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Merge patch series "riscv: access_ok() optimization"

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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: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Palmer Dabbelt 2024-05-16 13:00:00 -07:00
commit 12cf29c6f9
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2 changed files with 1 additions and 4 deletions
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2
arch/riscv/include/asm/pgtable-64.h
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@ -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 */

3
arch/riscv/include/asm/pgtable.h
View File

@ -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 */