linux-kernel - Re: [PATCH v4 0/4] riscv: Map the kernel with correct permissions the first time

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Date:   Fri, 11 Jun 2021 20:55:39 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     alex@...ti.fr
CC:     Paul Walmsley <paul.walmsley@...ive.com>, aou@...s.berkeley.edu,
        jszhang@...nel.org, Christoph Hellwig <hch@...radead.org>,
        zong.li@...ive.com, anup@...infault.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        alex@...ti.fr
Subject:     Re: [PATCH v4 0/4] riscv: Map the kernel with correct permissions the first time

On Fri, 04 Jun 2021 04:49:46 PDT (-0700), alex@...ti.fr wrote:
> The kernel permissions are fixed after the kernel page table is created:
> avoid that by mapping the kernel 'correctly' the first time.
>
> Patch 2 is a cleanup patch on which the next patches are based on, not
> necessary for this patchset though and relies on patch 1.
>
> Patch 3 introduces a new helper to set kernel mapping permissions while
> avoiding all the casts when using set_memory_* API.
>
> Patch 4  is the bulk of this work and deals with mapping the kernel with
> the right permissions.
>
> Changes in v4:
> * Add patch 1 as noted by Jisheng
> * Changes patch 2 title as suggested by Anup
> * Add Reviewed-by from Anup
>
> Changes in v3:
> * Add a patch that factorizes kernel address conversions
> * Add a helper called set_kernel_memory in its own patch, as suggested by
>   Christoph
> * Prefer IS_ENABLED over #ifdef, as suggested by Christoph
> * Split overly long lines, as suggested by Christoph
> * Simplify kernel mapping by mapping ALL text as readonly and taking advantage
>   of already present code that enables write for init text before
>   free_initmem_default.
>
> Changes in v2:
> * Rebased on top of for-next (and "riscv: mm: fix build errors caused by
>   mk_pmd()")
> * Get rid of protect_kernel_linear_mapping_text_rodata as suggested by
>   Jisheng
> * Improve code in general compared to previous RFC
>
> Alexandre Ghiti (4):
>   riscv: Remove CONFIG_PHYS_RAM_BASE_FIXED
>   riscv: Simplify xip and !xip kernel address conversion macros
>   riscv: Introduce set_kernel_memory helper
>   riscv: Map the kernel with correct permissions the first time
>
>  arch/riscv/Kconfig                  |   6 --
>  arch/riscv/include/asm/page.h       |  27 ++++----
>  arch/riscv/include/asm/pgtable.h    |   2 +
>  arch/riscv/include/asm/sections.h   |  17 +++++
>  arch/riscv/include/asm/set_memory.h |  13 ++--
>  arch/riscv/kernel/setup.c           |  11 +--
>  arch/riscv/mm/init.c                | 102 ++++++++++++----------------
>  arch/riscv/mm/pageattr.c            |  10 +++
>  8 files changed, 95 insertions(+), 93 deletions(-)

Thanks, these are on for-next.  I had a few conflicts, let me know if 
something went wrong.