1 files changed, 39 insertions, 4 deletions

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index dc0fb7a81371..a12efd0f43e8 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -17,6 +17,7 @@
 #include <linux/perf_event.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/smp.h>
+#include <linux/cfi.h>
 #include <linux/cpu_pm.h>
 #include <linux/coresight.h>
 
@@ -626,7 +627,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 	hw->address &= ~alignment_mask;
 	hw->ctrl.len <<= offset;
 
-	if (uses_default_overflow_handler(bp)) {
+	if (is_default_overflow_handler(bp)) {
 		/*
 		 * Mismatch breakpoints are required for single-stepping
 		 * breakpoints.
@@ -798,7 +799,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
 		 * Otherwise, insert a temporary mismatch breakpoint so that
 		 * we can single-step over the watchpoint trigger.
 		 */
-		if (!uses_default_overflow_handler(wp))
+		if (!is_default_overflow_handler(wp))
 			continue;
 step:
 		enable_single_step(wp, instruction_pointer(regs));
@@ -811,7 +812,7 @@ step:
 		info->trigger = addr;
 		pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
 		perf_bp_event(wp, regs);
-		if (uses_default_overflow_handler(wp))
+		if (is_default_overflow_handler(wp))
 			enable_single_step(wp, instruction_pointer(regs));
 	}
 
@@ -886,7 +887,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
 			info->trigger = addr;
 			pr_debug("breakpoint fired: address = 0x%x\n", addr);
 			perf_bp_event(bp, regs);
-			if (uses_default_overflow_handler(bp))
+			if (is_default_overflow_handler(bp))
 				enable_single_step(bp, addr);
 			goto unlock;
 		}
@@ -903,6 +904,37 @@ unlock:
 	watchpoint_single_step_handler(addr);
 }
 
+#ifdef CONFIG_CFI_CLANG
+static void hw_breakpoint_cfi_handler(struct pt_regs *regs)
+{
+	/*
+	 * TODO: implementing target and type to pass to CFI using the more
+	 * elaborate report_cfi_failure() requires compiler work. To be able
+	 * to properly extract target information the compiler needs to
+	 * emit a stable instructions sequence for the CFI checks so we can
+	 * decode the instructions preceding the trap and figure out which
+	 * registers were used.
+	 */
+
+	switch (report_cfi_failure_noaddr(regs, instruction_pointer(regs))) {
+	case BUG_TRAP_TYPE_BUG:
+		die("Oops - CFI", regs, 0);
+		break;
+	case BUG_TRAP_TYPE_WARN:
+		/* Skip the breaking instruction */
+		instruction_pointer(regs) += 4;
+		break;
+	default:
+		die("Unknown CFI error", regs, 0);
+		break;
+	}
+}
+#else
+static void hw_breakpoint_cfi_handler(struct pt_regs *regs)
+{
+}
+#endif
+
 /*
  * Called from either the Data Abort Handler [watchpoint] or the
  * Prefetch Abort Handler [breakpoint] with interrupts disabled.
@@ -932,6 +964,9 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
 	case ARM_ENTRY_SYNC_WATCHPOINT:
 		watchpoint_handler(addr, fsr, regs);
 		break;
+	case ARM_ENTRY_CFI_BREAKPOINT:
+		hw_breakpoint_cfi_handler(regs);
+		break;
 	default:
 		ret = 1; /* Unhandled fault. */
 	}