Re: [PATCH v8 0/1] riscv: Allow to downgrade paging mode from the command line

[Alexandre Ghiti]

On 3/29/23 19:59, Palmer Dabbelt wrote:
> On Tue, 28 Feb 2023 07:46:28 PST (-0800), alexghiti@xxxxxxxxxxxx wrote:
> > 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")
>
> I have that in my tree, I'm still getting a bunch of boot failures 
> though.  I can try to get a list if you're not seeing any, but I'm 
> kind of stuck on some other stuff for a bit...


I sent yesterday a v9 which fixes the medlow boot issues you mentioned, 
I did not have any boot failures after that on my side.


> > 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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