This patch reverted the meaning of the addr parameter in the mmap syscall
change from the previous commit b5b4287accd7 ("riscv: mm: Use hint address
in mmap if available") from patch[1] which treats hint addr + size as the
upper bound of the mmap return address. Result in ENOMEM error caused when
hint address + size is not big enough.Thus, this patch makes the behavior of mmap syscall to align with x86, arm64, powerpc by only limiting the address space to DEFAULT_MAP_WINDOW which is defined as not larger than 47-bit. If a user program wants to use sv57 address space, it can use mmap with a hint address larger than BIT(47) as it is already documented in x86 and arm64. [1] https://lore.kernel.org/linux-riscv/20240130-use_mmap_hint_address-v3-0-8a655cfa8...@rivosinc.com/ Signed-off-by: Yangyu Chen <c...@cyyself.name> --- arch/riscv/include/asm/processor.h | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-) diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index 8702b8721a27..faf3e230ab24 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -13,22 +13,17 @@ #include <vdso/processor.h> #include <asm/ptrace.h> +#include <asm/mman.h> -/* - * addr is a hint to the maximum userspace address that mmap should provide, so - * this macro needs to return the largest address space available so that - * mmap_end < addr, being mmap_end the top of that address space. - * See Documentation/arch/riscv/vm-layout.rst for more details. - */ #define arch_get_mmap_end(addr, len, flags) \ ({ \ unsigned long mmap_end; \ typeof(addr) _addr = (addr); \ - if ((_addr) == 0 || is_compat_task() || \ - ((_addr + len) > BIT(VA_BITS - 1))) \ + if (((_addr + len) > DEFAULT_MAP_WINDOW) || \ + ((flags) & MAP_FIXED)) \ mmap_end = STACK_TOP_MAX; \ else \ - mmap_end = (_addr + len); \ + mmap_end = DEFAULT_MAP_WINDOW; \ mmap_end; \ }) @@ -38,11 +33,10 @@ typeof(addr) _addr = (addr); \ typeof(base) _base = (base); \ unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base); \ - if ((_addr) == 0 || is_compat_task() || \ - ((_addr + len) > BIT(VA_BITS - 1))) \ - mmap_base = (_base); \ + if ((_addr + len) > DEFAULT_MAP_WINDOW) \ + mmap_base = (STACK_TOP_MAX - rnd_gap); \ else \ - mmap_base = (_addr + len) - rnd_gap; \ + mmap_base = (_base); \ mmap_base; \ }) -- 2.45.2
