On 1/19/2021 4:04 AM, Borislav Petkov wrote:

On Tue, Dec 29, 2020 at 01:30:33PM -0800, Yu-cheng Yu wrote:

[...]

quoted

+DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
+{
+	struct task_struct *tsk;
+
+	if (!user_mode(regs)) {
+		if (notify_die(DIE_TRAP, "control protection fault", regs,
+			       error_code, X86_TRAP_CP, SIGSEGV) == NOTIFY_STOP)
+			return;
+		die("Upexpected/unsupported kernel control protection fault", regs, error_code);

Isn't the machine supposed to panic() here and do no further progress?

Ok, make it panic().

quoted

+	}
+
+	cond_local_irq_enable(regs);
+
+	if (!boot_cpu_has(X86_FEATURE_CET))
+		WARN_ONCE(1, "Control protection fault with CET support disabled\n");
+
+	tsk = current;
+	tsk->thread.error_code = error_code;
+	tsk->thread.trap_nr = X86_TRAP_CP;
+
+	if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+	    printk_ratelimit()) {

WARNING: Prefer printk_ratelimited or pr_<level>_ratelimited to printk_ratelimit
#136: FILE: arch/x86/kernel/traps.c:645:
+	    printk_ratelimit()) {

Still not using checkpatch?

Most places in arch/x86 still use printk_ratelimit().  I should have 
trusted checkpatch.  I will fix it.

quoted

+		unsigned int max_err;
+		unsigned long ssp;
+
+		max_err = ARRAY_SIZE(control_protection_err) - 1;
+		if ((error_code < 0) || (error_code > max_err))
+			error_code = 0;
+
+		rdmsrl(MSR_IA32_PL3_SSP, ssp);
+		pr_info("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)",

If anything, all this stuff should be pr_emerg().

I will fix it.

--
Yu-cheng