* [PATCH V3] [X86] Fix potential issue on memmove
@ 2010-09-15 1:50 ling.ma
2010-09-15 19:08 ` H. Peter Anvin
0 siblings, 1 reply; 2+ messages in thread
From: ling.ma @ 2010-09-15 1:50 UTC (permalink / raw)
To: mingo; +Cc: hpa, tglx, linux-kernel, Ma Ling
From: Ma Ling <ling.ma@intel.com>
memmove allow source and destination address to be overlap,
but no limitation for memcpy. So memmove use forward or
backward copy mode to handle src > dest and dest > src cases respectively.
However memcpy has not address overlap, it may use any copy mode
theoretically. Our original memmove will call memcpy and assume
it must use forward copy mode, otherwise the system will crash,
it is potential issue. The patch based on tip/x86/mem avoids
this assumption.
Signed-off-by: Ma Ling <ling.ma@intel.com>
---
In this version we optimized original 32 and 64bit memmove.
arch/x86/lib/memcpy_32.c | 199 +++++++++++++++++++++++++++++++++++++++++----
arch/x86/lib/memmove_64.c | 189 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 362 insertions(+), 26 deletions(-)
diff --git a/arch/x86/lib/memcpy_32.c b/arch/x86/lib/memcpy_32.c
index 5415a9d..5b2c4e4 100644
--- a/arch/x86/lib/memcpy_32.c
+++ b/arch/x86/lib/memcpy_32.c
@@ -22,22 +22,187 @@ EXPORT_SYMBOL(memset);
void *memmove(void *dest, const void *src, size_t n)
{
- int d0, d1, d2;
-
- if (dest < src) {
- memcpy(dest, src, n);
- } else {
- __asm__ __volatile__(
- "std\n\t"
- "rep\n\t"
- "movsb\n\t"
- "cld"
- : "=&c" (d0), "=&S" (d1), "=&D" (d2)
- :"0" (n),
- "1" (n-1+src),
- "2" (n-1+dest)
- :"memory");
- }
- return dest;
+
+ int d0,d1,d2,d3,d4,d5;
+ char *ret = dest;
+
+ __asm__ __volatile__(
+ /* Handle more 16bytes in loop */
+ "cmp $0x10, %0\n\t"
+ "jb 1f\n\t"
+
+ /* Decide forward/backward copy mode */
+ "cmp %2, %1\n\t"
+ "jb 2f\n\t"
+
+ /*
+ * movs instruction have many startup latency
+ * so we handle small size by general register.
+ */
+ "cmp $680, %0\n\t"
+ "jb 3f\n\t"
+ /*
+ * movs instruction is only good for aligned case.
+ */
+ "mov %1, %3\n\t"
+ "xor %2, %3\n\t"
+ "and $0xff, %3\n\t"
+ "jz 4f\n\t"
+ "3:\n\t"
+ "sub $0x10, %0\n\t"
+
+ /*
+ * We gobble 16byts forward in each loop.
+ */
+ "3:\n\t"
+ "sub $0x10, %0\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov 1*4(%1), %4\n\t"
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, 1*4(%2)\n\t"
+ "mov 2*4(%1), %3\n\t"
+ "mov 3*4(%1), %4\n\t"
+ "mov %3, 2*4(%2)\n\t"
+ "mov %4, 3*4(%2)\n\t"
+ "lea 0x10(%1), %1\n\t"
+ "lea 0x10(%2), %2\n\t"
+ "jae 3b\n\t"
+ "add $0x10, %0\n\t"
+ "jmp 1f\n\t"
+
+ /*
+ * Handle data forward by movs.
+ */
+ ".p2align 4\n\t"
+ "4:\n\t"
+ "mov -4(%1, %0), %3\n\t"
+ "lea -4(%2, %0), %4\n\t"
+ "shr $2, %0\n\t"
+ "rep movsl\n\t"
+ "mov %3, (%4)\n\t"
+ "jmp 11f\n\t"
+ /*
+ * Handle data backward by movs.
+ */
+ ".p2align 4\n\t"
+ "6:\n\t"
+ "mov (%1), %3\n\t"
+ "mov %2, %4\n\t"
+ "lea -4(%1, %0), %1\n\t"
+ "lea -4(%2, %0), %2\n\t"
+ "shr $2, %0\n\t"
+ "std\n\t"
+ "rep movsl\n\t"
+ "mov %3,(%4)\n\t"
+ "cld\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Start to prepare for backward copy.
+ */
+ ".p2align 4\n\t"
+ "2:\n\t"
+ "cmp $680, %0\n\t"
+ "jb 5f\n\t"
+ "mov %1, %3\n\t"
+ "xor %2, %3\n\t"
+ "and $0xff, %3\n\t"
+ "jz 6b\n\t"
+
+ /*
+ * Calculate copy position to tail.
+ */
+ "5:\n\t"
+ "add %0, %1\n\t"
+ "add %0, %2\n\t"
+ "sub $0x10, %0\n\t"
+
+ /*
+ * We gobble 16byts backward in each loop.
+ */
+ "7:\n\t"
+ "sub $0x10, %0\n\t"
+
+ "mov -1*4(%1), %3\n\t"
+ "mov -2*4(%1), %4\n\t"
+ "mov %3, -1*4(%2)\n\t"
+ "mov %4, -2*4(%2)\n\t"
+ "mov -3*4(%1), %3\n\t"
+ "mov -4*4(%1), %4\n\t"
+ "mov %3, -3*4(%2)\n\t"
+ "mov %4, -4*4(%2)\n\t"
+ "lea -0x10(%1), %1\n\t"
+ "lea -0x10(%2), %2\n\t"
+ "jae 7b\n\t"
+ /*
+ * Calculate copy position to head.
+ */
+ "add $0x10, %0\n\t"
+ "sub %0, %1\n\t"
+ "sub %0, %2\n\t"
+
+ /*
+ * Move data from 8 bytes to 15 bytes.
+ */
+ ".p2align 4\n\t"
+ "1:\n\t"
+ "cmp $8, %0\n\t"
+ "jb 8f\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov 1*4(%1), %4\n\t"
+ "mov -2*4(%1, %0), %5\n\t"
+ "mov -1*4(%1, %0), %1\n\t"
+
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, 1*4(%2)\n\t"
+ "mov %5, -2*4(%2, %0)\n\t"
+ "mov %1, -1*4(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data from 4 bytes to 7 bytes.
+ */
+ ".p2align 4\n\t"
+ "8:\n\t"
+ "cmp $4, %0\n\t"
+ "jb 9f\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov -1*4(%1, %0), %4\n\t"
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, -1*4(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data from 2 bytes to 3 bytes.
+ */
+ ".p2align 4\n\t"
+ "9:\n\t"
+ "cmp $2, %0\n\t"
+ "jb 10f\n\t"
+ "movw 0*2(%1), %%dx\n\t"
+ "movw -1*2(%1, %0), %%bx\n\t"
+ "movw %%dx, 0*2(%2)\n\t"
+ "movw %%bx, -1*2(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data for 1 byte.
+ */
+ ".p2align 4\n\t"
+ "10:\n\t"
+ "cmp $1, %0\n\t"
+ "jb 11f\n\t"
+ "movb (%1), %%cl\n\t"
+ "movb %%cl, (%2)\n\t"
+ ".p2align 4\n\t"
+ "11:"
+ : "=&c" (d0), "=&S" (d1), "=&D" (d2),
+ "=r" (d3),"=r" (d4), "=r"(d5)
+ :"0" (n),
+ "1" (src),
+ "2" (dest)
+ :"memory");
+
+
}
EXPORT_SYMBOL(memmove);
diff --git a/arch/x86/lib/memmove_64.c b/arch/x86/lib/memmove_64.c
index 0a33909..a6d7808 100644
--- a/arch/x86/lib/memmove_64.c
+++ b/arch/x86/lib/memmove_64.c
@@ -8,14 +8,185 @@
#undef memmove
void *memmove(void *dest, const void *src, size_t count)
{
- if (dest < src) {
- return memcpy(dest, src, count);
- } else {
- char *p = dest + count;
- const char *s = src + count;
- while (count--)
- *--p = *--s;
- }
- return dest;
+
+ unsigned long d0,d1,d2,d3,d4,d5,d6,d7;
+ char *ret;
+
+ __asm__ __volatile__(
+ /* Handle more 32bytes in loop */
+ "mov %2, %3\n\t"
+ "cmp $0x20, %0\n\t"
+ "jb 1f\n\t"
+
+ /* Decide forward/backward copy mode */
+ "cmp %2, %1\n\t"
+ "jb 2f\n\t"
+
+ /*
+ * movsq instruction have many startup latency
+ * so we handle small size by general register.
+ */
+ "cmp $680, %0\n\t"
+ "jb 3f\n\t"
+ /*
+ * movsq instruction is only good for aligned case.
+ */
+ "cmpb %%dil, %%sil\n\t"
+ "je 4f\n\t"
+ "3:\n\t"
+ "sub $0x20, %0\n\t"
+ /*
+ * We gobble 32byts forward in each loop.
+ */
+ "5:\n\t"
+ "sub $0x20, %0\n\t"
+ "movq 0*8(%1), %4\n\t"
+ "movq 1*8(%1), %5\n\t"
+ "movq 2*8(%1), %6\n\t"
+ "movq 3*8(%1), %7\n\t"
+ "leaq 4*8(%1), %1\n\t"
+
+ "movq %4, 0*8(%2)\n\t"
+ "movq %5, 1*8(%2)\n\t"
+ "movq %6, 2*8(%2)\n\t"
+ "movq %7, 3*8(%2)\n\t"
+ "leaq 4*8(%2), %2\n\t"
+ "jae 5b\n\t"
+ "addq $0x20, %0\n\t"
+ "jmp 1f\n\t"
+ /*
+ * Handle data forward by movsq.
+ */
+ ".p2align 4\n\t"
+ "4:\n\t"
+ "movq %0, %8\n\t"
+ "movq -8(%1, %0), %4\n\t"
+ "lea -8(%2, %0), %5\n\t"
+ "shrq $3, %8\n\t"
+ "rep movsq\n\t"
+ "movq %4, (%5)\n\t"
+ "jmp 13f\n\t"
+ /*
+ * Handle data backward by movsq.
+ */
+ ".p2align 4\n\t"
+ "7:\n\t"
+ "movq %0, %8\n\t"
+ "movq (%1), %4\n\t"
+ "movq %2, %5\n\t"
+ "leaq -8(%1, %0), %1\n\t"
+ "leaq -8(%2, %0), %2\n\t"
+ "shrq $3, %8\n\t"
+ "std\n\t"
+ "rep movsq\n\t"
+ "cld\n\t"
+ "movq %4, (%5)\n\t"
+ "jmp 13f\n\t"
+
+ /*
+ * Start to prepare for backward copy.
+ */
+ ".p2align 4\n\t"
+ "2:\n\t"
+ "cmp $680, %0\n\t"
+ //"jb 6f \n\t"
+ "cmp %%dil, %%sil\n\t"
+ "je 7b \n\t"
+ "6:\n\t"
+ /*
+ * Calculate copy position to tail.
+ */
+ "addq %0, %1\n\t"
+ "addq %0, %2\n\t"
+ "subq $0x20, %0\n\t"
+ /*
+ * We gobble 32byts backward in each loop.
+ */
+ "8:\n\t"
+ "subq $0x20, %0\n\t"
+ "movq -1*8(%1), %4\n\t"
+ "movq -2*8(%1), %5\n\t"
+ "movq -3*8(%1), %6\n\t"
+ "movq -4*8(%1), %7\n\t"
+ "leaq -4*8(%1), %1\n\t"
+
+ "movq %4, -1*8(%2)\n\t"
+ "movq %5, -2*8(%2)\n\t"
+ "movq %6, -3*8(%2)\n\t"
+ "movq %7, -4*8(%2)\n\t"
+ "leaq -4*8(%2), %2\n\t"
+ "jae 8b\n\t"
+ /*
+ * Calculate copy position to head.
+ */
+ "addq $0x20, %0\n\t"
+ "subq %0, %1\n\t"
+ "subq %0, %2\n\t"
+ "1:\n\t"
+ "cmpq $16, %0\n\t"
+ "jb 9f\n\t"
+ /*
+ * Move data from 16 bytes to 31 bytes.
+ */
+ "movq 0*8(%1), %4\n\t"
+ "movq 1*8(%1), %5\n\t"
+ "movq -2*8(%1, %0), %6\n\t"
+ "movq -1*8(%1, %0), %7\n\t"
+ "movq %4, 0*8(%2)\n\t"
+ "movq %5, 1*8(%2)\n\t"
+ "movq %6, -2*8(%2, %0)\n\t"
+ "movq %7, -1*8(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ ".p2align 4\n\t"
+ "9:\n\t"
+ "cmpq $8, %0\n\t"
+ "jb 10f\n\t"
+ /*
+ * Move data from 8 bytes to 15 bytes.
+ */
+ "movq 0*8(%1), %4\n\t"
+ "movq -1*8(%1, %0), %5\n\t"
+ "movq %4, 0*8(%2)\n\t"
+ "movq %5, -1*8(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ "10:\n\t"
+ "cmpq $4, %0\n\t"
+ "jb 11f\n\t"
+ /*
+ * Move data from 4 bytes to 7 bytes.
+ */
+ "movl (%1), %4d\n\t"
+ "movl -4(%1, %0), %5d\n\t"
+ "movl %4d, (%2)\n\t"
+ "movl %5d, -4(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ "11:\n\t"
+ "cmp $2, %0\n\t"
+ "jb 12f\n\t"
+ /*
+ * Move data from 2 bytes to 3 bytes.
+ */
+ "movw (%1), %4w\n\t"
+ "movw -2(%1, %0), %5w\n\t"
+ "movw %4w, (%2)\n\t"
+ "movw %5w, -2(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ "12:\n\t"
+ "cmp $1, %0\n\t"
+ "jb 13f\n\t"
+ /*
+ * Move data for 1 byte.
+ */
+ "movb (%1), %4b\n\t"
+ "movb %4b, (%2)\n\t"
+ "13:\n\t"
+ : "=&d" (d0), "=&S" (d1), "=&D" (d2), "=&a" (ret) ,
+ "=r"(d3), "=r"(d4), "=r"(d5), "=r"(d6), "=&c" (d7)
+ :
+ :"memory");
+
+ return ret;
+
+
}
EXPORT_SYMBOL(memmove);
--
1.6.5.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH V3] [X86] Fix potential issue on memmove
2010-09-15 1:50 [PATCH V3] [X86] Fix potential issue on memmove ling.ma
@ 2010-09-15 19:08 ` H. Peter Anvin
0 siblings, 0 replies; 2+ messages in thread
From: H. Peter Anvin @ 2010-09-15 19:08 UTC (permalink / raw)
To: ling.ma; +Cc: mingo, tglx, linux-kernel
On 09/14/2010 06:50 PM, ling.ma@intel.com wrote:
> From: Ma Ling <ling.ma@intel.com>
>
> memmove allow source and destination address to be overlap,
> but no limitation for memcpy. So memmove use forward or
> backward copy mode to handle src > dest and dest > src cases respectively.
> However memcpy has not address overlap, it may use any copy mode
> theoretically. Our original memmove will call memcpy and assume
> it must use forward copy mode, otherwise the system will crash,
> it is potential issue. The patch based on tip/x86/mem avoids
> this assumption.
>
> Signed-off-by: Ma Ling <ling.ma@intel.com>
This patch is certainly not based on the current tip:x86/mem. Could you
check out the current tip:x86/mem (which has a previous patch of yours
in it) and submit an incremental patch with a description about what
updates the previous patch and why?
-hpa
^ permalink raw reply [flat|nested] 2+ messages in thread
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2010-09-15 19:08 ` H. Peter Anvin
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