uml: eliminate setjmp_wrapper

setjmp_wrapper existed to provide setjmp to kernel code when UML used libc's
setjmp and longjmp.  Now that UML has its own implementation, this isn't
needed and kernel code can invoke setjmp directly.

do_buffer_op is massively cleaned up since it is no longer a callback from
setjmp_wrapper and given a va_list from which it must extract its arguments.

The actual setjmp is moved from buffer_op to do_op_one_page because the copy
operation is inside an atomic section (kmap_atomic to kunmap_atomic) and it
shouldn't be longjmp-ed out of.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 27 insertions, 46 deletions

diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index 05b41dbc1dd9..e22c96993db3 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -58,9 +58,10 @@ static pte_t *maybe_map(unsigned long virt, int is_write)
 static int do_op_one_page(unsigned long addr, int len, int is_write,
 		 int (*op)(unsigned long addr, int len, void *arg), void *arg)
 {
+	jmp_buf buf;
 	struct page *page;
 	pte_t *pte;
-	int n;
+	int n, faulted;
 
 	pte = maybe_map(addr, is_write);
 	if (pte == NULL)
@@ -70,82 +71,62 @@ static int do_op_one_page(unsigned long addr, int len, int is_write,
 	addr = (unsigned long) kmap_atomic(page, KM_UML_USERCOPY) +
 		(addr & ~PAGE_MASK);
 
-	n = (*op)(addr, len, arg);
+	current->thread.fault_catcher = &buf;
+
+	faulted = UML_SETJMP(&buf);
+	if (faulted == 0)
+		n = (*op)(addr, len, arg);
+	else
+		n = -1;
+
+	current->thread.fault_catcher = NULL;
 
 	kunmap_atomic(page, KM_UML_USERCOPY);
 
 	return n;
 }
 
-static void do_buffer_op(void *jmpbuf, void *arg_ptr)
+static int buffer_op(unsigned long addr, int len, int is_write,
+		     int (*op)(unsigned long, int, void *), void *arg)
 {
-	va_list args;
-	unsigned long addr;
-	int len, is_write, size, remain, n;
-	int (*op)(unsigned long, int, void *);
-	void *arg;
-	int *res;
-
-	va_copy(args, *(va_list *)arg_ptr);
-	addr = va_arg(args, unsigned long);
-	len = va_arg(args, int);
-	is_write = va_arg(args, int);
-	op = va_arg(args, void *);
-	arg = va_arg(args, void *);
-	res = va_arg(args, int *);
-	va_end(args);
+	int size, remain, n;
+
 	size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
 	remain = len;
 
-	current->thread.fault_catcher = jmpbuf;
 	n = do_op_one_page(addr, size, is_write, op, arg);
 	if (n != 0) {
-		*res = (n < 0 ? remain : 0);
+		remain = (n < 0 ? remain : 0);
 		goto out;
 	}
 
 	addr += size;
 	remain -= size;
-	if (remain == 0) {
-		*res = 0;
+	if (remain == 0)
 		goto out;
-	}
 
-	while(addr < ((addr + remain) & PAGE_MASK)) {
+	while (addr < ((addr + remain) & PAGE_MASK)) {
 		n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
 		if (n != 0) {
-			*res = (n < 0 ? remain : 0);
+			remain = (n < 0 ? remain : 0);
 			goto out;
 		}
 
 		addr += PAGE_SIZE;
 		remain -= PAGE_SIZE;
 	}
-	if (remain == 0) {
-		*res = 0;
+	if (remain == 0)
 		goto out;
-	}
 
 	n = do_op_one_page(addr, remain, is_write, op, arg);
-	if (n != 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;
+	if (n != 0) {
+		remain = (n < 0 ? remain : 0);
+		goto out;
+	}
 
-	return addr + len - (unsigned long) current->thread.fault_addr;
+	return 0;
+ out:
+	return remain;
 }
 
 static int copy_chunk_from_user(unsigned long from, int len, void *arg)