UML - Stop specially protecting kernel stacks

PATCH New Jeff Dike 1 participant 1 message Aug 2, 2007 User-mode Linux (UML)

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Jeff Dike

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2007-08-02 21:04 UTC #0 lore raw

PATCH 4/6 UML - Stop specially protecting kernel stacks

Map all of physical memory as executable to avoid having to change stack protections during fork and exit.

unprotect_stack is now called only from MODE_TT code, so it is marked as such.

Signed-off-by Jeff Dike <[email protected]>

 arch/um/include/kern_util.h |    2 ++
 arch/um/kernel/init_task.c  |    2 ++
 arch/um/kernel/physmem.c    |    2 +-
 arch/um/kernel/process.c    |    5 ++---
 4 files changed, 7 insertions(+), 4 deletions(-)

arch/um/kernel/physmem.c +1 -1

Index: linux-2.6.21-mm/arch/um/kernel/physmem.c
===================================================================
@@ -105,7 +105,7 @@ void __init setup_physmem(unsigned long 
 
 	offset = uml_reserved - uml_physmem;
 	err = os_map_memory((void *) uml_reserved, physmem_fd, offset,
-			    len - offset, 1, 1, 0);
+			    len - offset, 1, 1, 1);
 	if(err < 0){
 		os_print_error(err, "Mapping memory");
 		exit(1);

arch/um/kernel/process.c +2 -3

Index: linux-2.6.21-mm/arch/um/kernel/process.c
===================================================================
@@ -82,9 +82,9 @@ unsigned long alloc_stack(int order, int
 	if (atomic)
 		flags = GFP_ATOMIC;
 	page = __get_free_pages(flags, order);
-	if(page == 0)
+	if (page == 0)
 		return 0;
-	stack_protections(page);
+
 	return page;
 }

@@ -141,7 +141,6 @@ void release_thread(struct task_struct *
 
 void exit_thread(void)
 {
-	unprotect_stack((unsigned long) current_thread);
 }
 
 void *get_current(void)

arch/um/include/kern_util.h +2 -0

Index: linux-2.6.21-mm/arch/um/include/kern_util.h
===================================================================
@@ -82,7 +82,9 @@ extern void check_stack_overflow(void *p
 extern void relay_signal(int sig, union uml_pt_regs *regs);
 extern int user_context(unsigned long sp);
 extern void timer_irq(union uml_pt_regs *regs);
+#ifdef CONFIG_MODE_TT
 extern void unprotect_stack(unsigned long stack);
+#endif
 extern void do_uml_exitcalls(void);
 extern int attach_debugger(int idle_pid, int pid, int stop);
 extern int config_gdb(char *str);

arch/um/kernel/init_task.c +2 -0

Index: linux-2.6.21-mm/arch/um/kernel/init_task.c
===================================================================
@@ -47,7 +47,9 @@ union thread_union cpu0_irqstack
 	__attribute__((__section__(".data.init_irqstack"))) =
 		{ INIT_THREAD_INFO(init_task) };
 
+#ifdef CONFIG_MODE_TT
 void unprotect_stack(unsigned long stack)
 {
 	os_protect_memory((void *) stack, THREAD_SIZE, 1, 1, 0);
 }
+#endif

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