linux-kernel - [PATCH v7 0/2] Map the kernel with correct permissions the first time

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Date:   Tue, 22 Jun 2021 10:21:32 +0200
From:   Alexandre Ghiti <alex@...ti.fr>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Jisheng Zhang <jszhang@...nel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Zong Li <zong.li@...ive.com>, Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Alexandre Ghiti <alex@...ti.fr>
Subject: [PATCH v7 0/2] Map the kernel with correct permissions the first time 

The kernel permissions are fixed after the kernel page table is created:         
avoid that by mapping the kernel 'correctly' the first time.                       

Patch 1 introduces a new helper to set kernel mapping permissions while          
avoiding all the casts when using set_memory_* API.                              

Patch 2  is the bulk of this work and deals with mapping the kernel with          
the right permissions.                                                           

Changes in v7:
* Split long lines and reintroduce parameters names of set_kernel_memory
  callback, as suggested by Christoph
* Make set_kernel_memory __always_inline as suggested by Christoph
* Change 64b spelling into 64-bit, as suggested by Christoph

Changes in v6:
* load_sz was placed in init section but is now used in kernel address
  conversions macros, so remove this attribute.

Changes in v5:
* Remove non-relevant commits to this patchset that raised issues
* Make load_sz non-static as it is used in kernel address conversions
  macros
* Rebased on top for-next

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 (2):
  riscv: Introduce set_kernel_memory helper
  riscv: Map the kernel with correct permissions the first time

 arch/riscv/include/asm/page.h       |  13 +++-
 arch/riscv/include/asm/sections.h   |  17 +++++
 arch/riscv/include/asm/set_memory.h |  16 ++--
 arch/riscv/kernel/setup.c           |  12 +--
 arch/riscv/mm/init.c                | 112 ++++++++++++----------------
 arch/riscv/mm/pageattr.c            |  11 +++
 6 files changed, 100 insertions(+), 81 deletions(-)

-- 
2.30.2