s390/mem_detect: replace tprot loop with binary search
In a situation when other memory detection methods are not available
(no SCLP and no z/VM diag260), continuous online memory is assumed.
Replacing tprot loop with faster binary search, as only online memory
end has to be found.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
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/mem_detect.c b/arch/s390/boot/mem_detect.c
index 3becf6b..65ae3c9 100644
--- a/arch/s390/boot/mem_detect.c
+++ b/arch/s390/boot/mem_detect.c
@@ -3,12 +3,10 @@
#include <asm/sclp.h>
#include <asm/sections.h>
#include <asm/mem_detect.h>
+#include <asm/sparsemem.h>
#include "compressed/decompressor.h"
#include "boot.h"
-#define CHUNK_READ_WRITE 0
-#define CHUNK_READ_ONLY 1
-
unsigned long __bootdata(max_physmem_end);
struct mem_detect_info __bootdata(mem_detect);
@@ -141,38 +139,25 @@ static int tprot(unsigned long addr)
return rc;
}
-static void scan_memory(unsigned long rzm)
+static void search_mem_end(void)
{
- unsigned long addr, size;
- int type;
+ unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
+ unsigned long offset = 0;
+ unsigned long pivot;
- if (!rzm)
- rzm = 1UL << 20;
+ while (range > 1) {
+ range >>= 1;
+ pivot = offset + range;
+ if (!tprot(pivot << 20))
+ offset = pivot;
+ }
- addr = 0;
- do {
- size = 0;
- /* assume lowcore is writable */
- type = addr ? tprot(addr) : CHUNK_READ_WRITE;
- do {
- size += rzm;
- if (max_physmem_end && addr + size >= max_physmem_end)
- break;
- } while (type == tprot(addr + size));
- if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
- if (max_physmem_end && (addr + size > max_physmem_end))
- size = max_physmem_end - addr;
- add_mem_detect_block(addr, addr + size);
- }
- addr += size;
- } while (addr < max_physmem_end);
+ add_mem_detect_block(0, (offset + 1) << 20);
}
void detect_memory(void)
{
- unsigned long rzm;
-
- sclp_early_get_meminfo(&max_physmem_end, &rzm);
+ sclp_early_get_memsize(&max_physmem_end);
if (!sclp_early_read_storage_info()) {
mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
@@ -190,7 +175,7 @@ void detect_memory(void)
return;
}
- scan_memory(rzm);
- mem_detect.info_source = MEM_DETECT_TPROT_LOOP;
+ search_mem_end();
+ mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
max_physmem_end = get_mem_detect_end();
}
diff --git a/arch/s390/include/asm/mem_detect.h b/arch/s390/include/asm/mem_detect.h
index 153c354..6114b92 100644
--- a/arch/s390/include/asm/mem_detect.h
+++ b/arch/s390/include/asm/mem_detect.h
@@ -9,7 +9,7 @@ enum mem_info_source {
MEM_DETECT_SCLP_STOR_INFO,
MEM_DETECT_DIAG260,
MEM_DETECT_SCLP_READ_INFO,
- MEM_DETECT_TPROT_LOOP
+ MEM_DETECT_BIN_SEARCH
};
struct mem_detect_block {
diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h
index e0da13c..32b683f 100644
--- a/arch/s390/include/asm/sclp.h
+++ b/arch/s390/include/asm/sclp.h
@@ -114,7 +114,7 @@ void sclp_early_printk(const char *s);
void sclp_early_printk_force(const char *s);
void __sclp_early_printk(const char *s, unsigned int len, unsigned int force);
-int sclp_early_get_meminfo(unsigned long *mem, unsigned long *rzm);
+int sclp_early_get_memsize(unsigned long *mem);
int _sclp_get_core_info(struct sclp_core_info *info);
int sclp_core_configure(u8 core);
int sclp_core_deconfigure(u8 core);
diff --git a/drivers/s390/char/sclp_early_core.c b/drivers/s390/char/sclp_early_core.c
index 0df08dc..acfe0931 100644
--- a/drivers/s390/char/sclp_early_core.c
+++ b/drivers/s390/char/sclp_early_core.c
@@ -272,7 +272,7 @@ int __init sclp_early_get_info(struct read_info_sccb *info)
return 0;
}
-int __init sclp_early_get_meminfo(unsigned long *mem, unsigned long *rzm)
+int __init sclp_early_get_memsize(unsigned long *mem)
{
unsigned long rnmax;
unsigned long rnsize;
@@ -285,7 +285,6 @@ int __init sclp_early_get_meminfo(unsigned long *mem, unsigned long *rzm)
rnsize = sccb->rnsize ? sccb->rnsize : sccb->rnsize2;
rnsize <<= 20;
*mem = rnsize * rnmax;
- *rzm = rnsize;
return 0;
}