s390/kernel: introduce .dma sections

With a relocatable kernel that could reside at any place in memory, code
and data that has to stay below 2 GB needs special handling.

This patch introduces .dma sections for such text, data and ex_table.
The sections will be part of the decompressor kernel, so they will not
be relocated and stay below 2 GB. Their location is passed over to the
decompressed / relocated kernel via the .boot.preserved.data section.

The duald and aste for control register setup also need to stay below
2 GB, so move the setup code from arch/s390/kernel/head64.S to
arch/s390/boot/head.S. The duct and linkage_stack could reside above
2 GB, but their content has to be preserved for the decompresed kernel,
so they are also moved into the .dma section.

The start and end address of the .dma sections is added to vmcoreinfo,
for crash support, to help debugging in case the kernel crashed there.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

5 files changed, 28 insertions, 1 deletions

diff --git a/arch/s390/include/asm/diag.h b/arch/s390/include/asm/diag.h
index 19562be22b7e..0036eab14391 100644
--- a/arch/s390/include/asm/diag.h
+++ b/arch/s390/include/asm/diag.h
@@ -308,4 +308,17 @@ union diag318_info {
 int diag204(unsigned long subcode, unsigned long size, void *addr);
 int diag224(void *ptr);
 int diag26c(void *req, void *resp, enum diag26c_sc subcode);
+
+struct hypfs_diag0c_entry;
+
+struct diag_ops {
+	int (*diag210)(struct diag210 *addr);
+	int (*diag26c)(void *req, void *resp, enum diag26c_sc subcode);
+	int (*diag14)(unsigned long rx, unsigned long ry1, unsigned long subcode);
+	void (*diag0c)(struct hypfs_diag0c_entry *entry);
+	void (*diag308_reset)(void);
+};
+
+extern struct diag_ops diag_dma_ops;
+extern struct diag210 *__diag210_tmp_dma;
 #endif /* _ASM_S390_DIAG_H */
diff --git a/arch/s390/include/asm/extable.h b/arch/s390/include/asm/extable.h
index 80a4e5a9cb46..ae27f756b409 100644
--- a/arch/s390/include/asm/extable.h
+++ b/arch/s390/include/asm/extable.h
@@ -19,6 +19,11 @@ struct exception_table_entry
 	int insn, fixup;
 };
 
+extern struct exception_table_entry *__start_dma_ex_table;
+extern struct exception_table_entry *__stop_dma_ex_table;
+
+const struct exception_table_entry *s390_search_extables(unsigned long addr);
+
 static inline unsigned long extable_fixup(const struct exception_table_entry *x)
 {
 	return (unsigned long)&x->fixup + x->fixup;
diff --git a/arch/s390/include/asm/ipl.h b/arch/s390/include/asm/ipl.h
index 420d39ebdc46..084e71b7272a 100644
--- a/arch/s390/include/asm/ipl.h
+++ b/arch/s390/include/asm/ipl.h
@@ -127,7 +127,6 @@ enum diag308_rc {
 };
 
 extern int diag308(unsigned long subcode, void *addr);
-extern void diag308_reset(void);
 extern void store_status(void (*fn)(void *), void *data);
 extern void lgr_info_log(void);
 
diff --git a/arch/s390/include/asm/linkage.h b/arch/s390/include/asm/linkage.h
index 1b95da3fdd64..7f22262b0e46 100644
--- a/arch/s390/include/asm/linkage.h
+++ b/arch/s390/include/asm/linkage.h
@@ -28,5 +28,12 @@
 	.long	(_target) - . ;		\
 	.previous
 
+#define EX_TABLE_DMA(_fault, _target)	\
+	.section .dma.ex_table, "a" ;	\
+	.align	4 ;			\
+	.long	(_fault) - . ;		\
+	.long	(_target) - . ;		\
+	.previous
+
 #endif /* __ASSEMBLY__ */
 #endif
diff --git a/arch/s390/include/asm/sections.h b/arch/s390/include/asm/sections.h
index 29e55739b516..af670fa4b12a 100644
--- a/arch/s390/include/asm/sections.h
+++ b/arch/s390/include/asm/sections.h
@@ -23,4 +23,7 @@
  */
 #define __bootdata_preserved(var) __section(.boot.preserved.data.var) var
 
+extern unsigned long __sdma, __edma;
+extern unsigned long __stext_dma, __etext_dma;
+
 #endif