s390: remove decompressor's head.S
Decompressor's head.S provided "data mover" sole purpose of which has
been to safely move uncompressed kernel at 0x100000 and jump to it.
With current bzImage layout entire decompressor's code guaranteed to be
in a safe location under 0x100000, and hence could not be overwritten
during kernel move. For that reason head.S could be replaced with simple
memmove function. To do so introduce early boot code phase which is
executed from arch/s390/boot/head.S after "verify_facilities" and takes
care of optional kernel image decompression and transition to it.
Reviewed-by: Martin Schwidefsky <schwidefsky@de.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/Makefile b/arch/s390/boot/Makefile
index 9e6668e..1b5a95b 100644
--- a/arch/s390/boot/Makefile
+++ b/arch/s390/boot/Makefile
@@ -27,7 +27,7 @@
CFLAGS_sclp_early_core.o += -I$(srctree)/drivers/s390/char
-obj-y := head.o als.o ebcdic.o sclp_early_core.o mem.o
+obj-y := head.o als.o startup.o ebcdic.o sclp_early_core.o mem.o
targets := bzImage startup.a $(obj-y)
subdir- := compressed
diff --git a/arch/s390/boot/boot.h b/arch/s390/boot/boot.h
new file mode 100644
index 0000000..36c93e6
--- /dev/null
+++ b/arch/s390/boot/boot.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef BOOT_BOOT_H
+#define BOOT_BOOT_H
+
+void startup_kernel(void);
+
+#endif /* BOOT_BOOT_H */
diff --git a/arch/s390/boot/compressed/Makefile b/arch/s390/boot/compressed/Makefile
index 0460947..c16ded8 100644
--- a/arch/s390/boot/compressed/Makefile
+++ b/arch/s390/boot/compressed/Makefile
@@ -9,7 +9,7 @@
GCOV_PROFILE := n
UBSAN_SANITIZE := n
-obj-y := $(if $(CONFIG_KERNEL_UNCOMPRESSED),,head.o misc.o) piggy.o
+obj-y := $(if $(CONFIG_KERNEL_UNCOMPRESSED),,misc.o) piggy.o
targets := vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2
targets += vmlinux.bin.xz vmlinux.bin.lzma vmlinux.bin.lzo vmlinux.bin.lz4
targets += vmlinux.scr.lds $(obj-y) $(if $(CONFIG_KERNEL_UNCOMPRESSED),,sizes.h)
@@ -32,9 +32,6 @@
$(obj)/sizes.h: vmlinux
$(call if_changed,sizes)
-AFLAGS_head.o += -I$(objtree)/$(obj)
-$(obj)/head.o: $(obj)/sizes.h
-
CFLAGS_misc.o += -I$(objtree)/$(obj)
$(obj)/misc.o: $(obj)/sizes.h
diff --git a/arch/s390/boot/compressed/decompressor.h b/arch/s390/boot/compressed/decompressor.h
new file mode 100644
index 0000000..0dd0b84
--- /dev/null
+++ b/arch/s390/boot/compressed/decompressor.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef BOOT_COMPRESSED_DECOMPRESSOR_H
+#define BOOT_COMPRESSED_DECOMPRESSOR_H
+
+#ifdef CONFIG_KERNEL_UNCOMPRESSED
+static inline void *decompress_kernel(unsigned long *uncompressed_size) {}
+#else
+void *decompress_kernel(unsigned long *uncompressed_size);
+#endif
+
+#endif /* BOOT_COMPRESSED_DECOMPRESSOR_H */
diff --git a/arch/s390/boot/compressed/head.S b/arch/s390/boot/compressed/head.S
deleted file mode 100644
index 4041fcf..0000000
--- a/arch/s390/boot/compressed/head.S
+++ /dev/null
@@ -1,52 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Startup glue code to uncompress the kernel
- *
- * Copyright IBM Corp. 2010
- *
- * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
- */
-
-#include <linux/init.h>
-#include <linux/linkage.h>
-#include <asm/asm-offsets.h>
-#include <asm/thread_info.h>
-#include <asm/page.h>
-#include <asm/ptrace.h>
-#include "sizes.h"
-
-__HEAD
-ENTRY(startup_decompressor)
- basr %r13,0 # get base
-.LPG1:
- # setup stack
- lg %r15,.Lstack-.LPG1(%r13)
- brasl %r14,decompress_kernel
- # Set up registers for memory mover. We move the decompressed image to
- # 0x100000, where startup_continue of the decompressed image is supposed
- # to be.
- lgr %r4,%r2
- lg %r2,.Loffset-.LPG1(%r13)
- lg %r3,.Lmvsize-.LPG1(%r13)
- lgr %r5,%r3
- # Move the memory mover someplace safe so it doesn't overwrite itself.
- la %r1,0x200
- mvc 0(mover_end-mover,%r1),mover-.LPG1(%r13)
- # When the memory mover is done we pass control to
- # arch/s390/kernel/head64.S:startup_continue which lives at 0x100000 in
- # the decompressed image.
- lgr %r6,%r2
- br %r1
-mover:
- mvcle %r2,%r4,0
- jo mover
- br %r6
-mover_end:
-
- .align 8
-.Lstack:
- .quad 0x8000 + THREAD_SIZE - STACK_FRAME_OVERHEAD
-.Loffset:
- .quad 0x100000
-.Lmvsize:
- .quad SZ__bss_start
diff --git a/arch/s390/boot/compressed/misc.c b/arch/s390/boot/compressed/misc.c
index f66ad73..321f615 100644
--- a/arch/s390/boot/compressed/misc.c
+++ b/arch/s390/boot/compressed/misc.c
@@ -12,6 +12,7 @@
#include <asm/sclp.h>
#include <asm/ipl.h>
#include "sizes.h"
+#include "decompressor.h"
/*
* gzip declarations
@@ -82,7 +83,7 @@ static void error(char *x)
asm volatile("lpsw %0" : : "Q" (psw));
}
-unsigned long decompress_kernel(void)
+void *decompress_kernel(unsigned long *uncompressed_size)
{
void *output, *kernel_end;
@@ -111,6 +112,8 @@ unsigned long decompress_kernel(void)
free_mem_end_ptr = free_mem_ptr + HEAP_SIZE;
__decompress(input_data, input_len, NULL, NULL, output, 0, NULL, error);
- return (unsigned long) output;
+ if (uncompressed_size)
+ *uncompressed_size = SZ__bss_start;
+ return output;
}
diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index d0736a0..e209cfe 100644
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -312,11 +312,7 @@
mvc __LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)
l %r15,.Lstack-.LPG0(%r13)
brasl %r14,verify_facilities
-#ifdef CONFIG_KERNEL_UNCOMPRESSED
- jg startup_continue
-#else
- jg startup_decompressor
-#endif
+ brasl %r14,startup_kernel
.Lstack:
.long 0x8000 + THREAD_SIZE - STACK_FRAME_OVERHEAD
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
new file mode 100644
index 0000000..2a9ce35
--- /dev/null
+++ b/arch/s390/boot/startup.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/string.h>
+#include "compressed/decompressor.h"
+#include "boot.h"
+
+void startup_kernel(void)
+{
+ void (*startup_continue)(void) = (void *)0x100000;
+ unsigned long uncompressed_size;
+ void *uncompressed_img;
+
+ if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {
+ uncompressed_img = decompress_kernel(&uncompressed_size);
+ memmove(startup_continue, uncompressed_img, uncompressed_size);
+ }
+ startup_continue();
+}