From ad5643cf2f699989daa85d909403febd6712fccb Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Wed, 27 Mar 2024 07:38:13 -0700 Subject: [PATCH] riscv: Define TASK_SIZE_MAX for __access_ok() TASK_SIZE_MAX should be set to a constant value, at least the largest valid userspace address under any runtime configuration. This optimizes the check in __access_ok(), which no longer needs to compute the runtime value of TASK_SIZE. The check does not need to be exact, as long as it accepts all valid userspace addresses and rejects all valid kernel addresses; well-behaved programs will never fail the access_ok() check. For RISC-V, which requires all virtual addresses to be sign extended, the optimal choice is LONG_MAX because it simplifies the limit comparison to a sign bit test. This removes about half of the references to pgtable_l[45]_enabled. Signed-off-by: Samuel Holland Reviewed-by: Arnd Bergmann Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20240327143858.711792-3-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/pgtable.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index f5cc8bcc7f8d..762a85551764 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -870,6 +870,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) */ #ifdef CONFIG_64BIT #define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2) +#define TASK_SIZE_MAX LONG_MAX #ifdef CONFIG_COMPAT #define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE) -- 2.25.1