Hi Song,
On Tue, Aug 15, 2023 at 1:24 PM Song Shuai <songshuaishuai@xxxxxxxxxxx> wrote:
>
>
> 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?
I'd rather keep it as it shows the "nokaslr" flag was taken into account.
>
> 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?
I don't understand your question here
>
>
> [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
Thanks for testing this and your suggestions!
Alex
