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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d

 kernel/kernel/events/callchain.c
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@@ -1,3 +1,4 @@
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+// SPDX-License-Identifier: GPL-2.0
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 /*
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  * Performance events callchain code, extracted from core.c:
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  *
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@@ -5,8 +6,6 @@
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  *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
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  *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
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  *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
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- *
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- * For licensing details see kernel-base/COPYING
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  */
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 #include <linux/perf_event.h>
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@@ -17,7 +16,7 @@
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16
 
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 struct callchain_cpus_entries {
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 	struct rcu_head			rcu_head;
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-	struct perf_callchain_entry	*cpu_entries[0];
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+	struct perf_callchain_entry	*cpu_entries[];
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 };
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 int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;
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@@ -150,7 +149,7 @@
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 	}
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 }
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-static struct perf_callchain_entry *get_callchain_entry(int *rctx)
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+struct perf_callchain_entry *get_callchain_entry(int *rctx)
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 {
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 	int cpu;
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 	struct callchain_cpus_entries *entries;
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@@ -160,8 +159,10 @@
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 		return NULL;
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 	entries = rcu_dereference(callchain_cpus_entries);
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-	if (!entries)
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+	if (!entries) {
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+		put_recursion_context(this_cpu_ptr(callchain_recursion), *rctx);
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 		return NULL;
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+	}
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 	cpu = smp_processor_id();
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@@ -169,7 +170,7 @@
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 		(*rctx * perf_callchain_entry__sizeof()));
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 }
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-static void
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+void
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 put_callchain_entry(int rctx)
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 {
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 	put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
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@@ -184,11 +185,8 @@
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 	int rctx;
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 	entry = get_callchain_entry(&rctx);
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-	if (rctx == -1)
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-		return NULL;
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-
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 	if (!entry)
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-		goto exit_put;
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+		return NULL;
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 	ctx.entry     = entry;
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 	ctx.max_stack = max_stack;
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@@ -219,10 +217,9 @@
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 			if (add_mark)
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 				perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
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-			fs = get_fs();
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-			set_fs(USER_DS);
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+			fs = force_uaccess_begin();
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 			perf_callchain_user(&ctx, regs);
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-			set_fs(fs);
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+			force_uaccess_end(fs);
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 		}
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 	}
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@@ -237,7 +234,7 @@
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  * sysctl_perf_event_max_contexts_per_stack.
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  */
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 int perf_event_max_stack_handler(struct ctl_table *table, int write,
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-				 void __user *buffer, size_t *lenp, loff_t *ppos)
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+				 void *buffer, size_t *lenp, loff_t *ppos)
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 {
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 	int *value = table->data;
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 	int new_value = *value, ret;