From: Ard Biesheuvel <ardb@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-hardening@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Mark Brown <broonie@kernel.org>,
Anshuman Khandual <anshuman.khandual@arm.com>
Subject: Re: [PATCH v4 22/26] arm64: mm: move ro_after_init section into the data segment
Date: Thu, 16 Jun 2022 18:31:55 +0200 [thread overview]
Message-ID: <CAMj1kXG8mWVkrGtb-eSASrOBK4BiMF1b5XUui2cVt33xi23Mwg@mail.gmail.com> (raw)
In-Reply-To: <202206160917.D7DB8221@keescook>
On Thu, 16 Jun 2022 at 18:18, Kees Cook <keescook@chromium.org> wrote:
>
> On Thu, Jun 16, 2022 at 01:31:23PM +0200, Ard Biesheuvel wrote:
> > We used to have
> >
> > text
> > --
> > rodata
> > (ro_after_init)
> > --
> > inittext
> > --
> > initdata
> > --
> > data
> > bss
> >
> > where -- are the segment boundaries, which are always aligned to 64k on arm64
> >
> > After this patch, we get
> >
> > text
> > --
> > rodata
> > --
> > inittext
> > --
> > initdata
> > --
> > (ro_after_init)
> > data
> > bss
> >
> > so in terms of padding due to alignment, there is not a lot of difference.
>
> But how is ro_after_init read-only and data isn't, if there isn't a
> segment alignment to make that work out?
>
Actually, there is a segment alignment between ro_after_init and data
- my diagram is inaccurate. But we don't actually need that to remap
this slice of memory r/o
next prev parent reply other threads:[~2022-06-16 16:32 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-13 14:45 [PATCH v4 00/26] arm64: refactor boot flow and add support for WXN Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 01/26] arm64: head: move kimage_vaddr variable into C file Ard Biesheuvel
2022-06-14 8:26 ` Anshuman Khandual
2022-06-13 14:45 ` [PATCH v4 02/26] arm64: mm: make vabits_actual a build time constant if possible Ard Biesheuvel
2022-06-14 8:25 ` Anshuman Khandual
2022-06-14 8:34 ` Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 03/26] arm64: head: move assignment of idmap_t0sz to C code Ard Biesheuvel
2022-06-14 9:22 ` Anshuman Khandual
2022-06-14 9:34 ` Ard Biesheuvel
2022-06-24 12:36 ` Will Deacon
2022-06-24 12:57 ` Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 04/26] arm64: head: drop idmap_ptrs_per_pgd Ard Biesheuvel
2022-06-15 4:07 ` Anshuman Khandual
2022-06-13 14:45 ` [PATCH v4 05/26] arm64: head: simplify page table mapping macros (slightly) Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 06/26] arm64: head: switch to map_memory macro for the extended ID map Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 07/26] arm64: head: split off idmap creation code Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 08/26] arm64: kernel: drop unnecessary PoC cache clean+invalidate Ard Biesheuvel
2022-06-15 4:32 ` Anshuman Khandual
2022-06-13 14:45 ` [PATCH v4 09/26] arm64: head: pass ID map root table address to __enable_mmu() Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 10/26] arm64: mm: provide idmap pointer to cpu_replace_ttbr1() Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 11/26] arm64: head: add helper function to remap regions in early page tables Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 12/26] arm64: head: cover entire kernel image in initial ID map Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 13/26] arm64: head: use relative references to the RELA and RELR tables Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 14/26] arm64: head: create a temporary FDT mapping in the initial ID map Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 15/26] arm64: idreg-override: use early FDT mapping in " Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 16/26] arm64: head: factor out TTBR1 assignment into a macro Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 17/26] arm64: head: populate kernel page tables with MMU and caches on Ard Biesheuvel
2022-06-24 12:56 ` Will Deacon
2022-06-24 13:07 ` Ard Biesheuvel
2022-06-24 13:29 ` Will Deacon
2022-06-24 14:07 ` Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 18/26] arm64: head: record CPU boot mode after enabling the MMU Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 19/26] arm64: kaslr: defer initialization to late initcall where permitted Ard Biesheuvel
2022-06-24 13:08 ` Will Deacon
2022-06-24 13:09 ` Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 20/26] arm64: head: avoid relocating the kernel twice for KASLR Ard Biesheuvel
2022-06-24 13:16 ` Will Deacon
2022-06-24 13:17 ` Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 21/26] arm64: setup: drop early FDT pointer helpers Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 22/26] arm64: mm: move ro_after_init section into the data segment Ard Biesheuvel
2022-06-13 17:00 ` Kees Cook
2022-06-13 17:16 ` Ard Biesheuvel
2022-06-13 23:38 ` Kees Cook
2022-06-16 11:31 ` Ard Biesheuvel
2022-06-16 16:18 ` Kees Cook
2022-06-16 16:31 ` Ard Biesheuvel [this message]
2022-06-13 14:45 ` [PATCH v4 23/26] arm64: head: remap the kernel text/inittext region read-only Ard Biesheuvel
2022-06-13 16:57 ` Kees Cook
2022-06-13 14:45 ` [PATCH v4 24/26] mm: add arch hook to validate mmap() prot flags Ard Biesheuvel
2022-06-13 16:37 ` Kees Cook
2022-06-13 16:44 ` Ard Biesheuvel
2022-06-13 14:45 ` [PATCH v4 25/26] arm64: mm: add support for WXN memory translation attribute Ard Biesheuvel
2022-06-13 16:51 ` Kees Cook
2022-06-13 14:45 ` [PATCH v4 26/26] arm64: kernel: move ID map out of .text mapping Ard Biesheuvel
2022-06-13 16:52 ` Kees Cook
2022-06-24 13:19 ` [PATCH v4 00/26] arm64: refactor boot flow and add support for WXN Will Deacon
2022-06-24 14:40 ` Ard Biesheuvel
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