x86/traps: Weaken context tracking entry assertions
authorAndy Lutomirski <luto@kernel.org>
Fri, 21 Aug 2015 05:03:21 +0000 (22:03 -0700)
committerIngo Molnar <mingo@kernel.org>
Sat, 22 Aug 2015 09:12:10 +0000 (11:12 +0200)
commitf0a97af83f6287357dcc100c859ec0066f164f32
tree7be5d8bc2240bfd9533c654b464fa9ca9575947a
parent99770737ca7e3ebc14e66460a69b7032de9421e1
x86/traps: Weaken context tracking entry assertions

We were asserting that we were all the way in CONTEXT_KERNEL
when exception handlers were called.  While having this be true
is, I think, a nice goal (or maybe a variant in which we assert
that we're in CONTEXT_KERNEL or some new IRQ context), we're not
quite there.

In particular, if an IRQ interrupts the SYSCALL prologue and the
IRQ handler in turn causes an exception, the exception entry
will be called in RCU IRQ mode but with CONTEXT_USER.

This is okay (nothing goes wrong), but until we fix up the
SYSCALL prologue, we need to avoid warning.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/c81faf3916346c0e04346c441392974f49cd7184.1440133286.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/traps.c