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Message-Id: <20230809015110.3290774-2-charlie@rivosinc.com>
Date: Tue, 8 Aug 2023 18:51:07 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: charlie@...osinc.com, conor@...nel.org, paul.walmsley@...ive.com,
palmer@...osinc.com, aou@...s.berkeley.edu, anup@...infault.org,
konstantin@...uxfoundation.org, linux-doc@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-mm@...ck.org,
mick@....forth.gr, jrtc27@...c27.com, rdunlap@...radead.org,
alexghiti@...osinc.com
Subject: [PATCH v9 1/4] RISC-V: mm: Restrict address space for sv39,sv48,sv57
Make sv48 the default address space for mmap as some applications
currently depend on this assumption. 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, an sv39 address will
be used. An exception is that if the hint address is 0, then a sv48
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 | 21 +++++++++++-
arch/riscv/include/asm/processor.h | 52 ++++++++++++++++++++++++++----
3 files changed, 67 insertions(+), 8 deletions(-)
diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index c24280774caf..5d3368d5585c 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..2611c1324a7c 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -63,8 +63,27 @@
* position vmemmap directly below the VMALLOC region.
*/
#ifdef CONFIG_64BIT
+#define VA_BITS_SV32 32
+#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))
+
+#ifdef CONFIG_COMPAT
+#define MMAP_VA_BITS_64 ((VA_BITS >= VA_BITS_SV48) ? VA_BITS_SV48 : VA_BITS)
+#define MMAP_MIN_VA_BITS_64 (VA_BITS_SV39)
+#define MMAP_VA_BITS (is_compat_task() ? VA_BITS_SV32 : MMAP_VA_BITS_64)
+#define MMAP_MIN_VA_BITS (is_compat_task() ? VA_BITS_SV32 : MMAP_MIN_VA_BITS_64)
+#else
+#define MMAP_VA_BITS ((VA_BITS >= VA_BITS_SV48) ? VA_BITS_SV48 : VA_BITS)
+#define MMAP_MIN_VA_BITS (VA_BITS_SV39)
+#endif
#else
#define VA_BITS 32
#endif
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index c950a8d9edef..3e23e1786d05 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -13,19 +13,59 @@
#include <asm/ptrace.h>
+#ifdef CONFIG_64BIT
+#define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
+#define STACK_TOP_MAX TASK_SIZE_64
+
+#define arch_get_mmap_end(addr, len, flags) \
+({ \
+ unsigned long mmap_end; \
+ typeof(addr) _addr = (addr); \
+ if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \
+ mmap_end = STACK_TOP_MAX; \
+ else if ((_addr) >= VA_USER_SV57) \
+ mmap_end = STACK_TOP_MAX; \
+ else if ((((_addr) >= VA_USER_SV48)) && (VA_BITS >= VA_BITS_SV48)) \
+ mmap_end = VA_USER_SV48; \
+ else \
+ mmap_end = VA_USER_SV39; \
+ mmap_end; \
+})
+
+#define arch_get_mmap_base(addr, base) \
+({ \
+ unsigned long mmap_base; \
+ typeof(addr) _addr = (addr); \
+ typeof(base) _base = (base); \
+ unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base); \
+ if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \
+ mmap_base = (_base); \
+ else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
+ mmap_base = VA_USER_SV57 - rnd_gap; \
+ else if ((((_addr) >= VA_USER_SV48)) && (VA_BITS >= VA_BITS_SV48)) \
+ mmap_base = VA_USER_SV48 - rnd_gap; \
+ else \
+ mmap_base = VA_USER_SV39 - rnd_gap; \
+ mmap_base; \
+})
+
+#else
+#define DEFAULT_MAP_WINDOW TASK_SIZE
+#define STACK_TOP_MAX TASK_SIZE
+#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(TASK_SIZE / 3)
-
-#define STACK_TOP TASK_SIZE
#ifdef CONFIG_64BIT
-#define STACK_TOP_MAX TASK_SIZE_64
+#define TASK_UNMAPPED_BASE PAGE_ALIGN((UL(1) << MMAP_MIN_VA_BITS) / 3)
#else
-#define STACK_TOP_MAX TASK_SIZE
+#define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE / 3)
#endif
-#define STACK_ALIGN 16
#ifndef __ASSEMBLY__
--
2.34.1
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