The branch stable/13 has been updated by luporl:
URL:
https://cgit.FreeBSD.org/src/commit/?id=1805ce694542f03a95a064aa3be5905ce9cffa3b
commit 1805ce694542f03a95a064aa3be5905ce9cffa3b
Author: Leandro Lupori <lup...@freebsd.org>
AuthorDate: 2021-03-25 14:54:06 +0000
Commit: Leandro Lupori <lup...@freebsd.org>
CommitDate: 2021-04-06 11:28:26 +0000
powerpc64: enforce natural alignment in bcopy
POWER architecture CPUs (Book-S) require natural alignment for
cache-inhibited storage accesses. Since we can't know the caching model
for a page ahead of time, always enforce natural alignment in bcopy.
This fixes a SIGBUS when calling the function with misaligned pointers
on POWER7.
Submitted by: Bruno Larsen <bruno.lar...@eldorado.org.br>
Reviewed by: luporl, bdragon (IRC)
MFC after: 1 week
Sponsored by: Eldorado Research Institute (eldorado.org.br)
Differential Revision: https://reviews.freebsd.org/D28776
(cherry picked from commit 2f561284033c0f53d0911baf9056078e6026a278)
---
lib/libc/powerpc64/string/bcopy.S | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/lib/libc/powerpc64/string/bcopy.S
b/lib/libc/powerpc64/string/bcopy.S
index bb860c098feb..4dc80c264362 100644
--- a/lib/libc/powerpc64/string/bcopy.S
+++ b/lib/libc/powerpc64/string/bcopy.S
@@ -34,6 +34,11 @@ __FBSDID("$FreeBSD$");
#define BLOCK_SIZE (1 << BLOCK_SIZE_BITS)
#define BLOCK_SIZE_MASK (BLOCK_SIZE - 1)
+/* Minimum 8 byte alignment, to avoid cache-inhibited alignment faults.*/
+#ifndef ALIGN_MASK
+#define ALIGN_MASK 0x7
+#endif
+
#define MULTI_PHASE_THRESHOLD 512
#ifndef FN_NAME
@@ -66,9 +71,38 @@ ENTRY(FN_NAME)
mr %r4, %r0
#endif
+ /* First check for relative alignment, if unaligned copy one byte at a
time */
+ andi. %r8, %r3, ALIGN_MASK
+ andi. %r7, %r4, ALIGN_MASK
+ cmpd %r7, %r8
+ bne .Lunaligned
+
+
cmpldi %r5, MULTI_PHASE_THRESHOLD
bge .Lmulti_phase
+ b .Lfast_copy
+
+.Lunaligned:
+ /* forward or backward copy? */
+ cmpd %r4, %r3
+ blt .Lbackward_unaligned
+
+ /* Just need to setup increment and jump to copy */
+ li %r0, 1
+ mtctr %r5
+ b .Lsingle_1_loop
+
+.Lbackward_unaligned:
+ /* advance src and dst to last byte, set decrement and jump to copy */
+ add %r3, %r3, %r5
+ addi %r3, %r3, -1
+ add %r4, %r4, %r5
+ addi %r4, %r4, -1
+ li %r0, -1
+ mtctr %r5
+ b .Lsingle_1_loop
+.Lfast_copy:
/* align src */
cmpd %r4, %r3 /* forward or backward copy? */
blt .Lbackward_align
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