linux-efi.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Alexandre Ghiti <alexandre.ghiti@canonical.com>
To: Jonathan Corbet <corbet@lwn.net>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>, Zong Li <zong.li@sifive.com>,
	Anup Patel <anup@brainfault.org>,
	Atish Patra <Atish.Patra@wdc.com>, Christoph Hellwig <hch@lst.de>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Kees Cook <keescook@chromium.org>,
	Guo Ren <guoren@linux.alibaba.com>,
	Heinrich Schuchardt <heinrich.schuchardt@canonical.com>,
	Mayuresh Chitale <mchitale@ventanamicro.com>,
	linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	linux-efi@vger.kernel.org, linux-arch@vger.kernel.org
Cc: Alexandre Ghiti <alexandre.ghiti@canonical.com>,
	Palmer Dabbelt <palmerdabbelt@google.com>
Subject: [PATCH v2 06/10] riscv: Explicit comment about user virtual address space size
Date: Wed, 29 Sep 2021 16:51:09 +0200	[thread overview]
Message-ID: <20210929145113.1935778-7-alexandre.ghiti@canonical.com> (raw)
In-Reply-To: <20210929145113.1935778-1-alexandre.ghiti@canonical.com>

Define precisely the size of the user accessible virtual space size
for sv32/39/48 mmu types and explain why the whole virtual address
space is split into 2 equal chunks between kernel and user space.

Signed-off-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/include/asm/pgtable.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 2f92d61237b4..fd37cc45ef2a 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -664,6 +664,15 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 /*
  * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32.
  * Note that PGDIR_SIZE must evenly divide TASK_SIZE.
+ * Task size is:
+ * -     0x9fc00000 (~2.5GB) for RV32.
+ * -   0x4000000000 ( 256GB) for RV64 using SV39 mmu
+ * - 0x800000000000 ( 128TB) for RV64 using SV48 mmu
+ *
+ * Note that PGDIR_SIZE must evenly divide TASK_SIZE since "RISC-V
+ * Instruction Set Manual Volume II: Privileged Architecture" states that
+ * "load and store effective addresses, which are 64bits, must have bits
+ * 63–48 all equal to bit 47, or else a page-fault exception will occur."
  */
 #ifdef CONFIG_64BIT
 #define TASK_SIZE      (PGDIR_SIZE * PTRS_PER_PGD / 2)
-- 
2.30.2


  parent reply	other threads:[~2021-09-29 14:57 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29 14:51 [PATCH v2 00/10] Introduce sv48 support without relocatable kernel Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 01/10] riscv: Allow to dynamically define VA_BITS Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 02/10] riscv: Get rid of MAXPHYSMEM configs Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 03/10] asm-generic: Prepare for riscv use of pud_alloc_one and pud_free Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 04/10] riscv: Implement sv48 support Alexandre Ghiti
2021-10-04  1:34   ` Samuel Holland
2021-10-04  7:31     ` Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 05/10] riscv: Use pgtable_l4_enabled to output mmu_type in cpuinfo Alexandre Ghiti
2021-09-29 14:51 ` Alexandre Ghiti [this message]
2021-09-29 14:51 ` [PATCH v2 07/10] riscv: Improve virtual kernel memory layout dump Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 08/10] Documentation: riscv: Add sv48 description to VM layout Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 09/10] riscv: Initialize thread pointer before calling C functions Alexandre Ghiti
2021-09-29 14:51 ` [PATCH v2 10/10] riscv: Allow user to downgrade to sv39 when hw supports sv48 Alexandre Ghiti
2021-11-24 23:29 ` [PATCH v2 00/10] Introduce sv48 support without relocatable kernel Heiko Stübner
2021-12-06 10:49   ` Alexandre ghiti
2021-12-06 11:17     ` Heiko Stübner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210929145113.1935778-7-alexandre.ghiti@canonical.com \
    --to=alexandre.ghiti@canonical.com \
    --cc=Atish.Patra@wdc.com \
    --cc=andreyknvl@gmail.com \
    --cc=anup@brainfault.org \
    --cc=aou@eecs.berkeley.edu \
    --cc=ardb@kernel.org \
    --cc=arnd@arndb.de \
    --cc=corbet@lwn.net \
    --cc=dvyukov@google.com \
    --cc=glider@google.com \
    --cc=guoren@linux.alibaba.com \
    --cc=hch@lst.de \
    --cc=heinrich.schuchardt@canonical.com \
    --cc=kasan-dev@googlegroups.com \
    --cc=keescook@chromium.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-efi@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=mchitale@ventanamicro.com \
    --cc=palmer@dabbelt.com \
    --cc=palmerdabbelt@google.com \
    --cc=paul.walmsley@sifive.com \
    --cc=ryabinin.a.a@gmail.com \
    --cc=zong.li@sifive.com \
    --subject='Re: [PATCH v2 06/10] riscv: Explicit comment about user virtual address space size' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).