sparc64: fix fault handling in NGbzero.S and GENbzero.S

When any of the functions contained in NGbzero.S and GENbzero.S
vector through *bzero_from_clear_user, we may end up taking a
fault when executing one of the store alternate address space
instructions. If this happens, the exception handler does not
restore the %asi register.

This commit fixes the issue by introducing a new exception
handler that ensures the %asi register is restored when
a fault is handled.

Orabug: 25577560

Signed-off-by: Dave Aldridge <david.j.aldridge@oracle.com>
Reviewed-by: Rob Gardner <rob.gardner@oracle.com>
Reviewed-by: Babu Moger <babu.moger@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
index 4410119..41a4073 100644 (file)
--- a/arch/sparc/kernel/head_64.S
+++ b/arch/sparc/kernel/head_64.S
@@ -939,3 +939,9 @@ ENTRY(__retl_o1)
        retl
         mov    %o1, %o0
 ENDPROC(__retl_o1)
+
+ENTRY(__retl_o1_asi)
+       wr      %o5, 0x0, %asi
+       retl
+        mov    %o1, %o0
+ENDPROC(__retl_o1_asi)

diff --git a/arch/sparc/lib/GENbzero.S b/arch/sparc/lib/GENbzero.S
index 8e7a843..2fbf629 100644 (file)
--- a/arch/sparc/lib/GENbzero.S
+++ b/arch/sparc/lib/GENbzero.S
@@ -8,7 +8,7 @@
 98:    x,y;                    \
        .section __ex_table,"a";\
        .align 4;               \
-       .word 98b, __retl_o1;   \
+       .word 98b, __retl_o1_asi;\
        .text;                  \
        .align 4;
 

diff --git a/arch/sparc/lib/NGbzero.S b/arch/sparc/lib/NGbzero.S
index beab29b..33053bd 100644 (file)
--- a/arch/sparc/lib/NGbzero.S
+++ b/arch/sparc/lib/NGbzero.S
@@ -8,7 +8,7 @@
 98:    x,y;                    \
        .section __ex_table,"a";\
        .align 4;               \
-       .word 98b, __retl_o1;   \
+       .word 98b, __retl_o1_asi;\
        .text;                  \
        .align 4;