v4.19.13 snapshot.
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
new file mode 100644
index 0000000..02a0b01
--- /dev/null
+++ b/kernel/kallsyms.c
@@ -0,0 +1,710 @@
+/*
+ * 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/compiler.h>
+
+/*
+ * These will be re-linked against their real values
+ * during the second link stage.
+ */
+extern const unsigned long kallsyms_addresses[] __weak;
+extern const int kallsyms_offsets[] __weak;
+extern const u8 kallsyms_names[] __weak;
+
+/*
+ * Tell the compiler that the count isn't in the small data section if the arch
+ * has one (eg: FRV).
+ */
+extern const unsigned long kallsyms_num_syms
+__attribute__((weak, section(".rodata")));
+
+extern const unsigned long kallsyms_relative_base
+__attribute__((weak, section(".rodata")));
+
+extern const u8 kallsyms_token_table[] __weak;
+extern const u16 kallsyms_token_index[] __weak;
+
+extern const unsigned long kallsyms_markers[] __weak;
+
+/*
+ * 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 u8 *tptr, *data;
+
+ /* Get the compressed symbol length from the first symbol byte. */
+ data = &kallsyms_names[off];
+ len = *data;
+ data++;
+
+ /*
+ * Update the offset to return the offset for the next symbol on
+ * the compressed stream.
+ */
+ off += len + 1;
+
+ /*
+ * 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;
+
+ /*
+ * 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++)
+ name = name + (*name) + 1;
+
+ return name - kallsyms_names;
+}
+
+static 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];
+}
+
+/* Lookup the address for this symbol. Returns 0 if not found. */
+unsigned long kallsyms_lookup_name(const char *name)
+{
+ char namebuf[KSYM_NAME_LEN];
+ unsigned long i;
+ unsigned int off;
+
+ for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
+ off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
+
+ if (strcmp(namebuf, name) == 0)
+ return kallsyms_sym_address(i);
+ }
+ return module_kallsyms_lookup_name(name);
+}
+EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
+
+int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
+ 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, NULL, kallsyms_sym_address(i));
+ if (ret != 0)
+ return ret;
+ }
+ return module_kallsyms_on_each_symbol(fn, data);
+}
+EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
+
+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))
+ return !!get_symbol_pos(addr, symbolsize, offset);
+ return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) ||
+ !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
+}
+
+/*
+ * 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)
+{
+ 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;
+ return namebuf;
+ }
+
+ /* See if it's in a module or a BPF JITed image. */
+ ret = module_address_lookup(addr, symbolsize, offset,
+ modname, namebuf);
+ if (!ret)
+ ret = bpf_address_lookup(addr, symbolsize,
+ offset, modname, namebuf);
+
+ if (!ret)
+ ret = ftrace_mod_address_lookup(addr, symbolsize,
+ offset, modname, namebuf);
+ return ret;
+}
+
+int lookup_symbol_name(unsigned long addr, char *symname)
+{
+ 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);
+ return 0;
+ }
+ /* See if it's in a module. */
+ return lookup_module_symbol_name(addr, symname);
+}
+
+int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
+ unsigned long *offset, char *modname, char *name)
+{
+ name[0] = '\0';
+ name[KSYM_NAME_LEN - 1] = '\0';
+
+ if (is_ksym_addr(addr)) {
+ unsigned long pos;
+
+ pos = get_symbol_pos(addr, size, offset);
+ /* Grab name */
+ kallsyms_expand_symbol(get_symbol_offset(pos),
+ name, KSYM_NAME_LEN);
+ modname[0] = '\0';
+ return 0;
+ }
+ /* See if it's in a module. */
+ return lookup_module_symbol_attrs(addr, size, offset, modname, name);
+}
+
+/* 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)
+{
+ char *modname;
+ const char *name;
+ unsigned long offset, size;
+ int len;
+
+ address += symbol_offset;
+ name = kallsyms_lookup(address, &size, &offset, &modname, 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);
+
+ 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);
+}
+EXPORT_SYMBOL_GPL(sprint_symbol);
+
+/**
+ * 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);
+}
+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);
+}
+
+/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
+struct kallsym_iter {
+ loff_t pos;
+ loff_t pos_arch_end;
+ loff_t pos_mod_end;
+ loff_t pos_ftrace_mod_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;
+};
+
+int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
+ char *type, char *name)
+{
+ return -EINVAL;
+}
+
+static int get_ksymbol_arch(struct kallsym_iter *iter)
+{
+ int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
+ &iter->value, &iter->type,
+ iter->name);
+
+ if (ret < 0) {
+ iter->pos_arch_end = iter->pos;
+ return 0;
+ }
+
+ return 1;
+}
+
+static int get_ksymbol_mod(struct kallsym_iter *iter)
+{
+ int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
+ &iter->value, &iter->type,
+ iter->name, iter->module_name,
+ &iter->exported);
+ if (ret < 0) {
+ iter->pos_mod_end = iter->pos;
+ return 0;
+ }
+
+ return 1;
+}
+
+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)
+{
+ iter->module_name[0] = '\0';
+ iter->exported = 0;
+ return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_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_arch_end = 0;
+ iter->pos_mod_end = 0;
+ iter->pos_ftrace_mod_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_arch_end || iter->pos_arch_end > pos) &&
+ get_ksymbol_arch(iter))
+ return 1;
+
+ 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;
+
+ return get_ksymbol_bpf(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
+};
+
+static inline int kallsyms_for_perf(void)
+{
+#ifdef CONFIG_PERF_EVENTS
+ extern int sysctl_perf_event_paranoid;
+ if (sysctl_perf_event_paranoid <= 1)
+ return 1;
+#endif
+ return 0;
+}
+
+/*
+ * We show kallsyms information even to normal users if we've enabled
+ * kernel profiling and are explicitly not paranoid (so kptr_restrict
+ * is clear, and sysctl_perf_event_paranoid isn't set).
+ *
+ * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
+ * block even that).
+ */
+int kallsyms_show_value(void)
+{
+ switch (kptr_restrict) {
+ case 0:
+ if (kallsyms_for_perf())
+ return 1;
+ /* fallthrough */
+ case 1:
+ if (has_capability_noaudit(current, CAP_SYSLOG))
+ return 1;
+ /* fallthrough */
+ default:
+ return 0;
+ }
+}
+
+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);
+
+ iter->show_value = kallsyms_show_value();
+ 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 file_operations kallsyms_operations = {
+ .open = kallsyms_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release_private,
+};
+
+static int __init kallsyms_init(void)
+{
+ proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
+ return 0;
+}
+device_initcall(kallsyms_init);