Added support for using /dev/anon.

1 files changed, 56 insertions, 4 deletions

diff --git a/arch/um/kernel/mem_user.c b/arch/um/kernel/mem_user.c
index f56081f..9ad1882 100644
--- a/arch/um/kernel/mem_user.c
+++ b/arch/um/kernel/mem_user.c
@@ -36,6 +36,7 @@
 #include <unistd.h>
 #include <errno.h>
 #include <string.h>
+#include <fcntl.h>
 #include <sys/types.h>
 #include <sys/mman.h>
 #include "kern_util.h"
@@ -51,7 +52,7 @@ extern struct mem_region physmem_region;
 
 #define TEMPNAME_TEMPLATE "vm_file-XXXXXX"
 
-int create_mem_file(unsigned long len)
+static int create_tmp_file(unsigned long len)
 {
 	int fd, err;
 	char zero;
@@ -61,22 +62,73 @@ int create_mem_file(unsigned long len)
 		os_print_error(fd, "make_tempfile");
 		exit(1);
 	}
+
 	err = os_mode_fd(fd, 0777);
 	if(err < 0){
-		os_print_error(err, "change_mode");
+		os_print_error(err, "os_mode_fd");
 		exit(1);
 	}
 	err = os_seek_file(fd, len);
 	if(err < 0){
-		os_print_error(err, "seek_file");
+		os_print_error(err, "os_seek_file");
 		exit(1);
 	}
 	zero = 0;
 	err = os_write_file(fd, &zero, 1);
 	if(err != 1){
-		os_print_error(err, "write_file");
+		os_print_error(err, "os_write_file");
+		exit(1);
+	}
+
+	return(fd);
+}
+
+static int have_devanon = 0;
+
+void check_devanon(void)
+{
+	int fd;
+
+	printk("Checking for /dev/anon on the host...");
+	fd = open("/dev/anon", O_RDWR);
+	if(fd < 0){
+		printk("Not available (open failed with errno %d)\n", errno);
+		return;
+	}
+
+	printk("OK\n");
+	have_devanon = 1;
+}
+
+static int create_anon_file(unsigned long len)
+{
+	void *addr;
+	int fd;
+
+	fd = open("/dev/anon", O_RDWR);
+	if(fd < 0) {
+		os_print_error(fd, "opening /dev/anon");
 		exit(1);
 	}
+
+	addr = mmap(NULL, len, PROT_READ | PROT_WRITE , MAP_PRIVATE, fd, 0);
+	if(addr == MAP_FAILED){
+		os_print_error((int) addr, "mapping physmem file");
+		exit(1);
+	}
+	munmap(addr, len);
+
+	return(fd);
+}
+
+int create_mem_file(unsigned long len)
+{
+	int err, fd;
+
+	if(have_devanon)
+		fd = create_anon_file(len);
+	else fd = create_tmp_file(len);
+
 	err = os_set_exec_close(fd, 1);
 	if(err < 0)
 		os_print_error(err, "exec_close");