[PATCH v2 09/14] Estimate phys_base based on linux_banner position

[HATAYAMA Daisuke]

sadump doesn't save phys_base, so we must estimate it in any way. Here
we borrow the method in crash utility that we search a certain range
of addresses for linux_banner symbol value.

Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
---

 makedumpfile.c |   12 ++++++++++++
 sadump_info.c  |   47 +++++++++++++++++++++++++++++++++++++++++++++++
 sadump_info.h  |   13 +++++++++++++
 3 files changed, 72 insertions(+), 0 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 205d3de..6e9dd83 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -2504,6 +2504,15 @@ initial(void)
 
 		(void) sadump_set_timestamp(&info->timestamp);
 
+		/*
+		 * NOTE: phys_base is never saved by sadump and so
+		 * must be computed in some way. We here choose the
+		 * way of looking at linux_banner. See
+		 * sadump_virt_phys_base(). The processing is
+		 * postponed until debug information becomes
+		 * available.
+		 */
+
 	} else if (!get_phys_base())
 		return FALSE;
 
@@ -2579,6 +2588,9 @@ out:
 		return FALSE;
 
 	if (debug_info) {
+		if (info->flag_sadump)
+			(void) sadump_virt_phys_base();
+
 		if (!get_machdep_info())
 			return FALSE;
 
diff --git a/sadump_info.c b/sadump_info.c
index abc81d9..adca47b 100644
--- a/sadump_info.c
+++ b/sadump_info.c
@@ -22,6 +22,12 @@
 #include "print_info.h"
 #include "sadump_mod.h"
 
+#ifdef __x86_64__
+
+#define MEGABYTES(x)	((x) * (1048576))
+
+#endif
+
 struct sadump_diskset_info {
 	char *name_memory;
 	int fd_memory;
@@ -666,6 +672,47 @@ sadump_get_max_mapnr(void)
 	return si->sh_memory->max_mapnr;
 }
 
+#ifdef __x86_64__
+
+int
+sadump_virt_phys_base(void)
+{
+        char buf[BUFSIZE];
+        unsigned long phys, linux_banner_phys;
+
+	if (SYMBOL(linux_banner) == NOT_FOUND_SYMBOL) {
+		DEBUG_MSG("sadump: symbol linux_banner is not found\n");
+		goto failed;
+	}
+
+        linux_banner_phys = SYMBOL(linux_banner) - __START_KERNEL_map;
+
+        if (readmem(PADDR, linux_banner_phys + info->phys_base, buf,
+		    strlen("Linux version")) && STRNEQ(buf, "Linux version"))
+                return TRUE;
+
+        for (phys = (-MEGABYTES(16)); phys != MEGABYTES(16+1);
+             phys += MEGABYTES(1)) {
+                if (readmem(PADDR, linux_banner_phys + phys, buf,
+			    strlen("Linux version")) &&
+		    STRNEQ(buf, "Linux version")) {
+                        DEBUG_MSG("sadump: phys_base: %lx %s\n", phys,
+				  info->phys_base != phys ? "override" : "");
+                        info->phys_base = phys;
+                        return TRUE;
+                }
+        }
+
+failed:
+	info->phys_base = 0;
+
+	DEBUG_MSG("sadump: failed to calculate phys_base; default to 0\n");
+
+        return FALSE;
+}
+
+#endif /* __x86_64__ */
+
 int
 readpmem_sadump(unsigned long long paddr, void *bufptr, size_t size)
 {
diff --git a/sadump_info.h b/sadump_info.h
index b6b9cdd..401b769 100644
--- a/sadump_info.h
+++ b/sadump_info.h
@@ -22,6 +22,19 @@
 
 #include "makedumpfile.h"
 
+#ifdef __x86_64__
+
+int sadump_virt_phys_base(void);
+
+#else
+
+static inline int sadump_virt_phys_base(void)
+{
+	return TRUE;
+}
+
+#endif
+
 #if defined(__x86__) || defined(__x86_64__)
 
 int check_and_get_sadump_header_info(char *filename);