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kbuild: modpost warn if export version crc is missing

RFC PATCH New Nicholas Piggin 1 participant 1 message Aug 26, 2016 Kbuild

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RFC PATCH 1/1 kbuild: modpost warn if export version crc is missing

This catches the failing ceph CRC on with:

LD vmlinux.o
MODPOST vmlinux.o
WARNING: EXPORT symbol "ceph_monc_do_statfs" [vmlinux] version generation failed, symbol will not be versioned.

When the modules referring to exported symbols are built, there is an existing warning for missing CRC, but it's not always the case such any such module will be built, and in any case it is useful to get a warning at the source.

This gets a little verbose with CONFIG_DEBUG_SECTION_MISMATCH, producing a warning with each object linked, but I didn't think that warranted extra complexity to avoid.

---
 scripts/mod/modpost.c | 6 ++++++
 1 file changed, 6 insertions(+)
scripts/mod/modpost.c +6 -0
index 4b8ffd3..ea87cb3 100644
@@ -609,6 +609,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
 {
 	unsigned int crc;
 	enum export export;
+	bool is_crc = false;
 
 	if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
 	    strncmp(symname, "__ksymtab", 9) == 0)
@@ -618,6 +619,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
 
 	/* CRC'd symbol */
 	if (strncmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
+		is_crc = true;
 		crc = (unsigned int) sym->st_value;
 		sym_update_crc(symname + strlen(CRC_PFX), mod, crc,
 				export);
@@ -663,6 +665,10 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
 		else
 			symname++;
 #endif
+		if (is_crc) {
+			const char *e = is_vmlinux(mod->name) ?"":".ko";
+			warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n", symname + strlen(CRC_PFX), mod->name, e);
+		}
 		mod->unres = alloc_symbol(symname,
 					  ELF_ST_BIND(sym->st_info) == STB_WEAK,
 					  mod->unres);
Signature · 1 line
2.9.3