s390/kprobes: add support for pc-relative long displacement instructions

With the general-instruction extension facility (z10) a couple of
instructions with a pc-relative long displacement were introduced.  The
kprobes support for these instructions however was never implemented.

In result, if anybody ever put a probe on any of these instructions the
result would have been random behaviour after the instruction got executed
within the insn slot.

So lets add the missing handling for these instructions.  Since all of the
new instructions have 32 bit signed displacement the easiest solution is
to allocate an insn slot that is within the same 2GB area like the
original instruction and patch the displacement field.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/s390/include/asm/kprobes.h b/arch/s390/include/asm/kprobes.h
index dcf6948a875c..4176dfe0fba1 100644
--- a/arch/s390/include/asm/kprobes.h
+++ b/arch/s390/include/asm/kprobes.h
@@ -31,6 +31,8 @@
 #include <linux/ptrace.h>
 #include <linux/percpu.h>
 
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+
 struct pt_regs;
 struct kprobe;
 
@@ -57,7 +59,7 @@ typedef u16 kprobe_opcode_t;
 /* Architecture specific copy of original instruction */
 struct arch_specific_insn {
 	/* copy of original instruction */
-	kprobe_opcode_t insn[MAX_INSN_SIZE];
+	kprobe_opcode_t *insn;
 };
 
 struct prev_kprobe {