[S390] zfcpdump support.

s390 machines provide hardware support for creating Linux dumps on SCSI
disks. For creating a dump a special purpose dump Linux is used. The first
32 MB of memory are saved by the hardware before the dump Linux is
booted. Via an SCLP interface, the saved memory can be accessed from
Linux. This patch exports memory and registers of the crashed Linux to
userspace via a debugfs file. For more information refer to
Documentation/s390/zfcpdump.txt, which is included in this patch.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 71 insertions, 1 deletions

diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index 37010709fe68..a87b1976d409 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -39,7 +39,69 @@ startup_continue:
         basr    %r13,0                  # get base
 .LPG1:  sll     %r13,1                  # remove high order bit
         srl     %r13,1
-        lhi     %r1,1                   # mode 1 = esame
+
+#ifdef CONFIG_ZFCPDUMP
+
+        # check if we have been ipled using zfcp dump:
+
+        tm      0xb9,0x01               # test if subchannel is enabled
+        jno     .nodump                 # subchannel disabled
+        l       %r1,0xb8
+        la      %r5,.Lipl_schib-.LPG1(%r13)
+        stsch   0(%r5)                  # get schib of subchannel
+        jne     .nodump                 # schib not available
+        tm      5(%r5),0x01             # devno valid?
+        jno     .nodump
+        tm      4(%r5),0x80             # qdio capable device?
+        jno     .nodump
+        l       %r2,20(%r0)             # address of ipl parameter block
+        lhi     %r3,0
+        ic      %r3,0x148(%r2)          # get opt field
+        chi     %r3,0x20                # load with dump?
+        jne     .nodump
+
+        # store all prefix registers in case of load with dump:
+
+        la      %r7,0                   # base register for 0 page
+        la      %r8,0                   # first cpu
+        l       %r11,.Lpref_arr_ptr-.LPG1(%r13) # address of prefix array
+        ahi     %r11,4                  # skip boot cpu
+        lr      %r12,%r11
+        ahi     %r12,(CONFIG_NR_CPUS*4) # end of prefix array
+        stap    .Lcurrent_cpu+2-.LPG1(%r13)     # store current cpu addr
+1:
+        cl      %r8,.Lcurrent_cpu-.LPG1(%r13)   # is ipl cpu ?
+        je      4f                              # if yes get next cpu
+2:
+        lr      %r9,%r7
+        sigp    %r9,%r8,0x9             # stop & store status of cpu
+        brc     8,3f                    # accepted
+        brc     4,4f                    # status stored: next cpu
+        brc     2,2b                    # busy:          try again
+        brc     1,4f                    # not op:        next cpu
+3:
+        mvc     0(4,%r11),264(%r7)      # copy prefix register to prefix array
+        ahi     %r11,4                  # next element in prefix array
+        clr     %r11,%r12
+        je      5f                      # no more space in prefix array
+4:
+        ahi     %r8,1                           # next cpu (r8 += 1)
+        cl      %r8,.Llast_cpu-.LPG1(%r13)      # is last possible cpu ?
+        jl      1b                              # jump if not last cpu
+5:
+        lhi     %r1,2                   # mode 2 = esame (dump)
+        j       6f
+        .align 4
+.Lipl_schib:
+        .rept 13
+        .long 0
+        .endr
+.nodump:
+        lhi     %r1,1                   # mode 1 = esame (normal ipl)
+6:
+#else
+        lhi     %r1,1                   # mode 1 = esame (normal ipl)
+#endif /* CONFIG_ZFCPDUMP */
         mvi     __LC_AR_MODE_ID,1       # set esame flag
         slr     %r0,%r0                 # set cpuid to zero
         sigp    %r1,%r0,0x12            # switch to esame mode
@@ -149,6 +211,14 @@ startup_continue:
 .L4malign:.quad 0xffffffffffc00000
 .Lscan2g:.quad  0x80000000 + 0x20000 - 8        # 2GB + 128K - 8
 .Lnop:  .long   0x07000700
+#ifdef CONFIG_ZFCPDUMP
+.Lcurrent_cpu:
+        .long 0x0
+.Llast_cpu:
+        .long 0x0000ffff
+.Lpref_arr_ptr:
+        .long zfcpdump_prefix_array
+#endif /* CONFIG_ZFCPDUMP */
 .Lparmaddr:
         .quad   PARMAREA
         .align  64