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Message-ID: <f55f7f0b1410b4d75133e059646c4fc72b8cb581.1726268190.git.jpoimboe@kernel.org>
Date: Sat, 14 Sep 2024 01:02:03 +0200
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
linux-kernel@...r.kernel.org,
Indu Bhagat <indu.bhagat@...cle.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org,
Mark Brown <broonie@...nel.org>,
linux-toolchains@...r.kernel.org,
Jordan Rome <jordalgo@...a.com>,
Sam James <sam@...too.org>
Subject: [PATCH v2 01/11] unwind: Introduce generic user space unwinding interface
Introduce a user space unwinder interface which will provide a generic
way for architectures to unwind different user space stack frame types.
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
arch/Kconfig | 3 ++
include/linux/user_unwind.h | 31 ++++++++++++++
kernel/Makefile | 1 +
kernel/unwind/Makefile | 1 +
kernel/unwind/user.c | 81 +++++++++++++++++++++++++++++++++++++
5 files changed, 117 insertions(+)
create mode 100644 include/linux/user_unwind.h
create mode 100644 kernel/unwind/Makefile
create mode 100644 kernel/unwind/user.c
diff --git a/arch/Kconfig b/arch/Kconfig
index 975dd22a2dbd..b1002b2da331 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -425,6 +425,9 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH
It uses the same command line parameters, and sysctl interface,
as the generic hardlockup detectors.
+config HAVE_USER_UNWIND
+ bool
+
config HAVE_PERF_REGS
bool
help
diff --git a/include/linux/user_unwind.h b/include/linux/user_unwind.h
new file mode 100644
index 000000000000..0a19ac6c92b2
--- /dev/null
+++ b/include/linux/user_unwind.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_USER_UNWIND_H
+#define _LINUX_USER_UNWIND_H
+
+#include <linux/types.h>
+
+enum user_unwind_type {
+ USER_UNWIND_TYPE_AUTO,
+ USER_UNWIND_TYPE_FP,
+};
+
+struct user_unwind_frame {
+ s32 cfa_off;
+ s32 ra_off;
+ s32 fp_off;
+ bool use_fp;
+};
+
+struct user_unwind_state {
+ unsigned long ip, sp, fp;
+ enum user_unwind_type type;
+ bool done;
+};
+
+extern int user_unwind_start(struct user_unwind_state *state, enum user_unwind_type);
+extern int user_unwind_next(struct user_unwind_state *state);
+
+#define for_each_user_frame(state, type) \
+ for (user_unwind_start(state, type); !state.done; user_unwind_next(state))
+
+#endif /* _LINUX_USER_UNWIND_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index 3c13240dfc9f..259581df82dd 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -50,6 +50,7 @@ obj-y += rcu/
obj-y += livepatch/
obj-y += dma/
obj-y += entry/
+obj-y += unwind/
obj-$(CONFIG_MODULES) += module/
obj-$(CONFIG_KCMP) += kcmp.o
diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile
new file mode 100644
index 000000000000..eb466d6a3295
--- /dev/null
+++ b/kernel/unwind/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_HAVE_USER_UNWIND) += user.o
diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
new file mode 100644
index 000000000000..5d16f9604a61
--- /dev/null
+++ b/kernel/unwind/user.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+* Generic interface for unwinding user space
+*
+* Copyright (C) 2024 Josh Poimboeuf <jpoimboe@...nel.org>
+*/
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/user_unwind.h>
+#include <linux/uaccess.h>
+#include <asm/user_unwind.h>
+
+static struct user_unwind_frame fp_frame = {
+ ARCH_INIT_USER_FP_FRAME
+};
+
+int user_unwind_next(struct user_unwind_state *state)
+{
+ struct user_unwind_frame _frame;
+ struct user_unwind_frame *frame = &_frame;
+ unsigned long cfa, fp, ra;
+ int ret = -EINVAL;
+
+ if (state->done)
+ return -EINVAL;
+
+ switch (state->type) {
+ case USER_UNWIND_TYPE_FP:
+ frame = &fp_frame;
+ break;
+ default:
+ BUG();
+ }
+
+ cfa = (frame->use_fp ? state->fp : state->sp) + frame->cfa_off;
+
+ if (frame->ra_off && get_user(ra, (unsigned long *)(cfa + frame->ra_off)))
+ goto the_end;
+
+ if (frame->fp_off && get_user(fp, (unsigned long *)(cfa + frame->fp_off)))
+ goto the_end;
+
+ state->sp = cfa;
+ state->ip = ra;
+ if (frame->fp_off)
+ state->fp = fp;
+
+ return 0;
+
+the_end:
+ state->done = true;
+ return ret;
+}
+
+int user_unwind_start(struct user_unwind_state *state,
+ enum user_unwind_type type)
+{
+ struct pt_regs *regs = task_pt_regs(current);
+
+ memset(state, 0, sizeof(*state));
+
+ if (!current->mm) {
+ state->done = true;
+ return -EINVAL;
+ }
+
+ switch (type) {
+ case USER_UNWIND_TYPE_AUTO:
+ case USER_UNWIND_TYPE_FP:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ state->sp = user_stack_pointer(regs);
+ state->ip = instruction_pointer(regs);
+ state->fp = frame_pointer(regs);
+
+ return user_unwind_next(state);
+}
--
2.46.0
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