From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit f9c87a6f46d508eae0d9ae640be98d50f237f827 upstream. If the kernel is compiled with gcc 5.1 and the XZ compression option the decompress_kernel function calls _sclp_print_early in 64-bit mode while the content of the upper register half of %r6 is non-zero. This causes a specification exception on the servc instruction in _sclp_servc. The _sclp_print_early function saves and restores the upper registers halves but it fails to clear them for the 31-bit code of the mini sclp driver. Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- arch/s390/kernel/sclp.S | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/s390/kernel/sclp.S b/arch/s390/kernel/sclp.S index 29bd7bec4176..1ecd47b5e250 100644 --- a/arch/s390/kernel/sclp.S +++ b/arch/s390/kernel/sclp.S @@ -276,6 +276,8 @@ ENTRY(_sclp_print_early) jno .Lesa2 ahi %r15,-80 stmh %r6,%r15,96(%r15) # store upper register halves + basr %r13,0 + lmh %r0,%r15,.Lzeroes-.(%r13) # clear upper register halves .Lesa2: #endif lr %r10,%r2 # save string pointer @@ -299,6 +301,8 @@ ENTRY(_sclp_print_early) #endif lm %r6,%r15,120(%r15) # restore registers br %r14 +.Lzeroes: + .fill 64,4,0 .LwritedataS4: .long 0x00760005 # SCLP command for write data -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html