modpost: support objects with more than 64k sections
This patch makes modpost able to process object files with more than
64k sections. Needed for huge kernel builds (allyesconfig, for example)
with -ffunction-sections. 64k sections handling is covered, for example,
by this document:
"IA-64 gABI Proposal 74: Section Indexes"
http://www.codesourcery.com/public/cxx-abi/abi/prop-74-sindex.html
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 3318692..7249ab4 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -253,7 +253,7 @@
return export_unknown;
}
-static enum export export_from_sec(struct elf_info *elf, Elf_Section sec)
+static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
{
if (sec == elf->export_sec)
return export_plain;
@@ -373,6 +373,8 @@
Elf_Ehdr *hdr;
Elf_Shdr *sechdrs;
Elf_Sym *sym;
+ const char *secstrings;
+ unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U;
hdr = grab_file(filename, &info->size);
if (!hdr) {
@@ -417,8 +419,27 @@
return 0;
}
+ if (hdr->e_shnum == 0) {
+ /*
+ * There are more than 64k sections,
+ * read count from .sh_size.
+ * note: it doesn't need shndx2secindex()
+ */
+ info->num_sections = TO_NATIVE(sechdrs[0].sh_size);
+ }
+ else {
+ info->num_sections = hdr->e_shnum;
+ }
+ if (hdr->e_shstrndx == SHN_XINDEX) {
+ info->secindex_strings =
+ shndx2secindex(TO_NATIVE(sechdrs[0].sh_link));
+ }
+ else {
+ info->secindex_strings = hdr->e_shstrndx;
+ }
+
/* Fix endianness in section headers */
- for (i = 0; i < hdr->e_shnum; i++) {
+ for (i = 0; i < info->num_sections; i++) {
sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name);
sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type);
sechdrs[i].sh_flags = TO_NATIVE(sechdrs[i].sh_flags);
@@ -431,9 +452,8 @@
sechdrs[i].sh_entsize = TO_NATIVE(sechdrs[i].sh_entsize);
}
/* Find symbol table. */
- for (i = 1; i < hdr->e_shnum; i++) {
- const char *secstrings
- = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+ secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset;
+ for (i = 1; i < info->num_sections; i++) {
const char *secname;
int nobits = sechdrs[i].sh_type == SHT_NOBITS;
@@ -461,14 +481,26 @@
else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
info->export_gpl_future_sec = i;
- if (sechdrs[i].sh_type != SHT_SYMTAB)
- continue;
+ if (sechdrs[i].sh_type == SHT_SYMTAB) {
+ unsigned int sh_link_idx;
+ symtab_idx = i;
+ info->symtab_start = (void *)hdr +
+ sechdrs[i].sh_offset;
+ info->symtab_stop = (void *)hdr +
+ sechdrs[i].sh_offset + sechdrs[i].sh_size;
+ sh_link_idx = shndx2secindex(sechdrs[i].sh_link);
+ info->strtab = (void *)hdr +
+ sechdrs[sh_link_idx].sh_offset;
+ }
- info->symtab_start = (void *)hdr + sechdrs[i].sh_offset;
- info->symtab_stop = (void *)hdr + sechdrs[i].sh_offset
- + sechdrs[i].sh_size;
- info->strtab = (void *)hdr +
- sechdrs[sechdrs[i].sh_link].sh_offset;
+ /* 32bit section no. table? ("more than 64k sections") */
+ if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) {
+ symtab_shndx_idx = i;
+ info->symtab_shndx_start = (void *)hdr +
+ sechdrs[i].sh_offset;
+ info->symtab_shndx_stop = (void *)hdr +
+ sechdrs[i].sh_offset + sechdrs[i].sh_size;
+ }
}
if (!info->symtab_start)
fatal("%s has no symtab?\n", filename);
@@ -480,6 +512,21 @@
sym->st_value = TO_NATIVE(sym->st_value);
sym->st_size = TO_NATIVE(sym->st_size);
}
+
+ if (symtab_shndx_idx != ~0U) {
+ Elf32_Word *p;
+ if (symtab_idx !=
+ shndx2secindex(sechdrs[symtab_shndx_idx].sh_link))
+ fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n",
+ filename,
+ shndx2secindex(sechdrs[symtab_shndx_idx].sh_link),
+ symtab_idx);
+ /* Fix endianness */
+ for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop;
+ p++)
+ *p = TO_NATIVE(*p);
+ }
+
return 1;
}
@@ -514,7 +561,7 @@
Elf_Sym *sym, const char *symname)
{
unsigned int crc;
- enum export export = export_from_sec(info, sym->st_shndx);
+ enum export export = export_from_sec(info, get_secindex(info, sym));
switch (sym->st_shndx) {
case SHN_COMMON:
@@ -656,19 +703,19 @@
return "(unknown)";
}
-static const char *sec_name(struct elf_info *elf, int shndx)
+static const char *sec_name(struct elf_info *elf, int secindex)
{
Elf_Shdr *sechdrs = elf->sechdrs;
return (void *)elf->hdr +
- elf->sechdrs[elf->hdr->e_shstrndx].sh_offset +
- sechdrs[shndx].sh_name;
+ elf->sechdrs[elf->secindex_strings].sh_offset +
+ sechdrs[secindex].sh_name;
}
static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr)
{
return (void *)elf->hdr +
- elf->sechdrs[elf->hdr->e_shstrndx].sh_offset +
- sechdr->sh_name;
+ elf->sechdrs[elf->secindex_strings].sh_offset +
+ sechdr->sh_name;
}
/* if sym is empty or point to a string
@@ -1047,11 +1094,14 @@
Elf_Sym *near = NULL;
Elf64_Sword distance = 20;
Elf64_Sword d;
+ unsigned int relsym_secindex;
if (relsym->st_name != 0)
return relsym;
+
+ relsym_secindex = get_secindex(elf, relsym);
for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
- if (sym->st_shndx != relsym->st_shndx)
+ if (get_secindex(elf, sym) != relsym_secindex)
continue;
if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
continue;
@@ -1113,9 +1163,9 @@
for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
const char *symsec;
- if (sym->st_shndx >= SHN_LORESERVE)
+ if (is_shndx_special(sym->st_shndx))
continue;
- symsec = sec_name(elf, sym->st_shndx);
+ symsec = sec_name(elf, get_secindex(elf, sym));
if (strcmp(symsec, sec) != 0)
continue;
if (!is_valid_name(elf, sym))
@@ -1311,7 +1361,7 @@
const char *tosec;
const struct sectioncheck *mismatch;
- tosec = sec_name(elf, sym->st_shndx);
+ tosec = sec_name(elf, get_secindex(elf, sym));
mismatch = section_mismatch(fromsec, tosec);
if (mismatch) {
Elf_Sym *to;
@@ -1339,7 +1389,7 @@
Elf_Shdr *sechdr, Elf_Rela *r)
{
Elf_Shdr *sechdrs = elf->sechdrs;
- int section = sechdr->sh_info;
+ int section = shndx2secindex(sechdr->sh_info);
return (void *)elf->hdr + sechdrs[section].sh_offset +
(r->r_offset - sechdrs[section].sh_addr);
@@ -1447,7 +1497,7 @@
r.r_addend = TO_NATIVE(rela->r_addend);
sym = elf->symtab_start + r_sym;
/* Skip special sections */
- if (sym->st_shndx >= SHN_LORESERVE)
+ if (is_shndx_special(sym->st_shndx))
continue;
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
@@ -1505,7 +1555,7 @@
}
sym = elf->symtab_start + r_sym;
/* Skip special sections */
- if (sym->st_shndx >= SHN_LORESERVE)
+ if (is_shndx_special(sym->st_shndx))
continue;
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
@@ -1530,7 +1580,7 @@
Elf_Shdr *sechdrs = elf->sechdrs;
/* Walk through all sections */
- for (i = 0; i < elf->hdr->e_shnum; i++) {
+ for (i = 0; i < elf->num_sections; i++) {
check_section(modname, elf, &elf->sechdrs[i]);
/* We want to process only relocation sections and not .init */
if (sechdrs[i].sh_type == SHT_RELA)