[S390] fix boot failures with compressed kernels

Fix two bugs with the kernel image compression:
1) reset the bss section of the compressed vmlinux
2) clear the high half of the registers for 64 bit early enough
   for the decompression step

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 7 insertions, 6 deletions

diff --git a/arch/s390/boot/compressed/misc.c b/arch/s390/boot/compressed/misc.c
index a97d69525829..14e0479d3888 100644
--- a/arch/s390/boot/compressed/misc.c
+++ b/arch/s390/boot/compressed/misc.c
@@ -24,8 +24,8 @@
 /* Symbols defined by linker scripts */
 extern char input_data[];
 extern int input_len;
-extern int _text;
-extern int _end;
+extern char _text, _end;
+extern char _bss, _ebss;
 
 static void error(char *m);
 
@@ -129,12 +129,12 @@ unsigned long decompress_kernel(void)
         unsigned long output_addr;
         unsigned char *output;
 
+        check_ipl_parmblock((void *) 0, (unsigned long) output + SZ__bss_start);
+        memset(&_bss, 0, &_ebss - &_bss);
         free_mem_ptr = (unsigned long)&_end;
         free_mem_end_ptr = free_mem_ptr + HEAP_SIZE;
         output = (unsigned char *) ((free_mem_end_ptr + 4095UL) & -4096UL);
 
-        check_ipl_parmblock((void *) 0, (unsigned long) output + SZ__bss_start);
-
 #ifdef CONFIG_BLK_DEV_INITRD
         /*
          * Move the initrd right behind the end of the decompressed
diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index ca4a62bd862f..9d1f76702d47 100644
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -517,7 +517,10 @@ startup:
         lhi     %r1,2                   # mode 2 = esame (dump)
         sigp    %r1,%r0,0x12            # switch to esame mode
         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)
         l       %r13,4f-.LPG0(%r13)
diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index 39580e768658..1f70970de0aa 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -21,7 +21,6 @@ startup_continue:
         larl    %r1,sched_clock_base_cc
         mvc     0(8,%r1),__LC_LAST_UPDATE_CLOCK
         larl    %r13,.LPG1              # get base
-        lmh     %r0,%r15,.Lzero64-.LPG1(%r13)   # clear high-order half
         lctlg   %c0,%c15,.Lctl-.LPG1(%r13)      # load control registers
         lg      %r12,.Lparmaddr-.LPG1(%r13)     # pointer to parameter area
                                         # move IPL device to lowcore
@@ -67,7 +66,6 @@ startup_continue:
 .L4malign:.quad 0xffffffffffc00000
 .Lscan2g:.quad  0x80000000 + 0x20000 - 8        # 2GB + 128K - 8
 .Lnop:  .long   0x07000700
-.Lzero64:.fill  16,4,0x0
 .Lparmaddr:
         .quad   PARMAREA
         .align  64