Unverified Commit 12cf29c6 authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

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.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parents 2aff5f95 ad5643cf

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

+0 −2
Original line number Diff line number Diff line
@@ -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

+1 −2
Original line number Diff line number Diff line
@@ -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 */