linux-kernel - [PATCH v5 07/17] x86/traps: Assert that we're in CONTEXT

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Date:	Fri,  3 Jul 2015 12:44:24 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	Frédéric Weisbecker <fweisbec@...il.com>,
	Rik van Riel <riel@...hat.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Denys Vlasenko <vda.linux@...glemail.com>,
	Borislav Petkov <bp@...en8.de>,
	Kees Cook <keescook@...omium.org>,
	Brian Gerst <brgerst@...il.com>, paulmck@...ux.vnet.ibm.com,
	Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v5 07/17] x86/traps: 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@...nel.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 f5791927aa64..2a783c4fe0e9 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;
-- 
2.4.3

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