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Message-ID: <20250611010428.092934995@goodmis.org>
Date: Tue, 10 Jun 2025 20:54:23 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org,
bpf@...r.kernel.org,
x86@...nel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Andrii Nakryiko <andrii@...nel.org>,
Indu Bhagat <indu.bhagat@...cle.com>,
"Jose E. Marchesi" <jemarch@....org>,
Beau Belgrave <beaub@...ux.microsoft.com>,
Jens Remus <jremus@...ux.ibm.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v10 02/14] unwind_user: Add frame pointer support
From: Josh Poimboeuf <jpoimboe@...nel.org>
Add optional support for user space frame pointer unwinding. If
supported, the arch needs to enable CONFIG_HAVE_UNWIND_USER_FP and
define ARCH_INIT_USER_FP_FRAME.
By encoding the frame offsets in struct unwind_user_frame, much of this
code can also be reused for future unwinder implementations like sframe.
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
Co-developed-by: Steven Rostedt (Google) <rostedt@...dmis.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
Changes since v9: https://lore.kernel.org/linux-trace-kernel/20250513223551.290698040@goodmis.org/
As asm-generic headers are not included when an architecture defines the
header, having more than one #ifndef and setting variables does not work
with those checks in the asm-generic header and the architecture header
does not define all the values.
- Move ARCH_INIT_USER_FP_FRAME check to linux/user_unwind.h
- Have linux/user_unwind.h include asm/user_unwind.h and not have C files
have to call the asm header directly
- Remove unnecessary frame initialization
- Added unwind_user.h to asm-generic/Kbuild
arch/Kconfig | 4 +++
include/asm-generic/Kbuild | 1 +
include/asm-generic/unwind_user.h | 5 ++++
include/linux/unwind_user.h | 5 ++++
include/linux/unwind_user_types.h | 1 +
kernel/unwind/user.c | 49 +++++++++++++++++++++++++++++--
6 files changed, 63 insertions(+), 2 deletions(-)
create mode 100644 include/asm-generic/unwind_user.h
diff --git a/arch/Kconfig b/arch/Kconfig
index ea59e5d7cc69..8e3fd723bd74 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -438,6 +438,10 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH
config UNWIND_USER
bool
+config HAVE_UNWIND_USER_FP
+ bool
+ select UNWIND_USER
+
config HAVE_PERF_REGS
bool
help
diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild
index 8675b7b4ad23..295c94a3ccc1 100644
--- a/include/asm-generic/Kbuild
+++ b/include/asm-generic/Kbuild
@@ -59,6 +59,7 @@ mandatory-y += tlbflush.h
mandatory-y += topology.h
mandatory-y += trace_clock.h
mandatory-y += uaccess.h
+mandatory-y += unwind_user.h
mandatory-y += vermagic.h
mandatory-y += vga.h
mandatory-y += video.h
diff --git a/include/asm-generic/unwind_user.h b/include/asm-generic/unwind_user.h
new file mode 100644
index 000000000000..b8882b909944
--- /dev/null
+++ b/include/asm-generic/unwind_user.h
@@ -0,0 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_UNWIND_USER_H
+#define _ASM_GENERIC_UNWIND_USER_H
+
+#endif /* _ASM_GENERIC_UNWIND_USER_H */
diff --git a/include/linux/unwind_user.h b/include/linux/unwind_user.h
index aa7923c1384f..a405111c41b0 100644
--- a/include/linux/unwind_user.h
+++ b/include/linux/unwind_user.h
@@ -3,6 +3,11 @@
#define _LINUX_UNWIND_USER_H
#include <linux/unwind_user_types.h>
+#include <asm/unwind_user.h>
+
+#ifndef ARCH_INIT_USER_FP_FRAME
+ #define ARCH_INIT_USER_FP_FRAME
+#endif
int unwind_user_start(struct unwind_user_state *state);
int unwind_user_next(struct unwind_user_state *state);
diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_types.h
index 6ed1b4ae74e1..65bd070eb6b0 100644
--- a/include/linux/unwind_user_types.h
+++ b/include/linux/unwind_user_types.h
@@ -6,6 +6,7 @@
enum unwind_user_type {
UNWIND_USER_TYPE_NONE,
+ UNWIND_USER_TYPE_FP,
};
struct unwind_stacktrace {
diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
index d30449328981..4fc550356b33 100644
--- a/kernel/unwind/user.c
+++ b/kernel/unwind/user.c
@@ -6,10 +6,52 @@
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/unwind_user.h>
+#include <linux/uaccess.h>
+
+static struct unwind_user_frame fp_frame = {
+ ARCH_INIT_USER_FP_FRAME
+};
+
+static inline bool fp_state(struct unwind_user_state *state)
+{
+ return IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP) &&
+ state->type == UNWIND_USER_TYPE_FP;
+}
int unwind_user_next(struct unwind_user_state *state)
{
- /* no implementation yet */
+ struct unwind_user_frame *frame;
+ unsigned long cfa = 0, fp, ra = 0;
+
+ if (state->done)
+ return -EINVAL;
+
+ if (fp_state(state))
+ frame = &fp_frame;
+ else
+ goto the_end;
+
+ cfa = (frame->use_fp ? state->fp : state->sp) + frame->cfa_off;
+
+ /* stack going in wrong direction? */
+ if (cfa <= state->sp)
+ goto the_end;
+
+ if (get_user(ra, (unsigned long *)(cfa + frame->ra_off)))
+ goto the_end;
+
+ if (frame->fp_off && get_user(fp, (unsigned long __user *)(cfa + frame->fp_off)))
+ goto the_end;
+
+ state->ip = ra;
+ state->sp = cfa;
+ if (frame->fp_off)
+ state->fp = fp;
+
+ return 0;
+
+the_end:
+ state->done = true;
return -EINVAL;
}
@@ -24,7 +66,10 @@ int unwind_user_start(struct unwind_user_state *state)
return -EINVAL;
}
- state->type = UNWIND_USER_TYPE_NONE;
+ if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP))
+ state->type = UNWIND_USER_TYPE_FP;
+ else
+ state->type = UNWIND_USER_TYPE_NONE;
state->ip = instruction_pointer(regs);
state->sp = user_stack_pointer(regs);
--
2.47.2
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