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Currently, the modules region is 128M in size, which is a problem for some large modules. Shanker reports [1] that the NVIDIA GPU driver alone can consume 110M of module space in some configurations. We'd like to make the modules region a full 2G such that we can always make use of a 2G range. It's possible to build kernel images which are larger than 128M in some configurations, such as when many debug options are selected and many drivers are built in. In these configurations, we can't legitimately select a base for a 128M module region, though we currently select a value for which allocation will fail. It would be nicer to have a diagnostic message in this case. Similarly, in theory it's possible to build a kernel image which is larger than 2G and which cannot support modules. While this isn't likely to be the case for any realistic kernel deplyed in the field, it would be nice if we could print a diagnostic in this case. This patch reworks the module VA range selection to use a 2G range, and improves handling of cases where we cannot select legitimate module regions. We now attempt to select a 128M region and a 2G region: * The 128M region is selected such that modules can use direct branches (with JUMP26/CALL26 relocations) to branch to kernel code and other modules, and so that modules can reference data and text (using PREL32 relocations) anywhere in the kernel image and other modules. This region covers the entire kernel image (rather than just the text) to ensure that all PREL32 relocations are in range even when the kernel data section is absurdly large. Where we cannot allocate from this region, we'll fall back to the full 2G region. * The 2G region is selected such that modules can use direct branches with PLTs to branch to kernel code and other modules, and so that modules can use reference data and text (with PREL32 relocations) in the kernel image and other modules. This region covers the entire kernel image, and the 128M region (if one is selected). The two module regions are randomized independently while ensuring the constraints described above. [1] https://lore.kernel.org/linux-arm-kernel/159ceeab-09af-3174-5058-445bc8dcf85b@nvidia.com/ Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Cc: Shanker Donthineni <sdonthineni@nvidia.com> Cc: Will Deacon <will@kernel.org> Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> Link: https://lore.kernel.org/r/20230530110328.2213762-7-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
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| .. | ||
| acpi_object_usage.rst | ||
| amu.rst | ||
| arm-acpi.rst | ||
| asymmetric-32bit.rst | ||
| booting.rst | ||
| cpu-feature-registers.rst | ||
| elf_hwcaps.rst | ||
| features.rst | ||
| hugetlbpage.rst | ||
| index.rst | ||
| kasan-offsets.sh | ||
| legacy_instructions.rst | ||
| memory-tagging-extension.rst | ||
| memory.rst | ||
| perf.rst | ||
| pointer-authentication.rst | ||
| silicon-errata.rst | ||
| sme.rst | ||
| sve.rst | ||
| tagged-address-abi.rst | ||
| tagged-pointers.rst | ||