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Message-ID: <bd5cff471e67cf8d2b2d3bd8db35007ccc86f6a4.1699487758.git.jpoimboe@kernel.org>
Date: Wed, 8 Nov 2023 16:41:11 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: linux-kernel@...r.kernel.org, x86@...nel.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
Subject: [PATCH RFC 06/10] unwind: Introduce generic user space unwinding interfaces
Introduce generic user space unwinder interfaces which will provide a
unified 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 | 32 +++++++++++++++
kernel/Makefile | 1 +
kernel/unwind/Makefile | 1 +
kernel/unwind/user.c | 77 +++++++++++++++++++++++++++++++++++++
5 files changed, 114 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 690c82212224..c4a08485835e 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -428,6 +428,9 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH
config HAVE_PERF_CALLCHAIN_DEFERRED
bool
+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..2812b88c95fd
--- /dev/null
+++ b/include/linux/user_unwind.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_USER_UNWIND_H
+#define _LINUX_USER_UNWIND_H
+
+#include <linux/types.h>
+#include <linux/sframe.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 3947122d618b..bddf58b3b496 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..8f9432306482
--- /dev/null
+++ b/kernel/unwind/user.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/user_unwind.h>
+#include <linux/sframe.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);
+
+ might_sleep();
+
+ memset(state, 0, sizeof(*state));
+
+ if (!current->mm) {
+ state->done = true;
+ return -EINVAL;
+ }
+
+ if (type == USER_UNWIND_TYPE_AUTO)
+ state->type = USER_UNWIND_TYPE_FP;
+ else
+ state->type = type;
+
+ state->sp = user_stack_pointer(regs);
+ state->ip = instruction_pointer(regs);
+ state->fp = frame_pointer(regs);
+
+ return user_unwind_next(state);
+}
--
2.41.0
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