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authorRoland McGrath <roland@redhat.com>2008-02-26 13:00:18 -0800
committerIngo Molnar <mingo@elte.hu>2008-02-29 18:55:39 +0100
commit3d00daf44654dc75629caf42816ac4e293658724 (patch)
tree82775510cc3975ef28e800b6d0ea4032cbf86b79
parentc0f4133b8f70769bc8dda977feb9a29109d6ccca (diff)
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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 <tomasz@grobelny.oswiecenia.net> Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/kernel/tls.c8
1 files 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,