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sparc64: Fix probe_kernel_{read,write}(). 

This is based upon a report from Chris Torek and his initial patch.
From Chris's report:

--------------------
This came up in testing kgdb, using the built-in tests -- turn
on CONFIG_KGDB_TESTS, then

    echo V1 > /sys/module/kgdbts/parameters/kgdbts

-- but it would affect using kgdb if you were debugging and looking
at bad pointers.
--------------------

When we get a copy_{from,to}_user() request and the %asi is set to
something other than ASI_AIUS (which is userspace) then we branch off
to a routine called memcpy_user_stub().  It just does a straight
memcpy since we are copying from kernel to kernel in this case.

The logic was that since source and destination are both kernel
pointers we don't need to have exception checks.

But for what probe_kernel_{read,write}() is trying to do, we have to
have the checks, otherwise things like kgdb bad kernel pointer
accesses don't do the right thing.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2009-02-08 22:32:31 -08:00
parent 40bdac7dbc
commit aeb3987683
10 changed files with 25 additions and 48 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/sparc/lib/GENcopy_from_user.S
View File

@ -23,7 +23,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop
#endif

2
arch/sparc/lib/GENcopy_to_user.S
View File

@ -27,7 +27,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop
#endif

2
arch/sparc/lib/NG2copy_from_user.S
View File

@ -28,7 +28,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop
#endif

2
arch/sparc/lib/NG2copy_to_user.S
View File

@ -37,7 +37,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop
#endif

2
arch/sparc/lib/NGcopy_from_user.S
View File

@ -25,7 +25,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop
#endif

2
arch/sparc/lib/NGcopy_to_user.S
View File

@ -28,7 +28,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop
#endif

2
arch/sparc/lib/U1copy_from_user.S
View File

@ -23,7 +23,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop; \
#include "U1memcpy.S"

2
arch/sparc/lib/U1copy_to_user.S
View File

@ -23,7 +23,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop; \
#include "U1memcpy.S"

2
arch/sparc/lib/U3copy_to_user.S
View File

@ -23,7 +23,7 @@
#define PREAMBLE \
rd %asi, %g1; \
cmp %g1, ASI_AIUS; \
bne,pn %icc, memcpy_user_stub; \
bne,pn %icc, ___copy_in_user; \
nop; \
#include "U3memcpy.S"

55
arch/sparc/lib/copy_in_user.S
View File

@ -3,6 +3,7 @@
* Copyright (C) 1999, 2000, 2004 David S. Miller (davem@redhat.com)
*/
#include <linux/linkage.h>
#include <asm/asi.h>
#define XCC xcc
@ -27,18 +28,7 @@
* to copy register windows around during thread cloning.
*/
.globl ___copy_in_user
.type ___copy_in_user,#function
___copy_in_user: /* %o0=dst, %o1=src, %o2=len */
/* Writing to %asi is _expensive_ so we hardcode it.
* Reading %asi to check for KERNEL_DS is comparatively
* cheap.
*/
rd %asi, %g1
cmp %g1, ASI_AIUS
bne,pn %icc, memcpy_user_stub
nop
ENTRY(___copy_in_user) /* %o0=dst, %o1=src, %o2=len */
cmp %o2, 0
be,pn %XCC, 85f
or %o0, %o1, %o3
@ -49,22 +39,24 @@ ___copy_in_user: /* %o0=dst, %o1=src, %o2=len */
/* 16 < len <= 64 */
andcc %o3, 0x7, %g0
bne,pn %XCC, 90f
sub %o0, %o1, %o3
nop
andn %o2, 0x7, %o4
and %o2, 0x7, %o2
1: subcc %o4, 0x8, %o4
EX(ldxa [%o1] %asi, %o5)
EX(stxa %o5, [%o1 + %o3] ASI_AIUS)
EX(stxa %o5, [%o0] %asi)
add %o1, 0x8, %o1
bgu,pt %XCC, 1b
add %o1, 0x8, %o1
add %o0, 0x8, %o0
andcc %o2, 0x4, %g0
be,pt %XCC, 1f
nop
sub %o2, 0x4, %o2
EX(lduwa [%o1] %asi, %o5)
EX(stwa %o5, [%o1 + %o3] ASI_AIUS)
EX(stwa %o5, [%o0] %asi)
add %o1, 0x4, %o1
add %o0, 0x4, %o0
1: cmp %o2, 0
be,pt %XCC, 85f
nop
@ -74,14 +66,15 @@ ___copy_in_user: /* %o0=dst, %o1=src, %o2=len */
80: /* 0 < len <= 16 */
andcc %o3, 0x3, %g0
bne,pn %XCC, 90f
sub %o0, %o1, %o3
nop
82:
subcc %o2, 4, %o2
EX(lduwa [%o1] %asi, %g1)
EX(stwa %g1, [%o1 + %o3] ASI_AIUS)
EX(stwa %g1, [%o0] %asi)
add %o1, 4, %o1
bgu,pt %XCC, 82b
add %o1, 4, %o1
add %o0, 4, %o0
85: retl
clr %o0
@ -90,26 +83,10 @@ ___copy_in_user: /* %o0=dst, %o1=src, %o2=len */
90:
subcc %o2, 1, %o2
EX(lduba [%o1] %asi, %g1)
EX(stba %g1, [%o1 + %o3] ASI_AIUS)
EX(stba %g1, [%o0] %asi)
add %o1, 1, %o1
bgu,pt %XCC, 90b
add %o1, 1, %o1
add %o0, 1, %o0
retl
clr %o0
.size ___copy_in_user, .-___copy_in_user
/* Act like copy_{to,in}_user(), ie. return zero instead
* of original destination pointer. This is invoked when
* copy_{to,in}_user() finds that %asi is kernel space.
*/
.globl memcpy_user_stub
.type memcpy_user_stub,#function
memcpy_user_stub:
save %sp, -192, %sp
mov %i0, %o0
mov %i1, %o1
call memcpy
mov %i2, %o2
ret
restore %g0, %g0, %o0
.size memcpy_user_stub, .-memcpy_user_stub
ENDPROC(___copy_in_user)