From: Philipp Rudo prudo@linux.ibm.com
commit 613775d62ec60202f98d2c5f520e6e9ba6dd4ac4 upstream.
diag308 subcode 0 performes a clear reset which inlcudes the reset of all registers in the system. While this is the preferred behavior when loading a normal kernel via kexec it prevents the crash kernel to store the register values in the dump. To prevent this use subcode 1 when loading a crash kernel instead.
Fixes: ee337f5469fd ("s390/kexec_file: Add crash support to image loader") Cc: stable@vger.kernel.org # 4.17 Signed-off-by: Philipp Rudo prudo@linux.ibm.com Reported-by: Xiaoying Yan yiyan@redhat.com Tested-by: Lianbo Jiang lijiang@redhat.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/purgatory/head.S | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
--- a/arch/s390/purgatory/head.S +++ b/arch/s390/purgatory/head.S @@ -61,14 +61,15 @@ jh 10b .endm
-.macro START_NEXT_KERNEL base +.macro START_NEXT_KERNEL base subcode lg %r4,kernel_entry-\base(%r13) lg %r5,load_psw_mask-\base(%r13) ogr %r4,%r5 stg %r4,0(%r0)
xgr %r0,%r0 - diag %r0,%r0,0x308 + lghi %r1,\subcode + diag %r0,%r1,0x308 .endm
.text @@ -123,7 +124,7 @@ ENTRY(purgatory_start) je .start_crash_kernel
/* start normal kernel */ - START_NEXT_KERNEL .base_crash + START_NEXT_KERNEL .base_crash 0
.return_old_kernel: lmg %r6,%r15,gprregs-.base_crash(%r13) @@ -227,7 +228,7 @@ ENTRY(purgatory_start) MEMCPY %r9,%r10,%r11
/* start crash kernel */ - START_NEXT_KERNEL .base_dst + START_NEXT_KERNEL .base_dst 1
load_psw_mask: