On Wed, May 01, 2019 at 11:59:05AM -0700, Linus Torvalds wrote:
> On Wed, May 1, 2019 at 11:52 AM Steven Rostedt <[email protected]> wrote:
> >
> > I got Peter's patch working. Here it is. What do you think?
>
> I can tell from just looking at it for five seconds that at least the
> 32-bit case is buggy.
>
> You can't look at CS(%rsp) without first also checking that you're not
> coming from vm86 mode.
Something like so then?
Index: linux-2.6/arch/x86/entry/entry_32.S
===================================================================
--- linux-2.6.orig/arch/x86/entry/entry_32.S
+++ linux-2.6/arch/x86/entry/entry_32.S
@@ -1479,6 +1479,10 @@ ENTRY(int3)
ASM_CLAC
pushl $-1 # mark this as an int
+#ifdef CONFIG_VM86
+ testl $X86_EFLAGS_VM, PT_EFLAGS(%esp)
+ jnz .Lfrom_usermode_no_gap
+#endif
testl $SEGMENT_RPL_MASK, PT_CS(%esp)
jnz .Lfrom_usermode_no_gap
.rept 6
