/*
   * sortextable.c: Sort the kernel's exception table
   *

   * Copyright 2011 - 2012 Cavium, Inc.

   *
   * Based on code taken from recortmcount.c which is:
   *
   * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
   * Licensed under the GNU General Public License, version 2 (GPLv2).
   *
   * Restructured to fit Linux format, as well as other updates:
   *  Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
   */
  
  /*
   * Strategy: alter the vmlinux file in-place.
   */
  
  #include <sys/types.h>
  #include <sys/mman.h>
  #include <sys/stat.h>
  #include <getopt.h>
  #include <elf.h>
  #include <fcntl.h>
  #include <setjmp.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>

  #include <tools/be_byteshift.h>
  #include <tools/le_byteshift.h>

  #ifndef EM_ARCOMPACT
  #define EM_ARCOMPACT	93
  #endif

  #ifndef EM_XTENSA
  #define EM_XTENSA	94
  #endif

  #ifndef EM_AARCH64
  #define EM_AARCH64	183
  #endif

  #ifndef EM_MICROBLAZE
  #define EM_MICROBLAZE	189
  #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)
  {
  	void *addr;
  
  	fd_map = open(fname, O_RDWR);
  	if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
  		perror(fname);
  		fail_file();
  	}
  	if (!S_ISREG(sb.st_mode)) {
  		fprintf(stderr, "not a regular file: %s
  ", fname);
  		fail_file();
  	}
  	addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
  		    fd_map, 0);
  	if (addr == MAP_FAILED) {
  		mmap_failed = 1;
  		fprintf(stderr, "Could not mmap file: %s
  ", fname);
  		fail_file();
  	}
  	return addr;
  }

  static uint64_t r8be(const uint64_t *x)

  {

  	return get_unaligned_be64(x);

  }

  static uint32_t rbe(const uint32_t *x)

  {

  	return get_unaligned_be32(x);

  }

  static uint16_t r2be(const uint16_t *x)

  {

  	return get_unaligned_be16(x);

  }

  static uint64_t r8le(const uint64_t *x)

  {

  	return get_unaligned_le64(x);

  }

  static uint32_t rle(const uint32_t *x)
  {
  	return get_unaligned_le32(x);
  }
  static uint16_t r2le(const uint16_t *x)

  {

  	return get_unaligned_le16(x);

  }

  static void w8be(uint64_t val, uint64_t *x)
  {
  	put_unaligned_be64(val, x);
  }
  static void wbe(uint32_t val, uint32_t *x)
  {
  	put_unaligned_be32(val, x);
  }
  static void w2be(uint16_t val, uint16_t *x)
  {
  	put_unaligned_be16(val, x);
  }
  static void w8le(uint64_t val, uint64_t *x)
  {
  	put_unaligned_le64(val, x);
  }
  static void wle(uint32_t val, uint32_t *x)
  {
  	put_unaligned_le32(val, x);
  }
  static void w2le(uint16_t val, uint16_t *x)

  {

  	put_unaligned_le16(val, x);

  }

  static uint64_t (*r8)(const uint64_t *);
  static uint32_t (*r)(const uint32_t *);
  static uint16_t (*r2)(const uint16_t *);
  static void (*w8)(uint64_t, uint64_t *);
  static void (*w)(uint32_t, uint32_t *);
  static void (*w2)(uint16_t, uint16_t *);

  typedef void (*table_sort_t)(char *, int);

  /*
   * 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))
  
  static inline int is_shndx_special(unsigned int i)
  {
  	return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
  }
  
  /* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
  static inline unsigned int get_secindex(unsigned int shndx,
  					unsigned int sym_offs,
  					const Elf32_Word *symtab_shndx_start)
  {
  	if (is_shndx_special(shndx))
  		return SPECIAL(shndx);
  	if (shndx != SHN_XINDEX)
  		return shndx;
  	return r(&symtab_shndx_start[sym_offs]);
  }

  /* 32 bit and 64 bit are very similar */
  #include "sortextable.h"
  #define SORTEXTABLE_64
  #include "sortextable.h"

  static int compare_relative_table(const void *a, const void *b)

  {
  	int32_t av = (int32_t)r(a);
  	int32_t bv = (int32_t)r(b);
  
  	if (av < bv)
  		return -1;
  	if (av > bv)
  		return 1;
  	return 0;
  }

  static void sort_relative_table(char *extab_image, int image_size)

  {
  	int i;
  
  	/*
  	 * Do the same thing the runtime sort does, first normalize to
  	 * being relative to the start of the section.
  	 */
  	i = 0;
  	while (i < image_size) {
  		uint32_t *loc = (uint32_t *)(extab_image + i);
  		w(r(loc) + i, loc);
  		i += 4;
  	}

  	qsort(extab_image, image_size / 8, 8, compare_relative_table);

  
  	/* Now denormalize. */
  	i = 0;
  	while (i < image_size) {
  		uint32_t *loc = (uint32_t *)(extab_image + i);
  		w(r(loc) - i, loc);
  		i += 4;
  	}
  }

  
  static void
  do_file(char const *const fname)
  {

  	table_sort_t custom_sort;
  	Elf32_Ehdr *ehdr = mmap_file(fname);

  
  	ehdr_curr = ehdr;

  	switch (ehdr->e_ident[EI_DATA]) {

  	default:
  		fprintf(stderr, "unrecognized ELF data encoding %d: %s
  ",
  			ehdr->e_ident[EI_DATA], fname);
  		fail_file();
  		break;
  	case ELFDATA2LSB:

  		r = rle;
  		r2 = r2le;
  		r8 = r8le;
  		w = wle;
  		w2 = w2le;
  		w8 = w8le;

  		break;
  	case ELFDATA2MSB:

  		r = rbe;
  		r2 = r2be;
  		r8 = r8be;
  		w = wbe;
  		w2 = w2be;
  		w8 = w8be;

  		break;
  	}  /* end switch */
  	if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0

  	||  r2(&ehdr->e_type) != ET_EXEC

  	||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
  		fprintf(stderr, "unrecognized ET_EXEC file %s
  ", fname);
  		fail_file();
  	}

  	custom_sort = NULL;
  	switch (r2(&ehdr->e_machine)) {

  	default:
  		fprintf(stderr, "unrecognized e_machine %d %s
  ",

  			r2(&ehdr->e_machine), fname);

  		fail_file();
  		break;
  	case EM_386:

  	case EM_X86_64:

  	case EM_S390:

  		custom_sort = sort_relative_table;
  		break;

  	case EM_ARCOMPACT:

  	case EM_ARM:

  	case EM_AARCH64:

  	case EM_MICROBLAZE:

  	case EM_MIPS:

  	case EM_XTENSA:

  		break;
  	}  /* end switch */
  
  	switch (ehdr->e_ident[EI_CLASS]) {
  	default:
  		fprintf(stderr, "unrecognized ELF class %d %s
  ",
  			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 file: %s
  ", fname);
  			fail_file();
  		}

  		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 file: %s
  ", fname);
  			fail_file();
  		}

  		do64(ghdr, fname, custom_sort);

  		break;
  	}
  	}  /* end switch */
  
  	cleanup();
  }
  
  int
  main(int argc, char *argv[])
  {
  	int n_error = 0;  /* gcc-4.3.0 false positive complaint */
  	int i;
  
  	if (argc < 2) {
  		fprintf(stderr, "usage: sortextable vmlinux...
  ");
  		return 0;
  	}
  
  	/* Process each file in turn, allowing deep failure. */
  	for (i = 1; i < argc; i++) {
  		char *file = argv[i];
  		int const sjval = setjmp(jmpenv);
  
  		switch (sjval) {
  		default:
  			fprintf(stderr, "internal error: %s
  ", 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 */
  			++n_error;
  			break;
  		case SJ_SUCCEED:    /* premature success */
  			/* do nothing */
  			break;
  		}  /* end switch */
  	}
  	return !!n_error;
  }