[tip:x86/asm] x86/traps, context_tracking: Assert that we' re in CONTEXT_KERNEL in exception entries

tip-bot for Andy Lutomirski
2015-07-07T10:52:20Z

Commit-ID: 02fdcd5eac9d653d1addbd69b0c58d73650e1c00
Gitweb: http://git.kernel.org/tip/02fdcd5eac9d653d1addbd69b0c58d73650e1c00
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Fri, 3 Jul 2015 12:44:24 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 7 Jul 2015 10:59:05 +0200

x86/traps, context_tracking: Assert that we're in CONTEXT_KERNEL in exception entries

Other than the super-atomic exception entries, all exception
entries are supposed to switch our context tracking state to
CONTEXT_KERNEL. Assert that they do. These assertions appear
trivial at this point, as exception_enter() is the function
responsible for switching context, but I'm planning on reworking
x86's exception context tracking, and these assertions will help
make sure that all of this code keeps working.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/20fa1ee2d943233a184aaf96ff75394d3b34dfba.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/traps.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index f579192..2a783c4 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -292,6 +292,8 @@ static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
enum ctx_state prev_state = exception_enter();
siginfo_t info;

+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
NOTIFY_STOP) {
conditional_sti(regs);
@@ -376,6 +378,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
siginfo_t *info;

prev_state = exception_enter();
+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
if (notify_die(DIE_TRAP, "bounds", regs, error_code,
X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
goto exit;
@@ -457,6 +460,7 @@ do_general_protection(struct pt_regs *regs, long error_code)
enum ctx_state prev_state;

prev_state = exception_enter();
+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
conditional_sti(regs);

if (v8086_mode(regs)) {
@@ -514,6 +518,7 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
return;

prev_state = ist_enter(regs);
+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
@@ -750,6 +755,7 @@ dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
enum ctx_state prev_state;

prev_state = exception_enter();
+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
math_error(regs, error_code, X86_TRAP_MF);
exception_exit(prev_state);
}
@@ -760,6 +766,7 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
enum ctx_state prev_state;

prev_state = exception_enter();
+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
math_error(regs, error_code, X86_TRAP_XF);
exception_exit(prev_state);
}
@@ -776,6 +783,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
enum ctx_state prev_state;

prev_state = exception_enter();
+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
BUG_ON(use_eager_fpu());

#ifdef CONFIG_MATH_EMULATION
@@ -805,6 +813,7 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
enum ctx_state prev_state;

prev_state = exception_enter();
+ CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
local_irq_enable();

info.si_signo = SIGILL;