[RFC PATCH v1 11/25] unwind_user/eh_frame: Wire up unwind_user to eh_frame

[Jens Remus <jremus@linux.ibm.com>]

Now that the eh_frame infrastructure is fully in place, make it work by
hooking it up to the unwind_user interface.

Based on Josh Poimboeuf's, Steven Rostedt's, and my unwind user sframe
implementation.

Signed-off-by: Jens Remus <jremus@linux.ibm.com>
---
 arch/Kconfig                      |  1 +
 include/linux/unwind_user_types.h |  4 +++-
 kernel/unwind/user.c              | 23 +++++++++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 60542d5e5731..ea969811f798 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -488,6 +488,7 @@ config UNWIND_USER
 
 config HAVE_UNWIND_USER_EH_FRAME
 	bool
+	select UNWIND_USER
 
 config HAVE_UNWIND_USER_FP
 	bool
diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_types.h
index 4da058096259..88fc2fee8534 100644
--- a/include/linux/unwind_user_types.h
+++ b/include/linux/unwind_user_types.h
@@ -9,7 +9,8 @@
  * available.
  */
 enum unwind_user_type_bits {
-	UNWIND_USER_TYPE_FP_BIT =		0,
+	UNWIND_USER_TYPE_EH_FRAME_BIT =		0,
+	UNWIND_USER_TYPE_FP_BIT =		1,
 
 	NR_UNWIND_USER_TYPE_BITS,
 };
@@ -17,6 +18,7 @@ enum unwind_user_type_bits {
 enum unwind_user_type {
 	/* Type "none" for the start of stack walk iteration. */
 	UNWIND_USER_TYPE_NONE =			0,
+	UNWIND_USER_TYPE_EH_FRAME =		BIT(UNWIND_USER_TYPE_EH_FRAME_BIT),
 	UNWIND_USER_TYPE_FP =			BIT(UNWIND_USER_TYPE_FP_BIT),
 };
 
diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
index 830c620fe453..85fc82252af1 100644
--- a/kernel/unwind/user.c
+++ b/kernel/unwind/user.c
@@ -10,6 +10,7 @@
 #include <linux/sched/task_stack.h>
 #include <linux/unwind_user.h>
 #include <linux/uaccess.h>
+#include <linux/eh_frame.h>
 
 #ifdef CONFIG_DYNAMIC_DEBUG
 
@@ -173,6 +174,16 @@ static int unwind_user_next_fp(struct unwind_user_state *state)
 	return unwind_user_next_common(state, &fp_frame);
 }
 
+static int unwind_user_next_eh_frame(struct unwind_user_state *state)
+{
+	struct unwind_user_frame frame;
+
+	/* eh_frame expects the frame to be local storage */
+	if (eh_frame_find(state->ip, &frame))
+		return -ENOENT;
+	return unwind_user_next_common(state, &frame);
+}
+
 static int unwind_user_next(struct unwind_user_state *state)
 {
 	unsigned long iter_mask = state->available_types;
@@ -186,6 +197,16 @@ static int unwind_user_next(struct unwind_user_state *state)
 
 		state->current_type = type;
 		switch (type) {
+		case UNWIND_USER_TYPE_EH_FRAME:
+			switch (unwind_user_next_eh_frame(state)) {
+			case 0:
+				return 0;
+			case -ENOENT:
+				continue;	/* Try next method. */
+			default:
+				state->done = true;
+			}
+			break;
 		case UNWIND_USER_TYPE_FP:
 			if (!unwind_user_next_fp(state))
 				return 0;
@@ -214,6 +235,8 @@ static int unwind_user_start(struct unwind_user_state *state)
 		return -EINVAL;
 	}
 
+	if (current_has_eh_frame())
+		state->available_types |= UNWIND_USER_TYPE_EH_FRAME;
 	if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP))
 		state->available_types |= UNWIND_USER_TYPE_FP;
 
-- 
2.53.0