Re: Two more arm aeabi functions for the kernel

[Philip Guenther]

On Thu, Sep 22, 2016 at 1:09 PM, Mark Kettenis  wrote:
> These functions are necessary to build our kernel with clang.  I
> picked these from NetBSD as I didn't quite like the way FreeBSD
> implemented them.  I stripped all the unecessary bits from the NetBSD
> implementation (which is shared with userland).
>
> Do the file names with the leading underscores bother people?  I could
> rename the files ldivmod.S and uldivmod.S.

There are other leading underbar filenames under libkern.  Leave the
names the way they are, IMO.


> ok?

They look basically sane.  ok guenther@
If you want a review of numerical correctness, poke martynas@.

Two more arm aeabi functions for the kernel

[Mark Kettenis]

These functions are necessary to build our kernel with clang.  I
picked these from NetBSD as I didn't quite like the way FreeBSD
implemented them.  I stripped all the unecessary bits from the NetBSD
implementation (which is shared with userland).

Do the file names with the leading underscores bother people?  I could
rename the files ldivmod.S and uldivmod.S.

These seem to be the last two missing symbols.

ok?


Index: lib/libkern/arch/arm/__aeabi_ldivmod.S
===
RCS file: lib/libkern/arch/arm/__aeabi_ldivmod.S
diff -N lib/libkern/arch/arm/__aeabi_ldivmod.S
--- /dev/null   1 Jan 1970 00:00:00 -
+++ lib/libkern/arch/arm/__aeabi_ldivmod.S  22 Sep 2016 20:03:42 -
@@ -0,0 +1,133 @@
+/*-
+ * Copyright (c) 2012 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Matt Thomas of 3am Software Foundry.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *notice, this list of conditions and the following disclaimer in the
+ *documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include 
+
+#ifdef __ARMEB__
+#defineALO r1  /* incoming numerator, outgoing quotient */
+#defineAHI r0  /* incoming numerator, outgoing quotient */
+#defineBLO r3  /* incoming denominator, outgoing remainder */
+#defineBHI r2  /* incoming denominator, outgoing remainder */
+#else
+#defineALO r0  /* incoming numerator, outgoing quotient */
+#defineAHI r1  /* incoming numerator, outgoing quotient */
+#defineBLO r2  /* incoming denominator, outgoing remainder */
+#defineBHI r3  /* incoming denominator, outgoing remainder */
+#endif
+
+ENTRY(__aeabi_ldivmod)
+   push{r4-r6, lr}
+#defineNEG r5
+   movsNEG, #0
+
+   cmp BHI, #0
+   bge 2f
+   movsNEG, #1 /* flip quotient sign */
+   bl  .Lnegate_b
+   bcs .Lmaxdenom
+
+2:
+   cmp AHI, #0
+   eorlt   NEG, NEG, #3/* flip quotient sign, flip remainder sign */
+   bllt.Lnegate_a
+
+   /*
+* Arguments are setup, allocate some stack for the remainder
+* and call __qdivrem for the heavy lifting.
+*/
+   sub sp, sp, #16
+   addsr4, sp, #8
+   str r4, [sp]
+   bl  __qdivrem
+   add sp, sp, #8
+
+   /*
+* The quotient is already in the right place and neither value
+* needs its sign flipped.
+*/
+   cmp NEG, #0 /* any signs to flip? */
+   beq .Lnegate_neither
+
+   cmp NEG, #2 /* does remainder need to be negative? */
+   beq .Lnegate_b_only /* 2 means b only */
+   bgt .Lnegate_both   /* 3 means both */
+.Lnegate_a_only:
+   bl  .Lnegate_a  /* 1 means a only */
+.Lnegate_neither:
+   pop {r2-r6, pc} /* grab b from stack */
+.Lnegate_both:
+   bl  .Lnegate_a
+.Lnegate_b_only:
+   pop {r2-r3} /* get remainder */
+   bl  .Lnegate_b  /* negate it */
+   pop {r4-r6, pc}
+
+   .align  0
+.Lnegate_a:
+   negsALO, ALO
+   rsc AHI, AHI, #0
+   mov pc, lr
+
+   .align  0
+.Lnegate_b:
+   negsBLO, BLO
+   rsc BHI, BHI, #0
+   mov pc, lr
+
+   .align  0
+.Lmaxdenom:
+   /*
+* We had a carry so the denominator must have INT64_MIN
+* Also BLO and BHI never changed values so we can use
+* them to see if the numerator has the same value.  We
+* don't have to worry about sign.
+*/
+   cmp BHI, AHI
+   cmpeq   BLO, ALO
+   bne 1f
+
+   /*
+* They were