[PATCH v5 06/12] unwind_user/sframe: Add prctl() interface for registering .sframe sections

From: Josh Poimboeuf <[email protected]>

The kernel doesn't have direct visibility to the ELF contents of shared
libraries.  Add some prctl() interfaces which allow glibc to tell the
kernel where to find .sframe sections.

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
---
 include/uapi/linux/prctl.h | 5 ++++-
 kernel/sys.c               | 9 +++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 15c18ef4eb11..4973c932341b 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -351,7 +351,7 @@ struct prctl_mm_map {
  * configuration.  All bits may be locked via this call, including
  * undefined bits.
  */
-#define PR_LOCK_SHADOW_STACK_STATUS      76
+#define PR_LOCK_SHADOW_STACK_STATUS	76
 
 /*
  * Controls the mode of timer_create() for CRIU restore operations.
@@ -364,4 +364,7 @@ struct prctl_mm_map {
 # define PR_TIMER_CREATE_RESTORE_IDS_ON		1
 # define PR_TIMER_CREATE_RESTORE_IDS_GET	2
 
+#define PR_ADD_SFRAME			78
+#define PR_REMOVE_SFRAME		79
+
 #endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index c434968e9f5d..d76665e4df7e 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -64,6 +64,7 @@
 #include <linux/rcupdate.h>
 #include <linux/uidgid.h>
 #include <linux/cred.h>
+#include <linux/sframe.h>
 
 #include <linux/nospec.h>
 
@@ -2820,6 +2821,14 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 			return -EINVAL;
 		error = posixtimer_create_prctl(arg2);
 		break;
+	case PR_ADD_SFRAME:
+		error = sframe_add_section(arg2, arg3, arg4, arg5);
+		break;
+	case PR_REMOVE_SFRAME:
+		if (arg3 || arg4 || arg5)
+			return -EINVAL;
+		error = sframe_remove_section(arg2);
+		break;
 	default:
 		trace_task_prctl_unknown(option, arg2, arg3, arg4, arg5);
 		error = -EINVAL;
-- 
2.47.2