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authorMasahiro Yamada <masahiroy@kernel.org>2022-05-13 14:39:22 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2022-05-24 10:33:20 +0300
commit7b4537199a4a8480b8c3ba37a2d44765ce76cd9b (patch)
tree0690afa62208ca15fd36069afcbdac85908d0676 /scripts/mod
parentf292d875d0dc700b3af0bef04c5abc1dc7b3b62c (diff)
downloadlinux-7b4537199a4a8480b8c3ba37a2d44765ce76cd9b.tar.xz
kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS
include/{linux,asm-generic}/export.h defines a weak symbol, __crc_* as a placeholder. Genksyms writes the version CRCs into the linker script, which will be used for filling the __crc_* symbols. The linker script format depends on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset to the reference of CRC. It is time to get rid of this complexity. Now that modpost parses text files (.*.cmd) to collect all the CRCs, it can generate C code that will be linked to the vmlinux or modules. Generate a new C file, .vmlinux.export.c, which contains the CRCs of symbols exported by vmlinux. It is compiled and linked to vmlinux in scripts/link-vmlinux.sh. Put the CRCs of symbols exported by modules into the existing *.mod.c files. No additional build step is needed for modules. As before, *.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal. No linker magic is used here. The new C implementation works in the same way, whether CONFIG_RELOCATABLE is enabled or not. CONFIG_MODULE_REL_CRCS is no longer needed. Previously, Kbuild invoked additional $(LD) to update the CRCs in objects, but this step is unneeded too. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Diffstat (limited to 'scripts/mod')
-rw-r--r--scripts/mod/modpost.c28
1 files changed, 24 insertions, 4 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 1e2949775e1b..42e949cbc255 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2234,6 +2234,7 @@ static void add_header(struct buffer *b, struct module *mod)
buf_printf(b, "#define INCLUDE_VERMAGIC\n");
buf_printf(b, "#include <linux/build-salt.h>\n");
buf_printf(b, "#include <linux/elfnote-lto.h>\n");
+ buf_printf(b, "#include <linux/export-internal.h>\n");
buf_printf(b, "#include <linux/vermagic.h>\n");
buf_printf(b, "#include <linux/compiler.h>\n");
buf_printf(b, "\n");
@@ -2268,20 +2269,26 @@ static void add_header(struct buffer *b, struct module *mod)
buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
}
-static void check_symversions(struct module *mod)
+static void add_exported_symbols(struct buffer *buf, struct module *mod)
{
struct symbol *sym;
if (!modversions)
return;
+ /* record CRCs for exported symbols */
+ buf_printf(buf, "\n");
list_for_each_entry(sym, &mod->exported_symbols, list) {
if (!sym->crc_valid) {
warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n"
"Is \"%s\" prototyped in <asm/asm-prototypes.h>?\n",
sym->name, mod->name, mod->is_vmlinux ? "" : ".ko",
sym->name);
+ continue;
}
+
+ buf_printf(buf, "SYMBOL_CRC(%s, 0x%08x, \"%s\");\n",
+ sym->name, sym->crc, sym->is_gpl_only ? "_gpl" : "");
}
}
@@ -2418,6 +2425,18 @@ static void write_if_changed(struct buffer *b, const char *fname)
write_buf(b, fname);
}
+static void write_vmlinux_export_c_file(struct module *mod)
+{
+ struct buffer buf = { };
+
+ buf_printf(&buf,
+ "#include <linux/export-internal.h>\n");
+
+ add_exported_symbols(&buf, mod);
+ write_if_changed(&buf, ".vmlinux.export.c");
+ free(buf.p);
+}
+
/* do sanity checks, and generate *.mod.c file */
static void write_mod_c_file(struct module *mod)
{
@@ -2429,6 +2448,7 @@ static void write_mod_c_file(struct module *mod)
check_exports(mod);
add_header(&buf, mod);
+ add_exported_symbols(&buf, mod);
add_versions(&buf, mod);
add_depends(&buf, mod);
add_moddevtable(&buf, mod);
@@ -2626,9 +2646,9 @@ int main(int argc, char **argv)
if (mod->from_dump)
continue;
- check_symversions(mod);
-
- if (!mod->is_vmlinux)
+ if (mod->is_vmlinux)
+ write_vmlinux_export_c_file(mod);
+ else
write_mod_c_file(mod);
}