s390: avoid vmlinux segments overlap

Currently .vmlinux.info section of uncompressed vmlinux elf image is
included into the data segment and load address specified as 0. That
extends data segment to address 0 and makes "text" and "data" segments
overlap.
Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  LOAD           0x0000000000001000 0x0000000000100000 0x0000000000100000
                 0x0000000000ead03c 0x0000000000ead03c  R E    0x1000
  LOAD           0x0000000000eaf000 0x0000000000000000 0x0000000000000000
                 0x0000000001a13400 0x000000000233b520  RWE    0x1000
  NOTE           0x0000000000eae000 0x0000000000fad000 0x0000000000fad000
                 0x000000000000003c 0x000000000000003c         0x4

 Section to Segment mapping:
  Segment Sections...
   00     .text .notes
   01     .rodata __ksymtab __ksymtab_gpl __ksymtab_strings __param
   __modver .data..ro_after_init __ex_table .data __bug_table .init.text
   .exit.text .exit.data .altinstructions .altinstr_replacement
   .nospec_call_table .nospec_return_table .boot.data .init.data
   .data..percpu .bss .vmlinux.info
   02     .notes

Later when vmlinux.bin is produced from vmlinux, .vmlinux.info section
is removed. But elf vmlinux file, even though it is not bootable anymore,
used for debugging and loadable segments overlap should be avoided.

Utilize special ":NONE" phdr specification to avoid adding .vmlinux.info
into loadable data segment. Also set .vmlinux.info section type to INFO,
which allows to get a not-loadable info CONTENTS section.

Since minimal supported version of binutils 2.20 does not have
--dump-section objcopy option, make .vmlinux.info section loadable during
info.bin creation to get actual section contents.

Reported-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/boot/compressed/Makefile b/arch/s390/boot/compressed/Makefile
index 92b5487..b1bdd15 100644 (file)
--- a/arch/s390/boot/compressed/Makefile
+++ b/arch/s390/boot/compressed/Makefile
@@ -25,7 +25,7 @@ LDFLAGS_vmlinux := --oformat $(LD_BFD) -e startup -T
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(objtree)/arch/s390/boot/startup.a $(OBJECTS) FORCE
        $(call if_changed,ld)
 
-OBJCOPYFLAGS_info.bin := -O binary --only-section=.vmlinux.info
+OBJCOPYFLAGS_info.bin := -O binary --only-section=.vmlinux.info --set-section-flags .vmlinux.info=load
 $(obj)/info.bin: vmlinux FORCE
        $(call if_changed,objcopy)
 

diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 21eb740..8429ab0 100644 (file)
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -154,14 +154,14 @@ SECTIONS
         * uncompressed image info used by the decompressor
         * it should match struct vmlinux_info
         */
-       .vmlinux.info 0 : {
+       .vmlinux.info 0 (INFO) : {
                QUAD(_stext)                                    /* default_lma */
                QUAD(startup_continue)                          /* entry */
                QUAD(__bss_start - _stext)                      /* image_size */
                QUAD(__bss_stop - __bss_start)                  /* bss_size */
                QUAD(__boot_data_start)                         /* bootdata_off */
                QUAD(__boot_data_end - __boot_data_start)       /* bootdata_size */
-       }
+       } :NONE
 
        /* Debugging sections.  */
        STABS_DEBUG