Added mainpfn guest utility to determine rough pfn for userspace code

1 files changed, 51 insertions, 0 deletions

diff --git a/util/mainpfn.c b/util/mainpfn.c
new file mode 100644
index 0000000..17c1b18
--- /dev/null
+++ b/util/mainpfn.c
@@ -0,0 +1,51 @@
+#include <unistd.h>
+#include <fcntl.h>
+#include <err.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct pageinfo {
+	uint64_t pfn : 54;
+	unsigned int soft_dirty : 1;
+	unsigned int file_page : 1;
+	unsigned int swapped : 1;
+	unsigned int present : 1;
+};
+
+void
+pagemap_get_entry(struct pageinfo *entry, int fd, uintptr_t vaddr)
+{
+	uint64_t data;
+	size_t offset;
+
+	offset = (vaddr / sysconf(_SC_PAGE_SIZE)) * 8;
+	if (pread(fd, (void *) &data, 8, offset) != 8)
+		err(1, "pread");
+
+	entry->pfn = data & ((1ULL << 54) - 1);
+	entry->soft_dirty = (data >> 54) & 1;
+	entry->file_page = (data >> 61) & 1;
+	entry->swapped = (data >> 62) & 1;
+	entry->present = (data >> 63) & 1;
+}
+
+int
+main(int argc, const char **argv)
+{
+	char filepath[256];
+	struct pageinfo info;
+	pid_t pid;
+	int fd;
+
+	pid = getpid();
+	snprintf(filepath, sizeof(filepath), "/proc/%u/pagemap", pid);
+
+	fd = open(filepath, O_RDONLY);
+	if (!fd) err(1, "open");
+
+	pagemap_get_entry(&info, fd, (uintptr_t) main);
+	printf("PFN: %08lx\n", info.pfn);
+
+	close(fd);
+}