Signed-off-by: Yu-cheng Yu <redacted>
---
 arch/x86/entry/entry_64.S    |  2 +-
 arch/x86/include/asm/traps.h |  3 ++
 arch/x86/kernel/idt.c        |  4 +++
 arch/x86/kernel/traps.c      | 58 ++++++++++++++++++++++++++++++++++++
 4 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 957dfb693ecc..5f4914e988df 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S

@@ -1000,7 +1000,7 @@ idtentry spurious_interrupt_bug           do_spurious_interrupt_bug       has_error_code=0
 idtentry coprocessor_error             do_coprocessor_error            has_error_code=0
 idtentry alignment_check               do_alignment_check              has_error_code=1
 idtentry simd_coprocessor_error                do_simd_coprocessor_error       has_error_code=0
-
+idtentry control_protection            do_control_protection           has_error_code=1

        /*
         * Reload gs selector with exception handling

diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
index 3de69330e6c5..5196050ff3d5 100644
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h

@@ -26,6 +26,7 @@ asmlinkage void invalid_TSS(void);
 asmlinkage void segment_not_present(void);
 asmlinkage void stack_segment(void);
 asmlinkage void general_protection(void);
+asmlinkage void control_protection(void);
 asmlinkage void page_fault(void);
 asmlinkage void async_page_fault(void);
 asmlinkage void spurious_interrupt_bug(void);

@@ -77,6 +78,7 @@ dotraplinkage void do_stack_segment(struct pt_regs *, long);
 dotraplinkage void do_double_fault(struct pt_regs *, long);
 #endif
 dotraplinkage void do_general_protection(struct pt_regs *, long);
+dotraplinkage void do_control_protection(struct pt_regs *, long);
 dotraplinkage void do_page_fault(struct pt_regs *, unsigned long);
 dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *, long);
 dotraplinkage void do_coprocessor_error(struct pt_regs *, long);

@@ -142,6 +144,7 @@ enum {
        X86_TRAP_AC,            /* 17, Alignment Check */
        X86_TRAP_MC,            /* 18, Machine Check */
        X86_TRAP_XF,            /* 19, SIMD Floating-Point Exception */
+       X86_TRAP_CP = 21,       /* 21 Control Protection Fault */
        X86_TRAP_IRET = 32,     /* 32, IRET Exception */
 };

diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index 01adea278a71..2d02fdd599a2 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c

@@ -104,6 +104,10 @@ static const __initconst struct idt_data def_idts[] = {
 #elif defined(CONFIG_X86_32)
        SYSG(IA32_SYSCALL_VECTOR,       entry_INT80_32),
 #endif
+
+#ifdef CONFIG_X86_INTEL_CET
+       INTG(X86_TRAP_CP,               control_protection),
+#endif
 };

 /*

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index e6db475164ed..21a713b96148 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c

@@ -578,6 +578,64 @@ do_general_protection(struct pt_regs *regs, long error_code)
 }
 NOKPROBE_SYMBOL(do_general_protection);

+static const char *control_protection_err[] =
+{
+       "unknown",
+       "near-ret",
+       "far-ret/iret",
+       "endbranch",
+       "rstorssp",
+       "setssbsy",
+};
+
+/*
+ * When a control protection exception occurs, send a signal
+ * to the responsible application.  Currently, control
+ * protection is only enabled for the user mode.  This
+ * exception should not come from the kernel mode.
+ */
+dotraplinkage void
+do_control_protection(struct pt_regs *regs, long error_code)
+{
+       struct task_struct *tsk;
+
+       RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
+       if (notify_die(DIE_TRAP, "control protection fault", regs,
+                      error_code, X86_TRAP_CP, SIGSEGV) == NOTIFY_STOP)
+               return;
+       cond_local_irq_enable(regs);
+
+       if (!user_mode(regs))
+               die("kernel control protection fault", regs, error_code);
+
+       if (!static_cpu_has(X86_FEATURE_SHSTK) &&
+           !static_cpu_has(X86_FEATURE_IBT))
+               WARN_ONCE(1, "CET is disabled but got control "
+                         "protection fault\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()) {
+               unsigned int max_err;
+
+               max_err = ARRAY_SIZE(control_protection_err) - 1;
+               if ((error_code < 0) || (error_code > max_err))
+                       error_code = 0;
+               pr_info("%s[%d] control protection ip:%lx sp:%lx error:%lx(%s)",
+                       tsk->comm, task_pid_nr(tsk),
+                       regs->ip, regs->sp, error_code,
+                       control_protection_err[error_code]);
+               print_vma_addr(" in ", regs->ip);