[tip: core/objtool] scripts/sortextable: Rewrite error/success handling

From: tip-bot2 for Shile Zhang
Date: Fri Dec 13 2019 - 05:03:58 EST

The following commit has been merged into the core/objtool branch of tip:

Commit-ID: 3c47b787b6516d2c3cbaa193fe13a83adbaaad1f
Gitweb: https://git.kernel.org/tip/3c47b787b6516d2c3cbaa193fe13a83adbaaad1f
Author: Shile Zhang <shile.zhang@xxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 04 Dec 2019 08:46:27 +08:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 13 Dec 2019 10:47:31 +01:00

scripts/sortextable: Rewrite error/success handling

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:

3f1df12019f3 ("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@xxxxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
Cc: linux-kbuild@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20191204004633.88660-2-shile.zhang@xxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
scripts/sortextable.c | 119 ++++++++++++++---------------------------
scripts/sortextable.h | 11 ++--
2 files changed, 48 insertions(+), 82 deletions(-)

diff --git a/scripts/sortextable.c b/scripts/sortextable.c
index 5576865..cd9762b 100644
--- a/scripts/sortextable.c
+++ b/scripts/sortextable.c
@@ -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>
@@ -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;
}

@@ -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;
@@ -298,7 +276,7 @@ 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;
@@ -306,7 +284,6 @@ do_file(char const *const fname)
default:
fprintf(stderr, "unrecognized e_machine %d %s\n",
r2(&ehdr->e_machine), fname);
- fail_file();
break;
case EM_386:
case EM_X86_64:
@@ -333,16 +310,15 @@ 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;
@@ -350,21 +326,22 @@ do_file(char const *const fname)
|| 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");
@@ -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;
}
diff --git a/scripts/sortextable.h b/scripts/sortextable.h
index d4b3f6c..5a62e94 100644
--- a/scripts/sortextable.h
+++ b/scripts/sortextable.h
@@ -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;
@@ -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);

@@ -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,
@@ -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;
}