The following KASLR implementation allows to randomize the kernel mapping:
- virtually: we expect the bootloader to provide a seed in the device-tree
- physically: only implemented in the EFI stub, it relies on the firmware to
provide a seed using EFI_RNG_PROTOCOL. arm64 has a similar implementation
hence the patch 3 factorizes KASLR related functions for riscv to take
advantage.
The new virtual kernel location is limited by the early page table that only
has one PUD and with the PMD alignment constraint, the kernel can only take
< 512 positions.
base-commit-tag: v6.5-rc1
Changes in v4:
* Fix efi_get_kimg macro that returned nothing
* Moved new kaslr functions into their own files to avoid zboot link
failures, as suggested by Ard
Changes in v3:
* Rebase on top of 6.4-rc2
* Make RANDOMIZE_BASE depend on 64bit
* Fix efi_icache_sync and efi_get_kimg_min_align which were undefined
in x86 (and certainly other archs)
* Add patch 4 to fix warning on rv32
Changes in v2:
* Rebase on top of 6.3-rc1
* Add a riscv cache sync after memcpying the kernel
* Add kaslr_offset implementation for KCOV
* Add forward declaration to quiet LLVM
Alexandre Ghiti (5):
riscv: Introduce virtual kernel mapping KASLR
riscv: Dump out kernel offset information on panic
arm64: libstub: Move KASLR handling functions to efi-stub-helper.c
libstub: Fix compilation warning for rv32
riscv: libstub: Implement KASLR by using generic functions
arch/arm64/include/asm/efi.h | 4 +
arch/riscv/Kconfig | 19 +++
arch/riscv/include/asm/efi.h | 4 +
arch/riscv/include/asm/page.h | 3 +
arch/riscv/kernel/image-vars.h | 1 +
arch/riscv/kernel/pi/Makefile | 2 +-
arch/riscv/kernel/pi/cmdline_early.c | 13 ++
arch/riscv/kernel/pi/fdt_early.c | 30 ++++
arch/riscv/kernel/setup.c | 25 +++
arch/riscv/mm/init.c | 36 +++-
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/firmware/efi/libstub/arm64-stub.c | 117 ++-----------
drivers/firmware/efi/libstub/efi-stub-kaslr.c | 159 ++++++++++++++++++
drivers/firmware/efi/libstub/efistub.h | 18 ++
drivers/firmware/efi/libstub/riscv-stub.c | 33 ++--
15 files changed, 342 insertions(+), 125 deletions(-)
create mode 100644 arch/riscv/kernel/pi/fdt_early.c
create mode 100644 drivers/firmware/efi/libstub/efi-stub-kaslr.c
--
2.39.2
