On Sun, Aug 06, 2023 at 11:53:51AM +0200, Alexandre Ghiti wrote:
On 27/07/2023 23:26, Charlie Jenkins wrote:
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
arch/riscv/include/asm/elf.h | 2 +- arch/riscv/include/asm/pgtable.h | 20 +++++++++++- arch/riscv/include/asm/processor.h | 52 ++++++++++++++++++++++++++---- 3 files changed, 66 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..c76a1ef094a4 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -63,8 +63,26 @@
- 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))+#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 >= VA_BITS_SV39) ? VA_BITS_SV39 : VA_BITS)
Here the condition is always true right?
Yes, that condition is always true, I can eliminate the conditional.
+#define MMAP_VA_BITS (test_thread_flag(TIF_32BIT) ? 32 : MMAP_VA_BITS_64) +#define MMAP_MIN_VA_BITS (test_thread_flag(TIF_32BIT) ? 32 : MMAP_MIN_VA_BITS_64)
I think you should use is_compat_task() here instead of test_thread_flag(TIF_32BIT). And what about introducing VA_BITS_SV32 instead of hardcoding 32?
Sounds good.
+#else +#define MMAP_VA_BITS ((VA_BITS >= VA_BITS_SV48) ? VA_BITS_SV48 : VA_BITS) +#define MMAP_MIN_VA_BITS ((VA_BITS >= VA_BITS_SV39) ? VA_BITS_SV39 : VA_BITS)
Ditto here.
+#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..e810244ea951 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) && test_thread_flag(TIF_32BIT))) \
mmap_end = DEFAULT_MAP_WINDOW; \Wouldn't that prevent a sv57 system to allocate sv57 addresses when sv48 is full unless explicitly asked?
Yes that is a good point, that should be STACK_TOP_MAX as well.
- 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 = (_base) - DEFAULT_MAP_WINDOW; \
- if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && test_thread_flag(TIF_32BIT))) \
mmap_base = (_base); \- else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
mmap_base = VA_USER_SV57 + rnd_gap; \Shouldn't it be mmap_base = VA_USER_SV57 - rnd_gap?
No, rnd_gap is a negative number here. 'base' is equal to DEFAULT_MAP_WINDOW - gap - rnd. It does seem more clear if it is a positive number so I will set rnd_gap to DEFAULT_MAP_WINDOW - (_base).
- 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__