Commit 3c47b787 authored by Shile Zhang's avatar Shile Zhang Committed by Ingo Molnar
Browse files

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:

   3f1df120 ("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: default avatarShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: default avatarPeter 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: default avatarIngo Molnar <mingo@kernel.org>
parent 37d4e84f

scripts/sortextable.c

+42 −77
Original line number Diff line number Diff line
@@ -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;

}

scripts/sortextable.h

+6 −5
Original line number Diff line number Diff line
@@ -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;

}

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