Fixed the kmem bug by handling kernel-space faults.

4 files changed, 70 insertions, 21 deletions

diff --git a/arch/um/include/user_util.h b/arch/um/include/user_util.h
index a94c461..892691d 100644
--- a/arch/um/include/user_util.h
+++ b/arch/um/include/user_util.h
@@ -88,6 +88,7 @@ extern int arch_handle_signal(int sig, union uml_pt_regs *regs);
 extern int arch_fixup(unsigned long address, void *sc_ptr);
 extern int can_do_skas(void);
 extern void arch_init_thread(void);
+extern int setjmp_wrapper(void (*proc)(void *, void *), ...);
 
 #endif
 
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index 0720ed5..972cdf9 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -12,6 +12,7 @@
 #include "asm/pgtable.h"
 #include "asm/uaccess.h"
 #include "kern_util.h"
+#include "user_util.h"
 
 extern void *um_virt_to_phys(struct task_struct *task, unsigned long addr, 
 			     pte_t *pte_out);
@@ -49,37 +50,67 @@ static int do_op(unsigned long addr, int len, int is_write,
 	return(n);
 }
 
-static int buffer_op(unsigned long addr, int len, int is_write,
-		     int (*op)(unsigned long addr, int len, void *arg),
-		     void *arg)
+static void do_buffer_op(void *jmpbuf, void *arg_ptr)
 {
+	va_list args = *((va_list *) arg_ptr);
+	unsigned long addr = va_arg(args, unsigned long);
+	int len = va_arg(args, int);
+	int is_write = va_arg(args, int);
+	int (*op)(unsigned long, int, void *) = va_arg(args, void *);
+	void *arg = va_arg(args, void *);
+	int *res = va_arg(args, int *);
 	int size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
 	int remain = len, n;
 
+	current->thread.fault_catcher = jmpbuf;
 	n = do_op(addr, size, is_write, op, arg);
-	if(n != 0)
-		return(n < 0 ? remain : 0);
+	if(n != 0){
+		*res = (n < 0 ? remain : 0);
+		goto out;
+	}
 
 	addr += size;
 	remain -= size;
-	if(remain == 0) 
-		return(0);
+	if(remain == 0){
+		*res = 0;
+		goto out;
+	}
 
 	while(addr < ((addr + remain) & PAGE_MASK)){
 		n = do_op(addr, PAGE_SIZE, is_write, op, arg);
-		if(n != 0)
-			return(n < 0 ? remain : 0);
+		if(n != 0){
+			*res = (n < 0 ? remain : 0);
+			goto out;
+		}
 
 		addr += PAGE_SIZE;
 		remain -= PAGE_SIZE;
 	}
-	if(remain == 0)
-		return(0);
+	if(remain == 0){
+		*res = 0;
+		goto out;
+	}
 
 	n = do_op(addr, remain, is_write, op, arg);
 	if(n != 0)
-		return(n < 0 ? remain : 0);
-	return(0);
+		*res = (n < 0 ? remain : 0);
+	else *res = 0;
+ out:
+	current->thread.fault_catcher = NULL;
+}
+
+static int buffer_op(unsigned long addr, int len, int is_write,
+		     int (*op)(unsigned long addr, int len, void *arg),
+		     void *arg)
+{
+	int faulted, res;
+	
+	faulted = setjmp_wrapper(do_buffer_op, addr, len, is_write, op, arg, 
+				 &res);
+	if(!faulted)
+		return(res);
+
+	return(addr + len - (unsigned long) current->thread.fault_addr);
 }
 
 static int copy_chunk_from_user(unsigned long from, int len, void *arg)
diff --git a/arch/um/kernel/user_util.c b/arch/um/kernel/user_util.c
index 41da13e..f3afe27 100644
--- a/arch/um/kernel/user_util.c
+++ b/arch/um/kernel/user_util.c
@@ -7,6 +7,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <limits.h>
+#include <setjmp.h>
 #include <sys/mman.h> 
 #include <sys/stat.h>
 #include <sys/ptrace.h>
@@ -89,11 +90,11 @@ int wait_for_stop(int pid, int sig, int cont_type, void *relay)
 				       errno);
 			}
 			else if(WIFEXITED(status)) 
-				printk("process exited with status %d\n", 
-				       WEXITSTATUS(status));
+				printk("process %d exited with status %d\n", 
+				       pid, WEXITSTATUS(status));
 			else if(WIFSIGNALED(status))
-				printk("process exited with signal %d\n", 
-				       WTERMSIG(status));
+				printk("process %d exited with signal %d\n", 
+				       pid, WTERMSIG(status));
 			else if((WSTOPSIG(status) == SIGVTALRM) ||
 				(WSTOPSIG(status) == SIGALRM) ||
 				(WSTOPSIG(status) == SIGIO) ||
@@ -109,8 +110,8 @@ int wait_for_stop(int pid, int sig, int cont_type, void *relay)
 				ptrace(cont_type, pid, 0, WSTOPSIG(status));
 				continue;
 			}
-			else printk("process stopped with signal %d\n", 
-				    WSTOPSIG(status));
+			else printk("process %d stopped with signal %d\n", 
+				    pid, WSTOPSIG(status));
 			panic("wait_for_stop failed to wait for %d to stop "
 			      "with %d\n", pid, sig);
 		}
@@ -152,6 +153,21 @@ void setup_hostinfo(void)
 		host.release, host.version, host.machine);
 }
 
+int setjmp_wrapper(void (*proc)(void *, void *), ...)
+{
+        va_list args;
+	sigjmp_buf buf;
+	int n;
+
+	n = sigsetjmp(buf, 1);
+	if(n == 0){
+		va_start(args, proc);
+		(*proc)(&buf, &args);
+	}
+	va_end(args);
+	return(n);
+}
+
 /*
  * Overrides for Emacs so that we follow Linus's tabbing style.
  * Emacs will notice this stuff at the end of the file and automatically
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index bd5bef5..9b934ed 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -221,7 +221,6 @@ static ssize_t read_kmem(struct file *file, char *buf,
 	ssize_t virtr = 0;
 	char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 
-	p = (unsigned long) __va(p);
 	if (p < (unsigned long) high_memory) {
 		read = count;
 		if (count > (unsigned long) high_memory - p)
@@ -270,7 +269,7 @@ static ssize_t read_kmem(struct file *file, char *buf,
 		}
 		free_page((unsigned long)kbuf);
 	}
- 	*ppos = __pa((void *) p);
+ 	*ppos = p;
  	return virtr + read;
 }
 
@@ -293,6 +292,8 @@ static ssize_t write_kmem(struct file * file, const char * buf,
 			wrote = (unsigned long) high_memory - p;
 
 		wrote = do_write_mem(file, (void*)p, p, buf, wrote, ppos);
+		if(wrote < 0)
+			return(wrote);
 
 		p += wrote;
 		buf += wrote;