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[PATCH v3 05/15] x86/traps: Assert that we're in CONTEXT_KERNEL in exception entries

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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>
---
 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 de379366f6d1..3f947488c9c1 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -291,6 +291,8 @@ 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);
@@ -377,6 +379,7 @@ 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;
@@ -458,6 +461,7 @@ 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)) {
@@ -515,6 +519,7 @@ 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)
@@ -794,6 +799,7 @@ 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);
 }
@@ -804,6 +810,7 @@ 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);
 }
@@ -862,6 +869,7 @@ 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
@@ -891,6 +899,7 @@ 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;
-- 
2.4.3

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[PATCH v3 00/15] x86: Rewrite exit-to-userspace code Andy Lutomirski <luto@kernel.org> - 2015-06-24 04:50 +0200
  [PATCH v3 10/15] x86/asm/entry/64: Save all regs on interrupt entry Andy Lutomirski <luto@kernel.org> - 2015-06-24 04:50 +0200
  [PATCH v3 04/15] x86: Move C entry and exit code to arch/x86/entry/common.c Andy Lutomirski <luto@kernel.org> - 2015-06-24 04:50 +0200
  [PATCH v3 15/15] x86/irq: Document how IRQ context tracking works and add an assertion Andy Lutomirski <luto@kernel.org> - 2015-06-24 04:50 +0200
  [PATCH v3 13/15] x86/entry: Remove exception_enter from trap handlers Andy Lutomirski <luto@kernel.org> - 2015-06-24 04:50 +0200
  [PATCH v3 05/15] x86/traps: Assert that we're in CONTEXT_KERNEL in exception entries Andy Lutomirski <luto@kernel.org> - 2015-06-24 04:50 +0200

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