[PATCH 3/4] symbol namespaces: revert to previous __ksymtab name scheme
From: Matthias Maennich
Date: Thu Oct 10 2019 - 11:16:14 EST
The introduction Symbol Namespaces changed the naming schema of the
__ksymtab entries from __kysmtab__symbol to __ksymtab_NAMESPACE.symbol.
That caused some breakages in tools that depend on the name layout in
either the binaries(vmlinux,*.ko) or in System.map. E.g. kmod's depmod
would not be able to read System.map without a patch to support symbol
namespaces. A warning reported by depmod for namespaced symbols would
look like
depmod: WARNING: [...]/uas.ko needs unknown symbol usb_stor_adjust_quirks
In order to address this issue, revert to the original naming scheme and
rather read the __kstrtabns_<symbol> entries and their corresponding
values from __ksymtab_strings to update the namespace values for
symbols. After having read all symbols and handled them in
handle_modversions(), the symbols are created. In a second pass, read
the __kstrtabns_ entries and update the namespaces accordingly.
Suggested-by: Jessica Yu <jeyu@xxxxxxxxxx>
Fixes: 8651ec01daed ("module: add support for symbol namespaces.")
Signed-off-by: Matthias Maennich <maennich@xxxxxxxxxx>
---
include/linux/export.h | 13 +++++--------
scripts/mod/modpost.c | 33 ++++++++++++++++++---------------
scripts/mod/modpost.h | 1 +
3 files changed, 24 insertions(+), 23 deletions(-)
diff --git a/include/linux/export.h b/include/linux/export.h
index 621158ecd2e2..f24b86d7dd4d 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -18,8 +18,6 @@ extern struct module __this_module;
#define THIS_MODULE ((struct module *)0)
#endif
-#define NS_SEPARATOR "."
-
#ifdef CONFIG_MODVERSIONS
/* Mark the CRC weak since genksyms apparently decides not to
* generate a checksums for some symbols */
@@ -48,11 +46,11 @@ extern struct module __this_module;
* absolute relocations that require runtime processing on relocatable
* kernels.
*/
-#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \
+#define __KSYMTAB_ENTRY_NS(sym, sec) \
__ADDRESSABLE(sym) \
asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
" .balign 4 \n" \
- "__ksymtab_" #ns NS_SEPARATOR #sym ": \n" \
+ "__ksymtab_" #sym ": \n" \
" .long " #sym "- . \n" \
" .long __kstrtab_" #sym "- . \n" \
" .long __kstrtabns_" #sym "- . \n" \
@@ -74,9 +72,8 @@ struct kernel_symbol {
int namespace_offset;
};
#else
-#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \
- static const struct kernel_symbol __ksymtab_##sym##__##ns \
- asm("__ksymtab_" #ns NS_SEPARATOR #sym) \
+#define __KSYMTAB_ENTRY_NS(sym, sec) \
+ static const struct kernel_symbol __ksymtab_##sym \
__attribute__((section("___ksymtab" sec "+" #sym), used)) \
__aligned(sizeof(void *)) \
= { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym }
@@ -115,7 +112,7 @@ struct kernel_symbol {
static const char __kstrtabns_##sym[] \
__attribute__((section("__ksymtab_strings"), used, aligned(1))) \
= #ns; \
- __KSYMTAB_ENTRY_NS(sym, sec, ns)
+ __KSYMTAB_ENTRY_NS(sym, sec)
#define ___EXPORT_SYMBOL(sym, sec) \
___export_symbol_common(sym, sec); \
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 46137b730447..7cf0065ac95f 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -348,18 +348,11 @@ static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
return export_unknown;
}
-static char *sym_extract_namespace(const char **symname)
+static const char *namespace_from_kstrtabns(struct elf_info *info,
+ Elf_Sym *kstrtabns)
{
- char *namespace = NULL;
- char *ns_separator;
-
- ns_separator = strchr(*symname, '.');
- if (ns_separator) {
- namespace = NOFAIL(strndup(*symname, ns_separator - *symname));
- *symname = ns_separator + 1;
- }
-
- return namespace;
+ char *value = info->ksymtab_strings + kstrtabns->st_value;
+ return value[0] ? value : NULL;
}
static void sym_update_namespace(const char *symname, const char *namespace)
@@ -597,6 +590,10 @@ static int parse_elf(struct elf_info *info, const char *filename)
info->export_unused_gpl_sec = i;
else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
info->export_gpl_future_sec = i;
+ else if (strcmp(secname, "__ksymtab_strings") == 0)
+ info->ksymtab_strings = (void *)hdr +
+ sechdrs[i].sh_offset -
+ sechdrs[i].sh_addr;
if (sechdrs[i].sh_type == SHT_SYMTAB) {
unsigned int sh_link_idx;
@@ -686,7 +683,6 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
enum export export;
bool is_crc = false;
const char *name;
- char *namespace;
if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
strstarts(symname, "__ksymtab"))
@@ -759,10 +755,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
/* All exported symbols */
if (strstarts(symname, "__ksymtab_")) {
name = symname + strlen("__ksymtab_");
- namespace = sym_extract_namespace(&name);
sym_add_exported(name, mod, export);
- sym_update_namespace(name, namespace);
- free(namespace);
}
if (strcmp(symname, "init_module") == 0)
mod->has_init = 1;
@@ -2058,6 +2051,16 @@ static void read_symbols(const char *modname)
handle_moddevtable(mod, &info, sym, symname);
}
+ /* Apply symbol namespaces from __kstrtabns_<symbol> entries. */
+ for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
+ symname = remove_dot(info.strtab + sym->st_name);
+
+ if (strstarts(symname, "__kstrtabns_"))
+ sym_update_namespace(symname + strlen("__kstrtabns_"),
+ namespace_from_kstrtabns(&info,
+ sym));
+ }
+
// check for static EXPORT_SYMBOL_* functions && global vars
for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
unsigned char bind = ELF_ST_BIND(sym->st_info);
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 92a926d375d2..ad271bc6c313 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -143,6 +143,7 @@ struct elf_info {
Elf_Section export_gpl_sec;
Elf_Section export_unused_gpl_sec;
Elf_Section export_gpl_future_sec;
+ char *ksymtab_strings;
char *strtab;
char *modinfo;
unsigned int modinfo_len;
--
2.23.0.581.g78d2f28ef7-goog