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b3484a1d4d
For the non VSX version, that's trivial. Just use unsafe_copy_to_user()
instead of __copy_to_user().
For the VSX version, remove the intermediate step through a buffer and
use unsafe_put_user() directly. This generates a far smaller code which
is acceptable to inline, see below:
Standard VSX version:
0000000000000000 <.copy_fpr_to_user>:
0: 7c 08 02 a6 mflr r0
4: fb e1 ff f8 std r31,-8(r1)
8: 39 00 00 20 li r8,32
c: 39 24 0b 80 addi r9,r4,2944
10: 7d 09 03 a6 mtctr r8
14: f8 01 00 10 std r0,16(r1)
18: f8 21 fe 71 stdu r1,-400(r1)
1c: 39 41 00 68 addi r10,r1,104
20: e9 09 00 00 ld r8,0(r9)
24: 39 4a 00 08 addi r10,r10,8
28: 39 29 00 10 addi r9,r9,16
2c: f9 0a 00 00 std r8,0(r10)
30: 42 00 ff f0 bdnz 20 <.copy_fpr_to_user+0x20>
34: e9 24 0d 80 ld r9,3456(r4)
38: 3d 42 00 00 addis r10,r2,0
3a: R_PPC64_TOC16_HA .toc
3c: eb ea 00 00 ld r31,0(r10)
3e: R_PPC64_TOC16_LO_DS .toc
40: f9 21 01 70 std r9,368(r1)
44: e9 3f 00 00 ld r9,0(r31)
48: 81 29 00 20 lwz r9,32(r9)
4c: 2f 89 00 00 cmpwi cr7,r9,0
50: 40 9c 00 18 bge cr7,68 <.copy_fpr_to_user+0x68>
54: 4c 00 01 2c isync
58: 3d 20 40 00 lis r9,16384
5c: 79 29 07 c6 rldicr r9,r9,32,31
60: 7d 3d 03 a6 mtspr 29,r9
64: 4c 00 01 2c isync
68: 38 a0 01 08 li r5,264
6c: 38 81 00 70 addi r4,r1,112
70: 48 00 00 01 bl 70 <.copy_fpr_to_user+0x70>
70: R_PPC64_REL24 .__copy_tofrom_user
74: 60 00 00 00 nop
78: e9 3f 00 00 ld r9,0(r31)
7c: 81 29 00 20 lwz r9,32(r9)
80: 2f 89 00 00 cmpwi cr7,r9,0
84: 40 9c 00 18 bge cr7,9c <.copy_fpr_to_user+0x9c>
88: 4c 00 01 2c isync
8c: 39 20 ff ff li r9,-1
90: 79 29 00 44 rldicr r9,r9,0,1
94: 7d 3d 03 a6 mtspr 29,r9
98: 4c 00 01 2c isync
9c: 38 21 01 90 addi r1,r1,400
a0: e8 01 00 10 ld r0,16(r1)
a4: eb e1 ff f8 ld r31,-8(r1)
a8: 7c 08 03 a6 mtlr r0
ac: 4e 80 00 20 blr
'unsafe' simulated VSX version (The ... are only nops) using
unsafe_copy_fpr_to_user() macro:
unsigned long copy_fpr_to_user(void __user *to,
struct task_struct *task)
{
unsafe_copy_fpr_to_user(to, task, failed);
return 0;
failed:
return 1;
}
0000000000000000 <.copy_fpr_to_user>:
0: 39 00 00 20 li r8,32
4: 39 44 0b 80 addi r10,r4,2944
8: 7d 09 03 a6 mtctr r8
c: 7c 69 1b 78 mr r9,r3
...
20: e9 0a 00 00 ld r8,0(r10)
24: f9 09 00 00 std r8,0(r9)
28: 39 4a 00 10 addi r10,r10,16
2c: 39 29 00 08 addi r9,r9,8
30: 42 00 ff f0 bdnz 20 <.copy_fpr_to_user+0x20>
34: e9 24 0d 80 ld r9,3456(r4)
38: f9 23 01 00 std r9,256(r3)
3c: 38 60 00 00 li r3,0
40: 4e 80 00 20 blr
...
50: 38 60 00 01 li r3,1
54: 4e 80 00 20 blr
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/29f6c4b8e7a5bbc61e6a8801b78bbf493f9f819e.1597770847.git.christophe.leroy@csgroup.eu
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.