Add vtop.c - for finding physical address in arbitrary process.

1 files changed, 81 insertions, 0 deletions

diff --git a/vtop.c b/vtop.c
new file mode 100755
index 0000000..f292218
--- /dev/null
+++ b/vtop.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2014 Intel Corporation
+ * Authors: Tony Luck
+ *
+ * This software may be redistributed and/or modified under the terms of
+ * the GNU General Public License ("GPL") version 2 only as published by the
+ * Free Software Foundation.
+ */
+
+/*
+ * Given a process if and virtual address, dig around in
+ * /proc/id/pagemap to find the physical address (if present)
+ * behind the virtual one.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <time.h>
+#include <signal.h>
+#include <sys/mman.h>
+
+static int pagesize=0x1000;
+
+/*
+ * get information about address from /proc/{pid}/pagemap
+ */
+
+unsigned long long vtop(unsigned long long addr, int proc_id)
+{
+	unsigned long  pinfo;
+	
+	int fd;
+	char	pagemapname[64];
+	long offset;
+	
+	offset = addr / pagesize * (sizeof pinfo);
+	
+	/* sprintf(pagemapname, "/proc/%d/pagemap", getpid()); */
+	sprintf(pagemapname, "/proc/%d/pagemap",proc_id);
+
+	fd = open(pagemapname, O_RDONLY);
+	if (fd == -1) {
+		perror(pagemapname);
+		exit(1);
+	}
+	if (pread(fd, &pinfo, sizeof pinfo, offset) != sizeof pinfo) {
+		perror(pagemapname);
+		exit(1);
+	}
+	close(fd);
+	if ((pinfo & (1ull << 63)) == 0) {
+		printf("page not present\n");
+		exit(1);
+	}
+	return ((pinfo & 0x007fffffffffffffull) << 12) + (addr & (pagesize - 1));
+}
+
+int main(int argc, char **argv)
+{
+	int process_id;
+	unsigned long long buf, phys;
+
+	if(argc < 2) {
+		printf("require virtual address and pid: 'vtop vaddress pid'\n");
+		return 1;
+	}		
+		
+	pagesize = getpagesize();	
+	buf = strtoul(argv[1], NULL, 16);
+	
+	process_id = atol(argv[2]);
+ 
+	phys =  vtop(buf, process_id);
+
+	printf("vtop(%llx,%d) = %llx\n", buf, process_id, phys);
+ 
+	return 0;
+}