[PATCH] operf: prefer _stext over _text as the kernel address range start

In newer kernels, _stext is the right pseudo-symbol for marking the
start address of the kernel address range. The older _text symbol is
rather architecture specific.

With this patch, the _stext symbol is preferred (if found). In case
_stext is not there (an older kernel), _text is accepted like before.
---
  pe_profiling/operf.cpp | 19 ++++++++++++++++++-
  1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/pe_profiling/operf.cpp b/pe_profiling/operf.cpp
index 5585b34..06a0ea3 100644
--- a/pe_profiling/operf.cpp
+++ b/pe_profiling/operf.cpp
@@ -87,8 +87,9 @@ bool track_new_forks;


  #define DEFAULT_OPERF_OUTFILE "operf.data"
-#define KERN_ADDR_SPACE_START_SYMBOL  "_text"
+#define KERN_ADDR_SPACE_START_SYMBOL  "_stext"
  #define KERN_ADDR_SPACE_END_SYMBOL    "_etext"
+#define KERN_ADDR_SPACE_START_SYMBOL_OBSOLETE  "_text"

  static operf_record * operfRecord = NULL;
  static char * app_name_SAVE = NULL;
@@ -1141,6 +1142,22 @@ static bool _process_kallsyms(void)
  		iss >> type;
  		iss >> name;

+		/* accept _text as the start symbol only in case there is no _stext
+		 * because _stext has higher priority
+		*/
+		if (start_addr_str.empty()) {
+			if (strncmp(name.c_str(), KERN_ADDR_SPACE_START_SYMBOL_OBSOLETE,
+					strlen(name.c_str())) == 0) {
+				/* found the symbol for the start of the kernel
+				 * address space.
+				*/
+				start_addr_str.assign(address_str);
+			}
+		}
+
+		/* if _stext is found, it will overwrite the _text if it has been
+		 * already found
+		*/
  		if (strncmp(name.c_str(), KERN_ADDR_SPACE_START_SYMBOL,
  			    strlen(name.c_str())) == 0) {
  			/* found the symbol for the start of the kernel
-- 
1.8.3.1


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