From: Nadav Amit <namit@vmware.com>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
Andrea Arcangeli <aarcange@redhat.com>,
"luto@kernel.org" <luto@kernel.org>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
"keescook@google.com" <keescook@google.com>,
"hughd@google.com" <hughd@google.com>,
"jgross@suse.com" <jgross@suse.com>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH 05/11] x86/mm: do not auto-massage page protections
Date: Fri, 23 Mar 2018 19:15:55 +0000 [thread overview]
Message-ID: <224464E0-1D3A-4ED8-88E0-A8E84C4265FC@vmware.com> (raw)
In-Reply-To: <20180323174454.CD00F614@viggo.jf.intel.com>
Dave Hansen <dave.hansen@linux.intel.com> wrote:
>
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> A PTE is constructed from a physical address and a pgprotval_t.
> __PAGE_KERNEL, for instance, is a pgprot_t and must be converted
> into a pgprotval_t before it can be used to create a PTE. This is
> done implicitly within functions like set_pte() by massage_pgprot().
>
> However, this makes it very challenging to set bits (and keep them
> set) if your bit is being filtered out by massage_pgprot().
>
> This moves the bit filtering out of set_pte() and friends. For
I don’t see that set_pte() filters the bits, so I am confused by this
sentence...
> +static inline pgprotval_t check_pgprot(pgprot_t pgprot)
> +{
> + pgprotval_t massaged_val = massage_pgprot(pgprot);
> +
> + /* mmdebug.h can not be included here because of dependencies */
> +#ifdef CONFIG_DEBUG_VM
> + WARN_ONCE(pgprot_val(pgprot) != massaged_val,
> + "attempted to set unsupported pgprot: %016lx "
> + "bits: %016lx supported: %016lx\n",
> + pgprot_val(pgprot),
> + pgprot_val(pgprot) ^ massaged_val,
> + __supported_pte_mask);
> +#endif
Why not to use VM_WARN_ON_ONCE() and avoid the ifdef?
next prev parent reply other threads:[~2018-03-23 19:15 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-23 17:44 [PATCH 00/11] Use global pages with PTI Dave Hansen
2018-03-23 17:44 ` [PATCH 01/11] x86/mm: factor out pageattr _PAGE_GLOBAL setting Dave Hansen
2018-03-23 17:44 ` [PATCH 02/11] x86/mm: undo double _PAGE_PSE clearing Dave Hansen
2018-03-23 17:44 ` [PATCH 03/11] x86/mm: introduce "default" kernel PTE mask Dave Hansen
2018-03-23 17:44 ` [PATCH 04/11] x86/espfix: document use of _PAGE_GLOBAL Dave Hansen
2018-03-23 17:44 ` [PATCH 05/11] x86/mm: do not auto-massage page protections Dave Hansen
2018-03-23 19:15 ` Nadav Amit [this message]
2018-03-23 19:26 ` Dave Hansen
2018-03-23 19:34 ` Nadav Amit
2018-03-23 19:38 ` Dave Hansen
2018-03-24 15:10 ` kbuild test robot
2018-03-24 15:21 ` kbuild test robot
2018-03-23 17:44 ` [PATCH 06/11] x86/mm: remove extra filtering in pageattr code Dave Hansen
2018-03-23 17:44 ` [PATCH 07/11] x86/mm: comment _PAGE_GLOBAL mystery Dave Hansen
2018-03-23 17:44 ` [PATCH 08/11] x86/mm: do not forbid _PAGE_RW before init for __ro_after_init Dave Hansen
2018-03-23 17:45 ` [PATCH 09/11] x86/pti: enable global pages for shared areas Dave Hansen
2018-03-23 19:12 ` Nadav Amit
2018-03-23 19:36 ` Dave Hansen
2018-03-23 17:45 ` [PATCH 10/11] x86/pti: clear _PAGE_GLOBAL for kernel image Dave Hansen
2018-03-23 17:45 ` [PATCH 11/11] x86/pti: leave kernel text global for !PCID Dave Hansen
2018-03-23 18:26 ` [PATCH 00/11] Use global pages with PTI Linus Torvalds
2018-03-24 0:40 ` Dave Hansen
2018-03-24 0:46 ` Linus Torvalds
2018-03-24 0:54 ` Linus Torvalds
2018-03-24 11:05 ` Ingo Molnar
2018-03-27 13:36 ` Thomas Gleixner
2018-03-27 16:32 ` Dave Hansen
2018-03-27 17:51 ` Thomas Gleixner
2018-03-27 20:07 ` Ingo Molnar
2018-03-27 20:19 ` Dave Hansen
2018-03-29 0:17 ` Dave Hansen
2018-03-30 12:09 ` Ingo Molnar
2018-03-30 12:17 ` Ingo Molnar
2018-03-30 20:26 ` Dave Hansen
2018-03-30 20:32 ` Thomas Gleixner
2018-03-30 21:40 ` Dave Hansen
2018-03-31 5:39 ` Ingo Molnar
2018-03-31 18:19 ` Dave Hansen
2018-04-02 17:27 [PATCH 00/11] [v3] " Dave Hansen
2018-04-02 17:27 ` [PATCH 05/11] x86/mm: do not auto-massage page protections Dave Hansen
2018-04-04 1:09 [PATCH 00/11] [v4] Use global pages with PTI Dave Hansen
2018-04-04 1:09 ` [PATCH 05/11] x86/mm: do not auto-massage page protections Dave Hansen
2018-04-05 19:49 ` Tom Lendacky
2018-04-06 20:55 [PATCH 00/11] [v5] Use global pages with PTI Dave Hansen
2018-04-06 20:55 ` [PATCH 05/11] x86/mm: do not auto-massage page protections Dave Hansen
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