Hi, Alex:
在 2023/7/22 20:38, Alexandre Ghiti 写道:
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.
I have gone through the code and tested this series with RiscVVirt edk2.
All seems good to me, you can add :
Tested-by: Song Shuai <songshuaishuai@xxxxxxxxxxx>
And a few questions about patch 2 ("riscv: Dump out kernel offset
information on panic"):
1. The dump_kernel_offset() function would output "Kernel Offset: 0x0
from 0xffffffff80000000" when booting with "nokaslr" option.
How about disabling the registration of "kernel_offset_notifier" with
"nokaslr" option?
2. Inspired by patch 2, I added the Crash KASLR support based on this
series [1].
So is it necessary to keep this patch if we have Crash KASLR support?
[1]:
https://lore.kernel.org/linux-riscv/20230815104800.705753-1-songshuaishuai@xxxxxxxxxxx/T/#u
base-commit-tag: v6.5-rc1
Changes in v6:
* Fix reintroduced build failures by compiling kaslr.c only for arm64
and riscv, as suggested by Ard
Changes in v5:
* Renamed efi-stub-kaslr.c into kaslr.c and fix commit log of patch 3,
as suggested by Ard
* Removed stubs since the kaslr functions were moved to their own file
(and then does not trigger any build failure for architectures that do
not call those functions since they are in their own compilation unit)
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 kaslr.c
libstub: Fix compilation warning for rv32
riscv: libstub: Implement KASLR by using generic functions
arch/arm64/include/asm/efi.h | 2 +
arch/riscv/Kconfig | 19 +++
arch/riscv/include/asm/efi.h | 2 +
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 | 4 +-
drivers/firmware/efi/libstub/arm64-stub.c | 117 ++--------------
drivers/firmware/efi/libstub/efistub.h | 8 ++
drivers/firmware/efi/libstub/kaslr.c | 159 ++++++++++++++++++++++
drivers/firmware/efi/libstub/riscv-stub.c | 33 ++---
15 files changed, 328 insertions(+), 126 deletions(-)
create mode 100644 arch/riscv/kernel/pi/fdt_early.c
create mode 100644 drivers/firmware/efi/libstub/kaslr.c
--
Thanks
Song Shuai
