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.
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
