Re: [PATCH 00/11] ARM: qemu-virt: remap cfi-flash from 0 to 0x1000

[Sascha Hauer <sha@pengutronix.de>]

On Mon, May 22, 2023 at 07:28:24AM +0200, Ahmad Fatoum wrote:
> When MMU is enabled, barebox maintains a single address space with
> 1:1 physical to virtual mapping by default. Furthermore, the zero
> page is marked inaccessible to trap NULL pointer dereferences.
> 
> This is problematic on the Qemu ARM Virt platform, because the
> cfi-flash is memory mapped starting with address zero, so users need
> to decide whether they want the cfi-flash or the MMU. The decision
> so far, was to disable CONFIG_MMU in the Qemu Virt configs, but this
> holds us back from removing these configs in favor of the new
> multi_v7_defconfig/multi_v8_defconfig.
> 
> Make everyone happy by shifting the virtual cfi-flash mapping by 4K:
> 
>     virt   ->    phys
> 
>     0x0000 ->    0x0000 [faulting]
>     0x1000 ->    0x0000 [(uncached) alias]
>     0x2000 ->    0x1000
>            .
>            .
>            .
>  0x7fff000 -> 0x7ffe000
>  0x8000000 -> 0x7fff000
> 
> This eats one page into the memory region starting at 0x8000000.
> That's ok though, because that's where the GIC is located on both
> ARM32 and ARM64 and we don't do interrupts in barebox.
> 
> This applies on top of Sascha's MMU rempping rework in next and
> has been tested on both 32-bit and 64-bit QEMU ARM.

Applied, thanks

Sascha

> 
> Ahmad Fatoum (11):
>   treewide: use remap_range instead of arch_remap_range
>   mmu: add physical address parameter to arch_remap_range
>   ARM: mmu32: support non-1:1 mappings in arch_remap_range
>   ARM: mmu64: support non-1:1 mappings in arch_remap_range
>   of: platform: remap memory when encountering virtual-reg property
>   common: boards: qemu-virt: remap cfi-flash from 0 to 0x1000
>   ARM: prepare extending mmuinfo beyond ARMv7
>   ARM64: mmu: implement ARMv8 mmuinfo command
>   common: memtest: prepare for reuse in self test
>   test: self: add MMU remapping self test
>   ARM: mmuinfo: add options for enabling/disabling zero page trapping
> 
>  .../bindings/barebox/virtual-reg.rst          |  29 +++
>  arch/arm/configs/multi_v8_defconfig           |   1 +
>  arch/arm/cpu/Makefile                         |   2 +-
>  arch/arm/cpu/mmu-common.c                     |   8 +-
>  arch/arm/cpu/mmu_32.c                         |  54 ++--
>  arch/arm/cpu/mmu_64.c                         |  18 +-
>  arch/arm/cpu/mmuinfo.c                        | 128 +++++-----
>  arch/arm/cpu/mmuinfo_32.c                     |  80 ++++++
>  arch/arm/cpu/mmuinfo_64.c                     | 215 ++++++++++++++++
>  arch/arm/include/asm/mmu.h                    |   2 +-
>  arch/arm/include/asm/mmuinfo.h                |   9 +
>  arch/arm/include/asm/sysreg.h                 |  76 ++++++
>  arch/powerpc/cpu-85xx/mmu.c                   |   7 +-
>  arch/powerpc/include/asm/mmu.h                |   2 +-
>  commands/Kconfig                              |   8 +-
>  commands/memtest.c                            |   5 +-
>  common/Kconfig                                |   6 +
>  common/Makefile                               |   2 +-
>  common/boards/qemu-virt/Makefile              |   3 +
>  common/boards/qemu-virt/overlay-of-flash.dts  |   5 +-
>  common/memtest.c                              |  44 ++--
>  drivers/hab/habv4.c                           |   2 +-
>  drivers/mtd/nor/cfi_flash.c                   |   5 +-
>  drivers/of/platform.c                         |  20 ++
>  include/memtest.h                             |   7 +-
>  include/mmu.h                                 |  19 +-
>  include/zero_page.h                           |  12 +
>  test/self/Kconfig                             |   6 +
>  test/self/Makefile                            |   1 +
>  test/self/mmu.c                               | 233 ++++++++++++++++++
>  30 files changed, 865 insertions(+), 144 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/barebox/virtual-reg.rst
>  create mode 100644 arch/arm/cpu/mmuinfo_32.c
>  create mode 100644 arch/arm/cpu/mmuinfo_64.c
>  create mode 100644 arch/arm/include/asm/mmuinfo.h
>  create mode 100644 arch/arm/include/asm/sysreg.h
>  create mode 100644 test/self/mmu.c
> 
> -- 
> 2.39.2
> 
> 
> 

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