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-rw-r--r--MAINTAINERS8
-rw-r--r--arch/Kconfig7
-rw-r--r--include/asm-generic/Kbuild1
-rw-r--r--include/asm-generic/unwind_user.h5
-rw-r--r--include/linux/unwind_user.h14
-rw-r--r--include/linux/unwind_user_types.h44
-rw-r--r--kernel/Makefile1
-rw-r--r--kernel/unwind/Makefile1
-rw-r--r--kernel/unwind/user.c128
9 files changed, 209 insertions, 0 deletions
diff --git a/MAINTAINERS b/MAINTAINERS
index fad6cb025a19..370d780fd5f8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -25928,6 +25928,14 @@ F: Documentation/driver-api/uio-howto.rst
F: drivers/uio/
F: include/linux/uio_driver.h
+USERSPACE STACK UNWINDING
+M: Josh Poimboeuf <jpoimboe@kernel.org>
+M: Steven Rostedt <rostedt@goodmis.org>
+S: Maintained
+F: include/linux/unwind*.h
+F: kernel/unwind/
+
+
UTIL-LINUX PACKAGE
M: Karel Zak <kzak@redhat.com>
L: util-linux@vger.kernel.org
diff --git a/arch/Kconfig b/arch/Kconfig
index a3308a220f86..8e3fd723bd74 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -435,6 +435,13 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH
It uses the same command line parameters, and sysctl interface,
as the generic hardlockup detectors.
+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
new file mode 100644
index 000000000000..7f7282516bf5
--- /dev/null
+++ b/include/linux/unwind_user.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_UNWIND_USER_H
+#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(struct unwind_stacktrace *trace, unsigned int max_entries);
+
+#endif /* _LINUX_UNWIND_USER_H */
diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_types.h
new file mode 100644
index 000000000000..a449f15be890
--- /dev/null
+++ b/include/linux/unwind_user_types.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_UNWIND_USER_TYPES_H
+#define _LINUX_UNWIND_USER_TYPES_H
+
+#include <linux/types.h>
+
+/*
+ * Unwind types, listed in priority order: lower numbers are attempted first if
+ * available.
+ */
+enum unwind_user_type_bits {
+ UNWIND_USER_TYPE_FP_BIT = 0,
+
+ NR_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_FP = BIT(UNWIND_USER_TYPE_FP_BIT),
+};
+
+struct unwind_stacktrace {
+ unsigned int nr;
+ unsigned long *entries;
+};
+
+struct unwind_user_frame {
+ s32 cfa_off;
+ s32 ra_off;
+ s32 fp_off;
+ bool use_fp;
+};
+
+struct unwind_user_state {
+ unsigned long ip;
+ unsigned long sp;
+ unsigned long fp;
+ enum unwind_user_type current_type;
+ unsigned int available_types;
+ bool done;
+};
+
+#endif /* _LINUX_UNWIND_USER_TYPES_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index 32e80dd626af..541186050251 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -55,6 +55,7 @@ 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..349ce3677526
--- /dev/null
+++ b/kernel/unwind/Makefile
@@ -0,0 +1 @@
+ obj-$(CONFIG_UNWIND_USER) += user.o
diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
new file mode 100644
index 000000000000..97a8415e3216
--- /dev/null
+++ b/kernel/unwind/user.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+* Generic interfaces for unwinding user space
+*/
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/unwind_user.h>
+#include <linux/uaccess.h>
+
+static const struct unwind_user_frame fp_frame = {
+ ARCH_INIT_USER_FP_FRAME
+};
+
+#define for_each_user_frame(state) \
+ for (unwind_user_start(state); !(state)->done; unwind_user_next(state))
+
+static int unwind_user_next_fp(struct unwind_user_state *state)
+{
+ const struct unwind_user_frame *frame = &fp_frame;
+ unsigned long cfa, fp, ra;
+ unsigned int shift;
+
+ if (frame->use_fp) {
+ if (state->fp < state->sp)
+ return -EINVAL;
+ cfa = state->fp;
+ } else {
+ cfa = state->sp;
+ }
+
+ /* Get the Canonical Frame Address (CFA) */
+ cfa += frame->cfa_off;
+
+ /* stack going in wrong direction? */
+ if (cfa <= state->sp)
+ return -EINVAL;
+
+ /* Make sure that the address is word aligned */
+ shift = sizeof(long) == 4 ? 2 : 3;
+ if (cfa & ((1 << shift) - 1))
+ return -EINVAL;
+
+ /* Find the Return Address (RA) */
+ if (get_user(ra, (unsigned long *)(cfa + frame->ra_off)))
+ return -EINVAL;
+
+ if (frame->fp_off && get_user(fp, (unsigned long __user *)(cfa + frame->fp_off)))
+ return -EINVAL;
+
+ state->ip = ra;
+ state->sp = cfa;
+ if (frame->fp_off)
+ state->fp = fp;
+ return 0;
+}
+
+static int unwind_user_next(struct unwind_user_state *state)
+{
+ unsigned long iter_mask = state->available_types;
+ unsigned int bit;
+
+ if (state->done)
+ return -EINVAL;
+
+ for_each_set_bit(bit, &iter_mask, NR_UNWIND_USER_TYPE_BITS) {
+ enum unwind_user_type type = BIT(bit);
+
+ state->current_type = type;
+ switch (type) {
+ case UNWIND_USER_TYPE_FP:
+ if (!unwind_user_next_fp(state))
+ return 0;
+ continue;
+ default:
+ WARN_ONCE(1, "Undefined unwind bit %d", bit);
+ break;
+ }
+ break;
+ }
+
+ /* No successful unwind method. */
+ state->current_type = UNWIND_USER_TYPE_NONE;
+ state->done = true;
+ return -EINVAL;
+}
+
+static int unwind_user_start(struct unwind_user_state *state)
+{
+ struct pt_regs *regs = task_pt_regs(current);
+
+ memset(state, 0, sizeof(*state));
+
+ if ((current->flags & PF_KTHREAD) || !user_mode(regs)) {
+ state->done = true;
+ return -EINVAL;
+ }
+
+ if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP))
+ state->available_types |= UNWIND_USER_TYPE_FP;
+
+ state->ip = instruction_pointer(regs);
+ state->sp = user_stack_pointer(regs);
+ state->fp = frame_pointer(regs);
+
+ return 0;
+}
+
+int unwind_user(struct unwind_stacktrace *trace, unsigned int max_entries)
+{
+ struct unwind_user_state state;
+
+ trace->nr = 0;
+
+ if (!max_entries)
+ return -EINVAL;
+
+ if (current->flags & PF_KTHREAD)
+ return 0;
+
+ for_each_user_frame(&state) {
+ trace->entries[trace->nr++] = state.ip;
+ if (trace->nr >= max_entries)
+ break;
+ }
+
+ return 0;
+}
generated by cgit v1.2.3 (git 2.0.4) at 2025-12-16 03:50:10 +0000