libdwfl: Use process_vm_readv when available.

If possible use process_vm_readv to read 4K blocks instead of fetching
each word individually with ptrace. For unwinding this often means we
only have to do one process_vm_readv of the stack instead of dozens of
ptrace calls. There is one 4K cache per process, cleared whenever a
thread is detached.

Signed-off-by: Mark Wielaard <mark@klomp.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 279c3b2b..81542414 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2018-03-17  Mark Wielaard  <mark@klomp.org>
+
+	* configure.ac (CHECK_FUNCS): Check for process_vm_readv.
+
 2018-02-09  Joshua Watt  <JPEWhacker@gmail.com>
 
 	* configure.ac (HAVE_FALLTHROUGH): New define.