@...1.net> To: Ingo Molnar <mingo@...nel.org> Cc: x86@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, Linus Torvalds <torvalds@...ux-foundation.org>, Andrew Morton <akpm@...ux-foundation.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>, Kees Cook <keescook@...gle.com>, Brian Gerst <brgerst@...il.com> Subject: Re: [PATCH 26/26] x86, pkeys: Documentation On 10/03/2015 01:17 AM, Ingo Molnar wrote: > Right now the native x86 PTE format allows two protection related bits for > user-space pages: > > _PAGE_BIT_RW: if 0 the page is read-only, if 1 then it's read-write > _PAGE_BIT_NX: if 0 the page is executable, if 1 then it's not executable > > As discussed previously, pkeys allows 'true execute only (--x)' mappings. > > Another possibility would be 'true write-only (-w-)' mappings. How would those work? Protection Keys has a Write-Disable and an Access-Disable bit. But, Access-Disable denies _all_ data access to the region. There's no way to allow only writes. Or am I missing something? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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