From: Kevin Brodsky <kevin.brodsky@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>,
Ard Biesheuvel <ardb+git@google.com>,
linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ryan Roberts <ryan.roberts@arm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Liz Prucka <lizprucka@google.com>,
Seth Jenkins <sethjenkins@google.com>,
Kees Cook <kees@kernel.org>, Mike Rapoport <rppt@kernel.org>,
David Hildenbrand <david@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v4 12/15] arm64: mm: Map the kernel data/bss read-only in the linear map
Date: Mon, 4 May 2026 10:50:17 +0200 [thread overview]
Message-ID: <49eb450b-0045-4add-b993-a8b518514c34@arm.com> (raw)
In-Reply-To: <9ff1d19d-f3f8-4106-aeeb-66c4c21742b9@app.fastmail.com>
On 29/04/2026 16:46, Ard Biesheuvel wrote:
>>> @@ -1155,7 +1157,11 @@ static void __init map_mem(void)
>>> * of the region accessible to subsystems such as hibernate,
>>> * but protects it from inadvertent modification or execution.
>>> */
>>> - __map_memblock(kernel_start, kernel_end, pgprot_tagged(PAGE_KERNEL),
>>> + __map_memblock(kernel_start, init_begin, pgprot_tagged(PAGE_KERNEL),
>>> + flags);
>>> +
>>> + /* Map the kernel data/bss so it can be remapped later */
>>> + __map_memblock(init_end, kernel_end, pgprot_tagged(PAGE_KERNEL),
>> Maybe I'm missing something obvious, but considering patch 3/4 couldn't
>> we directly map the range RO here?
>>
> After 3/4, __map_memblock() will no longer combine new mappings with existing
> ones into block mappings or contiguous ranges. However, it will still set the
> requested type and permission attributes on the entire range, and so the second
> invocation is needed to restore the read-only bit.
>
> IOW, we could also map it read-only twice, the result would be the same, but the
> second call is still needed.
Got it, thanks.
- Kevin
next prev parent reply other threads:[~2026-05-04 8:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 15:34 [PATCH v4 00/15] arm64: Unmap linear alias of kernel data/bss Ard Biesheuvel
2026-04-27 15:34 ` [PATCH v4 01/15] arm64: mm: Map the linear alias of text/rodata as tagged Ard Biesheuvel
2026-04-28 14:16 ` Kevin Brodsky
2026-04-28 16:23 ` Ard Biesheuvel
2026-04-29 7:57 ` Kevin Brodsky
2026-04-29 7:58 ` Ard Biesheuvel
2026-04-27 15:34 ` [PATCH v4 02/15] mm: Make empty_zero_page __ro_after_init Ard Biesheuvel
2026-04-28 12:27 ` Mike Rapoport
2026-04-28 14:16 ` Kevin Brodsky
2026-04-28 19:51 ` David Hildenbrand (Arm)
2026-04-27 15:34 ` [PATCH v4 03/15] arm64: mm: Preserve existing table mappings when mapping DRAM Ard Biesheuvel
2026-04-27 15:34 ` [PATCH v4 04/15] arm64: mm: Preserve non-contiguous descriptors " Ard Biesheuvel
2026-04-27 15:34 ` [PATCH v4 05/15] arm64: mm: Remove bogus stop condition from map_mem() loop Ard Biesheuvel
2026-04-28 14:33 ` Kevin Brodsky
2026-04-27 15:34 ` [PATCH v4 06/15] arm64: mm: Drop redundant pgd_t* argument from map_mem() Ard Biesheuvel
2026-04-28 14:33 ` Kevin Brodsky
2026-04-27 15:34 ` [PATCH v4 07/15] arm64: mm: Permit contiguous descriptors to be rewritten Ard Biesheuvel
2026-04-27 15:34 ` [PATCH v4 08/15] arm64: kfence: Avoid NOMAP tricks when mapping the early pool Ard Biesheuvel
2026-04-27 15:34 ` [PATCH v4 09/15] arm64: mm: Permit contiguous attribute for preliminary mappings Ard Biesheuvel
2026-04-27 15:34 ` [PATCH v4 10/15] arm64: Move fixmap page tables to end of kernel image Ard Biesheuvel
2026-04-29 13:52 ` Kevin Brodsky
2026-04-27 15:34 ` [PATCH v4 11/15] arm64: mm: Don't abuse memblock NOMAP to check for overlaps Ard Biesheuvel
2026-04-29 10:54 ` Kevin Brodsky
2026-04-29 14:23 ` Ard Biesheuvel
2026-04-29 14:30 ` Kevin Brodsky
2026-04-27 15:34 ` [PATCH v4 12/15] arm64: mm: Map the kernel data/bss read-only in the linear map Ard Biesheuvel
2026-04-29 13:54 ` Kevin Brodsky
2026-04-29 14:46 ` Ard Biesheuvel
2026-05-04 8:50 ` Kevin Brodsky [this message]
2026-04-27 15:34 ` [PATCH v4 13/15] arm64: mm: Unmap kernel data/bss entirely from " Ard Biesheuvel
2026-04-29 13:55 ` Kevin Brodsky
2026-04-29 17:37 ` Ard Biesheuvel
2026-05-04 8:52 ` Kevin Brodsky
2026-04-27 15:34 ` [PATCH v4 14/15] arm64: mm: Generalize manipulation code of read-only descriptors Ard Biesheuvel
2026-04-29 13:57 ` Kevin Brodsky
2026-04-27 15:34 ` [PATCH v4 15/15] arm64: mm: Remap linear aliases of the fixmap page tables read-only Ard Biesheuvel
2026-04-29 13:57 ` Kevin Brodsky
2026-04-29 14:08 ` Ard Biesheuvel
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