Skip to content

Commit

Permalink
scripts/sortextable: Rewrite error/success handling
Browse files Browse the repository at this point in the history 
The scripts/sortextable.c code has originally copied some code from
scripts/recordmount.c, which used the same setjmp/longjmp method to
manage control flow.

Meanwhile recordmcount has improved its error handling via:

   3f1df12 ("recordmcount: Rewrite error/success handling").

So rewrite this part of sortextable as well to get rid of the setjmp/longjmp
kludges, with additional refactoring, to make it more readable and
easier to extend.

No functional changes intended.

[ mingo: Rewrote the changelog. ]

Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: linux-kbuild@vger.kernel.org
Link: https://lkml.kernel.org/r/20191204004633.88660-2-shile.zhang@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
  • Loading branch information
Shile Zhang authored and Ingo Molnar committed Dec 13, 2019
1 parent 37d4e84 commit 3c47b78
Show file tree
Hide file tree
Showing 2 changed files with 48 additions and 82 deletions.
119 changes: 42 additions & 77 deletions scripts/sortextable.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@
#include <getopt.h>
#include <elf.h>
#include <fcntl.h>
#include <setjmp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
Expand Down Expand Up @@ -51,61 +50,41 @@
#define EM_ARCV2 195
#endif

static int fd_map; /* File descriptor for file being modified. */
static int mmap_failed; /* Boolean flag. */
static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */
static struct stat sb; /* Remember .st_size, etc. */
static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */

/* setjmp() return values */
enum {
SJ_SETJMP = 0, /* hardwired first return */
SJ_FAIL,
SJ_SUCCEED
};

/* Per-file resource cleanup when multiple files. */
static void
cleanup(void)
{
if (!mmap_failed)
munmap(ehdr_curr, sb.st_size);
close(fd_map);
}

static void __attribute__((noreturn))
fail_file(void)
{
cleanup();
longjmp(jmpenv, SJ_FAIL);
}

/*
* Get the whole file as a programming convenience in order to avoid
* malloc+lseek+read+free of many pieces. If successful, then mmap
* avoids copying unused pieces; else just read the whole file.
* Open for both read and write.
*/
static void *mmap_file(char const *fname)
static void *mmap_file(char const *fname, size_t *size)
{
void *addr;
int fd;
struct stat sb;
void *addr = NULL;

fd_map = open(fname, O_RDWR);
if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
fd = open(fname, O_RDWR);
if (fd < 0) {
perror(fname);
fail_file();
return NULL;
}
if (fstat(fd, &sb) < 0) {
perror(fname);
goto out;
}
if (!S_ISREG(sb.st_mode)) {
fprintf(stderr, "not a regular file: %s\n", fname);
fail_file();
goto out;
}
addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
fd_map, 0);
addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) {
mmap_failed = 1;
fprintf(stderr, "Could not mmap file: %s\n", fname);
fail_file();
goto out;
}

*size = sb.st_size;

out:
close(fd);
return addr;
}

Expand Down Expand Up @@ -264,19 +243,18 @@ static void sort_relative_table(char *extab_image, int image_size)
}
}

static void
do_file(char const *const fname)
static int
do_file(char const *const fname, void *addr)
{
table_sort_t custom_sort;
Elf32_Ehdr *ehdr = mmap_file(fname);
table_sort_t custom_sort = NULL;
Elf32_Ehdr *ehdr = addr;
int rc = -1;

ehdr_curr = ehdr;
switch (ehdr->e_ident[EI_DATA]) {
default:
fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
ehdr->e_ident[EI_DATA], fname);
fail_file();
break;
return -1;
case ELFDATA2LSB:
r = rle;
r2 = r2le;
Expand All @@ -298,15 +276,14 @@ do_file(char const *const fname)
|| (r2(&ehdr->e_type) != ET_EXEC && r2(&ehdr->e_type) != ET_DYN)
|| ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
fprintf(stderr, "unrecognized ET_EXEC/ET_DYN file %s\n", fname);
fail_file();
return -1;
}

custom_sort = NULL;
switch (r2(&ehdr->e_machine)) {
default:
fprintf(stderr, "unrecognized e_machine %d %s\n",
r2(&ehdr->e_machine), fname);
fail_file();
break;
case EM_386:
case EM_X86_64:
Expand All @@ -333,38 +310,38 @@ do_file(char const *const fname)
default:
fprintf(stderr, "unrecognized ELF class %d %s\n",
ehdr->e_ident[EI_CLASS], fname);
fail_file();
break;
case ELFCLASS32:
if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
|| r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
fail_file();
break;
}
do32(ehdr, fname, custom_sort);
rc = do32(ehdr, fname, custom_sort);
break;
case ELFCLASS64: {
Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
|| r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
fail_file();
break;
}
do64(ghdr, fname, custom_sort);
rc = do64(ghdr, fname, custom_sort);
break;
}
} /* end switch */

cleanup();
return rc;
}

int
main(int argc, char *argv[])
{
int n_error = 0; /* gcc-4.3.0 false positive complaint */
int i;
int i, n_error = 0; /* gcc-4.3.0 false positive complaint */
size_t size = 0;
void *addr = NULL;

if (argc < 2) {
fprintf(stderr, "usage: sortextable vmlinux...\n");
Expand All @@ -373,28 +350,16 @@ main(int argc, char *argv[])

/* Process each file in turn, allowing deep failure. */
for (i = 1; i < argc; i++) {
char *file = argv[i];
int const sjval = setjmp(jmpenv);
addr = mmap_file(argv[i], &size);
if (!addr) {
++n_error;
continue;
}

switch (sjval) {
default:
fprintf(stderr, "internal error: %s\n", file);
exit(1);
break;
case SJ_SETJMP: /* normal sequence */
/* Avoid problems if early cleanup() */
fd_map = -1;
ehdr_curr = NULL;
mmap_failed = 1;
do_file(file);
break;
case SJ_FAIL: /* error in do_file or below */
if (do_file(argv[i], addr))
++n_error;
break;
case SJ_SUCCEED: /* premature success */
/* do nothing */
break;
} /* end switch */

munmap(addr, size);
}
return !!n_error;
}
11 changes: 6 additions & 5 deletions scripts/sortextable.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,7 @@ static int compare_extable(const void *a, const void *b)
return 0;
}

static void
static int
do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
{
Elf_Shdr *shdr;
Expand Down Expand Up @@ -146,17 +146,17 @@ do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
}
if (strtab_sec == NULL) {
fprintf(stderr, "no .strtab in file: %s\n", fname);
fail_file();
return -1;
}
if (symtab_sec == NULL) {
fprintf(stderr, "no .symtab in file: %s\n", fname);
fail_file();
return -1;
}
symtab = (const Elf_Sym *)((const char *)ehdr +
_r(&symtab_sec->sh_offset));
if (extab_sec == NULL) {
fprintf(stderr, "no __ex_table in file: %s\n", fname);
fail_file();
return -1;
}
strtab = (const char *)ehdr + _r(&strtab_sec->sh_offset);

Expand Down Expand Up @@ -190,7 +190,7 @@ do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
fprintf(stderr,
"no main_extable_sort_needed symbol in file: %s\n",
fname);
fail_file();
return -1;
}
sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
sort_needed_sym - symtab,
Expand All @@ -206,4 +206,5 @@ do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
#endif
/* We sorted it, clear the flag. */
w(0, sort_done_location);
return 0;
}

0 comments on commit 3c47b78

Please sign in to comment.