s390/ftrace: make use of epsw to get psw mask

Finally use epsw to create a complete psw mask within pt_regs. Without
this only some bits are correct, while other bits are (incorrectly)
always zero.

The epsw instruction is quite heavy weight, however given that this
only effects ftrace_regs_caller this seems to be the right thing, so
we finally get a complete psw mask for ftrace kprobed functions.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index b882052..6ace43d 100644 (file)
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -33,9 +33,16 @@ ENDPROC(ftrace_stub)
        stg     %r14,(__SF_GPRS+8*8)(%r15)      # save traced function caller
 
        .if \allregs == 1
-       lghi    %r14,0                          # save condition code
-       ipm     %r14                            # don't put any instructions
-       sllg    %r14,%r14,16                    # clobbering CC before this point
+       # save psw mask
+       # don't put any instructions clobbering CC before this point
+#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
+       epsw    %r1,%r14
+       risbg   %r14,%r1,0,31,32
+#else
+       epsw    %r14,%r1
+       sllg    %r14,%r14,32
+       lr      %r14,%r1
+#endif
        .endif
 
        lgr     %r1,%r15
@@ -51,7 +58,6 @@ ENDPROC(ftrace_stub)
 
        .if \allregs == 1
        stg     %r14,(STACK_PTREGS_PSW)(%r15)
-       stosm   (STACK_PTREGS_PSW)(%r15),0
 #ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
        mvghi   STACK_PTREGS_FLAGS(%r15),_PIF_FTRACE_FULL_REGS
 #else