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s390/purgatory: Remove duplicate variable definitions

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Currently there are some variables in the purgatory (e.g. kernel_entry)
which are defined twice, once in assembler- and once in c-code. The reason
for this is that these variables are set during purgatory load, where
sanity checks on the corresponding Elf_Sym's are made, while they are used
in assembler-code. Thus adding a second definition in c-code is a handy
workaround to guarantee correct Elf_Sym's are created.

When the purgatory is compiled with -fcommon (default for gcc on s390) this
is no problem because both symbols are merged by the linker. However this
is not required by ISO C and when the purgatory is built with -fno-common
the linker fails with errors like

arch/s390/purgatory/purgatory.o:(.bss+0x18): multiple definition of `kernel_entry'
arch/s390/purgatory/head.o:/.../arch/s390/purgatory/head.S:230: first defined here

Thus remove the duplicate definitions and add the required size and type
information to the assembler definition. Also add -fno-common to the
command line options to prevent similar hacks in the future.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Philipp Rudo 2018-06-27 12:03:43 +02:00 committed by Martin Schwidefsky
parent c315e69308
commit 287d6070ac
4 changed files with 20 additions and 42 deletions
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6
arch/s390/include/asm/purgatory.h
View File

@ -13,11 +13,5 @@
int verify_sha256_digest(void);
extern u64 kernel_entry;
extern u64 kernel_type;
extern u64 crash_start;
extern u64 crash_size;
#endif /* __ASSEMBLY__ */
#endif /* _S390_PURGATORY_H_ */

2
arch/s390/purgatory/Makefile
View File

@ -21,7 +21,7 @@ LDFLAGS_purgatory.ro += -z nodefaultlib
KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes
KBUILD_CFLAGS += -Wno-pointer-sign -Wno-sign-compare
KBUILD_CFLAGS += -fno-zero-initialized-in-bss -fno-builtin -ffreestanding
KBUILD_CFLAGS += -c -MD -Os -m64 -msoft-float
KBUILD_CFLAGS += -c -MD -Os -m64 -msoft-float -fno-common
KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
KBUILD_AFLAGS := $(filter-out -DCC_USING_EXPOLINE,$(KBUILD_AFLAGS))

45
arch/s390/purgatory/head.S
View File

@ -243,33 +243,26 @@ gprregs:
.quad 0
.endr
purgatory_sha256_digest:
.global purgatory_sha256_digest
.rept 32 /* SHA256_DIGEST_SIZE */
.byte 0
.endr
/* Macro to define a global variable with name and size (in bytes) to be
* shared with C code.
*
* Add the .size and .type attribute to satisfy checks on the Elf_Sym during
* purgatory load.
*/
.macro GLOBAL_VARIABLE name,size
\name:
.global \name
.size \name,\size
.type \name,object
.skip \size,0
.endm
purgatory_sha_regions:
.global purgatory_sha_regions
.rept 16 * __KEXEC_SHA_REGION_SIZE /* KEXEC_SEGMENTS_MAX */
.byte 0
.endr
kernel_entry:
.global kernel_entry
.quad 0
kernel_type:
.global kernel_type
.quad 0
crash_start:
.global crash_start
.quad 0
crash_size:
.global crash_size
.quad 0
GLOBAL_VARIABLE purgatory_sha256_digest,32
GLOBAL_VARIABLE purgatory_sha_regions,16*__KEXEC_SHA_REGION_SIZE
GLOBAL_VARIABLE kernel_entry,8
GLOBAL_VARIABLE kernel_type,8
GLOBAL_VARIABLE crash_start,8
GLOBAL_VARIABLE crash_size,8
.align PAGE_SIZE
stack:

9
arch/s390/purgatory/purgatory.c
View File

@ -12,15 +12,6 @@
#include <linux/string.h>
#include <asm/purgatory.h>
struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX];
u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE];
u64 kernel_entry;
u64 kernel_type;
u64 crash_start;
u64 crash_size;
int verify_sha256_digest(void)
{
struct kexec_sha_region *ptr, *end;