Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 957 insertions, 0 deletions

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
new file mode 100644
index 000000000..18edd57b5
--- /dev/null
+++ b/kernel/kallsyms.c
@@ -0,0 +1,957 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
+ *
+ * Rewritten and vastly simplified by Rusty Russell for in-kernel
+ * module loader:
+ *   Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
+ *
+ * ChangeLog:
+ *
+ * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
+ *      Changed the compression method from stem compression to "table lookup"
+ *      compression (see scripts/kallsyms.c for a more complete description)
+ */
+#include <linux/kallsyms.h>
+#include <linux/init.h>
+#include <linux/seq_file.h>
+#include <linux/fs.h>
+#include <linux/kdb.h>
+#include <linux/err.h>
+#include <linux/proc_fs.h>
+#include <linux/sched.h>	/* for cond_resched */
+#include <linux/ctype.h>
+#include <linux/slab.h>
+#include <linux/filter.h>
+#include <linux/ftrace.h>
+#include <linux/kprobes.h>
+#include <linux/build_bug.h>
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/bsearch.h>
+#include <linux/btf_ids.h>
+
+#include "kallsyms_internal.h"
+
+/*
+ * Expand a compressed symbol data into the resulting uncompressed string,
+ * if uncompressed string is too long (>= maxlen), it will be truncated,
+ * given the offset to where the symbol is in the compressed stream.
+ */
+static unsigned int kallsyms_expand_symbol(unsigned int off,
+					   char *result, size_t maxlen)
+{
+	int len, skipped_first = 0;
+	const char *tptr;
+	const u8 *data;
+
+	/* Get the compressed symbol length from the first symbol byte. */
+	data = &kallsyms_names[off];
+	len = *data;
+	data++;
+	off++;
+
+	/* If MSB is 1, it is a "big" symbol, so needs an additional byte. */
+	if ((len & 0x80) != 0) {
+		len = (len & 0x7F) | (*data << 7);
+		data++;
+		off++;
+	}
+
+	/*
+	 * Update the offset to return the offset for the next symbol on
+	 * the compressed stream.
+	 */
+	off += len;
+
+	/*
+	 * For every byte on the compressed symbol data, copy the table
+	 * entry for that byte.
+	 */
+	while (len) {
+		tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
+		data++;
+		len--;
+
+		while (*tptr) {
+			if (skipped_first) {
+				if (maxlen <= 1)
+					goto tail;
+				*result = *tptr;
+				result++;
+				maxlen--;
+			} else
+				skipped_first = 1;
+			tptr++;
+		}
+	}
+
+tail:
+	if (maxlen)
+		*result = '\0';
+
+	/* Return to offset to the next symbol. */
+	return off;
+}
+
+/*
+ * Get symbol type information. This is encoded as a single char at the
+ * beginning of the symbol name.
+ */
+static char kallsyms_get_symbol_type(unsigned int off)
+{
+	/*
+	 * Get just the first code, look it up in the token table,
+	 * and return the first char from this token.
+	 */
+	return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
+}
+
+
+/*
+ * Find the offset on the compressed stream given and index in the
+ * kallsyms array.
+ */
+static unsigned int get_symbol_offset(unsigned long pos)
+{
+	const u8 *name;
+	int i, len;
+
+	/*
+	 * Use the closest marker we have. We have markers every 256 positions,
+	 * so that should be close enough.
+	 */
+	name = &kallsyms_names[kallsyms_markers[pos >> 8]];
+
+	/*
+	 * Sequentially scan all the symbols up to the point we're searching
+	 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
+	 * so we just need to add the len to the current pointer for every
+	 * symbol we wish to skip.
+	 */
+	for (i = 0; i < (pos & 0xFF); i++) {
+		len = *name;
+
+		/*
+		 * If MSB is 1, it is a "big" symbol, so we need to look into
+		 * the next byte (and skip it, too).
+		 */
+		if ((len & 0x80) != 0)
+			len = ((len & 0x7F) | (name[1] << 7)) + 1;
+
+		name = name + len + 1;
+	}
+
+	return name - kallsyms_names;
+}
+
+unsigned long kallsyms_sym_address(int idx)
+{
+	if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
+		return kallsyms_addresses[idx];
+
+	/* values are unsigned offsets if --absolute-percpu is not in effect */
+	if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
+		return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
+
+	/* ...otherwise, positive offsets are absolute values */
+	if (kallsyms_offsets[idx] >= 0)
+		return kallsyms_offsets[idx];
+
+	/* ...and negative offsets are relative to kallsyms_relative_base - 1 */
+	return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
+}
+
+static void cleanup_symbol_name(char *s)
+{
+	char *res;
+
+	if (!IS_ENABLED(CONFIG_LTO_CLANG))
+		return;
+
+	/*
+	 * LLVM appends various suffixes for local functions and variables that
+	 * must be promoted to global scope as part of LTO.  This can break
+	 * hooking of static functions with kprobes. '.' is not a valid
+	 * character in an identifier in C. Suffixes only in LLVM LTO observed:
+	 * - foo.llvm.[0-9a-f]+
+	 */
+	res = strstr(s, ".llvm.");
+	if (res)
+		*res = '\0';
+
+	return;
+}
+
+static int compare_symbol_name(const char *name, char *namebuf)
+{
+	/* The kallsyms_seqs_of_names is sorted based on names after
+	 * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled.
+	 * To ensure correct bisection in kallsyms_lookup_names(), do
+	 * cleanup_symbol_name(namebuf) before comparing name and namebuf.
+	 */
+	cleanup_symbol_name(namebuf);
+	return strcmp(name, namebuf);
+}
+
+static unsigned int get_symbol_seq(int index)
+{
+	unsigned int i, seq = 0;
+
+	for (i = 0; i < 3; i++)
+		seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i];
+
+	return seq;
+}
+
+static int kallsyms_lookup_names(const char *name,
+				 unsigned int *start,
+				 unsigned int *end)
+{
+	int ret;
+	int low, mid, high;
+	unsigned int seq, off;
+	char namebuf[KSYM_NAME_LEN];
+
+	low = 0;
+	high = kallsyms_num_syms - 1;
+
+	while (low <= high) {
+		mid = low + (high - low) / 2;
+		seq = get_symbol_seq(mid);
+		off = get_symbol_offset(seq);
+		kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
+		ret = compare_symbol_name(name, namebuf);
+		if (ret > 0)
+			low = mid + 1;
+		else if (ret < 0)
+			high = mid - 1;
+		else
+			break;
+	}
+
+	if (low > high)
+		return -ESRCH;
+
+	low = mid;
+	while (low) {
+		seq = get_symbol_seq(low - 1);
+		off = get_symbol_offset(seq);
+		kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
+		if (compare_symbol_name(name, namebuf))
+			break;
+		low--;
+	}
+	*start = low;
+
+	if (end) {
+		high = mid;
+		while (high < kallsyms_num_syms - 1) {
+			seq = get_symbol_seq(high + 1);
+			off = get_symbol_offset(seq);
+			kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
+			if (compare_symbol_name(name, namebuf))
+				break;
+			high++;
+		}
+		*end = high;
+	}
+
+	return 0;
+}
+
+/* Lookup the address for this symbol. Returns 0 if not found. */
+unsigned long kallsyms_lookup_name(const char *name)
+{
+	int ret;
+	unsigned int i;
+
+	/* Skip the search for empty string. */
+	if (!*name)
+		return 0;
+
+	ret = kallsyms_lookup_names(name, &i, NULL);
+	if (!ret)
+		return kallsyms_sym_address(get_symbol_seq(i));
+
+	return module_kallsyms_lookup_name(name);
+}
+
+/*
+ * Iterate over all symbols in vmlinux.  For symbols from modules use
+ * module_kallsyms_on_each_symbol instead.
+ */
+int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long),
+			    void *data)
+{
+	char namebuf[KSYM_NAME_LEN];
+	unsigned long i;
+	unsigned int off;
+	int ret;
+
+	for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
+		off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
+		ret = fn(data, namebuf, kallsyms_sym_address(i));
+		if (ret != 0)
+			return ret;
+		cond_resched();
+	}
+	return 0;
+}
+
+int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long),
+				  const char *name, void *data)
+{
+	int ret;
+	unsigned int i, start, end;
+
+	ret = kallsyms_lookup_names(name, &start, &end);
+	if (ret)
+		return 0;
+
+	for (i = start; !ret && i <= end; i++) {
+		ret = fn(data, kallsyms_sym_address(get_symbol_seq(i)));
+		cond_resched();
+	}
+
+	return ret;
+}
+
+static unsigned long get_symbol_pos(unsigned long addr,
+				    unsigned long *symbolsize,
+				    unsigned long *offset)
+{
+	unsigned long symbol_start = 0, symbol_end = 0;
+	unsigned long i, low, high, mid;
+
+	/* This kernel should never had been booted. */
+	if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
+		BUG_ON(!kallsyms_addresses);
+	else
+		BUG_ON(!kallsyms_offsets);
+
+	/* Do a binary search on the sorted kallsyms_addresses array. */
+	low = 0;
+	high = kallsyms_num_syms;
+
+	while (high - low > 1) {
+		mid = low + (high - low) / 2;
+		if (kallsyms_sym_address(mid) <= addr)
+			low = mid;
+		else
+			high = mid;
+	}
+
+	/*
+	 * Search for the first aliased symbol. Aliased
+	 * symbols are symbols with the same address.
+	 */
+	while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
+		--low;
+
+	symbol_start = kallsyms_sym_address(low);
+
+	/* Search for next non-aliased symbol. */
+	for (i = low + 1; i < kallsyms_num_syms; i++) {
+		if (kallsyms_sym_address(i) > symbol_start) {
+			symbol_end = kallsyms_sym_address(i);
+			break;
+		}
+	}
+
+	/* If we found no next symbol, we use the end of the section. */
+	if (!symbol_end) {
+		if (is_kernel_inittext(addr))
+			symbol_end = (unsigned long)_einittext;
+		else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
+			symbol_end = (unsigned long)_end;
+		else
+			symbol_end = (unsigned long)_etext;
+	}
+
+	if (symbolsize)
+		*symbolsize = symbol_end - symbol_start;
+	if (offset)
+		*offset = addr - symbol_start;
+
+	return low;
+}
+
+/*
+ * Lookup an address but don't bother to find any names.
+ */
+int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
+				unsigned long *offset)
+{
+	char namebuf[KSYM_NAME_LEN];
+
+	if (is_ksym_addr(addr)) {
+		get_symbol_pos(addr, symbolsize, offset);
+		return 1;
+	}
+	return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
+	       !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
+}
+
+static const char *kallsyms_lookup_buildid(unsigned long addr,
+			unsigned long *symbolsize,
+			unsigned long *offset, char **modname,
+			const unsigned char **modbuildid, char *namebuf)
+{
+	const char *ret;
+
+	namebuf[KSYM_NAME_LEN - 1] = 0;
+	namebuf[0] = 0;
+
+	if (is_ksym_addr(addr)) {
+		unsigned long pos;
+
+		pos = get_symbol_pos(addr, symbolsize, offset);
+		/* Grab name */
+		kallsyms_expand_symbol(get_symbol_offset(pos),
+				       namebuf, KSYM_NAME_LEN);
+		if (modname)
+			*modname = NULL;
+		if (modbuildid)
+			*modbuildid = NULL;
+
+		ret = namebuf;
+		goto found;
+	}
+
+	/* See if it's in a module or a BPF JITed image. */
+	ret = module_address_lookup(addr, symbolsize, offset,
+				    modname, modbuildid, namebuf);
+	if (!ret)
+		ret = bpf_address_lookup(addr, symbolsize,
+					 offset, modname, namebuf);
+
+	if (!ret)
+		ret = ftrace_mod_address_lookup(addr, symbolsize,
+						offset, modname, namebuf);
+
+found:
+	cleanup_symbol_name(namebuf);
+	return ret;
+}
+
+/*
+ * Lookup an address
+ * - modname is set to NULL if it's in the kernel.
+ * - We guarantee that the returned name is valid until we reschedule even if.
+ *   It resides in a module.
+ * - We also guarantee that modname will be valid until rescheduled.
+ */
+const char *kallsyms_lookup(unsigned long addr,
+			    unsigned long *symbolsize,
+			    unsigned long *offset,
+			    char **modname, char *namebuf)
+{
+	return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
+				       NULL, namebuf);
+}
+
+int lookup_symbol_name(unsigned long addr, char *symname)
+{
+	int res;
+
+	symname[0] = '\0';
+	symname[KSYM_NAME_LEN - 1] = '\0';
+
+	if (is_ksym_addr(addr)) {
+		unsigned long pos;
+
+		pos = get_symbol_pos(addr, NULL, NULL);
+		/* Grab name */
+		kallsyms_expand_symbol(get_symbol_offset(pos),
+				       symname, KSYM_NAME_LEN);
+		goto found;
+	}
+	/* See if it's in a module. */
+	res = lookup_module_symbol_name(addr, symname);
+	if (res)
+		return res;
+
+found:
+	cleanup_symbol_name(symname);
+	return 0;
+}
+
+/* Look up a kernel symbol and return it in a text buffer. */
+static int __sprint_symbol(char *buffer, unsigned long address,
+			   int symbol_offset, int add_offset, int add_buildid)
+{
+	char *modname;
+	const unsigned char *buildid;
+	const char *name;
+	unsigned long offset, size;
+	int len;
+
+	address += symbol_offset;
+	name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
+				       buffer);
+	if (!name)
+		return sprintf(buffer, "0x%lx", address - symbol_offset);
+
+	if (name != buffer)
+		strcpy(buffer, name);
+	len = strlen(buffer);
+	offset -= symbol_offset;
+
+	if (add_offset)
+		len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
+
+	if (modname) {
+		len += sprintf(buffer + len, " [%s", modname);
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+		if (add_buildid && buildid) {
+			/* build ID should match length of sprintf */
+#if IS_ENABLED(CONFIG_MODULES)
+			static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
+#endif
+			len += sprintf(buffer + len, " %20phN", buildid);
+		}
+#endif
+		len += sprintf(buffer + len, "]");
+	}
+
+	return len;
+}
+
+/**
+ * sprint_symbol - Look up a kernel symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function looks up a kernel symbol with @address and stores its name,
+ * offset, size and module name to @buffer if possible. If no symbol was found,
+ * just saves its @address as is.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_symbol(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, 0, 1, 0);
+}
+EXPORT_SYMBOL_GPL(sprint_symbol);
+
+/**
+ * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function looks up a kernel symbol with @address and stores its name,
+ * offset, size, module name and module build ID to @buffer if possible. If no
+ * symbol was found, just saves its @address as is.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_symbol_build_id(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, 0, 1, 1);
+}
+EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
+
+/**
+ * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function looks up a kernel symbol with @address and stores its name
+ * and module name to @buffer if possible. If no symbol was found, just saves
+ * its @address as is.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_symbol_no_offset(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, 0, 0, 0);
+}
+EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
+
+/**
+ * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function is for stack backtrace and does the same thing as
+ * sprint_symbol() but with modified/decreased @address. If there is a
+ * tail-call to the function marked "noreturn", gcc optimized out code after
+ * the call so that the stack-saved return address could point outside of the
+ * caller. This function ensures that kallsyms will find the original caller
+ * by decreasing @address.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_backtrace(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, -1, 1, 0);
+}
+
+/**
+ * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function is for stack backtrace and does the same thing as
+ * sprint_symbol() but with modified/decreased @address. If there is a
+ * tail-call to the function marked "noreturn", gcc optimized out code after
+ * the call so that the stack-saved return address could point outside of the
+ * caller. This function ensures that kallsyms will find the original caller
+ * by decreasing @address. This function also appends the module build ID to
+ * the @buffer if @address is within a kernel module.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_backtrace_build_id(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, -1, 1, 1);
+}
+
+/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
+struct kallsym_iter {
+	loff_t pos;
+	loff_t pos_mod_end;
+	loff_t pos_ftrace_mod_end;
+	loff_t pos_bpf_end;
+	unsigned long value;
+	unsigned int nameoff; /* If iterating in core kernel symbols. */
+	char type;
+	char name[KSYM_NAME_LEN];
+	char module_name[MODULE_NAME_LEN];
+	int exported;
+	int show_value;
+};
+
+static int get_ksymbol_mod(struct kallsym_iter *iter)
+{
+	int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,
+				     &iter->value, &iter->type,
+				     iter->name, iter->module_name,
+				     &iter->exported);
+	if (ret < 0) {
+		iter->pos_mod_end = iter->pos;
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
+ * purposes. In that case "__builtin__ftrace" is used as a module name, even
+ * though "__builtin__ftrace" is not a module.
+ */
+static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
+{
+	int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
+					 &iter->value, &iter->type,
+					 iter->name, iter->module_name,
+					 &iter->exported);
+	if (ret < 0) {
+		iter->pos_ftrace_mod_end = iter->pos;
+		return 0;
+	}
+
+	return 1;
+}
+
+static int get_ksymbol_bpf(struct kallsym_iter *iter)
+{
+	int ret;
+
+	strscpy(iter->module_name, "bpf", MODULE_NAME_LEN);
+	iter->exported = 0;
+	ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
+			      &iter->value, &iter->type,
+			      iter->name);
+	if (ret < 0) {
+		iter->pos_bpf_end = iter->pos;
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * This uses "__builtin__kprobes" as a module name for symbols for pages
+ * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
+ * module.
+ */
+static int get_ksymbol_kprobe(struct kallsym_iter *iter)
+{
+	strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
+	iter->exported = 0;
+	return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
+				  &iter->value, &iter->type,
+				  iter->name) < 0 ? 0 : 1;
+}
+
+/* Returns space to next name. */
+static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
+{
+	unsigned off = iter->nameoff;
+
+	iter->module_name[0] = '\0';
+	iter->value = kallsyms_sym_address(iter->pos);
+
+	iter->type = kallsyms_get_symbol_type(off);
+
+	off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
+
+	return off - iter->nameoff;
+}
+
+static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
+{
+	iter->name[0] = '\0';
+	iter->nameoff = get_symbol_offset(new_pos);
+	iter->pos = new_pos;
+	if (new_pos == 0) {
+		iter->pos_mod_end = 0;
+		iter->pos_ftrace_mod_end = 0;
+		iter->pos_bpf_end = 0;
+	}
+}
+
+/*
+ * The end position (last + 1) of each additional kallsyms section is recorded
+ * in iter->pos_..._end as each section is added, and so can be used to
+ * determine which get_ksymbol_...() function to call next.
+ */
+static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
+{
+	iter->pos = pos;
+
+	if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
+	    get_ksymbol_mod(iter))
+		return 1;
+
+	if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
+	    get_ksymbol_ftrace_mod(iter))
+		return 1;
+
+	if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
+	    get_ksymbol_bpf(iter))
+		return 1;
+
+	return get_ksymbol_kprobe(iter);
+}
+
+/* Returns false if pos at or past end of file. */
+static int update_iter(struct kallsym_iter *iter, loff_t pos)
+{
+	/* Module symbols can be accessed randomly. */
+	if (pos >= kallsyms_num_syms)
+		return update_iter_mod(iter, pos);
+
+	/* If we're not on the desired position, reset to new position. */
+	if (pos != iter->pos)
+		reset_iter(iter, pos);
+
+	iter->nameoff += get_ksymbol_core(iter);
+	iter->pos++;
+
+	return 1;
+}
+
+static void *s_next(struct seq_file *m, void *p, loff_t *pos)
+{
+	(*pos)++;
+
+	if (!update_iter(m->private, *pos))
+		return NULL;
+	return p;
+}
+
+static void *s_start(struct seq_file *m, loff_t *pos)
+{
+	if (!update_iter(m->private, *pos))
+		return NULL;
+	return m->private;
+}
+
+static void s_stop(struct seq_file *m, void *p)
+{
+}
+
+static int s_show(struct seq_file *m, void *p)
+{
+	void *value;
+	struct kallsym_iter *iter = m->private;
+
+	/* Some debugging symbols have no name.  Ignore them. */
+	if (!iter->name[0])
+		return 0;
+
+	value = iter->show_value ? (void *)iter->value : NULL;
+
+	if (iter->module_name[0]) {
+		char type;
+
+		/*
+		 * Label it "global" if it is exported,
+		 * "local" if not exported.
+		 */
+		type = iter->exported ? toupper(iter->type) :
+					tolower(iter->type);
+		seq_printf(m, "%px %c %s\t[%s]\n", value,
+			   type, iter->name, iter->module_name);
+	} else
+		seq_printf(m, "%px %c %s\n", value,
+			   iter->type, iter->name);
+	return 0;
+}
+
+static const struct seq_operations kallsyms_op = {
+	.start = s_start,
+	.next = s_next,
+	.stop = s_stop,
+	.show = s_show
+};
+
+#ifdef CONFIG_BPF_SYSCALL
+
+struct bpf_iter__ksym {
+	__bpf_md_ptr(struct bpf_iter_meta *, meta);
+	__bpf_md_ptr(struct kallsym_iter *, ksym);
+};
+
+static int ksym_prog_seq_show(struct seq_file *m, bool in_stop)
+{
+	struct bpf_iter__ksym ctx;
+	struct bpf_iter_meta meta;
+	struct bpf_prog *prog;
+
+	meta.seq = m;
+	prog = bpf_iter_get_info(&meta, in_stop);
+	if (!prog)
+		return 0;
+
+	ctx.meta = &meta;
+	ctx.ksym = m ? m->private : NULL;
+	return bpf_iter_run_prog(prog, &ctx);
+}
+
+static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p)
+{
+	return ksym_prog_seq_show(m, false);
+}
+
+static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p)
+{
+	if (!p)
+		(void) ksym_prog_seq_show(m, true);
+	else
+		s_stop(m, p);
+}
+
+static const struct seq_operations bpf_iter_ksym_ops = {
+	.start = s_start,
+	.next = s_next,
+	.stop = bpf_iter_ksym_seq_stop,
+	.show = bpf_iter_ksym_seq_show,
+};
+
+static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux)
+{
+	struct kallsym_iter *iter = priv_data;
+
+	reset_iter(iter, 0);
+
+	/* cache here as in kallsyms_open() case; use current process
+	 * credentials to tell BPF iterators if values should be shown.
+	 */
+	iter->show_value = kallsyms_show_value(current_cred());
+
+	return 0;
+}
+
+DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym)
+
+static const struct bpf_iter_seq_info ksym_iter_seq_info = {
+	.seq_ops		= &bpf_iter_ksym_ops,
+	.init_seq_private	= bpf_iter_ksym_init,
+	.fini_seq_private	= NULL,
+	.seq_priv_size		= sizeof(struct kallsym_iter),
+};
+
+static struct bpf_iter_reg ksym_iter_reg_info = {
+	.target                 = "ksym",
+	.feature		= BPF_ITER_RESCHED,
+	.ctx_arg_info_size	= 1,
+	.ctx_arg_info		= {
+		{ offsetof(struct bpf_iter__ksym, ksym),
+		  PTR_TO_BTF_ID_OR_NULL },
+	},
+	.seq_info		= &ksym_iter_seq_info,
+};
+
+BTF_ID_LIST(btf_ksym_iter_id)
+BTF_ID(struct, kallsym_iter)
+
+static int __init bpf_ksym_iter_register(void)
+{
+	ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
+	return bpf_iter_reg_target(&ksym_iter_reg_info);
+}
+
+late_initcall(bpf_ksym_iter_register);
+
+#endif /* CONFIG_BPF_SYSCALL */
+
+static int kallsyms_open(struct inode *inode, struct file *file)
+{
+	/*
+	 * We keep iterator in m->private, since normal case is to
+	 * s_start from where we left off, so we avoid doing
+	 * using get_symbol_offset for every symbol.
+	 */
+	struct kallsym_iter *iter;
+	iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
+	if (!iter)
+		return -ENOMEM;
+	reset_iter(iter, 0);
+
+	/*
+	 * Instead of checking this on every s_show() call, cache
+	 * the result here at open time.
+	 */
+	iter->show_value = kallsyms_show_value(file->f_cred);
+	return 0;
+}
+
+#ifdef	CONFIG_KGDB_KDB
+const char *kdb_walk_kallsyms(loff_t *pos)
+{
+	static struct kallsym_iter kdb_walk_kallsyms_iter;
+	if (*pos == 0) {
+		memset(&kdb_walk_kallsyms_iter, 0,
+		       sizeof(kdb_walk_kallsyms_iter));
+		reset_iter(&kdb_walk_kallsyms_iter, 0);
+	}
+	while (1) {
+		if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
+			return NULL;
+		++*pos;
+		/* Some debugging symbols have no name.  Ignore them. */
+		if (kdb_walk_kallsyms_iter.name[0])
+			return kdb_walk_kallsyms_iter.name;
+	}
+}
+#endif	/* CONFIG_KGDB_KDB */
+
+static const struct proc_ops kallsyms_proc_ops = {
+	.proc_open	= kallsyms_open,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= seq_release_private,
+};
+
+static int __init kallsyms_init(void)
+{
+	proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
+	return 0;
+}
+device_initcall(kallsyms_init);