From: Charlie Jenkins <charlie@rivosinc.com>
To: alexghiti@rivosinc.com
Cc: charlie@rivosinc.com, atishp@rivosinc.com, conor@kernel.org,
paul.walmsley@sifive.com, palmer@rivosinc.com,
aou@eecs.berkeley.edu, bjorn@rivosinc.com, anup@brainfault.org,
evan@rivosinc.com, linux-riscv@lists.infradead.org,
konstantin@linuxfoundation.org, linux-doc@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 1/2] RISC-V: mm: Restrict address space for sv39,sv48,sv57
Date: Tue, 27 Jun 2023 15:21:51 -0700 [thread overview]
Message-ID: <20230627222152.177716-2-charlie@rivosinc.com> (raw)
In-Reply-To: <20230627222152.177716-1-charlie@rivosinc.com>
Make sv39 the default address space for mmap as some applications
currently depend on this assumption. The RISC-V specification enforces
that bits outside of the virtual address range are not used, so
restricting the size of the default address space as such should be
temporary. A hint address passed to mmap will cause the largest address
space that fits entirely into the hint to be used. If the hint is less
than or equal to 1<<38, a 39-bit address will be used. After an address
space is completely full, the next smallest address space will be used.
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
arch/riscv/include/asm/elf.h | 2 +-
arch/riscv/include/asm/pgtable.h | 13 +++++++++-
arch/riscv/include/asm/processor.h | 41 +++++++++++++++++++++++++-----
3 files changed, 47 insertions(+), 9 deletions(-)
diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index 30e7d2455960..1b57f13a1afd 100644
--- a/arch/riscv/include/asm/elf.h
+++ b/arch/riscv/include/asm/elf.h
@@ -49,7 +49,7 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr);
* the loader. We need to make sure that it is out of the way of the program
* that it will "exec", and that there is sufficient room for the brk.
*/
-#define ELF_ET_DYN_BASE ((TASK_SIZE / 3) * 2)
+#define ELF_ET_DYN_BASE ((DEFAULT_MAP_WINDOW / 3) * 2)
#ifdef CONFIG_64BIT
#ifdef CONFIG_COMPAT
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 75970ee2bda2..e83912e97870 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -57,18 +57,29 @@
#define MODULES_END (PFN_ALIGN((unsigned long)&_start))
#endif
+
/*
* Roughly size the vmemmap space to be large enough to fit enough
* struct pages to map half the virtual address space. Then
* position vmemmap directly below the VMALLOC region.
*/
#ifdef CONFIG_64BIT
+#define VA_BITS_SV39 39
+#define VA_BITS_SV48 48
+#define VA_BITS_SV57 57
+
+#define VA_USER_SV39 (UL(1) << (VA_BITS_SV39 - 1))
+#define VA_USER_SV48 (UL(1) << (VA_BITS_SV48 - 1))
+#define VA_USER_SV57 (UL(1) << (VA_BITS_SV57 - 1))
+
#define VA_BITS (pgtable_l5_enabled ? \
- 57 : (pgtable_l4_enabled ? 48 : 39))
+ VA_BITS_SV57 : (pgtable_l4_enabled ? VA_BITS_SV48 : VA_BITS_SV39))
#else
#define VA_BITS 32
#endif
+#define DEFAULT_VA_BITS ((VA_BITS >= VA_BITS_SV39) ? VA_BITS_SV39 : VA_BITS)
+
#define VMEMMAP_SHIFT \
(VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT)
#define VMEMMAP_SIZE BIT(VMEMMAP_SHIFT)
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 6fb8bbec8459..019dcd4ecae4 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -12,20 +12,47 @@
#include <asm/ptrace.h>
-/*
- * This decides where the kernel will search for a free chunk of vm
- * space during mmap's.
- */
-#define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE / 3)
-
-#define STACK_TOP TASK_SIZE
#ifdef CONFIG_64BIT
+#define DEFAULT_MAP_WINDOW (UL(1) << (DEFAULT_VA_BITS - 1))
#define STACK_TOP_MAX TASK_SIZE_64
+
+#define arch_get_mmap_end(addr, len, flags) \
+ ((addr) == 0 || (addr) >= VA_USER_SV57 ? STACK_TOP_MAX : \
+ (((addr) >= VA_USER_SV48) && (VA_BITS >= VA_BITS_SV48)) ? \
+ VA_USER_SV48 : \
+ VA_USER_SV39)
+
+#define arch_get_mmap_base(addr, base) \
+ (((addr >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) ? \
+ base + STACK_TOP_MAX - DEFAULT_MAP_WINDOW : \
+ (((addr) >= VA_USER_SV48) && (VA_BITS >= VA_BITS_SV48)) ? \
+ base + VA_USER_SV48 - DEFAULT_MAP_WINDOW : \
+ base)
+
#else
+#define DEFAULT_MAP_WINDOW TASK_SIZE
#define STACK_TOP_MAX TASK_SIZE
+
+#define arch_get_mmap_end(addr, len, flags) \
+ ((addr) > DEFAULT_MAP_WINDOW ? STACK_TOP_MAX : DEFAULT_MAP_WINDOW)
+
+#define arch_get_mmap_base(addr, base) \
+ ((addr > DEFAULT_MAP_WINDOW) ? \
+ base + STACK_TOP_MAX - DEFAULT_MAP_WINDOW : \
+ base)
+
#endif
#define STACK_ALIGN 16
+
+#define STACK_TOP DEFAULT_MAP_WINDOW
+
+/*
+ * This decides where the kernel will search for a free chunk of vm
+ * space during mmap's.
+ */
+#define TASK_UNMAPPED_BASE PAGE_ALIGN(DEFAULT_MAP_WINDOW / 3)
+
#ifndef __ASSEMBLY__
struct task_struct;
--
2.34.1
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next prev parent reply other threads:[~2023-06-27 22:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-27 22:21 [PATCH 0/2] Make SV39 the default address space Charlie Jenkins
2023-06-27 22:21 ` Charlie Jenkins [this message]
2023-06-27 22:32 ` [PATCH 1/2] RISC-V: mm: Restrict address space for sv39,sv48,sv57 Jessica Clarke
2023-06-27 23:36 ` Palmer Dabbelt
2023-06-28 7:44 ` Nick Kossifidis
2023-06-27 23:38 ` Charlie Jenkins
2023-06-28 12:34 ` Anup Patel
2023-06-29 1:38 ` Charlie Jenkins
2023-06-27 22:21 ` [PATCH 2/2] RISC-V: mm: Update documentation and include test Charlie Jenkins
2023-06-28 10:18 ` Muhammad Usama Anjum
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