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Merge pull request #601 from flaming-toast/kpatch-elf

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Introduce a common kpatch-elf "api"
This commit is contained in:
Josh Poimboeuf 2016-07-13 10:31:11 -04:00 committed by GitHub
commit f678f31898
5 changed files with 963 additions and 852 deletions
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6
kpatch-build/Makefile
View File

@ -4,8 +4,10 @@ CFLAGS += -I../kmod/patch -Iinsn -Wall -g -Werror
LDFLAGS += -lelf
TARGETS = create-diff-object
OBJS = create-diff-object.o lookup.o insn/insn.o insn/inat.o
SOURCES = create-diff-object.c lookup.c insn/insn.c insn/inat.c
OBJS = create-diff-object.o kpatch-elf.o \
lookup.o insn/insn.o insn/inat.o
SOURCES = create-diff-object.c kpatch-elf.c \
lookup.c insn/insn.c insn/inat.c
all: $(TARGETS)

852
kpatch-build/create-diff-object.c
View File

@ -50,9 +50,7 @@
#include "lookup.h"
#include "asm/insn.h"
#include "kpatch-patch.h"
#define ERROR(format, ...) \
error(1, 0, "ERROR: %s: %s: %d: " format, childobj, __FUNCTION__, __LINE__, ##__VA_ARGS__)
#include "kpatch-elf.h"
#define DIFF_FATAL(format, ...) \
({ \
@ -60,478 +58,21 @@
error(2, 0, "unreconcilable difference"); \
})
#define log_debug(format, ...) log(DEBUG, format, ##__VA_ARGS__)
#define log_normal(format, ...) log(NORMAL, "%s: " format, childobj, ##__VA_ARGS__)
#define log(level, format, ...) \
({ \
if (loglevel <= (level)) \
printf(format, ##__VA_ARGS__); \
})
char *childobj;
enum loglevel {
DEBUG,
NORMAL
};
static enum loglevel loglevel = NORMAL;
enum loglevel loglevel = NORMAL;
/*******************
* Data structures
* ****************/
struct section;
struct symbol;
struct rela;
enum status {
NEW,
CHANGED,
SAME
};
struct section {
struct list_head list;
struct section *twin;
GElf_Shdr sh;
Elf_Data *data;
char *name;
int index;
enum status status;
int include;
int ignore;
int grouped;
union {
struct { /* if (is_rela_section()) */
struct section *base;
struct list_head relas;
};
struct { /* else */
struct section *rela;
struct symbol *secsym, *sym;
};
};
};
struct symbol {
struct list_head list;
struct symbol *twin;
struct section *sec;
GElf_Sym sym;
char *name;
int index;
unsigned char bind, type;
enum status status;
union {
int include; /* used in the patched elf */
int strip; /* used in the output elf */
};
int has_fentry_call;
};
struct rela {
struct list_head list;
GElf_Rela rela;
struct symbol *sym;
unsigned int type;
int addend;
int offset;
char *string;
};
struct string {
struct list_head list;
char *name;
};
struct kpatch_elf {
Elf *elf;
struct list_head sections;
struct list_head symbols;
struct list_head strings;
int fd;
};
struct special_section {
char *name;
int (*group_size)(struct kpatch_elf *kelf, int offset);
};
/*******************
* Helper functions
******************/
char *status_str(enum status status)
{
switch(status) {
case NEW:
return "NEW";
case CHANGED:
return "CHANGED";
case SAME:
return "SAME";
default:
ERROR("status_str");
}
/* never reached */
return NULL;
}
int is_rela_section(struct section *sec)
{
return (sec->sh.sh_type == SHT_RELA);
}
int is_text_section(struct section *sec)
{
return (sec->sh.sh_type == SHT_PROGBITS &&
(sec->sh.sh_flags & SHF_EXECINSTR));
}
int is_debug_section(struct section *sec)
{
char *name;
if (is_rela_section(sec))
name = sec->base->name;
else
name = sec->name;
return !strncmp(name, ".debug_", 7);
}
struct section *find_section_by_index(struct list_head *list, unsigned int index)
{
struct section *sec;
list_for_each_entry(sec, list, list)
if (sec->index == index)
return sec;
return NULL;
}
struct section *find_section_by_name(struct list_head *list, const char *name)
{
struct section *sec;
list_for_each_entry(sec, list, list)
if (!strcmp(sec->name, name))
return sec;
return NULL;
}
struct symbol *find_symbol_by_index(struct list_head *list, size_t index)
{
struct symbol *sym;
list_for_each_entry(sym, list, list)
if (sym->index == index)
return sym;
return NULL;
}
struct symbol *find_symbol_by_name(struct list_head *list, const char *name)
{
struct symbol *sym;
list_for_each_entry(sym, list, list)
if (sym->name && !strcmp(sym->name, name))
return sym;
return NULL;
}
#define ALLOC_LINK(_new, _list) \
{ \
(_new) = malloc(sizeof(*(_new))); \
if (!(_new)) \
ERROR("malloc"); \
memset((_new), 0, sizeof(*(_new))); \
INIT_LIST_HEAD(&(_new)->list); \
list_add_tail(&(_new)->list, (_list)); \
}
/* returns the offset of the string in the string table */
int offset_of_string(struct list_head *list, char *name)
{
struct string *string;
int index = 0;
/* try to find string in the string list */
list_for_each_entry(string, list, list) {
if (!strcmp(string->name, name))
return index;
index += strlen(string->name) + 1;
}
/* allocate a new string */
ALLOC_LINK(string, list);
string->name = name;
return index;
}
/*************
* Functions
* **********/
void kpatch_create_rela_list(struct kpatch_elf *kelf, struct section *sec)
{
int rela_nr, index = 0, skip = 0;
struct rela *rela;
unsigned int symndx;
/* find matching base (text/data) section */
sec->base = find_section_by_name(&kelf->sections, sec->name + 5);
if (!sec->base)
ERROR("can't find base section for rela section %s", sec->name);
/* create reverse link from base section to this rela section */
sec->base->rela = sec;
rela_nr = sec->sh.sh_size / sec->sh.sh_entsize;
log_debug("\n=== rela list for %s (%d entries) ===\n",
sec->base->name, rela_nr);
if (is_debug_section(sec)) {
log_debug("skipping rela listing for .debug_* section\n");
skip = 1;
}
/* read and store the rela entries */
while (rela_nr--) {
ALLOC_LINK(rela, &sec->relas);
if (!gelf_getrela(sec->data, index, &rela->rela))
ERROR("gelf_getrela");
index++;
rela->type = GELF_R_TYPE(rela->rela.r_info);
rela->addend = rela->rela.r_addend;
rela->offset = rela->rela.r_offset;
symndx = GELF_R_SYM(rela->rela.r_info);
rela->sym = find_symbol_by_index(&kelf->symbols, symndx);
if (!rela->sym)
ERROR("could not find rela entry symbol\n");
if (rela->sym->sec &&
(rela->sym->sec->sh.sh_flags & SHF_STRINGS)) {
rela->string = rela->sym->sec->data->d_buf + rela->addend;
if (!rela->string)
ERROR("could not lookup rela string for %s+%d",
rela->sym->name, rela->addend);
}
if (skip)
continue;
log_debug("offset %d, type %d, %s %s %d", rela->offset,
rela->type, rela->sym->name,
(rela->addend < 0)?"-":"+", abs(rela->addend));
if (rela->string)
log_debug(" (string = %s)", rela->string);
log_debug("\n");
}
}
void kpatch_create_section_list(struct kpatch_elf *kelf)
{
Elf_Scn *scn = NULL;
struct section *sec;
size_t shstrndx, sections_nr;
if (elf_getshdrnum(kelf->elf, &sections_nr))
ERROR("elf_getshdrnum");
/*
* elf_getshdrnum() includes section index 0 but elf_nextscn
* doesn't return that section so subtract one.
*/
sections_nr--;
if (elf_getshdrstrndx(kelf->elf, &shstrndx))
ERROR("elf_getshdrstrndx");
log_debug("=== section list (%zu) ===\n", sections_nr);
while (sections_nr--) {
ALLOC_LINK(sec, &kelf->sections);
scn = elf_nextscn(kelf->elf, scn);
if (!scn)
ERROR("scn NULL");
if (!gelf_getshdr(scn, &sec->sh))
ERROR("gelf_getshdr");
sec->name = elf_strptr(kelf->elf, shstrndx, sec->sh.sh_name);
if (!sec->name)
ERROR("elf_strptr");
sec->data = elf_getdata(scn, NULL);
if (!sec->data)
ERROR("elf_getdata");
sec->index = elf_ndxscn(scn);
log_debug("ndx %02d, data %p, size %zu, name %s\n",
sec->index, sec->data->d_buf, sec->data->d_size,
sec->name);
}
/* Sanity check, one more call to elf_nextscn() should return NULL */
if (elf_nextscn(kelf->elf, scn))
ERROR("expected NULL");
}
int is_bundleable(struct symbol *sym)
{
if (sym->type == STT_FUNC &&
!strncmp(sym->sec->name, ".text.",6) &&
!strcmp(sym->sec->name + 6, sym->name))
return 1;
if (sym->type == STT_FUNC &&
!strncmp(sym->sec->name, ".text.unlikely.",15) &&
!strcmp(sym->sec->name + 15, sym->name))
return 1;
if (sym->type == STT_OBJECT &&
!strncmp(sym->sec->name, ".data.",6) &&
!strcmp(sym->sec->name + 6, sym->name))
return 1;
if (sym->type == STT_OBJECT &&
!strncmp(sym->sec->name, ".rodata.",8) &&
!strcmp(sym->sec->name + 8, sym->name))
return 1;
if (sym->type == STT_OBJECT &&
!strncmp(sym->sec->name, ".bss.",5) &&
!strcmp(sym->sec->name + 5, sym->name))
return 1;
return 0;
}
void kpatch_create_symbol_list(struct kpatch_elf *kelf)
{
struct section *symtab;
struct symbol *sym;
int symbols_nr, index = 0;
symtab = find_section_by_name(&kelf->sections, ".symtab");
if (!symtab)
ERROR("missing symbol table");
symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
log_debug("\n=== symbol list (%d entries) ===\n", symbols_nr);
while (symbols_nr--) {
ALLOC_LINK(sym, &kelf->symbols);
sym->index = index;
if (!gelf_getsym(symtab->data, index, &sym->sym))
ERROR("gelf_getsym");
index++;
sym->name = elf_strptr(kelf->elf, symtab->sh.sh_link,
sym->sym.st_name);
if (!sym->name)
ERROR("elf_strptr");
sym->type = GELF_ST_TYPE(sym->sym.st_info);
sym->bind = GELF_ST_BIND(sym->sym.st_info);
if (sym->sym.st_shndx > SHN_UNDEF &&
sym->sym.st_shndx < SHN_LORESERVE) {
sym->sec = find_section_by_index(&kelf->sections,
sym->sym.st_shndx);
if (!sym->sec)
ERROR("couldn't find section for symbol %s\n",
sym->name);
if (is_bundleable(sym)) {
if (sym->sym.st_value != 0)
ERROR("symbol %s at offset %lu within section %s, expected 0",
sym->name, sym->sym.st_value, sym->sec->name);
sym->sec->sym = sym;
} else if (sym->type == STT_SECTION) {
sym->sec->secsym = sym;
/* use the section name as the symbol name */
sym->name = sym->sec->name;
}
}
log_debug("sym %02d, type %d, bind %d, ndx %02d, name %s",
sym->index, sym->type, sym->bind, sym->sym.st_shndx,
sym->name);
if (sym->sec)
log_debug(" -> %s", sym->sec->name);
log_debug("\n");
}
}
/* Check which functions have fentry calls; save this info for later use. */
static void kpatch_find_fentry_calls(struct kpatch_elf *kelf)
{
struct symbol *sym;
struct rela *rela;
list_for_each_entry(sym, &kelf->symbols, list) {
if (sym->type != STT_FUNC || !sym->sec->rela)
continue;
rela = list_first_entry(&sym->sec->rela->relas, struct rela,
list);
if (rela->type != R_X86_64_NONE ||
strcmp(rela->sym->name, "__fentry__"))
continue;
sym->has_fentry_call = 1;
}
}
struct kpatch_elf *kpatch_elf_open(const char *name)
{
Elf *elf;
int fd;
struct kpatch_elf *kelf;
struct section *sec;
fd = open(name, O_RDONLY);
if (fd == -1)
ERROR("open");
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (!elf)
ERROR("elf_begin");
kelf = malloc(sizeof(*kelf));
if (!kelf)
ERROR("malloc");
memset(kelf, 0, sizeof(*kelf));
INIT_LIST_HEAD(&kelf->sections);
INIT_LIST_HEAD(&kelf->symbols);
INIT_LIST_HEAD(&kelf->strings);
/* read and store section, symbol entries from file */
kelf->elf = elf;
kelf->fd = fd;
kpatch_create_section_list(kelf);
kpatch_create_symbol_list(kelf);
/* for each rela section, read and store the rela entries */
list_for_each_entry(sec, &kelf->sections, list) {
if (!is_rela_section(sec))
continue;
INIT_LIST_HEAD(&sec->relas);
kpatch_create_rela_list(kelf, sec);
}
kpatch_find_fentry_calls(kelf);
return kelf;
}
/*
* This function detects whether the given symbol is a "special" static local
@ -957,7 +498,6 @@ void kpatch_check_program_headers(Elf *elf)
DIFF_FATAL("ELF contains program header");
}
void kpatch_mark_grouped_sections(struct kpatch_elf *kelf)
{
struct section *groupsec, *sec;
@ -1448,54 +988,6 @@ void kpatch_replace_sections_syms(struct kpatch_elf *kelf)
log_debug("\n");
}
void kpatch_dump_kelf(struct kpatch_elf *kelf)
{
struct section *sec;
struct symbol *sym;
struct rela *rela;
if (loglevel > DEBUG)
return;
printf("\n=== Sections ===\n");
list_for_each_entry(sec, &kelf->sections, list) {
printf("%02d %s (%s)", sec->index, sec->name, status_str(sec->status));
if (is_rela_section(sec)) {
printf(", base-> %s\n", sec->base->name);
/* skip .debug_* sections */
if (is_debug_section(sec))
goto next;
printf("rela section expansion\n");
list_for_each_entry(rela, &sec->relas, list) {
printf("sym %d, offset %d, type %d, %s %s %d\n",
rela->sym->index, rela->offset,
rela->type, rela->sym->name,
(rela->addend < 0)?"-":"+",
abs(rela->addend));
}
} else {
if (sec->sym)
printf(", sym-> %s", sec->sym->name);
if (sec->secsym)
printf(", secsym-> %s", sec->secsym->name);
if (sec->rela)
printf(", rela-> %s", sec->rela->name);
}
next:
printf("\n");
}
printf("\n=== Symbols ===\n");
list_for_each_entry(sym, &kelf->symbols, list) {
printf("sym %02d, type %d, bind %d, ndx %02d, name %s (%s)",
sym->index, sym->type, sym->bind, sym->sym.st_shndx,
sym->name, status_str(sym->status));
if (sym->sec && (sym->type == STT_FUNC || sym->type == STT_OBJECT))
printf(" -> %s", sym->sec->name);
printf("\n");
}
}
static void kpatch_check_fentry_calls(struct kpatch_elf *kelf)
{
struct symbol *sym;
@ -1754,26 +1246,6 @@ void kpatch_migrate_symbols(struct list_head *src,
}
}
int is_null_sym(struct symbol *sym)
{
return !strlen(sym->name);
}
int is_file_sym(struct symbol *sym)
{
return sym->type == STT_FILE;
}
int is_local_func_sym(struct symbol *sym)
{
return sym->bind == STB_LOCAL && sym->type == STT_FUNC;
}
int is_local_sym(struct symbol *sym)
{
return sym->bind == STB_LOCAL;
}
void kpatch_migrate_included_elements(struct kpatch_elf *kelf, struct kpatch_elf **kelfout)
{
struct section *sec, *safesec;
@ -1856,7 +1328,6 @@ void kpatch_reindex_elements(struct kpatch_elf *kelf)
}
}
int bug_table_group_size(struct kpatch_elf *kelf, int offset)
{
static int size = 0;
@ -2289,214 +1760,6 @@ void kpatch_process_special_sections(struct kpatch_elf *kelf)
}
}
void print_strtab(char *buf, size_t size)
{
int i;
for (i = 0; i < size; i++) {
if (buf[i] == 0)
printf("\\0");
else
printf("%c",buf[i]);
}
}
void kpatch_create_shstrtab(struct kpatch_elf *kelf)
{
struct section *shstrtab, *sec;
size_t size, offset, len;
char *buf;
shstrtab = find_section_by_name(&kelf->sections, ".shstrtab");
if (!shstrtab)
ERROR("find_section_by_name");
/* determine size of string table */
size = 1; /* for initial NULL terminator */
list_for_each_entry(sec, &kelf->sections, list)
size += strlen(sec->name) + 1; /* include NULL terminator */
/* allocate data buffer */
buf = malloc(size);
if (!buf)
ERROR("malloc");
memset(buf, 0, size);
/* populate string table and link with section header */
offset = 1;
list_for_each_entry(sec, &kelf->sections, list) {
len = strlen(sec->name) + 1;
sec->sh.sh_name = offset;
memcpy(buf + offset, sec->name, len);
offset += len;
}
if (offset != size)
ERROR("shstrtab size mismatch");
shstrtab->data->d_buf = buf;
shstrtab->data->d_size = size;
if (loglevel <= DEBUG) {
printf("shstrtab: ");
print_strtab(buf, size);
printf("\n");
list_for_each_entry(sec, &kelf->sections, list)
printf("%s @ shstrtab offset %d\n",
sec->name, sec->sh.sh_name);
}
}
void kpatch_create_strtab(struct kpatch_elf *kelf)
{
struct section *strtab;
struct symbol *sym;
size_t size = 0, offset = 0, len;
char *buf;
strtab = find_section_by_name(&kelf->sections, ".strtab");
if (!strtab)
ERROR("find_section_by_name");
/* determine size of string table */
list_for_each_entry(sym, &kelf->symbols, list) {
if (sym->type == STT_SECTION)
continue;
size += strlen(sym->name) + 1; /* include NULL terminator */
}
/* allocate data buffer */
buf = malloc(size);
if (!buf)
ERROR("malloc");
memset(buf, 0, size);
/* populate string table and link with section header */
list_for_each_entry(sym, &kelf->symbols, list) {
if (sym->type == STT_SECTION) {
sym->sym.st_name = 0;
continue;
}
len = strlen(sym->name) + 1;
sym->sym.st_name = offset;
memcpy(buf + offset, sym->name, len);
offset += len;
}
if (offset != size)
ERROR("shstrtab size mismatch");
strtab->data->d_buf = buf;
strtab->data->d_size = size;
if (loglevel <= DEBUG) {
printf("strtab: ");
print_strtab(buf, size);
printf("\n");
list_for_each_entry(sym, &kelf->symbols, list)
printf("%s @ strtab offset %d\n",
sym->name, sym->sym.st_name);
}
}
void kpatch_create_symtab(struct kpatch_elf *kelf)
{
struct section *symtab;
struct symbol *sym;
char *buf;
size_t size;
int nr = 0, offset = 0, nr_local = 0;
symtab = find_section_by_name(&kelf->sections, ".symtab");
if (!symtab)
ERROR("find_section_by_name");
/* count symbols */
list_for_each_entry(sym, &kelf->symbols, list)
nr++;
/* create new symtab buffer */
size = nr * symtab->sh.sh_entsize;
buf = malloc(size);
if (!buf)
ERROR("malloc");
memset(buf, 0, size);
offset = 0;
list_for_each_entry(sym, &kelf->symbols, list) {
memcpy(buf + offset, &sym->sym, symtab->sh.sh_entsize);
offset += symtab->sh.sh_entsize;
if (is_local_sym(sym))
nr_local++;
}
symtab->data->d_buf = buf;
symtab->data->d_size = size;
/* update symtab section header */
symtab->sh.sh_link = find_section_by_name(&kelf->sections, ".strtab")->index;
symtab->sh.sh_info = nr_local;
}
struct section *create_section_pair(struct kpatch_elf *kelf, char *name,
int entsize, int nr)
{
char *relaname;
struct section *sec, *relasec;
int size = entsize * nr;
relaname = malloc(strlen(name) + strlen(".rela") + 1);
if (!relaname)
ERROR("malloc");
strcpy(relaname, ".rela");
strcat(relaname, name);
/* allocate text section resources */
ALLOC_LINK(sec, &kelf->sections);
sec->name = name;
/* set data */
sec->data = malloc(sizeof(*sec->data));
if (!sec->data)
ERROR("malloc");
sec->data->d_buf = malloc(size);
if (!sec->data->d_buf)
ERROR("malloc");
sec->data->d_size = size;
sec->data->d_type = ELF_T_BYTE;
/* set section header */
sec->sh.sh_type = SHT_PROGBITS;
sec->sh.sh_entsize = entsize;
sec->sh.sh_addralign = 8;
sec->sh.sh_flags = SHF_ALLOC;
sec->sh.sh_size = size;
/* allocate rela section resources */
ALLOC_LINK(relasec, &kelf->sections);
relasec->name = relaname;
relasec->base = sec;
INIT_LIST_HEAD(&relasec->relas);
/* set data, buffers generated by kpatch_rebuild_rela_section_data() */
relasec->data = malloc(sizeof(*relasec->data));
if (!relasec->data)
ERROR("malloc");
/* set section header */
relasec->sh.sh_type = SHT_RELA;
relasec->sh.sh_entsize = sizeof(GElf_Rela);
relasec->sh.sh_addralign = 8;
/* set text rela section pointer */
sec->rela = relasec;
return sec;
}
void kpatch_create_patches_sections(struct kpatch_elf *kelf,
struct lookup_table *table, char *hint,
char *objname)
@ -2982,76 +2245,6 @@ void kpatch_rebuild_rela_section_data(struct section *sec)
ERROR("size mismatch in rebuilt rela section");
}
void kpatch_write_output_elf(struct kpatch_elf *kelf, Elf *elf, char *outfile)
{
int fd;
struct section *sec;
Elf *elfout;
GElf_Ehdr eh, ehout;
Elf_Scn *scn;
Elf_Data *data;
GElf_Shdr sh;
/* TODO make this argv */
fd = creat(outfile, 0777);
if (fd == -1)
ERROR("creat");
elfout = elf_begin(fd, ELF_C_WRITE, NULL);
if (!elfout)
ERROR("elf_begin");
if (!gelf_newehdr(elfout, gelf_getclass(kelf->elf)))
ERROR("gelf_newehdr");
if (!gelf_getehdr(elfout, &ehout))
ERROR("gelf_getehdr");
if (!gelf_getehdr(elf, &eh))
ERROR("gelf_getehdr");
memset(&ehout, 0, sizeof(ehout));
ehout.e_ident[EI_DATA] = eh.e_ident[EI_DATA];
ehout.e_machine = eh.e_machine;
ehout.e_type = eh.e_type;
ehout.e_version = EV_CURRENT;
ehout.e_shstrndx = find_section_by_name(&kelf->sections, ".shstrtab")->index;
/* add changed sections */
list_for_each_entry(sec, &kelf->sections, list) {
scn = elf_newscn(elfout);
if (!scn)
ERROR("elf_newscn");
data = elf_newdata(scn);
if (!data)
ERROR("elf_newdata");
if (!elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY))
ERROR("elf_flagdata");
data->d_type = sec->data->d_type;
data->d_buf = sec->data->d_buf;
data->d_size = sec->data->d_size;
if(!gelf_getshdr(scn, &sh))
ERROR("gelf_getshdr");
sh = sec->sh;
if (!gelf_update_shdr(scn, &sh))
ERROR("gelf_update_shdr");
}
if (!gelf_update_ehdr(elfout, &ehout))
ERROR("gelf_update_ehdr");
if (elf_update(elfout, ELF_C_WRITE) < 0) {
printf("%s\n",elf_errmsg(-1));
ERROR("elf_update");
}
}
struct arguments {
char *args[4];
int debug;
@ -3094,47 +2287,6 @@ static error_t parse_opt (int key, char *arg, struct argp_state *state)
static struct argp argp = { options, parse_opt, args_doc, 0 };
/*
* While this is a one-shot program without a lot of proper cleanup in case
* of an error, this function serves a debugging purpose: to break down and
* zero data structures we shouldn't be accessing anymore. This should
* help cause an immediate and obvious issue when a logic error leads to
* accessing data that is not intended to be accessed past a particular point.
*/
void kpatch_elf_teardown(struct kpatch_elf *kelf)
{
struct section *sec, *safesec;
struct symbol *sym, *safesym;
struct rela *rela, *saferela;
list_for_each_entry_safe(sec, safesec, &kelf->sections, list) {
if (is_rela_section(sec)) {
list_for_each_entry_safe(rela, saferela, &sec->relas, list) {
memset(rela, 0, sizeof(*rela));
free(rela);
}
memset(sec, 0, sizeof(*sec));
free(sec);
}
}
list_for_each_entry_safe(sym, safesym, &kelf->symbols, list) {
memset(sym, 0, sizeof(*sym));
free(sym);
}
INIT_LIST_HEAD(&kelf->sections);
INIT_LIST_HEAD(&kelf->symbols);
}
void kpatch_elf_free(struct kpatch_elf *kelf)
{
elf_end(kelf->elf);
close(kelf->fd);
memset(kelf, 0, sizeof(*kelf));
free(kelf);
}
int main(int argc, char *argv[])
{
struct kpatch_elf *kelf_base, *kelf_patched, *kelf_out;

783
kpatch-build/kpatch-elf.c Normal file
View File

@ -0,0 +1,783 @@
/*
* kpatch-elf.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA,
* 02110-1301, USA.
*/
/*
* This file provides a common api to create, inspect, and manipulate
* kpatch_elf objects.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <error.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "kpatch-elf.h"
/*******************
* Helper functions
******************/
char *status_str(enum status status)
{
switch(status) {
case NEW:
return "NEW";
case CHANGED:
return "CHANGED";
case SAME:
return "SAME";
default:
ERROR("status_str");
}
/* never reached */
return NULL;
}
int is_rela_section(struct section *sec)
{
return (sec->sh.sh_type == SHT_RELA);
}
int is_text_section(struct section *sec)
{
return (sec->sh.sh_type == SHT_PROGBITS &&
(sec->sh.sh_flags & SHF_EXECINSTR));
}
int is_debug_section(struct section *sec)
{
char *name;
if (is_rela_section(sec))
name = sec->base->name;
else
name = sec->name;
return !strncmp(name, ".debug_", 7);
}
struct section *find_section_by_index(struct list_head *list, unsigned int index)
{
struct section *sec;
list_for_each_entry(sec, list, list)
if (sec->index == index)
return sec;
return NULL;
}
struct section *find_section_by_name(struct list_head *list, const char *name)
{
struct section *sec;
list_for_each_entry(sec, list, list)
if (!strcmp(sec->name, name))
return sec;
return NULL;
}
struct symbol *find_symbol_by_index(struct list_head *list, size_t index)
{
struct symbol *sym;
list_for_each_entry(sym, list, list)
if (sym->index == index)
return sym;
return NULL;
}
struct symbol *find_symbol_by_name(struct list_head *list, const char *name)
{
struct symbol *sym;
list_for_each_entry(sym, list, list)
if (sym->name && !strcmp(sym->name, name))
return sym;
return NULL;
}
/* returns the offset of the string in the string table */
int offset_of_string(struct list_head *list, char *name)
{
struct string *string;
int index = 0;
/* try to find string in the string list */
list_for_each_entry(string, list, list) {
if (!strcmp(string->name, name))
return index;
index += strlen(string->name) + 1;
}
/* allocate a new string */
ALLOC_LINK(string, list);
string->name = name;
return index;
}
void kpatch_create_rela_list(struct kpatch_elf *kelf, struct section *sec)
{
int rela_nr, index = 0, skip = 0;
struct rela *rela;
unsigned int symndx;
/* find matching base (text/data) section */
sec->base = find_section_by_name(&kelf->sections, sec->name + 5);
if (!sec->base)
ERROR("can't find base section for rela section %s", sec->name);
/* create reverse link from base section to this rela section */
sec->base->rela = sec;
rela_nr = sec->sh.sh_size / sec->sh.sh_entsize;
log_debug("\n=== rela list for %s (%d entries) ===\n",
sec->base->name, rela_nr);
if (is_debug_section(sec)) {
log_debug("skipping rela listing for .debug_* section\n");
skip = 1;
}
/* read and store the rela entries */
while (rela_nr--) {
ALLOC_LINK(rela, &sec->relas);
if (!gelf_getrela(sec->data, index, &rela->rela))
ERROR("gelf_getrela");
index++;
rela->type = GELF_R_TYPE(rela->rela.r_info);
rela->addend = rela->rela.r_addend;
rela->offset = rela->rela.r_offset;
symndx = GELF_R_SYM(rela->rela.r_info);
rela->sym = find_symbol_by_index(&kelf->symbols, symndx);
if (!rela->sym)
ERROR("could not find rela entry symbol\n");
if (rela->sym->sec &&
(rela->sym->sec->sh.sh_flags & SHF_STRINGS)) {
rela->string = rela->sym->sec->data->d_buf + rela->addend;
if (!rela->string)
ERROR("could not lookup rela string for %s+%d",
rela->sym->name, rela->addend);
}
if (skip)
continue;
log_debug("offset %d, type %d, %s %s %d", rela->offset,
rela->type, rela->sym->name,
(rela->addend < 0)?"-":"+", abs(rela->addend));
if (rela->string)
log_debug(" (string = %s)", rela->string);
log_debug("\n");
}
}
void kpatch_create_section_list(struct kpatch_elf *kelf)
{
Elf_Scn *scn = NULL;
struct section *sec;
size_t shstrndx, sections_nr;
if (elf_getshdrnum(kelf->elf, &sections_nr))
ERROR("elf_getshdrnum");
/*
* elf_getshdrnum() includes section index 0 but elf_nextscn
* doesn't return that section so subtract one.
*/
sections_nr--;
if (elf_getshdrstrndx(kelf->elf, &shstrndx))
ERROR("elf_getshdrstrndx");
log_debug("=== section list (%zu) ===\n", sections_nr);
while (sections_nr--) {
ALLOC_LINK(sec, &kelf->sections);
scn = elf_nextscn(kelf->elf, scn);
if (!scn)
ERROR("scn NULL");
if (!gelf_getshdr(scn, &sec->sh))
ERROR("gelf_getshdr");
sec->name = elf_strptr(kelf->elf, shstrndx, sec->sh.sh_name);
if (!sec->name)
ERROR("elf_strptr");
sec->data = elf_getdata(scn, NULL);
if (!sec->data)
ERROR("elf_getdata");
sec->index = elf_ndxscn(scn);
log_debug("ndx %02d, data %p, size %zu, name %s\n",
sec->index, sec->data->d_buf, sec->data->d_size,
sec->name);
}
/* Sanity check, one more call to elf_nextscn() should return NULL */
if (elf_nextscn(kelf->elf, scn))
ERROR("expected NULL");
}
static int is_bundleable(struct symbol *sym)
{
if (sym->type == STT_FUNC &&
!strncmp(sym->sec->name, ".text.",6) &&
!strcmp(sym->sec->name + 6, sym->name))
return 1;
if (sym->type == STT_FUNC &&
!strncmp(sym->sec->name, ".text.unlikely.",15) &&
!strcmp(sym->sec->name + 15, sym->name))
return 1;
if (sym->type == STT_OBJECT &&
!strncmp(sym->sec->name, ".data.",6) &&
!strcmp(sym->sec->name + 6, sym->name))
return 1;
if (sym->type == STT_OBJECT &&
!strncmp(sym->sec->name, ".rodata.",8) &&
!strcmp(sym->sec->name + 8, sym->name))
return 1;
if (sym->type == STT_OBJECT &&
!strncmp(sym->sec->name, ".bss.",5) &&
!strcmp(sym->sec->name + 5, sym->name))
return 1;
return 0;
}
void kpatch_create_symbol_list(struct kpatch_elf *kelf)
{
struct section *symtab;
struct symbol *sym;
int symbols_nr, index = 0;
symtab = find_section_by_name(&kelf->sections, ".symtab");
if (!symtab)
ERROR("missing symbol table");
symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
log_debug("\n=== symbol list (%d entries) ===\n", symbols_nr);
while (symbols_nr--) {
ALLOC_LINK(sym, &kelf->symbols);
sym->index = index;
if (!gelf_getsym(symtab->data, index, &sym->sym))
ERROR("gelf_getsym");
index++;
sym->name = elf_strptr(kelf->elf, symtab->sh.sh_link,
sym->sym.st_name);
if (!sym->name)
ERROR("elf_strptr");
sym->type = GELF_ST_TYPE(sym->sym.st_info);
sym->bind = GELF_ST_BIND(sym->sym.st_info);
if (sym->sym.st_shndx > SHN_UNDEF &&
sym->sym.st_shndx < SHN_LORESERVE) {
sym->sec = find_section_by_index(&kelf->sections,
sym->sym.st_shndx);
if (!sym->sec)
ERROR("couldn't find section for symbol %s\n",
sym->name);
if (is_bundleable(sym)) {
if (sym->sym.st_value != 0)
ERROR("symbol %s at offset %lu within section %s, expected 0",
sym->name, sym->sym.st_value, sym->sec->name);
sym->sec->sym = sym;
} else if (sym->type == STT_SECTION) {
sym->sec->secsym = sym;
/* use the section name as the symbol name */
sym->name = sym->sec->name;
}
}
log_debug("sym %02d, type %d, bind %d, ndx %02d, name %s",
sym->index, sym->type, sym->bind, sym->sym.st_shndx,
sym->name);
if (sym->sec)
log_debug(" -> %s", sym->sec->name);
log_debug("\n");
}
}
/* Check which functions have fentry calls; save this info for later use. */
static void kpatch_find_fentry_calls(struct kpatch_elf *kelf)
{
struct symbol *sym;
struct rela *rela;
list_for_each_entry(sym, &kelf->symbols, list) {
if (sym->type != STT_FUNC || !sym->sec->rela)
continue;
rela = list_first_entry(&sym->sec->rela->relas, struct rela,
list);
if (rela->type != R_X86_64_NONE ||
strcmp(rela->sym->name, "__fentry__"))
continue;
sym->has_fentry_call = 1;
}
}
struct kpatch_elf *kpatch_elf_open(const char *name)
{
Elf *elf;
int fd;
struct kpatch_elf *kelf;
struct section *sec;
fd = open(name, O_RDONLY);
if (fd == -1)
ERROR("open");
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (!elf)
ERROR("elf_begin");
kelf = malloc(sizeof(*kelf));
if (!kelf)
ERROR("malloc");
memset(kelf, 0, sizeof(*kelf));
INIT_LIST_HEAD(&kelf->sections);
INIT_LIST_HEAD(&kelf->symbols);
INIT_LIST_HEAD(&kelf->strings);
/* read and store section, symbol entries from file */
kelf->elf = elf;
kelf->fd = fd;
kpatch_create_section_list(kelf);
kpatch_create_symbol_list(kelf);
/* for each rela section, read and store the rela entries */
list_for_each_entry(sec, &kelf->sections, list) {
if (!is_rela_section(sec))
continue;
INIT_LIST_HEAD(&sec->relas);
kpatch_create_rela_list(kelf, sec);
}
kpatch_find_fentry_calls(kelf);
return kelf;
}
void kpatch_dump_kelf(struct kpatch_elf *kelf)
{
struct section *sec;
struct symbol *sym;
struct rela *rela;
if (loglevel > DEBUG)
return;
printf("\n=== Sections ===\n");
list_for_each_entry(sec, &kelf->sections, list) {
printf("%02d %s (%s)", sec->index, sec->name, status_str(sec->status));
if (is_rela_section(sec)) {
printf(", base-> %s\n", sec->base->name);
/* skip .debug_* sections */
if (is_debug_section(sec))
goto next;
printf("rela section expansion\n");
list_for_each_entry(rela, &sec->relas, list) {
printf("sym %d, offset %d, type %d, %s %s %d\n",
rela->sym->index, rela->offset,
rela->type, rela->sym->name,
(rela->addend < 0)?"-":"+",
abs(rela->addend));
}
} else {
if (sec->sym)
printf(", sym-> %s", sec->sym->name);
if (sec->secsym)
printf(", secsym-> %s", sec->secsym->name);
if (sec->rela)
printf(", rela-> %s", sec->rela->name);
}
next:
printf("\n");
}
printf("\n=== Symbols ===\n");
list_for_each_entry(sym, &kelf->symbols, list) {
printf("sym %02d, type %d, bind %d, ndx %02d, name %s (%s)",
sym->index, sym->type, sym->bind, sym->sym.st_shndx,
sym->name, status_str(sym->status));
if (sym->sec && (sym->type == STT_FUNC || sym->type == STT_OBJECT))
printf(" -> %s", sym->sec->name);
printf("\n");
}
}
int is_null_sym(struct symbol *sym)
{
return !strlen(sym->name);
}
int is_file_sym(struct symbol *sym)
{
return sym->type == STT_FILE;
}
int is_local_func_sym(struct symbol *sym)
{
return sym->bind == STB_LOCAL && sym->type == STT_FUNC;
}
int is_local_sym(struct symbol *sym)
{
return sym->bind == STB_LOCAL;
}
void print_strtab(char *buf, size_t size)
{
int i;
for (i = 0; i < size; i++) {
if (buf[i] == 0)
printf("\\0");
else
printf("%c",buf[i]);
}
}
void kpatch_create_shstrtab(struct kpatch_elf *kelf)
{
struct section *shstrtab, *sec;
size_t size, offset, len;
char *buf;
shstrtab = find_section_by_name(&kelf->sections, ".shstrtab");
if (!shstrtab)
ERROR("find_section_by_name");
/* determine size of string table */
size = 1; /* for initial NULL terminator */
list_for_each_entry(sec, &kelf->sections, list)
size += strlen(sec->name) + 1; /* include NULL terminator */
/* allocate data buffer */
buf = malloc(size);
if (!buf)
ERROR("malloc");
memset(buf, 0, size);
/* populate string table and link with section header */
offset = 1;
list_for_each_entry(sec, &kelf->sections, list) {
len = strlen(sec->name) + 1;
sec->sh.sh_name = offset;
memcpy(buf + offset, sec->name, len);
offset += len;
}
if (offset != size)
ERROR("shstrtab size mismatch");
shstrtab->data->d_buf = buf;
shstrtab->data->d_size = size;
if (loglevel <= DEBUG) {
printf("shstrtab: ");
print_strtab(buf, size);
printf("\n");
list_for_each_entry(sec, &kelf->sections, list)
printf("%s @ shstrtab offset %d\n",
sec->name, sec->sh.sh_name);
}
}
void kpatch_create_strtab(struct kpatch_elf *kelf)
{
struct section *strtab;
struct symbol *sym;
size_t size = 0, offset = 0, len;
char *buf;
strtab = find_section_by_name(&kelf->sections, ".strtab");
if (!strtab)
ERROR("find_section_by_name");
/* determine size of string table */
list_for_each_entry(sym, &kelf->symbols, list) {
if (sym->type == STT_SECTION)
continue;
size += strlen(sym->name) + 1; /* include NULL terminator */
}
/* allocate data buffer */
buf = malloc(size);
if (!buf)
ERROR("malloc");
memset(buf, 0, size);
/* populate string table and link with section header */
list_for_each_entry(sym, &kelf->symbols, list) {
if (sym->type == STT_SECTION) {
sym->sym.st_name = 0;
continue;
}
len = strlen(sym->name) + 1;
sym->sym.st_name = offset;
memcpy(buf + offset, sym->name, len);
offset += len;
}
if (offset != size)
ERROR("shstrtab size mismatch");
strtab->data->d_buf = buf;
strtab->data->d_size = size;
if (loglevel <= DEBUG) {
printf("strtab: ");
print_strtab(buf, size);
printf("\n");
list_for_each_entry(sym, &kelf->symbols, list)
printf("%s @ strtab offset %d\n",
sym->name, sym->sym.st_name);
}
}
void kpatch_create_symtab(struct kpatch_elf *kelf)
{
struct section *symtab;
struct symbol *sym;
char *buf;
size_t size;
int nr = 0, offset = 0, nr_local = 0;
symtab = find_section_by_name(&kelf->sections, ".symtab");
if (!symtab)
ERROR("find_section_by_name");
/* count symbols */
list_for_each_entry(sym, &kelf->symbols, list)
nr++;
/* create new symtab buffer */
size = nr * symtab->sh.sh_entsize;
buf = malloc(size);
if (!buf)
ERROR("malloc");
memset(buf, 0, size);
offset = 0;
list_for_each_entry(sym, &kelf->symbols, list) {
memcpy(buf + offset, &sym->sym, symtab->sh.sh_entsize);
offset += symtab->sh.sh_entsize;
if (is_local_sym(sym))
nr_local++;
}
symtab->data->d_buf = buf;
symtab->data->d_size = size;
/* update symtab section header */
symtab->sh.sh_link = find_section_by_name(&kelf->sections, ".strtab")->index;
symtab->sh.sh_info = nr_local;
}
struct section *create_section_pair(struct kpatch_elf *kelf, char *name,
int entsize, int nr)
{
char *relaname;
struct section *sec, *relasec;
int size = entsize * nr;
relaname = malloc(strlen(name) + strlen(".rela") + 1);
if (!relaname)
ERROR("malloc");
strcpy(relaname, ".rela");
strcat(relaname, name);
/* allocate text section resources */
ALLOC_LINK(sec, &kelf->sections);
sec->name = name;
/* set data */
sec->data = malloc(sizeof(*sec->data));
if (!sec->data)
ERROR("malloc");
sec->data->d_buf = malloc(size);
if (!sec->data->d_buf)
ERROR("malloc");
sec->data->d_size = size;
sec->data->d_type = ELF_T_BYTE;
/* set section header */
sec->sh.sh_type = SHT_PROGBITS;
sec->sh.sh_entsize = entsize;
sec->sh.sh_addralign = 8;
sec->sh.sh_flags = SHF_ALLOC;
sec->sh.sh_size = size;
/* allocate rela section resources */
ALLOC_LINK(relasec, &kelf->sections);
relasec->name = relaname;
relasec->base = sec;
INIT_LIST_HEAD(&relasec->relas);
/* set data, buffers generated by kpatch_rebuild_rela_section_data() */
relasec->data = malloc(sizeof(*relasec->data));
if (!relasec->data)
ERROR("malloc");
/* set section header */
relasec->sh.sh_type = SHT_RELA;
relasec->sh.sh_entsize = sizeof(GElf_Rela);
relasec->sh.sh_addralign = 8;
/* set text rela section pointer */
sec->rela = relasec;
return sec;
}
void kpatch_write_output_elf(struct kpatch_elf *kelf, Elf *elf, char *outfile)
{
int fd;
struct section *sec;
Elf *elfout;
GElf_Ehdr eh, ehout;
Elf_Scn *scn;
Elf_Data *data;
GElf_Shdr sh;
/* TODO make this argv */
fd = creat(outfile, 0777);
if (fd == -1)
ERROR("creat");
elfout = elf_begin(fd, ELF_C_WRITE, NULL);
if (!elfout)
ERROR("elf_begin");
if (!gelf_newehdr(elfout, gelf_getclass(kelf->elf)))
ERROR("gelf_newehdr");
if (!gelf_getehdr(elfout, &ehout))
ERROR("gelf_getehdr");
if (!gelf_getehdr(elf, &eh))
ERROR("gelf_getehdr");
memset(&ehout, 0, sizeof(ehout));
ehout.e_ident[EI_DATA] = eh.e_ident[EI_DATA];
ehout.e_machine = eh.e_machine;
ehout.e_type = eh.e_type;
ehout.e_version = EV_CURRENT;
ehout.e_shstrndx = find_section_by_name(&kelf->sections, ".shstrtab")->index;
/* add changed sections */
list_for_each_entry(sec, &kelf->sections, list) {
scn = elf_newscn(elfout);
if (!scn)
ERROR("elf_newscn");
data = elf_newdata(scn);
if (!data)
ERROR("elf_newdata");
if (!elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY))
ERROR("elf_flagdata");
data->d_type = sec->data->d_type;
data->d_buf = sec->data->d_buf;
data->d_size = sec->data->d_size;
if(!gelf_getshdr(scn, &sh))
ERROR("gelf_getshdr");
sh = sec->sh;
if (!gelf_update_shdr(scn, &sh))
ERROR("gelf_update_shdr");
}
if (!gelf_update_ehdr(elfout, &ehout))
ERROR("gelf_update_ehdr");
if (elf_update(elfout, ELF_C_WRITE) < 0) {
printf("%s\n",elf_errmsg(-1));
ERROR("elf_update");
}
}
/*
* While this is a one-shot program without a lot of proper cleanup in case
* of an error, this function serves a debugging purpose: to break down and
* zero data structures we shouldn't be accessing anymore. This should
* help cause an immediate and obvious issue when a logic error leads to
* accessing data that is not intended to be accessed past a particular point.
*/
void kpatch_elf_teardown(struct kpatch_elf *kelf)
{
struct section *sec, *safesec;
struct symbol *sym, *safesym;
struct rela *rela, *saferela;
list_for_each_entry_safe(sec, safesec, &kelf->sections, list) {
if (is_rela_section(sec)) {
list_for_each_entry_safe(rela, saferela, &sec->relas, list) {
memset(rela, 0, sizeof(*rela));
free(rela);
}
memset(sec, 0, sizeof(*sec));
free(sec);
}
}
list_for_each_entry_safe(sym, safesym, &kelf->symbols, list) {
memset(sym, 0, sizeof(*sym));
free(sym);
}
INIT_LIST_HEAD(&kelf->sections);
INIT_LIST_HEAD(&kelf->symbols);
}
void kpatch_elf_free(struct kpatch_elf *kelf)
{
elf_end(kelf->elf);
close(kelf->fd);
memset(kelf, 0, sizeof(*kelf));
free(kelf);
}

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/*
* kpatch-elf.h
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA,
* 02110-1301, USA.
*/
#ifndef _KPATCH_ELF_H_
#define _KPATCH_ELF_H_
#include <gelf.h>
#include "list.h"
#include "log.h"
/*******************
* Data structures
* ****************/
struct section;
struct symbol;
struct rela;
enum status {
NEW,
CHANGED,
SAME
};
struct section {
struct list_head list;
struct section *twin;
GElf_Shdr sh;
Elf_Data *data;
char *name;
int index;
enum status status;
int include;
int ignore;
int grouped;
union {
struct { /* if (is_rela_section()) */
struct section *base;
struct list_head relas;
};
struct { /* else */
struct section *rela;
struct symbol *secsym, *sym;
};
};
};
struct symbol {
struct list_head list;
struct symbol *twin;
struct section *sec;
GElf_Sym sym;
char *name;
int index;
unsigned char bind, type;
enum status status;
union {
int include; /* used in the patched elf */
int strip; /* used in the output elf */
};
int has_fentry_call;
};
struct rela {
struct list_head list;
GElf_Rela rela;
struct symbol *sym;
unsigned int type;
int addend;
int offset;
char *string;
};
struct string {
struct list_head list;
char *name;
};
struct kpatch_elf {
Elf *elf;
struct list_head sections;
struct list_head symbols;
struct list_head strings;
int fd;
};
/*******************
* Helper functions
******************/
char *status_str(enum status status);
int is_rela_section(struct section *sec);
int is_text_section(struct section *sec);
int is_debug_section(struct section *sec);
struct section *find_section_by_index(struct list_head *list, unsigned int index);
struct section *find_section_by_name(struct list_head *list, const char *name);
struct symbol *find_symbol_by_index(struct list_head *list, size_t index);
struct symbol *find_symbol_by_name(struct list_head *list, const char *name);
#define ALLOC_LINK(_new, _list) \
{ \
(_new) = malloc(sizeof(*(_new))); \
if (!(_new)) \
ERROR("malloc"); \
memset((_new), 0, sizeof(*(_new))); \
INIT_LIST_HEAD(&(_new)->list); \
list_add_tail(&(_new)->list, (_list)); \
}
int offset_of_string(struct list_head *list, char *name);
/*************
* Functions
* **********/
void kpatch_create_rela_list(struct kpatch_elf *kelf, struct section *sec);
void kpatch_create_section_list(struct kpatch_elf *kelf);
void kpatch_create_symbol_list(struct kpatch_elf *kelf);
struct kpatch_elf *kpatch_elf_open(const char *name);
void kpatch_dump_kelf(struct kpatch_elf *kelf);
int is_null_sym(struct symbol *sym);
int is_file_sym(struct symbol *sym);
int is_local_func_sym(struct symbol *sym);
int is_local_sym(struct symbol *sym);
void print_strtab(char *buf, size_t size);
void kpatch_create_shstrtab(struct kpatch_elf *kelf);
void kpatch_create_strtab(struct kpatch_elf *kelf);
void kpatch_create_symtab(struct kpatch_elf *kelf);
struct section *create_section_pair(struct kpatch_elf *kelf, char *name,
int entsize, int nr);
void kpatch_write_output_elf(struct kpatch_elf *kelf, Elf *elf, char *outfile);
void kpatch_elf_teardown(struct kpatch_elf *kelf);
void kpatch_elf_free(struct kpatch_elf *kelf);
#endif /* _KPATCH_ELF_H_ */

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#ifndef _LOG_H_
#define _LOG_H_
/* Files that include log.h must define loglevel and childobj */
extern enum loglevel loglevel;
extern char *childobj;
#define ERROR(format, ...) \
error(1, 0, "ERROR: %s: %s: %d: " format, childobj, __FUNCTION__, __LINE__, ##__VA_ARGS__)
#define log_debug(format, ...) log(DEBUG, format, ##__VA_ARGS__)
#define log_normal(format, ...) log(NORMAL, "%s: " format, childobj, ##__VA_ARGS__)
#define log(level, format, ...) \
({ \
if (loglevel <= (level)) \
printf(format, ##__VA_ARGS__); \
})
enum loglevel {
DEBUG,
NORMAL
};
#endif /* _LOG_H_ */