From 3d00daf44654dc75629caf42816ac4e293658724 Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Tue, 26 Feb 2008 13:00:18 -0800 Subject: 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 efd1ca52d04d2f6df337a3332cee56cd60e6d4c4 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: Tomasz Grobelny Signed-off-by: Roland McGrath Signed-off-by: Ingo Molnar --- arch/x86/kernel/tls.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c index 6dfd4e76661..022bcaa3b42 100644 --- a/arch/x86/kernel/tls.c +++ b/arch/x86/kernel/tls.c @@ -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, -- cgit v1.2.3