linux-stable/scripts/mod/modpost.h
Masahiro Yamada 0fd3fbadd9 modpost: refactor error handling and clarify error/fatal difference
We have 3 log functions. fatal() is special because it lets modpost bail
out immediately. The difference between warn() and error() is the only
prefix parts ("WARNING:" vs "ERROR:").

In my understanding, the expected handling of error() is to propagate
the return code of the function to the exit code of modpost, as
check_exports() etc. already does. This is a good manner in general
because we should display as many error messages as possible in a
single run of modpost.

What is annoying about fatal() is that it kills modpost at the first
error. People would need to run Kbuild again and again until they fix
all errors.

But, unfortunately, people tend to do:
"This case should not be allowed. Let's replace warn() with fatal()."

One of the reasons is probably it is tedious to manually hoist the error
code to the main() function.

This commit refactors error() so any single call for it automatically
makes modpost return the error code.

I also added comments in modpost.h for warn(), error(), and fatal().

Please use fatal() only when you have a strong reason to do so.
For example:

  - Memory shortage (i.e. malloc() etc. has failed)
  - The ELF file is broken, and there is no point to continue parsing
  - Something really odd has happened

For general coding errors, please use error().

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Quentin Perret <qperret@google.com>
2020-12-21 13:57:08 +09:00

219 lines
5.7 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <elf.h>
#include "elfconfig.h"
/* On BSD-alike OSes elf.h defines these according to host's word size */
#undef ELF_ST_BIND
#undef ELF_ST_TYPE
#undef ELF_R_SYM
#undef ELF_R_TYPE
#if KERNEL_ELFCLASS == ELFCLASS32
#define Elf_Ehdr Elf32_Ehdr
#define Elf_Shdr Elf32_Shdr
#define Elf_Sym Elf32_Sym
#define Elf_Addr Elf32_Addr
#define Elf_Sword Elf64_Sword
#define Elf_Section Elf32_Half
#define ELF_ST_BIND ELF32_ST_BIND
#define ELF_ST_TYPE ELF32_ST_TYPE
#define Elf_Rel Elf32_Rel
#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
#define Elf_Shdr Elf64_Shdr
#define Elf_Sym Elf64_Sym
#define Elf_Addr Elf64_Addr
#define Elf_Sword Elf64_Sxword
#define Elf_Section Elf64_Half
#define ELF_ST_BIND ELF64_ST_BIND
#define ELF_ST_TYPE ELF64_ST_TYPE
#define Elf_Rel Elf64_Rel
#define Elf_Rela Elf64_Rela
#define ELF_R_SYM ELF64_R_SYM
#define ELF_R_TYPE ELF64_R_TYPE
#endif
/* The 64-bit MIPS ELF ABI uses an unusual reloc format. */
typedef struct
{
Elf32_Word r_sym; /* Symbol index */
unsigned char r_ssym; /* Special symbol for 2nd relocation */
unsigned char r_type3; /* 3rd relocation type */
unsigned char r_type2; /* 2nd relocation type */
unsigned char r_type1; /* 1st relocation type */
} _Elf64_Mips_R_Info;
typedef union
{
Elf64_Xword r_info_number;
_Elf64_Mips_R_Info r_info_fields;
} _Elf64_Mips_R_Info_union;
#define ELF64_MIPS_R_SYM(i) \
((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_sym)
#define ELF64_MIPS_R_TYPE(i) \
((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_type1)
#if KERNEL_ELFDATA != HOST_ELFDATA
static inline void __endian(const void *src, void *dest, unsigned int size)
{
unsigned int i;
for (i = 0; i < size; i++)
((unsigned char*)dest)[i] = ((unsigned char*)src)[size - i-1];
}
#define TO_NATIVE(x) \
({ \
typeof(x) __x; \
__endian(&(x), &(__x), sizeof(__x)); \
__x; \
})
#else /* endianness matches */
#define TO_NATIVE(x) (x)
#endif
#define NOFAIL(ptr) do_nofail((ptr), #ptr)
void *do_nofail(void *ptr, const char *expr);
struct buffer {
char *p;
int pos;
int size;
};
void __attribute__((format(printf, 2, 3)))
buf_printf(struct buffer *buf, const char *fmt, ...);
void
buf_write(struct buffer *buf, const char *s, int len);
struct namespace_list {
struct namespace_list *next;
char namespace[];
};
struct module {
struct module *next;
int gpl_compatible;
struct symbol *unres;
int from_dump; /* 1 if module was loaded from *.symvers */
int is_vmlinux;
int seen;
int has_init;
int has_cleanup;
struct buffer dev_table_buf;
char srcversion[25];
// Missing namespace dependencies
struct namespace_list *missing_namespaces;
// Actual imported namespaces
struct namespace_list *imported_namespaces;
char name[];
};
struct elf_info {
size_t size;
Elf_Ehdr *hdr;
Elf_Shdr *sechdrs;
Elf_Sym *symtab_start;
Elf_Sym *symtab_stop;
Elf_Section export_sec;
Elf_Section export_unused_sec;
Elf_Section export_gpl_sec;
Elf_Section export_unused_gpl_sec;
Elf_Section export_gpl_future_sec;
char *strtab;
char *modinfo;
unsigned int modinfo_len;
/* support for 32bit section numbers */
unsigned int num_sections; /* max_secindex + 1 */
unsigned int secindex_strings;
/* if Nth symbol table entry has .st_shndx = SHN_XINDEX,
* take shndx from symtab_shndx_start[N] instead */
Elf32_Word *symtab_shndx_start;
Elf32_Word *symtab_shndx_stop;
};
static inline int is_shndx_special(unsigned int i)
{
return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
}
/*
* Move reserved section indices SHN_LORESERVE..SHN_HIRESERVE out of
* the way to -256..-1, to avoid conflicting with real section
* indices.
*/
#define SPECIAL(i) ((i) - (SHN_HIRESERVE + 1))
/* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
static inline unsigned int get_secindex(const struct elf_info *info,
const Elf_Sym *sym)
{
if (is_shndx_special(sym->st_shndx))
return SPECIAL(sym->st_shndx);
if (sym->st_shndx != SHN_XINDEX)
return sym->st_shndx;
return info->symtab_shndx_start[sym - info->symtab_start];
}
/* file2alias.c */
extern unsigned int cross_build;
void handle_moddevtable(struct module *mod, struct elf_info *info,
Elf_Sym *sym, const char *symname);
void add_moddevtable(struct buffer *buf, struct module *mod);
/* sumversion.c */
void get_src_version(const char *modname, char sum[], unsigned sumlen);
/* from modpost.c */
char *read_text_file(const char *filename);
char *get_line(char **stringp);
enum loglevel {
LOG_WARN,
LOG_ERROR,
LOG_FATAL
};
void modpost_log(enum loglevel loglevel, const char *fmt, ...);
/*
* warn - show the given message, then let modpost continue running, still
* allowing modpost to exit successfully. This should be used when
* we still allow to generate vmlinux and modules.
*
* error - show the given message, then let modpost continue running, but fail
* in the end. This should be used when we should stop building vmlinux
* or modules, but we can continue running modpost to catch as many
* issues as possible.
*
* fatal - show the given message, and bail out immediately. This should be
* used when there is no point to continue running modpost.
*/
#define warn(fmt, args...) modpost_log(LOG_WARN, fmt, ##args)
#define error(fmt, args...) modpost_log(LOG_ERROR, fmt, ##args)
#define fatal(fmt, args...) modpost_log(LOG_FATAL, fmt, ##args)