[PATCH v13 06/18] unwind_user/sframe: Wire up unwind_user to sframe

Jens Remus
2026-01-27T15:06:51Z

From: Josh Poimboeuf <jpoimboe@kernel.org>

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

[ Jens Remus: Remove unused pt_regs from unwind_user_next_common() and
its callers. Simplify unwind_user_next_sframe(). ]

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Indu Bhagat <indu.bhagat@oracle.com>
Cc: "Jose E. Marchesi" <jemarch@gnu.org>
Cc: Beau Belgrave <beaub@linux.microsoft.com>
Cc: Jens Remus <jremus@linux.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Sam James <sam@gentoo.org>
Cc: Kees Cook <kees@kernel.org>
Cc: "Carlos O'Donell" <codonell@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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 7d5517364d8b..2ece3df821b5 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -488,6 +488,7 @@ config HAVE_UNWIND_USER_FP

config HAVE_UNWIND_USER_SFRAME
bool
+ select UNWIND_USER

config HAVE_PERF_REGS
bool
diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_types.h
index 412729a269bc..43e4b160883f 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_SFRAME_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_SFRAME = BIT(UNWIND_USER_TYPE_SFRAME_BIT),
UNWIND_USER_TYPE_FP = BIT(UNWIND_USER_TYPE_FP_BIT),
};

diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
index 90ab3c1a205e..1fb272419733 100644
--- a/kernel/unwind/user.c
+++ b/kernel/unwind/user.c
@@ -7,6 +7,7 @@
#include <linux/sched/task_stack.h>
#include <linux/unwind_user.h>
#include <linux/uaccess.h>
+#include <linux/sframe.h>

#define for_each_user_frame(state) \
for (unwind_user_start(state); !(state)->done; unwind_user_next(state))
@@ -82,6 +83,16 @@ static int unwind_user_next_fp(struct unwind_user_state *state)
return unwind_user_next_common(state, &fp_frame);
}

+static int unwind_user_next_sframe(struct unwind_user_state *state)
+{
+ struct unwind_user_frame frame;
+
+ /* sframe expects the frame to be local storage */
+ if (sframe_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;
@@ -95,6 +106,16 @@ static int unwind_user_next(struct unwind_user_state *state)

state->current_type = type;
switch (type) {
+ case UNWIND_USER_TYPE_SFRAME:
+ switch (unwind_user_next_sframe(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;
@@ -123,6 +144,8 @@ static int unwind_user_start(struct unwind_user_state *state)
return -EINVAL;
}

+ if (current_has_sframe())
+ state->available_types |= UNWIND_USER_TYPE_SFRAME;
if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP))
state->available_types |= UNWIND_USER_TYPE_FP;

--
2.51.0