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authorZachary Amsden <zach@vmware.com>2005-09-03 15:56:43 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:06:12 -0700
commit0998e4228aca046fbd747c3fed909791d52e88eb (patch)
tree314cb04a6223100bf468cc420985bfe7e3680d44 /arch/i386/kernel/signal.c
parentf2ab4461249df85b20930a7a57b54f39c5ae291a (diff)
[PATCH] x86: privilege cleanup
Privilege checking cleanup. Originally, these diffs were much greater, but recent cleanups in Linux have already done much of the cleanup. I added some explanatory comments in places where the reasoning behind certain tests is rather subtle. Also, in traps.c, we can skip the user_mode check in handle_BUG(). The reason is, there are only two call chains - one via die_if_kernel() and one via do_page_fault(), both entering from die(). Both of these paths already ensure that a kernel mode failure has happened. Also, the original check here, if (user_mode(regs)) was insufficient anyways, since it would not rule out BUG faults from V8086 mode execution. Saving the %ss segment in show_regs() rather than assuming a fixed value also gives better information about the current kernel state in the register dump. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386/kernel/signal.c')
-rw-r--r--arch/i386/kernel/signal.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c
index 7bcda6d69d8..61eb0c8a6e4 100644
--- a/arch/i386/kernel/signal.c
+++ b/arch/i386/kernel/signal.c
@@ -604,7 +604,9 @@ int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
* We want the common case to go fast, which
* is why we may in certain cases get here from
* kernel mode. Just return without doing anything
- * if so.
+ * if so. vm86 regs switched out by assembly code
+ * before reaching here, so testing against kernel
+ * CS suffices.
*/
if (!user_mode(regs))
return 1;