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@rivosinc.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>,
panqinglin2020@iscas.ac.cn, 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 v3 09/13] riscv: Explicit comment about user virtual address space size
Date: Mon, 6 Dec 2021 11:46:53 +0100 [thread overview]
Message-ID: <20211206104657.433304-10-alexandre.ghiti@canonical.com> (raw)
In-Reply-To: <20211206104657.433304-1-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 e1c74ef4ead2..fe1701329237 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -677,6 +677,15 @@ 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)
--
2.32.0
next prev parent reply other threads:[~2021-12-06 10:56 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 10:46 [PATCH v3 00/13] Introduce sv48 support without relocatable kernel Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 01/13] riscv: Move KASAN mapping next to the kernel mapping Alexandre Ghiti
2021-12-06 16:18 ` Jisheng Zhang
2021-12-06 10:46 ` [PATCH v3 02/13] riscv: Split early kasan mapping to prepare sv48 introduction Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 03/13] riscv: Introduce functions to switch pt_ops Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 04/13] riscv: Allow to dynamically define VA_BITS Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 05/13] riscv: Get rid of MAXPHYSMEM configs Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 06/13] asm-generic: Prepare for riscv use of pud_alloc_one and pud_free Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 07/13] riscv: Implement sv48 support Alexandre Ghiti
2021-12-06 11:05 ` Alexandre ghiti
2021-12-09 4:32 ` 潘庆霖
2021-12-26 8:59 ` Jisheng Zhang
2022-01-04 12:44 ` Alexandre Ghiti
2021-12-29 3:42 ` Guo Ren
2022-01-04 12:42 ` Alexandre Ghiti
2022-04-26 5:57 ` Nick Kossifidis
2021-12-06 10:46 ` [PATCH v3 08/13] riscv: Use pgtable_l4_enabled to output mmu_type in cpuinfo Alexandre Ghiti
2021-12-06 10:46 ` Alexandre Ghiti [this message]
2021-12-06 10:46 ` [PATCH v3 10/13] riscv: Improve virtual kernel memory layout dump Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 11/13] Documentation: riscv: Add sv48 description to VM layout Alexandre Ghiti
2021-12-06 10:46 ` [PATCH v3 12/13] riscv: Initialize thread pointer before calling C functions Alexandre Ghiti
2021-12-20 9:11 ` Guo Ren
2021-12-20 9:17 ` Ard Biesheuvel
2021-12-20 13:40 ` Guo Ren
2022-01-10 8:03 ` Alexandre ghiti
2021-12-06 10:46 ` [PATCH v3 13/13] riscv: Allow user to downgrade to sv39 when hw supports sv48 if !KASAN Alexandre Ghiti
2021-12-06 11:08 ` [PATCH v3 00/13] Introduce sv48 support without relocatable kernel Alexandre ghiti
2022-01-20 4:18 ` Palmer Dabbelt
2022-01-20 7:30 ` Alexandre Ghiti
2022-01-20 10:05 ` Alexandre Ghiti
2022-02-18 10:45 ` Alexandre Ghiti
2022-04-01 12:56 ` Alexandre Ghiti
2022-04-23 1:50 ` Palmer Dabbelt
2022-06-02 3:43 ` Palmer Dabbelt
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