pc-bios/s390-ccw: Don't generate TEXTRELs

Commit 7cd50cbe4c ("pc-bios/s390-ccw: Don't use __bss_start with the
"larl" instruction") introduced the address constant bss_start_literal
for __bss_start in the .text section, which introduced a relocation in
code (i.e. TEXTREL). The dedicated constant is required, as __bss_start
may not necessarily be aligned on a 2-byte boundary (see subject commit
for details).

Move the constant to the .data section to get rid of the relocation in
the .text section. Add the linker option -z text to prevent TEXTRELs to
get introduced in the future.

Note that the R_390_RELATIVE relocations are taken care of by function
glue() in include/hw/elf_ops.h.inc introduced by commit 5dce07e1cb
("elf-loader: Provide the possibility to relocate s390 ELF files").

Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Message-ID: <20241001153618.17791-3-mhartmay@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

pc-bios/s390-ccw/Makefile

@@ -46,7 +46,7 @@ EXTRA_CFLAGS += -fwrapv -fno-strict-aliasing -fno-asynchronous-unwind-tables
 EXTRA_CFLAGS += -msoft-float
 EXTRA_CFLAGS += -std=gnu99
 EXTRA_CFLAGS += $(LIBC_INC) $(LIBNET_INC)
-LDFLAGS += -Wl,-pie -nostdlib -z noexecstack
+LDFLAGS += -Wl,-pie -nostdlib -z noexecstack -z text
 
 cc-test = $(CC) -Werror $1 -c -o /dev/null -xc /dev/null >/dev/null 2>/dev/null
 cc-option = if $(call cc-test, $1); then \

pc-bios/s390-ccw/start.S

@@ -113,8 +113,6 @@ io_new_code:
     br      %r14
 
     .balign 8
-bss_start_literal:
-    .quad   __bss_start
 disabled_wait_psw:
     .quad   0x0002000180000000,0x0000000000000000
 enabled_wait_psw:
@@ -124,6 +122,11 @@ external_new_mask:
 io_new_mask:
     .quad   0x0000000180000000
 
+.data
+    .balign 8
+bss_start_literal:
+    .quad   __bss_start
+
 .bss
     .balign 8
 stack: