Merge patch series "riscv: access_ok() optimization"

Samuel Holland <samuel.holland@sifive.com> says:

This series optimizes access_ok() by defining TASK_SIZE_MAX. At Alex's
suggestion, I also tried making TASK_SIZE constant (specifically by
making PGDIR_SHIFT a variable instead of a ternary expression, then
replacing the load with an immediate using ALTERNATIVE). This appeared
to slightly improve performance on some implementations (C906) but
regressed it on others (FU740). So I am leaving further optimizations to
a later series.

* b4-shazam-merge:
  riscv: Define TASK_SIZE_MAX for __access_ok()
  riscv: Remove PGDIR_SIZE_L3 and TASK_SIZE_MIN

Link: https://lore.kernel.org/r/20240327143858.711792-1-samuel.holland@sifive.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/pgtable-64.h

@@ -16,8 +16,6 @@ extern bool pgtable_l5_enabled;
 #define PGDIR_SHIFT_L3  30
 #define PGDIR_SHIFT_L4  39
 #define PGDIR_SHIFT_L5  48
-#define PGDIR_SIZE_L3   (_AC(1, UL) << PGDIR_SHIFT_L3)
-
 #define PGDIR_SHIFT     (pgtable_l5_enabled ? PGDIR_SHIFT_L5 : \
 		(pgtable_l4_enabled ? PGDIR_SHIFT_L4 : PGDIR_SHIFT_L3))
 /* Size of region mapped by a page global directory */

arch/riscv/include/asm/pgtable.h

@@ -880,7 +880,7 @@ 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	LONG_MAX
 
 #ifdef CONFIG_COMPAT
 #define TASK_SIZE_32	(_AC(0x80000000, UL) - PAGE_SIZE)
@@ -892,7 +892,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
 
 #else
 #define TASK_SIZE	FIXADDR_START
-#define TASK_SIZE_MIN	TASK_SIZE
 #endif
 
 #else /* CONFIG_MMU */