mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-15 00:04:15 +08:00
ec6347bb43
In reaction to a proposal to introduce a memcpy_mcsafe_fast() implementation Linus points out that memcpy_mcsafe() is poorly named relative to communicating the scope of the interface. Specifically what addresses are valid to pass as source, destination, and what faults / exceptions are handled. Of particular concern is that even though x86 might be able to handle the semantics of copy_mc_to_user() with its common copy_user_generic() implementation other archs likely need / want an explicit path for this case: On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote: > > > > However now I see that copy_user_generic() works for the wrong reason. > > It works because the exception on the source address due to poison > > looks no different than a write fault on the user address to the > > caller, it's still just a short copy. So it makes copy_to_user() work > > for the wrong reason relative to the name. > > Right. > > And it won't work that way on other architectures. On x86, we have a > generic function that can take faults on either side, and we use it > for both cases (and for the "in_user" case too), but that's an > artifact of the architecture oddity. > > In fact, it's probably wrong even on x86 - because it can hide bugs - > but writing those things is painful enough that everybody prefers > having just one function. Replace a single top-level memcpy_mcsafe() with either copy_mc_to_user(), or copy_mc_to_kernel(). Introduce an x86 copy_mc_fragile() name as the rename for the low-level x86 implementation formerly named memcpy_mcsafe(). It is used as the slow / careful backend that is supplanted by a fast copy_mc_generic() in a follow-on patch. One side-effect of this reorganization is that separating copy_mc_64.S to its own file means that perf no longer needs to track dependencies for its memcpy_64.S benchmarks. [ bp: Massage a bit. ] Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: <stable@vger.kernel.org> Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
243 lines
4.1 KiB
ArmAsm
243 lines
4.1 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* Copyright (C) IBM Corporation, 2011
|
|
* Derived from copyuser_power7.s by Anton Blanchard <anton@au.ibm.com>
|
|
* Author - Balbir Singh <bsingharora@gmail.com>
|
|
*/
|
|
#include <asm/ppc_asm.h>
|
|
#include <asm/errno.h>
|
|
#include <asm/export.h>
|
|
|
|
.macro err1
|
|
100:
|
|
EX_TABLE(100b,.Ldo_err1)
|
|
.endm
|
|
|
|
.macro err2
|
|
200:
|
|
EX_TABLE(200b,.Ldo_err2)
|
|
.endm
|
|
|
|
.macro err3
|
|
300: EX_TABLE(300b,.Ldone)
|
|
.endm
|
|
|
|
.Ldo_err2:
|
|
ld r22,STK_REG(R22)(r1)
|
|
ld r21,STK_REG(R21)(r1)
|
|
ld r20,STK_REG(R20)(r1)
|
|
ld r19,STK_REG(R19)(r1)
|
|
ld r18,STK_REG(R18)(r1)
|
|
ld r17,STK_REG(R17)(r1)
|
|
ld r16,STK_REG(R16)(r1)
|
|
ld r15,STK_REG(R15)(r1)
|
|
ld r14,STK_REG(R14)(r1)
|
|
addi r1,r1,STACKFRAMESIZE
|
|
.Ldo_err1:
|
|
/* Do a byte by byte copy to get the exact remaining size */
|
|
mtctr r7
|
|
46:
|
|
err3; lbz r0,0(r4)
|
|
addi r4,r4,1
|
|
err3; stb r0,0(r3)
|
|
addi r3,r3,1
|
|
bdnz 46b
|
|
li r3,0
|
|
blr
|
|
|
|
.Ldone:
|
|
mfctr r3
|
|
blr
|
|
|
|
|
|
_GLOBAL(copy_mc_generic)
|
|
mr r7,r5
|
|
cmpldi r5,16
|
|
blt .Lshort_copy
|
|
|
|
.Lcopy:
|
|
/* Get the source 8B aligned */
|
|
neg r6,r4
|
|
mtocrf 0x01,r6
|
|
clrldi r6,r6,(64-3)
|
|
|
|
bf cr7*4+3,1f
|
|
err1; lbz r0,0(r4)
|
|
addi r4,r4,1
|
|
err1; stb r0,0(r3)
|
|
addi r3,r3,1
|
|
subi r7,r7,1
|
|
|
|
1: bf cr7*4+2,2f
|
|
err1; lhz r0,0(r4)
|
|
addi r4,r4,2
|
|
err1; sth r0,0(r3)
|
|
addi r3,r3,2
|
|
subi r7,r7,2
|
|
|
|
2: bf cr7*4+1,3f
|
|
err1; lwz r0,0(r4)
|
|
addi r4,r4,4
|
|
err1; stw r0,0(r3)
|
|
addi r3,r3,4
|
|
subi r7,r7,4
|
|
|
|
3: sub r5,r5,r6
|
|
cmpldi r5,128
|
|
|
|
mflr r0
|
|
stdu r1,-STACKFRAMESIZE(r1)
|
|
std r14,STK_REG(R14)(r1)
|
|
std r15,STK_REG(R15)(r1)
|
|
std r16,STK_REG(R16)(r1)
|
|
std r17,STK_REG(R17)(r1)
|
|
std r18,STK_REG(R18)(r1)
|
|
std r19,STK_REG(R19)(r1)
|
|
std r20,STK_REG(R20)(r1)
|
|
std r21,STK_REG(R21)(r1)
|
|
std r22,STK_REG(R22)(r1)
|
|
std r0,STACKFRAMESIZE+16(r1)
|
|
|
|
blt 5f
|
|
srdi r6,r5,7
|
|
mtctr r6
|
|
|
|
/* Now do cacheline (128B) sized loads and stores. */
|
|
.align 5
|
|
4:
|
|
err2; ld r0,0(r4)
|
|
err2; ld r6,8(r4)
|
|
err2; ld r8,16(r4)
|
|
err2; ld r9,24(r4)
|
|
err2; ld r10,32(r4)
|
|
err2; ld r11,40(r4)
|
|
err2; ld r12,48(r4)
|
|
err2; ld r14,56(r4)
|
|
err2; ld r15,64(r4)
|
|
err2; ld r16,72(r4)
|
|
err2; ld r17,80(r4)
|
|
err2; ld r18,88(r4)
|
|
err2; ld r19,96(r4)
|
|
err2; ld r20,104(r4)
|
|
err2; ld r21,112(r4)
|
|
err2; ld r22,120(r4)
|
|
addi r4,r4,128
|
|
err2; std r0,0(r3)
|
|
err2; std r6,8(r3)
|
|
err2; std r8,16(r3)
|
|
err2; std r9,24(r3)
|
|
err2; std r10,32(r3)
|
|
err2; std r11,40(r3)
|
|
err2; std r12,48(r3)
|
|
err2; std r14,56(r3)
|
|
err2; std r15,64(r3)
|
|
err2; std r16,72(r3)
|
|
err2; std r17,80(r3)
|
|
err2; std r18,88(r3)
|
|
err2; std r19,96(r3)
|
|
err2; std r20,104(r3)
|
|
err2; std r21,112(r3)
|
|
err2; std r22,120(r3)
|
|
addi r3,r3,128
|
|
subi r7,r7,128
|
|
bdnz 4b
|
|
|
|
clrldi r5,r5,(64-7)
|
|
|
|
/* Up to 127B to go */
|
|
5: srdi r6,r5,4
|
|
mtocrf 0x01,r6
|
|
|
|
6: bf cr7*4+1,7f
|
|
err2; ld r0,0(r4)
|
|
err2; ld r6,8(r4)
|
|
err2; ld r8,16(r4)
|
|
err2; ld r9,24(r4)
|
|
err2; ld r10,32(r4)
|
|
err2; ld r11,40(r4)
|
|
err2; ld r12,48(r4)
|
|
err2; ld r14,56(r4)
|
|
addi r4,r4,64
|
|
err2; std r0,0(r3)
|
|
err2; std r6,8(r3)
|
|
err2; std r8,16(r3)
|
|
err2; std r9,24(r3)
|
|
err2; std r10,32(r3)
|
|
err2; std r11,40(r3)
|
|
err2; std r12,48(r3)
|
|
err2; std r14,56(r3)
|
|
addi r3,r3,64
|
|
subi r7,r7,64
|
|
|
|
7: ld r14,STK_REG(R14)(r1)
|
|
ld r15,STK_REG(R15)(r1)
|
|
ld r16,STK_REG(R16)(r1)
|
|
ld r17,STK_REG(R17)(r1)
|
|
ld r18,STK_REG(R18)(r1)
|
|
ld r19,STK_REG(R19)(r1)
|
|
ld r20,STK_REG(R20)(r1)
|
|
ld r21,STK_REG(R21)(r1)
|
|
ld r22,STK_REG(R22)(r1)
|
|
addi r1,r1,STACKFRAMESIZE
|
|
|
|
/* Up to 63B to go */
|
|
bf cr7*4+2,8f
|
|
err1; ld r0,0(r4)
|
|
err1; ld r6,8(r4)
|
|
err1; ld r8,16(r4)
|
|
err1; ld r9,24(r4)
|
|
addi r4,r4,32
|
|
err1; std r0,0(r3)
|
|
err1; std r6,8(r3)
|
|
err1; std r8,16(r3)
|
|
err1; std r9,24(r3)
|
|
addi r3,r3,32
|
|
subi r7,r7,32
|
|
|
|
/* Up to 31B to go */
|
|
8: bf cr7*4+3,9f
|
|
err1; ld r0,0(r4)
|
|
err1; ld r6,8(r4)
|
|
addi r4,r4,16
|
|
err1; std r0,0(r3)
|
|
err1; std r6,8(r3)
|
|
addi r3,r3,16
|
|
subi r7,r7,16
|
|
|
|
9: clrldi r5,r5,(64-4)
|
|
|
|
/* Up to 15B to go */
|
|
.Lshort_copy:
|
|
mtocrf 0x01,r5
|
|
bf cr7*4+0,12f
|
|
err1; lwz r0,0(r4) /* Less chance of a reject with word ops */
|
|
err1; lwz r6,4(r4)
|
|
addi r4,r4,8
|
|
err1; stw r0,0(r3)
|
|
err1; stw r6,4(r3)
|
|
addi r3,r3,8
|
|
subi r7,r7,8
|
|
|
|
12: bf cr7*4+1,13f
|
|
err1; lwz r0,0(r4)
|
|
addi r4,r4,4
|
|
err1; stw r0,0(r3)
|
|
addi r3,r3,4
|
|
subi r7,r7,4
|
|
|
|
13: bf cr7*4+2,14f
|
|
err1; lhz r0,0(r4)
|
|
addi r4,r4,2
|
|
err1; sth r0,0(r3)
|
|
addi r3,r3,2
|
|
subi r7,r7,2
|
|
|
|
14: bf cr7*4+3,15f
|
|
err1; lbz r0,0(r4)
|
|
err1; stb r0,0(r3)
|
|
|
|
15: li r3,0
|
|
blr
|
|
|
|
EXPORT_SYMBOL_GPL(copy_mc_generic);
|