MIPS: Unify memcpy.S and memcpy-inatomic.S
We can save the 451 lines of code that comprise memcpy-inatomic.S at the
expense of a single instruction in the memcpy prolog. We also use an
additional register (t6), so this may cause increased register pressure in
some places as well. But I think the reduced maintenance burden, of not
having two nearly identical implementations, makes it worth it.
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/lib/memcpy.S b/arch/mips/lib/memcpy.S
index 56a1f85..65192c0 100644
--- a/arch/mips/lib/memcpy.S
+++ b/arch/mips/lib/memcpy.S
@@ -183,6 +183,14 @@
#endif
/*
+ * t6 is used as a flag to note inatomic mode.
+ */
+LEAF(__copy_user_inatomic)
+ b __copy_user_common
+ li t6, 1
+ END(__copy_user_inatomic)
+
+/*
* A combined memcpy/__copy_user
* __copy_user sets len to 0 for success; else to an upper bound of
* the number of uncopied bytes.
@@ -193,6 +201,8 @@
move v0, dst /* return value */
.L__memcpy:
FEXPORT(__copy_user)
+ li t6, 0 /* not inatomic */
+__copy_user_common:
/*
* Note: dst & src may be unaligned, len may be 0
* Temps
@@ -458,6 +468,7 @@
LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address
nop
SUB len, AT, t0 # len number of uncopied bytes
+ bnez t6, .Ldone /* Skip the zeroing part if inatomic */
/*
* Here's where we rely on src and dst being incremented in tandem,
* See (3) above.