diff options
| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2021-10-19 09:29:18 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-12-09 22:41:17 +1100 |
| commit | 70428da94c7ad692d306747a04117543827292a7 (patch) | |
| tree | a9c27bfdbaa5b4b79a93564f80ac31165f4ff560 /arch/powerpc/mm/mmu_context.c | |
| parent | 526d4a4c77aedf1b7df1133e5cced29c70232e6e (diff) | |
powerpc/32s: Save content of sr0 to avoid 'mfsr'
Calling 'mfsr' to get the content of segment registers is heavy,
in addition it requires clearing of the 'reserved' bits.
In order to avoid this operation, save it in mm context and in
thread struct.
The saved sr0 is the one used by kernel, this means that on
locking entry it can be used as is.
For unlocking, the only thing to do is to clear SR_NX.
This improves null_syscall selftest by 12 cycles, ie 4%.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b02baf2ed8f09bad910dfaeeb7353b2ae6830525.1634627931.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/mm/mmu_context.c')
| -rw-r--r-- | arch/powerpc/mm/mmu_context.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/mm/mmu_context.c b/arch/powerpc/mm/mmu_context.c index 74246536b832..e618d5442a28 100644 --- a/arch/powerpc/mm/mmu_context.c +++ b/arch/powerpc/mm/mmu_context.c @@ -18,6 +18,9 @@ static inline void switch_mm_pgdir(struct task_struct *tsk, { /* 32-bit keeps track of the current PGDIR in the thread struct */ tsk->thread.pgdir = mm->pgd; +#ifdef CONFIG_PPC_BOOK3S_32 + tsk->thread.sr0 = mm->context.sr0; +#endif } #elif defined(CONFIG_PPC_BOOK3E_64) static inline void switch_mm_pgdir(struct task_struct *tsk, |