/* * 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_AARCH64 #define EM_AARCH64 183 #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\n", 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\n", 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\n", 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\n", fname); fail_file(); } 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: case EM_S390: custom_sort = sort_relative_table; break; case EM_ARM: case EM_AARCH64: case EM_MIPS: break; } /* end switch */ switch (ehdr->e_ident[EI_CLASS]) { 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 file: %s\n", 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\n", 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...\n"); 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\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 */ ++n_error; break; case SJ_SUCCEED: /* premature success */ /* do nothing */ break; } /* end switch */ } return !!n_error; }