s390: add support to start the kernel in 64 bit mode.

Do the switch to z/Architecture (alias 64 bit) mode early in head.S.
If the machine is already running in 64 bit mode the sigp turns into
a nop. With this change it doesn't matter in which mode the kernel
is started.

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

1 files changed, 70 insertions, 31 deletions

diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index 805b6686b641..984726cbce16 100644
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -52,7 +52,7 @@ __HEAD
         .long   0x02000370,0x60000050           # the channel program the PSW
         .long   0x020003c0,0x60000050           # at location 0 is loaded.
         .long   0x02000410,0x60000050           # Initial processing starts
-        .long   0x02000460,0x60000050           # at 0xf0 = iplstart.
+        .long   0x02000460,0x60000050           # at 0x200 = iplstart.
         .long   0x020004b0,0x60000050
         .long   0x02000500,0x60000050
         .long   0x02000550,0x60000050
@@ -62,11 +62,54 @@ __HEAD
         .long   0x02000690,0x60000050
         .long   0x020006e0,0x20000050
 
-        .org    0xf0
+        .org    0x200
+#
+# subroutine to set architecture mode
+#
+.Lsetmode:
+#ifdef CONFIG_64BIT
+        mvi     __LC_AR_MODE_ID,1       # set esame flag
+        slr     %r0,%r0                 # set cpuid to zero
+        lhi     %r1,2                   # mode 2 = esame (dump)
+        sigp    %r1,%r0,0x12            # switch to esame mode
+        bras    %r13,0f
+        .fill   16,4,0x0
+0:      lmh     %r0,%r15,0(%r13)        # clear high-order half of gprs
+        sam31                           # switch to 31 bit addressing mode
+#else
+        mvi     __LC_AR_MODE_ID,0       # set ESA flag (mode 0)
+#endif
+        br      %r14
+
+#
+# subroutine to wait for end I/O
+#
+.Lirqwait:
+#ifdef CONFIG_64BIT
+        mvc     0x1f0(16),.Lnewpsw      # set up IO interrupt psw
+        lpsw    .Lwaitpsw
+.Lioint:
+        br      %r14
+        .align  8
+.Lnewpsw:
+        .quad   0x0000000080000000,.Lioint
+#else
+        mvc     0x78(8),.Lnewpsw        # set up IO interrupt psw
+        lpsw    .Lwaitpsw
+.Lioint:
+        br      %r14
+        .align  8
+.Lnewpsw:
+        .long   0x00080000,0x80000000+.Lioint
+#endif
+.Lwaitpsw:
+        .long   0x020a0000,0x80000000+.Lioint
+
 #
 # subroutine for loading cards from the reader
 #
 .Lloader:
+        la      %r4,0(%r14)
         la      %r3,.Lorb               # r2 = address of orb into r2
         la      %r5,.Lirb               # r4 = address of irb
         la      %r6,.Lccws
@@ -83,9 +126,7 @@ __HEAD
         ssch    0(%r3)                  # load chunk of 1600 bytes
         bnz     .Llderr
 .Lwait4irq:
-        mvc     0x78(8),.Lnewpsw        # set up IO interrupt psw
-        lpsw    .Lwaitpsw
-.Lioint:
+        bas     %r14,.Lirqwait
         c       %r1,0xb8                # compare subchannel number
         bne     .Lwait4irq
         tsch    0(%r5)
@@ -104,7 +145,7 @@ __HEAD
         sr      %r0,%r3                 # #ccws*80-residual=#bytes read
         ar      %r2,%r0
 
-        br      %r14                    # r2 contains the total size
+        br      %r4                     # r2 contains the total size
 
 .Lcont:
         ahi     %r2,0x640               # add 0x640 to total size
@@ -128,10 +169,6 @@ __HEAD
 .Lloadp:.long   0,0
         .align  8
 .Lcrash:.long   0x000a0000,0x00000000
-.Lnewpsw:
-        .long   0x00080000,0x80000000+.Lioint
-.Lwaitpsw:
-        .long   0x020a0000,0x80000000+.Lioint
 
         .align  8
 .Lccws: .rept   19
@@ -140,6 +177,7 @@ __HEAD
         .long   0x02200050,0x00000000
 
 iplstart:
+        bas     %r14,.Lsetmode          # Immediately switch to 64 bit mode
         lh      %r1,0xb8                # test if subchannel number
         bct     %r1,.Lnoload            #  is valid
         l       %r1,0xb8                # load ipl subchannel number
@@ -209,8 +247,8 @@ iplstart:
 #
 # reset files in VM reader
 #
-        stidp   __LC_SAVE_AREA_SYNC     # store cpuid
-        tm      __LC_SAVE_AREA_SYNC,0xff# running VM ?
+        stidp   .Lcpuid                 # store cpuid
+        tm      .Lcpuid,0xff            # running VM ?
         bno     .Lnoreset
         la      %r2,.Lreset
         lhi     %r3,26
@@ -222,23 +260,14 @@ iplstart:
         tm      31(%r5),0xff            # bits is set in the schib
         bz      .Lnoreset
 .Lwaitforirq:
-        mvc     0x78(8),.Lrdrnewpsw     # set up IO interrupt psw
-.Lwaitrdrirq:
-        lpsw    .Lrdrwaitpsw
-.Lrdrint:
+        bas     %r14,.Lirqwait          # wait for IO interrupt
         c       %r1,0xb8                # compare subchannel number
-        bne     .Lwaitrdrirq
+        bne     .Lwaitforirq
         la      %r5,.Lirb
         tsch    0(%r5)
 .Lnoreset:
         b       .Lnoload
 
-        .align  8
-.Lrdrnewpsw:
-        .long   0x00080000,0x80000000+.Lrdrint
-.Lrdrwaitpsw:
-        .long   0x020a0000,0x80000000+.Lrdrint
-
 #
 # everything loaded, go for it
 #
@@ -254,6 +283,8 @@ iplstart:
         .byte   0xc8,0xd6,0xd3,0xc4     # "change rdr all keep nohold"
 .L_eof: .long   0xc5d6c600       /* C'EOF' */
 .L_hdr: .long   0xc8c4d900       /* C'HDR' */
+        .align  8
+.Lcpuid:.fill   8,1,0
 
 #
 # SALIPL loader support. Based on a patch by Rob van der Heij.
@@ -263,6 +294,7 @@ iplstart:
         .org    0x800
 ENTRY(start)
         stm     %r0,%r15,0x07b0         # store registers
+        bas     %r14,.Lsetmode          # Immediately switch to 64 bit mode
         basr    %r12,%r0
 .base:
         l       %r11,.parm
@@ -343,6 +375,18 @@ ENTRY(startup)
 ENTRY(startup_kdump)
         j       .Lep_startup_kdump
 .Lep_startup_normal:
+#ifdef CONFIG_64BIT
+        mvi     __LC_AR_MODE_ID,1       # set esame flag
+        slr     %r0,%r0                 # set cpuid to zero
+        lhi     %r1,2                   # mode 2 = esame (dump)
+        sigp    %r1,%r0,0x12            # switch to esame mode
+        bras    %r13,0f
+        .fill   16,4,0x0
+0:      lmh     %r0,%r15,0(%r13)        # clear high-order half of gprs
+        sam31                           # switch to 31 bit addressing mode
+#else
+        mvi     __LC_AR_MODE_ID,0       # set ESA flag (mode 0)
+#endif
         basr    %r13,0                  # get base
 .LPG0:
         xc      0x200(256),0x200        # partially clear lowcore
@@ -410,22 +454,17 @@ ENTRY(startup_kdump)
 #endif
 
 #ifdef CONFIG_64BIT
-        mvi     __LC_AR_MODE_ID,1       # set esame flag
-        slr     %r0,%r0                 # set cpuid to zero
-        lhi     %r1,2                   # mode 2 = esame (dump)
-        sigp    %r1,%r0,0x12            # switch to esame mode
+        /* Continue with 64bit startup code in head64.S */
         sam64                           # switch to 64 bit mode
-        larl    %r13,4f
-        lmh     %r0,%r15,0(%r13)        # clear high-order half
         jg      startup_continue
-4:      .fill   16,4,0x0
 #else
-        mvi     __LC_AR_MODE_ID,0       # set ESA flag (mode 0)
+        /* Continue with 31bit startup code in head31.S */
         l       %r13,4f-.LPG0(%r13)
         b       0(%r13)
         .align  8
 4:      .long   startup_continue
 #endif
+
         .align  8
 5:      .long   0x7fffffff,0xffffffff