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authorNicholas Piggin <npiggin@gmail.com>2018-03-07 11:37:09 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2018-03-13 23:43:05 +1100
commit1753dd1830367709144f68f539554dadd7a7ccba (patch)
treec77fbae605bafdcc4031b8e54327a02473f1b719 /arch/powerpc/mm/slice.c
parentab83dc794c9d8870e4844cca9a2945b782b8ee7e (diff)
powerpc/mm/slice: Simplify and optimise slice context initialisation
The slice state of an mm gets zeroed then initialised upon exec. This is the only caller of slice_set_user_psize now, so that can be removed and instead implement a faster and simplified approach that requires no locking or checking existing state. This speeds up vfork+exec+exit performance on POWER8 by 3%. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/mm/slice.c')
-rw-r--r--arch/powerpc/mm/slice.c72
1 files changed, 18 insertions, 54 deletions
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 5e9e1e57d580..7b51f962ce0c 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -671,70 +671,34 @@ unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr)
}
EXPORT_SYMBOL_GPL(get_slice_psize);
-/*
- * This is called by hash_page when it needs to do a lazy conversion of
- * an address space from real 64K pages to combo 4K pages (typically
- * when hitting a non cacheable mapping on a processor or hypervisor
- * that won't allow them for 64K pages).
- *
- * This is also called in init_new_context() to change back the user
- * psize from whatever the parent context had it set to
- * N.B. This may be called before mm->context.id has been set.
- *
- * This function will only change the content of the {low,high)_slice_psize
- * masks, it will not flush SLBs as this shall be handled lazily by the
- * caller.
- */
-void slice_set_user_psize(struct mm_struct *mm, unsigned int psize)
+void slice_init_new_context_exec(struct mm_struct *mm)
{
- int index, mask_index;
unsigned char *hpsizes, *lpsizes;
- unsigned long flags;
- unsigned int old_psize;
- int i;
+ unsigned int psize = mmu_virtual_psize;
- slice_dbg("slice_set_user_psize(mm=%p, psize=%d)\n", mm, psize);
+ slice_dbg("slice_init_new_context_exec(mm=%p)\n", mm);
- VM_BUG_ON(radix_enabled());
- spin_lock_irqsave(&slice_convert_lock, flags);
-
- old_psize = mm->context.user_psize;
- slice_dbg(" old_psize=%d\n", old_psize);
- if (old_psize == psize)
- goto bail;
+ /*
+ * In the case of exec, use the default limit. In the
+ * case of fork it is just inherited from the mm being
+ * duplicated.
+ */
+#ifdef CONFIG_PPC64
+ mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW_USER64;
+#else
+ mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW;
+#endif
mm->context.user_psize = psize;
- wmb();
+ /*
+ * Set all slice psizes to the default.
+ */
lpsizes = mm->context.low_slices_psize;
- for (i = 0; i < SLICE_NUM_LOW; i++) {
- mask_index = i & 0x1;
- index = i >> 1;
- if (((lpsizes[index] >> (mask_index * 4)) & 0xf) == old_psize)
- lpsizes[index] = (lpsizes[index] &
- ~(0xf << (mask_index * 4))) |
- (((unsigned long)psize) << (mask_index * 4));
- }
+ memset(lpsizes, (psize << 4) | psize, SLICE_NUM_LOW >> 1);
hpsizes = mm->context.high_slices_psize;
- for (i = 0; i < SLICE_NUM_HIGH; i++) {
- mask_index = i & 0x1;
- index = i >> 1;
- if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == old_psize)
- hpsizes[index] = (hpsizes[index] &
- ~(0xf << (mask_index * 4))) |
- (((unsigned long)psize) << (mask_index * 4));
- }
-
-
-
-
- slice_dbg(" lsps=%lx, hsps=%lx\n",
- (unsigned long)mm->context.low_slices_psize,
- (unsigned long)mm->context.high_slices_psize);
-
- bail:
- spin_unlock_irqrestore(&slice_convert_lock, flags);
+ memset(hpsizes, (psize << 4) | psize, SLICE_NUM_HIGH >> 1);
}
void slice_set_range_psize(struct mm_struct *mm, unsigned long start,