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| author | Leandro Lupori <luporl@FreeBSD.org> | 2021-03-25 14:54:06 +0000 |
|---|---|---|
| committer | Leandro Lupori <luporl@FreeBSD.org> | 2021-03-25 16:07:01 +0000 |
| commit | 2f561284033c0f53d0911baf9056078e6026a278 (patch) | |
| tree | b14e93b9f27f3ae1b8c31d39a6ebc2e8df4bc5f2 /lib/libc | |
| parent | 4e38478c595a9e6225b525890d7ee269a203c200 (diff) | |
| download | src-2f561284033c0f53d0911baf9056078e6026a278.tar.gz src-2f561284033c0f53d0911baf9056078e6026a278.zip | |
[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.larsen@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
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/powerpc64/string/bcopy.S | 34 |
1 files changed, 34 insertions, 0 deletions
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 |