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>

10 files changed, 25 insertions, 48 deletions

diff --git a/arch/sparc/lib/GENcopy_from_user.S b/arch/sparc/lib/GENcopy_from_user.S
index 9b0e58f9f970..b7d0bd6b1406 100644
--- a/arch/sparc/lib/GENcopy_from_user.S
+++ b/arch/sparc/lib/GENcopy_from_user.S
@@ -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
 
diff --git a/arch/sparc/lib/GENcopy_to_user.S b/arch/sparc/lib/GENcopy_to_user.S
index ce79b495c65d..780550e1afc7 100644
--- a/arch/sparc/lib/GENcopy_to_user.S
+++ b/arch/sparc/lib/GENcopy_to_user.S
@@ -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
 
diff --git a/arch/sparc/lib/NG2copy_from_user.S b/arch/sparc/lib/NG2copy_from_user.S
index 01ac546a86f4..119ccb9a54f4 100644
--- a/arch/sparc/lib/NG2copy_from_user.S
+++ b/arch/sparc/lib/NG2copy_from_user.S
@@ -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
 
diff --git a/arch/sparc/lib/NG2copy_to_user.S b/arch/sparc/lib/NG2copy_to_user.S
index c477e1594a72..7fe1ccefd9d0 100644
--- a/arch/sparc/lib/NG2copy_to_user.S
+++ b/arch/sparc/lib/NG2copy_to_user.S
@@ -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
 
diff --git a/arch/sparc/lib/NGcopy_from_user.S b/arch/sparc/lib/NGcopy_from_user.S
index 39bb8912c6e7..5d1e4d1ac21e 100644
--- a/arch/sparc/lib/NGcopy_from_user.S
+++ b/arch/sparc/lib/NGcopy_from_user.S
@@ -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
 
diff --git a/arch/sparc/lib/NGcopy_to_user.S b/arch/sparc/lib/NGcopy_to_user.S
index bf62fc1a26c7..ff630dcb273c 100644
--- a/arch/sparc/lib/NGcopy_to_user.S
+++ b/arch/sparc/lib/NGcopy_to_user.S
@@ -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
 
diff --git a/arch/sparc/lib/U1copy_from_user.S b/arch/sparc/lib/U1copy_from_user.S
index f14efdd6d4a9..a6ae2ea04bf5 100644
--- a/arch/sparc/lib/U1copy_from_user.S
+++ b/arch/sparc/lib/U1copy_from_user.S
@@ -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"
diff --git a/arch/sparc/lib/U1copy_to_user.S b/arch/sparc/lib/U1copy_to_user.S
index 59d531b4a1a5..f4b970eeb485 100644
--- a/arch/sparc/lib/U1copy_to_user.S
+++ b/arch/sparc/lib/U1copy_to_user.S
@@ -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"
diff --git a/arch/sparc/lib/U3copy_to_user.S b/arch/sparc/lib/U3copy_to_user.S
index b4cbfe5a97ba..ef1e493afdfa 100644
--- a/arch/sparc/lib/U3copy_to_user.S
+++ b/arch/sparc/lib/U3copy_to_user.S
@@ -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"
diff --git a/arch/sparc/lib/copy_in_user.S b/arch/sparc/lib/copy_in_user.S
index 884f46499d4e..302c0e60dc2c 100644
--- a/arch/sparc/lib/copy_in_user.S
+++ b/arch/sparc/lib/copy_in_user.S
@@ -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)