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2024-10-22 8ac6c7a54ed1b98d142dce24b11c6de6a1e239a5 
 kernel/arch/arm64/kernel/stacktrace.c
....@@ -1,19 +1,8 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * Stack tracing support
34  *
45  * Copyright (C) 2012 ARM Ltd.
5
- *
6
- * This program is free software; you can redistribute it and/or modify
7
- * it under the terms of the GNU General Public License version 2 as
8
- * published by the Free Software Foundation.
9
- *
10
- * This program is distributed in the hope that it will be useful,
11
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
12
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13
- * GNU General Public License for more details.
14
- *
15
- * You should have received a copy of the GNU General Public License
16
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
176  */
187 #include <linux/kernel.h>
198 #include <linux/export.h>
....@@ -25,6 +14,7 @@
2514 #include <linux/stacktrace.h>
2615 
2716 #include <asm/irq.h>
17
+#include <asm/pointer_auth.h>
2818 #include <asm/stack_pointer.h>
2919 #include <asm/stacktrace.h>
3020 
....@@ -41,9 +31,18 @@
4131  *	ldp	x29, x30, [sp]
4232  *	add	sp, sp, #0x10
4333  */
34
+
35
+/*
36
+ * Unwind from one frame record (A) to the next frame record (B).
37
+ *
38
+ * We terminate early if the location of B indicates a malformed chain of frame
39
+ * records (e.g. a cycle), determined based on the location and fp value of A
40
+ * and the location (but not the fp value) of B.
41
+ */
4442 int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
4543 {
4644 	unsigned long fp = frame->fp;
45
+	struct stack_info info;
4746 
4847 	if (fp & 0xf)
4948 		return -EINVAL;
....@@ -51,29 +50,59 @@
5150 	if (!tsk)
5251 		tsk = current;
5352 
54
-	if (!on_accessible_stack(tsk, fp, NULL))
53
+	if (!on_accessible_stack(tsk, fp, &info))
5554 		return -EINVAL;
5655 
56
+	if (test_bit(info.type, frame->stacks_done))
57
+		return -EINVAL;
58
+
59
+	/*
60
+	 * As stacks grow downward, any valid record on the same stack must be
61
+	 * at a strictly higher address than the prior record.
62
+	 *
63
+	 * Stacks can nest in several valid orders, e.g.
64
+	 *
65
+	 * TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL
66
+	 * TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW
67
+	 *
68
+	 * ... but the nesting itself is strict. Once we transition from one
69
+	 * stack to another, it's never valid to unwind back to that first
70
+	 * stack.
71
+	 */
72
+	if (info.type == frame->prev_type) {
73
+		if (fp <= frame->prev_fp)
74
+			return -EINVAL;
75
+	} else {
76
+		set_bit(frame->prev_type, frame->stacks_done);
77
+	}
78
+
79
+	/*
80
+	 * Record this frame record's values and location. The prev_fp and
81
+	 * prev_type are only meaningful to the next unwind_frame() invocation.
82
+	 */
5783 	frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
5884 	frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
85
+	frame->prev_fp = fp;
86
+	frame->prev_type = info.type;
5987 
6088 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
6189 	if (tsk->ret_stack &&
62
-			(frame->pc == (unsigned long)return_to_handler)) {
63
-		if (WARN_ON_ONCE(frame->graph == -1))
64
-			return -EINVAL;
65
-		if (frame->graph < -1)
66
-			frame->graph += FTRACE_NOTRACE_DEPTH;
67
-
90
+		(ptrauth_strip_insn_pac(frame->pc) == (unsigned long)return_to_handler)) {
91
+		struct ftrace_ret_stack *ret_stack;
6892 		/*
6993 		 * This is a case where function graph tracer has
7094 		 * modified a return address (LR) in a stack frame
7195 		 * to hook a function return.
7296 		 * So replace it to an original value.
7397 		 */
74
-		frame->pc = tsk->ret_stack[frame->graph--].ret;
98
+		ret_stack = ftrace_graph_get_ret_stack(tsk, frame->graph++);
99
+		if (WARN_ON_ONCE(!ret_stack))
100
+			return -EINVAL;
101
+		frame->pc = ret_stack->ret;
75102 	}
76103 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
104
+
105
+	frame->pc = ptrauth_strip_insn_pac(frame->pc);
77106 
78107 	/*
79108 	 * Frames created upon entry from EL0 have NULL FP and PC values, so
....@@ -89,12 +118,12 @@
89118 NOKPROBE_SYMBOL(unwind_frame);
90119 
91120 void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
92
-		     int (*fn)(struct stackframe *, void *), void *data)
121
+			     bool (*fn)(void *, unsigned long), void *data)
93122 {
94123 	while (1) {
95124 		int ret;
96125 
97
-		if (fn(frame, data))
126
+		if (!fn(data, frame->pc))
98127 			break;
99128 		ret = unwind_frame(tsk, frame);
100129 		if (ret < 0)
....@@ -103,94 +132,91 @@
103132 }
104133 NOKPROBE_SYMBOL(walk_stackframe);
105134 
106
-#ifdef CONFIG_STACKTRACE
107
-struct stack_trace_data {
108
-	struct stack_trace *trace;
109
-	unsigned int no_sched_functions;
110
-	unsigned int skip;
111
-};
112
-
113
-static int save_trace(struct stackframe *frame, void *d)
135
+static void dump_backtrace_entry(unsigned long where, const char *loglvl)
114136 {
115
-	struct stack_trace_data *data = d;
116
-	struct stack_trace *trace = data->trace;
117
-	unsigned long addr = frame->pc;
137
+	printk("%s %pS\n", loglvl, (void *)where);
138
+}
118139 
119
-	if (data->no_sched_functions && in_sched_functions(addr))
120
-		return 0;
121
-	if (data->skip) {
122
-		data->skip--;
123
-		return 0;
140
+void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
141
+		    const char *loglvl)
142
+{
143
+	struct stackframe frame;
144
+	int skip = 0;
145
+
146
+	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
147
+
148
+	if (regs) {
149
+		if (user_mode(regs))
150
+			return;
151
+		skip = 1;
124152 	}
125153 
126
-	trace->entries[trace->nr_entries++] = addr;
127
-
128
-	return trace->nr_entries >= trace->max_entries;
129
-}
130
-
131
-void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
132
-{
133
-	struct stack_trace_data data;
134
-	struct stackframe frame;
135
-
136
-	data.trace = trace;
137
-	data.skip = trace->skip;
138
-	data.no_sched_functions = 0;
139
-
140
-	frame.fp = regs->regs[29];
141
-	frame.pc = regs->pc;
142
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
143
-	frame.graph = current->curr_ret_stack;
144
-#endif
145
-
146
-	walk_stackframe(current, &frame, save_trace, &data);
147
-	if (trace->nr_entries < trace->max_entries)
148
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
149
-}
150
-
151
-static noinline void __save_stack_trace(struct task_struct *tsk,
152
-	struct stack_trace *trace, unsigned int nosched)
153
-{
154
-	struct stack_trace_data data;
155
-	struct stackframe frame;
154
+	if (!tsk)
155
+		tsk = current;
156156 
157157 	if (!try_get_task_stack(tsk))
158158 		return;
159159 
160
-	data.trace = trace;
161
-	data.skip = trace->skip;
162
-	data.no_sched_functions = nosched;
163
-
164
-	if (tsk != current) {
165
-		frame.fp = thread_saved_fp(tsk);
166
-		frame.pc = thread_saved_pc(tsk);
160
+	if (tsk == current) {
161
+		start_backtrace(&frame,
162
+				(unsigned long)__builtin_frame_address(0),
163
+				(unsigned long)dump_backtrace);
167164 	} else {
168
-		/* We don't want this function nor the caller */
169
-		data.skip += 2;
170
-		frame.fp = (unsigned long)__builtin_frame_address(0);
171
-		frame.pc = (unsigned long)__save_stack_trace;
165
+		/*
166
+		 * task blocked in __switch_to
167
+		 */
168
+		start_backtrace(&frame,
169
+				thread_saved_fp(tsk),
170
+				thread_saved_pc(tsk));
172171 	}
173
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
174
-	frame.graph = tsk->curr_ret_stack;
175
-#endif
176172 
177
-	walk_stackframe(tsk, &frame, save_trace, &data);
178
-	if (trace->nr_entries < trace->max_entries)
179
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
173
+	printk("%sCall trace:\n", loglvl);
174
+	do {
175
+		/* skip until specified stack frame */
176
+		if (!skip) {
177
+			dump_backtrace_entry(frame.pc, loglvl);
178
+		} else if (frame.fp == regs->regs[29]) {
179
+			skip = 0;
180
+			/*
181
+			 * Mostly, this is the case where this function is
182
+			 * called in panic/abort. As exception handler's
183
+			 * stack frame does not contain the corresponding pc
184
+			 * at which an exception has taken place, use regs->pc
185
+			 * instead.
186
+			 */
187
+			dump_backtrace_entry(regs->pc, loglvl);
188
+		}
189
+	} while (!unwind_frame(tsk, &frame));
180190 
181191 	put_task_stack(tsk);
182192 }
183
-EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
193
+EXPORT_SYMBOL_GPL(dump_backtrace);
184194 
185
-void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
195
+void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
186196 {
187
-	__save_stack_trace(tsk, trace, 1);
197
+	dump_backtrace(NULL, tsk, loglvl);
198
+	barrier();
188199 }
189200 
190
-void save_stack_trace(struct stack_trace *trace)
201
+#ifdef CONFIG_STACKTRACE
202
+
203
+noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
204
+			      void *cookie, struct task_struct *task,
205
+			      struct pt_regs *regs)
191206 {
192
-	__save_stack_trace(current, trace, 0);
207
+	struct stackframe frame;
208
+
209
+	if (regs)
210
+		start_backtrace(&frame, regs->regs[29], regs->pc);
211
+	else if (task == current)
212
+		start_backtrace(&frame,
213
+				(unsigned long)__builtin_frame_address(1),
214
+				(unsigned long)__builtin_return_address(0));
215
+	else
216
+		start_backtrace(&frame, thread_saved_fp(task),
217
+				thread_saved_pc(task));
218
+
219
+	walk_stackframe(task, &frame, consume_entry, cookie);
193220 }
194221 
195
-EXPORT_SYMBOL_GPL(save_stack_trace);
196222 #endif