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2024-09-20 a36159eec6ca17402b0e146b86efaf76568dc353 
 kernel/kernel/kallsyms.c
....@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
34  *
....@@ -23,6 +24,7 @@
2324 #include <linux/slab.h>
2425 #include <linux/filter.h>
2526 #include <linux/ftrace.h>
27
+#include <linux/kprobes.h>
2628 #include <linux/compiler.h>
2729 
2830 /*
....@@ -37,16 +39,16 @@
3739  * Tell the compiler that the count isn't in the small data section if the arch
3840  * has one (eg: FRV).
3941  */
40
-extern const unsigned long kallsyms_num_syms
41
-__attribute__((weak, section(".rodata")));
42
+extern const unsigned int kallsyms_num_syms
43
+__section(".rodata") __attribute__((weak));
4244 
4345 extern const unsigned long kallsyms_relative_base
44
-__attribute__((weak, section(".rodata")));
46
+__section(".rodata") __attribute__((weak));
4547 
46
-extern const u8 kallsyms_token_table[] __weak;
48
+extern const char kallsyms_token_table[] __weak;
4749 extern const u16 kallsyms_token_index[] __weak;
4850 
49
-extern const unsigned long kallsyms_markers[] __weak;
51
+extern const unsigned int kallsyms_markers[] __weak;
5052 
5153 /*
5254  * Expand a compressed symbol data into the resulting uncompressed string,
....@@ -57,7 +59,8 @@
5759 					   char *result, size_t maxlen)
5860 {
5961 	int len, skipped_first = 0;
60
-	const u8 *tptr, *data;
62
+	const char *tptr;
63
+	const u8 *data;
6164 
6265 	/* Get the compressed symbol length from the first symbol byte. */
6366 	data = &kallsyms_names[off];
....@@ -158,6 +161,26 @@
158161 	return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
159162 }
160163 
164
+#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_LTO_CLANG_THIN)
165
+/*
166
+ * LLVM appends a hash to static function names when ThinLTO and CFI are
167
+ * both enabled, which causes confusion and potentially breaks user space
168
+ * tools, so we will strip the postfix from expanded symbol names.
169
+ */
170
+static inline char *cleanup_symbol_name(char *s)
171
+{
172
+	char *res = NULL;
173
+
174
+	res = strrchr(s, '$');
175
+	if (res)
176
+		*res = '\0';
177
+
178
+	return res;
179
+}
180
+#else
181
+static inline char *cleanup_symbol_name(char *s) { return NULL; }
182
+#endif
183
+
161184 /* Lookup the address for this symbol. Returns 0 if not found. */
162185 unsigned long kallsyms_lookup_name(const char *name)
163186 {
....@@ -169,6 +192,9 @@
169192 		off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
170193 
171194 		if (strcmp(namebuf, name) == 0)
195
+			return kallsyms_sym_address(i);
196
+
197
+		if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0)
172198 			return kallsyms_sym_address(i);
173199 	}
174200 	return module_kallsyms_lookup_name(name);
....@@ -267,30 +293,6 @@
267293 	return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) ||
268294 	       !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
269295 }
270
-
271
-#ifdef CONFIG_CFI_CLANG
272
-/*
273
- * LLVM appends .cfi to function names when CONFIG_CFI_CLANG is enabled,
274
- * which causes confusion and potentially breaks user space tools, so we
275
- * will strip the postfix from expanded symbol names.
276
- */
277
-static inline void cleanup_symbol_name(char *s)
278
-{
279
-	char *res;
280
-
281
-#ifdef CONFIG_THINLTO
282
-	/* Filter out hashes from static functions */
283
-	res = strrchr(s, '$');
284
-	if (res)
285
-		*res = '\0';
286
-#endif
287
-	res = strrchr(s, '.');
288
-	if (res && !strcmp(res, ".cfi"))
289
-		*res = '\0';
290
-}
291
-#else
292
-static inline void cleanup_symbol_name(char *s) {}
293
-#endif
294296 
295297 /*
296298  * Lookup an address
....@@ -480,6 +482,7 @@
480482 	loff_t pos_arch_end;
481483 	loff_t pos_mod_end;
482484 	loff_t pos_ftrace_mod_end;
485
+	loff_t pos_bpf_end;
483486 	unsigned long value;
484487 	unsigned int nameoff; /* If iterating in core kernel symbols. */
485488 	char type;
....@@ -523,6 +526,11 @@
523526 	return 1;
524527 }
525528 
529
+/*
530
+ * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
531
+ * purposes. In that case "__builtin__ftrace" is used as a module name, even
532
+ * though "__builtin__ftrace" is not a module.
533
+ */
526534 static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
527535 {
528536 	int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
....@@ -539,11 +547,33 @@
539547 
540548 static int get_ksymbol_bpf(struct kallsym_iter *iter)
541549 {
542
-	iter->module_name[0] = '\0';
550
+	int ret;
551
+
552
+	strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
543553 	iter->exported = 0;
544
-	return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
545
-			       &iter->value, &iter->type,
546
-			       iter->name) < 0 ? 0 : 1;
554
+	ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
555
+			      &iter->value, &iter->type,
556
+			      iter->name);
557
+	if (ret < 0) {
558
+		iter->pos_bpf_end = iter->pos;
559
+		return 0;
560
+	}
561
+
562
+	return 1;
563
+}
564
+
565
+/*
566
+ * This uses "__builtin__kprobes" as a module name for symbols for pages
567
+ * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
568
+ * module.
569
+ */
570
+static int get_ksymbol_kprobe(struct kallsym_iter *iter)
571
+{
572
+	strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
573
+	iter->exported = 0;
574
+	return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
575
+				  &iter->value, &iter->type,
576
+				  iter->name) < 0 ? 0 : 1;
547577 }
548578 
549579 /* Returns space to next name. */
....@@ -570,6 +600,7 @@
570600 		iter->pos_arch_end = 0;
571601 		iter->pos_mod_end = 0;
572602 		iter->pos_ftrace_mod_end = 0;
603
+		iter->pos_bpf_end = 0;
573604 	}
574605 }
575606 
....@@ -594,7 +625,11 @@
594625 	    get_ksymbol_ftrace_mod(iter))
595626 		return 1;
596627 
597
-	return get_ksymbol_bpf(iter);
628
+	if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
629
+	    get_ksymbol_bpf(iter))
630
+		return 1;
631
+
632
+	return get_ksymbol_kprobe(iter);
598633 }
599634 
600635 /* Returns false if pos at or past end of file. */
....@@ -693,12 +728,12 @@
693728 	case 0:
694729 		if (kallsyms_for_perf())
695730 			return true;
696
-	/* fallthrough */
731
+		fallthrough;
697732 	case 1:
698733 		if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
699734 				     CAP_OPT_NOAUDIT) == 0)
700735 			return true;
701
-	/* fallthrough */
736
+		fallthrough;
702737 	default:
703738 		return false;
704739 	}
....@@ -745,16 +780,16 @@
745780 }
746781 #endif	/* CONFIG_KGDB_KDB */
747782 
748
-static const struct file_operations kallsyms_operations = {
749
-	.open = kallsyms_open,
750
-	.read = seq_read,
751
-	.llseek = seq_lseek,
752
-	.release = seq_release_private,
783
+static const struct proc_ops kallsyms_proc_ops = {
784
+	.proc_open	= kallsyms_open,
785
+	.proc_read	= seq_read,
786
+	.proc_lseek	= seq_lseek,
787
+	.proc_release	= seq_release_private,
753788 };
754789 
755790 static int __init kallsyms_init(void)
756791 {
757
-	proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
792
+	proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
758793 	return 0;
759794 }
760795 device_initcall(kallsyms_init);