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@rivosinc.com>
Link: https://lore.kernel.org/r/20230809232218.849726-2-charlie@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index c24280774caf7da63674a21b767a64086b9fb2dc..5d3368d5585cac7b054e556afd1d4ac3c46947dd 100644 (file)
--- 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 75970ee2bda223be83a567adab6fa327e8e58cd1..bb0b9ac7b581167c07b4788c6df59720666e07a4 100644 (file)
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -62,11 +62,16 @@
  * struct pages to map half the virtual address space. Then
  * position vmemmap directly below the VMALLOC region.
  */
+#define VA_BITS_SV32 32
 #ifdef CONFIG_64BIT
+#define VA_BITS_SV39 39
+#define VA_BITS_SV48 48
+#define VA_BITS_SV57 57
+
 #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
+#define VA_BITS                VA_BITS_SV32
 #endif
 
 #define VMEMMAP_SHIFT \
@@ -111,11 +116,27 @@
 #include <asm/page.h>
 #include <asm/tlbflush.h>
 #include <linux/mm_types.h>
+#include <asm/compat.h>
 
 #define __page_val_to_pfn(_val)  (((_val) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT)
 
 #ifdef CONFIG_64BIT
 #include <asm/pgtable-64.h>
+
+#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))
+
+#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 /* CONFIG_COMPAT */
+
 #else
 #include <asm/pgtable-32.h>
 #endif /* CONFIG_64BIT */

diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index c950a8d9edef8cb562b4d783360c3cbdf1cb5bf6..3e23e1786d0521678c111c5a94ed33332403b556 100644 (file)
--- 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__