riscv: Define TASK_SIZE_MAX for __access_ok()

TASK_SIZE_MAX should be set to the largest userspace address under any runtime configuration. This optimizes the check in __access_ok(), which no longer needs to compute the current value of TASK_SIZE. It is still safe because addresses between TASK_SIZE and TASK_SIZE_MAX are invalid at the hardware level. This removes about half of the references to pgtable_l[45]_enabled. Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
linux-riscv · Mar 21, 2024 · f6cb7b0 · f6cb7b0
1 parent b19dc4a
commit f6cb7b0
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diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
@@ -17,6 +17,7 @@ extern bool pgtable_l5_enabled;
 #define PGDIR_SHIFT_L4  39
 #define PGDIR_SHIFT_L5  48
 #define PGDIR_SIZE_L3   (_AC(1, UL) << PGDIR_SHIFT_L3)
+#define PGDIR_SIZE_L5   (_AC(1, UL) << PGDIR_SHIFT_L5)
 
 #define PGDIR_SHIFT     (pgtable_l5_enabled ? PGDIR_SHIFT_L5 : \
 		(pgtable_l4_enabled ? PGDIR_SHIFT_L4 : PGDIR_SHIFT_L3))

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
@@ -869,6 +869,7 @@ 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_MIN	(PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
+#define TASK_SIZE_MAX	(PGDIR_SIZE_L5 * PTRS_PER_PGD / 2)
 
 #ifdef CONFIG_COMPAT
 #define TASK_SIZE_32	(_AC(0x80000000, UL) - PAGE_SIZE)