Re: [PATCH v3 0/6] ARM: Map sections RO/XN

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 6/18/25 11:34, Sascha Hauer wrote:
> So far we mapped all RAM as read write with execute permission. This
> series series hardens this a bit. The barebox text segment will be
> mapped readonly with execute permission, the RO data section as readonly
> without execute permission and the remaining RAM will lose its execute
> permission.
> 
> I tested this series on ARMv5, ARMv7 and ARMv8. I am not confident
> though that there are no regressions, so this new behaviour is behind a
> Kconfig option. It is default-y, but can be disabled for debugging
> purposses.  Once this series has proven stable it can be removed.

Reservations aren't handled correctly and thus if there is e.g. an
OP-TEE memory region after the barebox code region, the system hangs.

I prepared patches and will send them out soon. Just wanted to give a
heads up, so next isn't merged into master before that.

Cheers,
Ahmad

> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
> Changes in v3:
> - rework create_sections() for Ahmads comments
> - mention CR_S bit and DOMAIN_CLIENT in commit message
> - Link to v2: https://lore.barebox.org/20250617-mmu-xn-ro-v2-0-3c7aa9046b67@pengutronix.de
> 
> Changes in v2:
> - Tested and fixed for ARMv5
> - merge create_pages() and create_sections() into one functions (ahmad)
> - introduce function to create mapping flags based on CONFIG_ARM_MMU_PERMISSIONS
> - Link to v1: https://lore.barebox.org/20250606-mmu-xn-ro-v1-0-7ee6ddd134d4@pengutronix.de
> 
> ---
> Sascha Hauer (6):
>       ARM: pass barebox base to mmu_early_enable()
>       ARM: mmu: move ARCH_MAP_WRITECOMBINE to header
>       ARM: MMU: map memory for barebox proper pagewise
>       ARM: MMU: map text segment ro and data segments execute never
>       ARM: MMU64: map memory for barebox proper pagewise
>       ARM: MMU64: map text segment ro and data segments execute never
> 
>  arch/arm/Kconfig                 | 12 ++++++
>  arch/arm/cpu/lowlevel_32.S       |  1 +
>  arch/arm/cpu/mmu-common.h        | 20 +++++++++
>  arch/arm/cpu/mmu_32.c            | 89 ++++++++++++++++++++++++++++++++--------
>  arch/arm/cpu/mmu_64.c            | 74 +++++++++++++++++++++++++--------
>  arch/arm/cpu/uncompress.c        |  9 ++--
>  arch/arm/include/asm/mmu.h       |  2 +-
>  arch/arm/include/asm/pgtable64.h |  1 +
>  arch/arm/lib32/barebox.lds.S     |  3 +-
>  arch/arm/lib64/barebox.lds.S     |  5 ++-
>  common/memory.c                  |  7 +++-
>  include/mmu.h                    |  1 +
>  12 files changed, 181 insertions(+), 43 deletions(-)
> ---
> base-commit: fa92c730b34d7ea90309ca10b399ab1a22dc761a
> change-id: 20250606-mmu-xn-ro-e2a4c4b080a4
> 
> Best regards,

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