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-rw-r--r--arch/um/os-Linux/process.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index d261888..8176b0b 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -11,6 +11,7 @@
#include <linux/unistd.h>
#include <sys/mman.h>
#include <sys/wait.h>
+#include <sys/mman.h>
#include "ptrace_user.h"
#include "os.h"
#include "user.h"
@@ -20,6 +21,7 @@
#include "kern_util.h"
#include "longjmp.h"
#include "skas_ptrace.h"
+#include "kern_constants.h"
#define ARBITRARY_ADDR -1
#define FAILURE_PID -1
@@ -187,6 +189,48 @@ int os_unmap_memory(void *addr, int len)
return(0);
}
+#ifndef MADV_REMOVE
+#define MADV_REMOVE 0x5 /* remove these pages & resources */
+#endif
+
+int os_drop_memory(void *addr, int length)
+{
+ int err;
+
+ err = madvise(addr, length, MADV_REMOVE);
+ if(err < 0)
+ err = -errno;
+ return err;
+}
+
+int can_drop_memory(void)
+{
+ void *addr;
+ int fd;
+
+ printk("Checking host MADV_REMOVE support...");
+ fd = create_mem_file(UM_KERN_PAGE_SIZE);
+ if(fd < 0){
+ printk("Creating test memory file failed, err = %d\n", -fd);
+ return 0;
+ }
+
+ addr = mmap64(NULL, UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE, fd, 0);
+ if(addr == MAP_FAILED){
+ printk("Mapping test memory file failed, err = %d\n", -errno);
+ return 0;
+ }
+
+ if(madvise(addr, UM_KERN_PAGE_SIZE, MADV_REMOVE) != 0){
+ printk("MADV_REMOVE failed, err = %d\n", -errno);
+ return 0;
+ }
+
+ printk("OK\n");
+ return 1;
+}
+
void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
{
int flags = 0, pages;
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