dtrace: support x86 CPUs with SMAP

We need to call STAC and CLAC at appropriate times, or the CPU will
fault us for accessing userspace without permission.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Acked-by: Kris Van Hees <kris.van.hees@oracle.com>
Orabug: 26166784

diff --git a/dtrace/dtrace_asm_x86_64.S b/dtrace/dtrace_asm_x86_64.S
index e84190d364f13a32685df7096341809e72917278..c8b6977d8ea1609d37e42a5ff004c85dd20a87f7 100644 (file)
--- a/dtrace/dtrace_asm_x86_64.S
+++ b/dtrace/dtrace_asm_x86_64.S
@@ -19,11 +19,12 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2010-2014 Oracle, Inc.  All rights reserved.
+ * Copyright 2010-2017 Oracle, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
 #include <linux/linkage.h>
+#include <asm/smap.h>
 
 #define CPU_DTRACE_BADADDR     0x0004  /* DTrace fault: bad address */
 
@@ -96,10 +97,12 @@
        pushq   %rbp
        movq    %rsp, %rbp
 
+       ASM_STAC
        xchgq   %rdi, %rsi              # make %rsi source, %rdi dest
        movq    %rdx, %rcx              # load count
        repz                            # repeat for count ...
        smovb                           #   move from %ds:rsi to %ed:rdi
+       ASM_CLAC
        leave
        ret
        ENDPROC(dtrace_copy)
@@ -133,6 +136,7 @@
        pushq   %rbp
        movq    %rsp, %rbp
 
+       ASM_STAC
 0:
        movb    (%rdi), %al             # load from source
        movb    %al, (%rsi)             # store to destination
@@ -149,6 +153,7 @@
        cmpq    $0, %rdx
        jne     0b
 2:
+       ASM_CLAC
        leave
        ret
 
@@ -196,7 +201,9 @@
 #if defined(__x86_64__)
 
        ENTRY(dtrace_fulword)
+       ASM_STAC
        movq    (%rdi), %rax
+       ASM_CLAC
        ret
        ENDPROC(dtrace_fulword)
 
@@ -215,7 +222,9 @@
 
        ENTRY(dtrace_fuword8_nocheck)
        xorq    %rax, %rax
+       ASM_STAC
        movb    (%rdi), %al
+       ASM_CLAC
        ret
        ENDPROC(dtrace_fuword8_nocheck)
 
@@ -234,7 +243,9 @@
 
        ENTRY(dtrace_fuword16_nocheck)
        xorq    %rax, %rax
+       ASM_STAC
        movw    (%rdi), %ax
+       ASM_CLAC
        ret
        ENDPROC(dtrace_fuword16_nocheck)
 
@@ -253,7 +264,9 @@
 
        ENTRY(dtrace_fuword32_nocheck)
        xorq    %rax, %rax
+       ASM_STAC
        movl    (%rdi), %eax
+       ASM_CLAC
        ret
        ENDPROC(dtrace_fuword32_nocheck)
 
@@ -271,7 +284,9 @@
 #if defined(__x86_64__)
 
        ENTRY(dtrace_fuword64_nocheck)
+       ASM_STAC
        movq    (%rdi), %rax
+       ASM_CLAC
        ret
        ENDPROC(dtrace_fuword64_nocheck)