Mailing List Archive

This new version gets rid of the limitation that prevented KASAN kernels
to use the newly introduced parameters.

While looking into KASLR, I fell onto commit aacd149b6238 ("arm64: head:
avoid relocating the kernel twice for KASLR"): it allows to use the fdt
functions very early in the boot process with KASAN enabled by simply
compiling a new version of those functions without instrumentation.

I had to change the handling of the command line parsing to make the
code self-contained in kernel/pi/cmd_early.c to avoid calling too many
__pi prefixed functions from outside this file.

I'll use this approach like arm64 to handle the extraction of the random
seedi from the device tree for KASLR.

base-commit: eb9be8310c58 ("RISC-V: add a spin_shadow_stack declaration")

v8:
- Fix LLVM ld warning by moving the section .init.sdata from
kernel/pi/string.c into the newly created section .init.pidata

v7:
- Rebased on top of for-next which introduces lots of errors (thanks to
the patchwork CI)
- Add __NO_FORTIFY to avoid undefined __pi_fortify_panic
- Add an alias to our newly introduced strlen
- Remove __init as sections are already prefixed in the Makefile
- Introduce new section for kernel/pi/string.c to quiet the following
warnings (once we have all the string functions, we'll be able to get
rid of this):

warning: orphan section `.init__bug_table' from `arch/riscv/kernel/pi/string.pi.o' being placed in section `.init__bug_table'
warning: orphan section `.init.srodata.cst8' from `arch/riscv/kernel/pi/string.pi.o' being placed in section `.init.srodata.cst8'

v6:
- Fix llvm warning by forward declaring set_satp_mode_from_cmdline

v5:
- Handle null command line, Thanks Björn!
- Add RB/TB from Björn

v4:
- Introduce pi/ for KASAN to work

v3:
- Massage commit log to make no4lvl clearer, as asked by Conor
- Add a note to kernel-parameters.txt regarding the impossibility to use
those parameters when KASAN is enabled, as suggested by Conor
- Add RB from Björn

v2:
- Honor CMDLINE_EXTEND and CMDLINE_FORCE as noticed by Björn


Alexandre Ghiti (1):
riscv: Allow to downgrade paging mode from the command line

.../admin-guide/kernel-parameters.txt | 5 +-
arch/riscv/kernel/Makefile | 2 +
arch/riscv/kernel/pi/Makefile | 37 +++++++++++
arch/riscv/kernel/pi/cmdline_early.c | 62 +++++++++++++++++++
arch/riscv/kernel/vmlinux.lds.S | 8 +++
arch/riscv/lib/memcpy.S | 2 +
arch/riscv/lib/memmove.S | 2 +
arch/riscv/lib/strlen.S | 1 +
arch/riscv/mm/init.c | 36 +++++++++--
9 files changed, 148 insertions(+), 7 deletions(-)
create mode 100644 arch/riscv/kernel/pi/Makefile
create mode 100644 arch/riscv/kernel/pi/cmdline_early.c

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2.37.2