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

From: Alexandre Ghiti
Date: Fri Jun 04 2021 - 07:49:58 EST


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(-)

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2.30.2