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>

1 files changed, 10 insertions, 57 deletions

diff --git a/arch/s390/kernel/diag.c b/arch/s390/kernel/diag.c
index 7edaa733a77f..e9dac9a24d3f 100644
--- a/arch/s390/kernel/diag.c
+++ b/arch/s390/kernel/diag.c
@@ -13,6 +13,7 @@
 #include <linux/debugfs.h>
 #include <asm/diag.h>
 #include <asm/trace/diag.h>
+#include <asm/sections.h>
 
 struct diag_stat {
 	unsigned int counter[NR_DIAG_STAT];
@@ -49,6 +50,9 @@ static const struct diag_desc diag_map[NR_DIAG_STAT] = {
 	[DIAG_STAT_X500] = { .code = 0x500, .name = "Virtio Service" },
 };
 
+struct diag_ops __bootdata_preserved(diag_dma_ops);
+struct diag210 *__bootdata_preserved(__diag210_tmp_dma);
+
 static int show_diag_stat(struct seq_file *m, void *v)
 {
 	struct diag_stat *stat;
@@ -139,30 +143,10 @@ EXPORT_SYMBOL(diag_stat_inc_norecursion);
 /*
  * Diagnose 14: Input spool file manipulation
  */
-static inline int __diag14(unsigned long rx, unsigned long ry1,
-			   unsigned long subcode)
-{
-	register unsigned long _ry1 asm("2") = ry1;
-	register unsigned long _ry2 asm("3") = subcode;
-	int rc = 0;
-
-	asm volatile(
-		"   sam31\n"
-		"   diag    %2,2,0x14\n"
-		"   sam64\n"
-		"   ipm     %0\n"
-		"   srl     %0,28\n"
-		: "=d" (rc), "+d" (_ry2)
-		: "d" (rx), "d" (_ry1)
-		: "cc");
-
-	return rc;
-}
-
 int diag14(unsigned long rx, unsigned long ry1, unsigned long subcode)
 {
 	diag_stat_inc(DIAG_STAT_X014);
-	return __diag14(rx, ry1, subcode);
+	return diag_dma_ops.diag14(rx, ry1, subcode);
 }
 EXPORT_SYMBOL(diag14);
 
@@ -195,30 +179,17 @@ EXPORT_SYMBOL(diag204);
  */
 int diag210(struct diag210 *addr)
 {
-	/*
-	 * diag 210 needs its data below the 2GB border, so we
-	 * use a static data area to be sure
-	 */
-	static struct diag210 diag210_tmp;
 	static DEFINE_SPINLOCK(diag210_lock);
 	unsigned long flags;
 	int ccode;
 
 	spin_lock_irqsave(&diag210_lock, flags);
-	diag210_tmp = *addr;
+	*__diag210_tmp_dma = *addr;
 
 	diag_stat_inc(DIAG_STAT_X210);
-	asm volatile(
-		"	lhi	%0,-1\n"
-		"	sam31\n"
-		"	diag	%1,0,0x210\n"
-		"0:	ipm	%0\n"
-		"	srl	%0,28\n"
-		"1:	sam64\n"
-		EX_TABLE(0b, 1b)
-		: "=&d" (ccode) : "a" (&diag210_tmp) : "cc", "memory");
-
-	*addr = diag210_tmp;
+	ccode = diag_dma_ops.diag210(__diag210_tmp_dma);
+
+	*addr = *__diag210_tmp_dma;
 	spin_unlock_irqrestore(&diag210_lock, flags);
 
 	return ccode;
@@ -243,27 +214,9 @@ EXPORT_SYMBOL(diag224);
 /*
  * Diagnose 26C: Access Certain System Information
  */
-static inline int __diag26c(void *req, void *resp, enum diag26c_sc subcode)
-{
-	register unsigned long _req asm("2") = (addr_t) req;
-	register unsigned long _resp asm("3") = (addr_t) resp;
-	register unsigned long _subcode asm("4") = subcode;
-	register unsigned long _rc asm("5") = -EOPNOTSUPP;
-
-	asm volatile(
-		"	sam31\n"
-		"	diag	%[rx],%[ry],0x26c\n"
-		"0:	sam64\n"
-		EX_TABLE(0b,0b)
-		: "+d" (_rc)
-		: [rx] "d" (_req), "d" (_resp), [ry] "d" (_subcode)
-		: "cc", "memory");
-	return _rc;
-}
-
 int diag26c(void *req, void *resp, enum diag26c_sc subcode)
 {
 	diag_stat_inc(DIAG_STAT_X26C);
-	return __diag26c(req, resp, subcode);
+	return diag_dma_ops.diag26c(req, resp, subcode);
 }
 EXPORT_SYMBOL(diag26c);