MMU issues are some of the most frustrating to debug. To make this
slightly less unbearable, introduce a software pagetable walker for
ARMv8. This can be called to dump a pagetable with the default
formatter, or a custom callback can be provided to implement more
complicated parsing.
This can also be useful to dump the pagetable used by a previous
bootloader stage (by reading out the ttbr register).
Here is an example of the output when walking U-Boot's own memory map
on a Qualcomm RB3 board:
Walking pagetable at 000000017df90000, va_bits: 36. Using 3 levels
[0x17df91000] | Table | |
[0x17df92000] | Table | |
[0x000001000 - 0x000200000] | Pages | Device-nGnRnE | Non-shareable
[0x000200000 - 0x040000000] | Block | Device-nGnRnE | Non-shareable
[0x040000000 - 0x080000000] | Block | Device-nGnRnE | Non-shareable
[0x080000000 - 0x140000000] | Block | Normal | Inner-shareable
[0x17df93000] | Table | |
[0x140000000 - 0x17de00000] | Block | Normal | Inner-shareable
[0x17df94000] | Table | |
[0x17de00000 - 0x17dfa0000] | Pages | Normal | Inner-shareable
---
Changes in v3:
- Add doc comments to __pagetable_walk()
- Include doc comments in documentation with kernel-doc::
- Link to v2:
https://lore.kernel.org/r/20240607-caleb-upstreaming-v2-0-bae407f51...@linaro.org
Changes in v2:
- Document the MMU debugging features in doc/arch/arm64.rst
- Mention that functions are stripped out when unused.
- Link to v1:
https://lore.kernel.org/r/20240607-caleb-upstreaming-v1-0-99094dabb...@linaro.org
---
Caleb Connolly (3):
arm64: mmu.h: fix PTE_TABLE_AP
arm64: add software pagetable walker
doc: arch: arm64: describe pagetable debugging
arch/arm/cpu/armv8/cache_v8.c | 245 +++++++++++++++++++++++++++++++++++++++
arch/arm/include/asm/armv8/mmu.h | 58 ++++++++-
doc/arch/arm64.rst | 49 ++++++++
3 files changed, 351 insertions(+), 1 deletion(-)
---
change-id: 20240607-caleb-upstreaming-82744a2786b3
base-commit: 5cff71259b26b73ed0e9e9acd12d16a4d8ede04b
// Caleb (they/them)
