Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) client-ip=2620:137:e000::3:3;
Date:   Fri, 29 Sep 2023 21:11:56 +0000
Mime-Version: 1.0
Message-ID: <20230929211155.3910949-4-samitolvanen@google.com>
Subject: [PATCH 0/2] riscv: Increase mmap_rnd_bits_max on Sv48/57
From:   Sami Tolvanen <samitolvanen@google.com>
To:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>
Cc:     linux-mm@kvack.org, linux-riscv@lists.infradead.org,
        llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
        Sami Tolvanen <samitolvanen@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi all,

We noticed that 64-bit RISC-V kernels limit mmap_rnd_bits to 24
even if the hardware supports a larger virtual address space size
[1]. These two patches allow mmap_rnd_bits_max to be changed during
init, and bumps up the maximum randomness if we end up setting up
4/5-level paging at boot.

Sami

 [1] https://github.com/google/android-riscv64/issues/1


Sami Tolvanen (2):
  mm: Change mmap_rnd_bits_max to __ro_after_init
  riscv: mm: Update mmap_rnd_bits_max

 arch/riscv/mm/init.c | 6 ++++++
 include/linux/mm.h   | 2 +-
 mm/mmap.c            | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)


base-commit: 6465e260f48790807eef06b583b38ca9789b6072
-- 
2.42.0.582.g8ccd20d70d-goog