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Message-Id: <20230626183611.40479-2-charlie@rivosinc.com>
Date: Mon, 26 Jun 2023 11:36:03 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: charlie@...osinc.com
Cc: Jonathan Corbet <corbet@....net>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Eric Biederman <ebiederm@...ssion.com>,
Kees Cook <keescook@...omium.org>,
Shuah Khan <shuah@...nel.org>,
Alexandre Ghiti <alexghiti@...osinc.com>,
Björn Töpel <bjorn@...osinc.com>,
Conor Dooley <conor.dooley@...rochip.com>,
Zong Li <zong.li@...ive.com>,
Greentime Hu <greentime.hu@...ive.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Guo Ren <guoren@...nel.org>,
David Hildenbrand <david@...hat.com>,
Sergey Matyukevich <sergey.matyukevich@...tacore.com>,
Juergen Gross <jgross@...e.com>,
Qinglin Pan <panqinglin2020@...as.ac.cn>,
Anshuman Khandual <anshuman.khandual@....com>,
Anup Patel <anup@...infault.org>,
Huacai Chen <chenhuacai@...nel.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Sunil V L <sunilvl@...tanamicro.com>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Evan Green <evan@...osinc.com>,
Mark Brown <broonie@...nel.org>,
Guillaume Tucker <guillaume.tucker@...labora.com>,
Catalin Marinas <catalin.marinas@....com>,
linux-doc@...r.kernel.org (open list:DOCUMENTATION),
linux-riscv@...ts.infradead.org (open list:RISC-V ARCHITECTURE),
linux-kernel@...r.kernel.org (open list),
linux-mm@...ck.org (open list:EXEC & BINFMT API),
linux-kselftest@...r.kernel.org (open list:KERNEL SELFTEST FRAMEWORK)
Subject: [PATCH 1/2] RISC-V: mm: Restrict address space for sv39,sv48,sv57
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@...osinc.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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