Hi Keith.
While doing some other modpost.c changes I thought about the
possibility to do the reference_init check during the modpost stage - so
it is done early and author can catch warning when he made the error.
Attached is first cut.
It does a much more lousy job than reference_init because it identifies
the module and not the .o file. I hope to later identify the function
where the illegal reference hapens.
I have only run it on a subset of the kernel and it found a few
warnings in ide-core.o + one warning in net/drivers/drgs.o.
I have not investigated if this is false positives yet.
make allmodconfig running in background - will check the result when I
wake up again.
Sam
modpost.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
modpost.h | 6 ++++
2 files changed, 97 insertions(+), 1 deletion(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index d901095..b41ae4f 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -451,6 +451,96 @@ static char *get_modinfo(void *modinfo,
return NULL;
}
+/**
+ * Is this section a true init section?
+ **/
+static int is_init_section(const char *name)
+{
+ if (strcmp(name, ".init") == 0)
+ return 1;
+ if (strncmp(name, ".init.", strlen(".init.")) == 0)
+ return 1;
+ return 0;
+}
+
+/**
+ * Check name - identify sections which is discarded by vmlinux
+ * after module is loaded. Here we are fine referencing __init.
+ **/
+static int is_ref_init_ok(const char *name)
+{
+ const char **s;
+ /* Absolute section names */
+ const char *namelist1[] = {
+ ".init",
+ ".stab",
+ ".rodata",
+ ".text.lock",
+ ".pci_fixup_header",
+ ".pci_fixup_final",
+ ".pdr",
+ "__param",
+ NULL
+ };
+ /* Start of section names */
+ const char *namelist2[] = {
+ ".init.",
+ ".altinstructions",
+ ".eh_frame",
+ ".debug",
+ NULL
+ };
+
+ for (s = namelist1; *s; s++)
+ if (strcmp(*s, name) == 0)
+ return 1;
+ for (s = namelist2; *s; s++)
+ if (strncmp(*s, name, strlen(*s)) == 0)
+ return 1;
+ return 0;
+}
+
+/**
+ * Walk through all sections.
+ * All sections with references to a section identified as "init"
+ * needs to be int too - otherwise we have a reference to code marked
+ * __init and which is discarded by vmlinux
+ **/
+static void handle_checkinitref(struct module *mod, const char *modname, struct elf_info *elf)
+{
+ int i;
+ Elf_Sym *sym;
+ Elf_Ehdr *hdr = elf->hdr;
+ Elf_Shdr *sechdrs = elf->sechdrs;
+ const char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+ /* Walk through all sections */
+ for (i = 0; i < hdr->e_shnum; i++) {
+ const char *name = secstrings + sechdrs[i].sh_name + strlen(".rela");
+ /* We want to process only relocation sections and not .init */
+ if (is_ref_init_ok(name) || (sechdrs[i].sh_type != SHT_RELA))
+ continue;
+ Elf_Rela *rela;
+ Elf_Rela *start = (void *)hdr + sechdrs[i].sh_offset;
+ Elf_Rela *stop = (void*)start + sechdrs[i].sh_size;
+ for (rela = start; rela < stop; rela++) {
+ Elf_Rela r;
+ const char *symname;
+ r.r_offset = TO_NATIVE(rela->r_offset);
+ r.r_info = TO_NATIVE(rela->r_info);
+ sym = elf->symtab_start + ELF_R_SYM(r.r_info);
+ symname = secstrings + sechdrs[sym->st_shndx].sh_name;
+
+ if (is_init_section(symname)) {
+ warn("%s: Reference to %s section from "
+ "offset 0x%lx within section %s\n",
+ modname, secstrings + sechdrs[sym->st_shndx].sh_name,
+ (long)r.r_offset, name);
+ }
+ }
+ }
+}
+
static void read_symbols(char *modname)
{
const char *symname;
@@ -476,6 +566,7 @@ static void read_symbols(char *modname)
handle_modversions(mod, &info, sym, symname);
handle_moddevtable(mod, &info, sym, symname);
}
+ handle_checkinitref(mod, modname, &info);
version = get_modinfo(info.modinfo, info.modinfo_len, "version");
if (version)
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index c0de7b9..f7126c1 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -19,6 +19,9 @@
#define ELF_ST_BIND ELF32_ST_BIND
#define ELF_ST_TYPE ELF32_ST_TYPE
+#define Elf_Rela Elf32_Rela
+#define ELF_R_SYM ELF32_R_SYM
+#define ELF_R_TYPE ELF32_R_TYPE
#else
#define Elf_Ehdr Elf64_Ehdr
@@ -27,6 +30,9 @@
#define ELF_ST_BIND ELF64_ST_BIND
#define ELF_ST_TYPE ELF64_ST_TYPE
+#define Elf_Rela Elf64_Rela
+#define ELF_R_SYM ELF64_R_SYM
+#define ELF_R_TYPE ELF64_R_TYPE
#endif
#if KERNEL_ELFDATA != HOST_ELFDATA
-
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