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Commit 3d00daf4 authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

x86: tls prevent_tail_call 



Fix a kernel bug (vmware boot problem) reported by Tomasz Grobelny,
which occurs with certain .config variants and gccs.

The x86 TLS cleanup in commit efd1ca52
made the sys_set_thread_area and sys_get_thread_area functions ripe for
tail call optimization.  If the compiler chooses to use it for them, it
can clobber the user trap frame because these are asmlinkage functions.

Reported-by: default avatarTomasz Grobelny <tomasz@grobelny.oswiecenia.net>
Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c0f4133b

arch/x86/kernel/tls.c

+6 −2
Original line number Diff line number Diff line
@@ -91,7 +91,9 @@ int do_set_thread_area(struct task_struct *p, int idx, 


asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)

{

	return do_set_thread_area(current, -1, u_info, 1);

	int ret = do_set_thread_area(current, -1, u_info, 1);

	prevent_tail_call(ret);

	return ret;

}
@@ -139,7 +141,9 @@ int do_get_thread_area(struct task_struct *p, int idx, 


asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)

{

	return do_get_thread_area(current, -1, u_info);

	int ret = do_get_thread_area(current, -1, u_info);

	prevent_tail_call(ret);

	return ret;

}



int regset_tls_active(struct task_struct *target,