Author: mjg
Date: Mon May 7 15:07:28 2018
New Revision: 333324
URL: https://svnweb.freebsd.org/changeset/base/333324
Log:
amd64: replace libkern's memset and memmove with assembly variants
memmove is repurposed bcopy (arguments swapped, return value added)
The libkern variant is a wrapper around bcopy, so this is a big
improvement.
memset is repurposed memcpy. The librkern variant is doing fishy stuff,
including branching on 0 and calling bzero.
Both functions are rather crude and subject to partial depessimization.
This is a soft prerequisite to adding variants utilizing the
'Enhanced REP MOVSB/STOSB' bit and let the kernel patch at runtime.
Modified:
head/sys/amd64/amd64/support.S
head/sys/conf/files.amd64
Modified: head/sys/amd64/amd64/support.S
==============================================================================
--- head/sys/amd64/amd64/support.S Mon May 7 15:07:26 2018
(r333323)
+++ head/sys/amd64/amd64/support.S Mon May 7 15:07:28 2018
(r333324)
@@ -162,6 +162,58 @@ ENTRY(bcopy)
END(bcopy)
/*
+ * memmove(dst, src, cnt)
+ * rdi, rsi, rdx
+ * Original by:
+ * w...@tools.de (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
+ */
+ENTRY(memmove)
+ PUSH_FRAME_POINTER
+ movq %rdi,%r9
+ movq %rdx,%rcx
+
+ movq %rdi,%rax
+ subq %rsi,%rax
+ cmpq %rcx,%rax /* overlapping && src < dst? */
+ jb 1f
+
+ shrq $3,%rcx /* copy by 64-bit words */
+ rep
+ movsq
+ movq %rdx,%rcx
+ andq $7,%rcx /* any bytes left? */
+ rep
+ movsb
+ movq %r9,%rax
+ POP_FRAME_POINTER
+ ret
+
+ /* ALIGN_TEXT */
+1:
+ addq %rcx,%rdi /* copy backwards */
+ addq %rcx,%rsi
+ decq %rdi
+ decq %rsi
+ andq $7,%rcx /* any fractional bytes? */
+ std
+ rep
+ movsb
+ movq %rdx,%rcx /* copy remainder by 32-bit
words */
+ shrq $3,%rcx
+ subq $7,%rsi
+ subq $7,%rdi
+ rep
+ movsq
+ cld
+ movq %r9,%rax
+ POP_FRAME_POINTER
+ ret
+END(memmove)
+
+/*
+ * memcpy(dst, src, len)
+ * rdi, rsi, rdx
+ *
* Note: memcpy does not support overlapping copies
*/
ENTRY(memcpy)
@@ -178,6 +230,27 @@ ENTRY(memcpy)
POP_FRAME_POINTER
ret
END(memcpy)
+
+/*
+ * memset(dst, c, len)
+ * rdi, rsi, rdx
+ */
+ENTRY(memset)
+ PUSH_FRAME_POINTER
+ movq %rdi,%r9
+ movq %rdx,%rcx
+ movq %rsi,%rax
+ shrq $3,%rcx
+ rep
+ stosq
+ movq %rdx,%rcx
+ andq $7,%rcx
+ rep
+ stosb
+ movq %r9,%rax
+ POP_FRAME_POINTER
+ ret
+END(memset)
/*
* pagecopy(%rdi=from, %rsi=to)
Modified: head/sys/conf/files.amd64
==============================================================================
--- head/sys/conf/files.amd64 Mon May 7 15:07:26 2018 (r333323)
+++ head/sys/conf/files.amd64 Mon May 7 15:07:28 2018 (r333324)
@@ -620,8 +620,6 @@ isa/vga_isa.c optional vga
kern/kern_clocksource.c standard
kern/link_elf_obj.c standard
libkern/x86/crc32_sse42.c standard
-libkern/memmove.c standard
-libkern/memset.c standard
#
# IA32 binary support
#
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