nbd: fix use-after-free of rq/bio in the xmit path
[pandora-kernel.git] / scripts / recordmcount.c
index f9f6f52..0d5ae4a 100644 (file)
@@ -24,6 +24,7 @@
 #include <sys/types.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
+#include <getopt.h>
 #include <elf.h>
 #include <fcntl.h>
 #include <setjmp.h>
 
 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 char gpfx;      /* prefix for global symbol name (sometimes '_') */
 static struct stat sb; /* Remember .st_size, etc. */
 static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
 static const char *altmcount;  /* alternate mcount symbol name */
+static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
+static void *file_map; /* pointer of the mapped file */
+static void *file_end; /* pointer to the end of the mapped file */
+static int file_updated; /* flag to state file was changed */
+static void *file_ptr; /* current file pointer location */
+static void *file_append; /* added to the end of the file */
+static size_t file_append_size; /* how much is added to end of file */
 
 /* setjmp() return values */
 enum {
@@ -52,10 +59,14 @@ static void
 cleanup(void)
 {
        if (!mmap_failed)
-               munmap(ehdr_curr, sb.st_size);
+               munmap(file_map, sb.st_size);
        else
-               free(ehdr_curr);
-       close(fd_map);
+               free(file_map);
+       file_map = NULL;
+       free(file_append);
+       file_append = NULL;
+       file_append_size = 0;
+       file_updated = 0;
 }
 
 static void __attribute__((noreturn))
@@ -77,12 +88,22 @@ succeed_file(void)
 static off_t
 ulseek(int const fd, off_t const offset, int const whence)
 {
-       off_t const w = lseek(fd, offset, whence);
-       if ((off_t)-1 == w) {
-               perror("lseek");
+       switch (whence) {
+       case SEEK_SET:
+               file_ptr = file_map + offset;
+               break;
+       case SEEK_CUR:
+               file_ptr += offset;
+               break;
+       case SEEK_END:
+               file_ptr = file_map + (sb.st_size - offset);
+               break;
+       }
+       if (file_ptr < file_map) {
+               fprintf(stderr, "lseek: seek before file\n");
                fail_file();
        }
-       return w;
+       return file_ptr - file_map;
 }
 
 static size_t
@@ -99,25 +120,79 @@ uread(int const fd, void *const buf, size_t const count)
 static size_t
 uwrite(int const fd, void const *const buf, size_t const count)
 {
-       size_t const n = write(fd, buf, count);
-       if (n != count) {
-               perror("write");
-               fail_file();
+       size_t cnt = count;
+       off_t idx = 0;
+
+       file_updated = 1;
+
+       if (file_ptr + count >= file_end) {
+               off_t aoffset = (file_ptr + count) - file_end;
+
+               if (aoffset > file_append_size) {
+                       file_append = realloc(file_append, aoffset);
+                       file_append_size = aoffset;
+               }
+               if (!file_append) {
+                       perror("write");
+                       fail_file();
+               }
+               if (file_ptr < file_end) {
+                       cnt = file_end - file_ptr;
+               } else {
+                       cnt = 0;
+                       idx = aoffset - count;
+               }
        }
-       return n;
+
+       if (cnt)
+               memcpy(file_ptr, buf, cnt);
+
+       if (cnt < count)
+               memcpy(file_append + idx, buf + cnt, count - cnt);
+
+       file_ptr += count;
+       return count;
 }
 
 static void *
 umalloc(size_t size)
 {
        void *const addr = malloc(size);
-       if (0 == addr) {
+       if (addr == 0) {
                fprintf(stderr, "malloc failed: %zu bytes\n", size);
                fail_file();
        }
        return addr;
 }
 
+static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
+static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
+static unsigned char *ideal_nop;
+
+static char rel_type_nop;
+
+static int (*make_nop)(void *map, size_t const offset);
+
+static int make_nop_x86(void *map, size_t const offset)
+{
+       uint32_t *ptr;
+       unsigned char *op;
+
+       /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
+       ptr = map + offset;
+       if (*ptr != 0)
+               return -1;
+
+       op = map + offset - 1;
+       if (*op != 0xe8)
+               return -1;
+
+       /* convert to nop */
+       ulseek(fd_map, offset - 1, SEEK_SET);
+       uwrite(fd_map, ideal_nop, 5);
+       return 0;
+}
+
 /*
  * Get the whole file as a programming convenience in order to avoid
  * malloc+lseek+read+free of many pieces.  If successful, then mmap
@@ -133,10 +208,8 @@ umalloc(size_t size)
  */
 static void *mmap_file(char const *fname)
 {
-       void *addr;
-
-       fd_map = open(fname, O_RDWR);
-       if (0 > fd_map || 0 > fstat(fd_map, &sb)) {
+       fd_map = open(fname, O_RDONLY);
+       if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
                perror(fname);
                fail_file();
        }
@@ -144,15 +217,58 @@ static void *mmap_file(char const *fname)
                fprintf(stderr, "not a regular file: %s\n", fname);
                fail_file();
        }
-       addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
-                   fd_map, 0);
+       file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
+                       fd_map, 0);
        mmap_failed = 0;
-       if (MAP_FAILED == addr) {
+       if (file_map == MAP_FAILED) {
                mmap_failed = 1;
-               addr = umalloc(sb.st_size);
-               uread(fd_map, addr, sb.st_size);
+               file_map = umalloc(sb.st_size);
+               uread(fd_map, file_map, sb.st_size);
+       }
+       close(fd_map);
+
+       file_end = file_map + sb.st_size;
+
+       return file_map;
+}
+
+static void write_file(const char *fname)
+{
+       char tmp_file[strlen(fname) + 4];
+       size_t n;
+
+       if (!file_updated)
+               return;
+
+       sprintf(tmp_file, "%s.rc", fname);
+
+       /*
+        * After reading the entire file into memory, delete it
+        * and write it back, to prevent weird side effects of modifying
+        * an object file in place.
+        */
+       fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
+       if (fd_map < 0) {
+               perror(fname);
+               fail_file();
+       }
+       n = write(fd_map, file_map, sb.st_size);
+       if (n != sb.st_size) {
+               perror("write");
+               fail_file();
+       }
+       if (file_append_size) {
+               n = write(fd_map, file_append, file_append_size);
+               if (n != file_append_size) {
+                       perror("write");
+                       fail_file();
+               }
+       }
+       close(fd_map);
+       if (rename(tmp_file, fname) < 0) {
+               perror(fname);
+               fail_file();
        }
-       return addr;
 }
 
 /* w8rev, w8nat, ...: Handle endianness. */
@@ -206,12 +322,13 @@ static uint32_t (*w2)(uint16_t);
 static int
 is_mcounted_section_name(char const *const txtname)
 {
-       return 0 == strcmp(".text",           txtname) ||
-               0 == strcmp(".ref.text",      txtname) ||
-               0 == strcmp(".sched.text",    txtname) ||
-               0 == strcmp(".spinlock.text", txtname) ||
-               0 == strcmp(".irqentry.text", txtname) ||
-               0 == strcmp(".text.unlikely", txtname);
+       return strcmp(".text",           txtname) == 0 ||
+               strcmp(".ref.text",      txtname) == 0 ||
+               strcmp(".sched.text",    txtname) == 0 ||
+               strcmp(".spinlock.text", txtname) == 0 ||
+               strcmp(".irqentry.text", txtname) == 0 ||
+               strcmp(".kprobes.text", txtname) == 0 ||
+               strcmp(".text.unlikely", txtname) == 0;
 }
 
 /* 32 bit and 64 bit are very similar */
@@ -258,49 +375,53 @@ do_file(char const *const fname)
        Elf32_Ehdr *const ehdr = mmap_file(fname);
        unsigned int reltype = 0;
 
-       ehdr_curr = ehdr;
        w = w4nat;
        w2 = w2nat;
        w8 = w8nat;
        switch (ehdr->e_ident[EI_DATA]) {
                static unsigned int const endian = 1;
-       default: {
+       default:
                fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
                        ehdr->e_ident[EI_DATA], fname);
                fail_file();
-       } break;
-       case ELFDATA2LSB: {
-               if (1 != *(unsigned char const *)&endian) {
+               break;
+       case ELFDATA2LSB:
+               if (*(unsigned char const *)&endian != 1) {
                        /* main() is big endian, file.o is little endian. */
                        w = w4rev;
                        w2 = w2rev;
                        w8 = w8rev;
                }
-       } break;
-       case ELFDATA2MSB: {
-               if (0 != *(unsigned char const *)&endian) {
+               break;
+       case ELFDATA2MSB:
+               if (*(unsigned char const *)&endian != 0) {
                        /* main() is little endian, file.o is big endian. */
                        w = w4rev;
                        w2 = w2rev;
                        w8 = w8rev;
                }
-       } break;
+               break;
        }  /* end switch */
-       if (0 != memcmp(ELFMAG, ehdr->e_ident, SELFMAG)
-       ||  ET_REL != w2(ehdr->e_type)
-       ||  EV_CURRENT != ehdr->e_ident[EI_VERSION]) {
+       if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
+       ||  w2(ehdr->e_type) != ET_REL
+       ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
                fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
                fail_file();
        }
 
        gpfx = 0;
        switch (w2(ehdr->e_machine)) {
-       default: {
+       default:
                fprintf(stderr, "unrecognized e_machine %d %s\n",
                        w2(ehdr->e_machine), fname);
                fail_file();
-       } break;
-       case EM_386:     reltype = R_386_32;                   break;
+               break;
+       case EM_386:
+               reltype = R_386_32;
+               make_nop = make_nop_x86;
+               ideal_nop = ideal_nop5_x86_32;
+               mcount_adjust_32 = -1;
+               break;
        case EM_ARM:     reltype = R_ARM_ABS32;
                         altmcount = "__gnu_mcount_nc";
                         break;
@@ -311,67 +432,92 @@ do_file(char const *const fname)
        case EM_S390:    /* reltype: e_class    */ gpfx = '_'; break;
        case EM_SH:      reltype = R_SH_DIR32;                 break;
        case EM_SPARCV9: reltype = R_SPARC_64;     gpfx = '_'; break;
-       case EM_X86_64:  reltype = R_X86_64_64;                break;
+       case EM_X86_64:
+               make_nop = make_nop_x86;
+               ideal_nop = ideal_nop5_x86_64;
+               reltype = R_X86_64_64;
+               mcount_adjust_64 = -1;
+               break;
        }  /* end switch */
 
        switch (ehdr->e_ident[EI_CLASS]) {
-       default: {
+       default:
                fprintf(stderr, "unrecognized ELF class %d %s\n",
                        ehdr->e_ident[EI_CLASS], fname);
                fail_file();
-       } break;
-       case ELFCLASS32: {
-               if (sizeof(Elf32_Ehdr) != w2(ehdr->e_ehsize)
-               ||  sizeof(Elf32_Shdr) != w2(ehdr->e_shentsize)) {
+               break;
+       case ELFCLASS32:
+               if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
+               ||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
                        fprintf(stderr,
                                "unrecognized ET_REL file: %s\n", fname);
                        fail_file();
                }
-               if (EM_S390 == w2(ehdr->e_machine))
+               if (w2(ehdr->e_machine) == EM_S390) {
                        reltype = R_390_32;
-               if (EM_MIPS == w2(ehdr->e_machine)) {
+                       mcount_adjust_32 = -4;
+               }
+               if (w2(ehdr->e_machine) == EM_MIPS) {
                        reltype = R_MIPS_32;
                        is_fake_mcount32 = MIPS32_is_fake_mcount;
                }
                do32(ehdr, fname, reltype);
-       } break;
+               break;
        case ELFCLASS64: {
                Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
-               if (sizeof(Elf64_Ehdr) != w2(ghdr->e_ehsize)
-               ||  sizeof(Elf64_Shdr) != w2(ghdr->e_shentsize)) {
+               if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
+               ||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
                        fprintf(stderr,
                                "unrecognized ET_REL file: %s\n", fname);
                        fail_file();
                }
-               if (EM_S390 == w2(ghdr->e_machine))
+               if (w2(ghdr->e_machine) == EM_S390) {
                        reltype = R_390_64;
-               if (EM_MIPS == w2(ghdr->e_machine)) {
+                       mcount_adjust_64 = -8;
+               }
+               if (w2(ghdr->e_machine) == EM_MIPS) {
                        reltype = R_MIPS_64;
                        Elf64_r_sym = MIPS64_r_sym;
                        Elf64_r_info = MIPS64_r_info;
                        is_fake_mcount64 = MIPS64_is_fake_mcount;
                }
                do64(ghdr, fname, reltype);
-       } break;
+               break;
+       }
        }  /* end switch */
 
+       write_file(fname);
        cleanup();
 }
 
 int
-main(int argc, char const *argv[])
+main(int argc, char *argv[])
 {
        const char ftrace[] = "/ftrace.o";
        int ftrace_size = sizeof(ftrace) - 1;
        int n_error = 0;  /* gcc-4.3.0 false positive complaint */
+       int c;
+       int i;
+
+       while ((c = getopt(argc, argv, "w")) >= 0) {
+               switch (c) {
+               case 'w':
+                       warn_on_notrace_sect = 1;
+                       break;
+               default:
+                       fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
+                       return 0;
+               }
+       }
 
-       if (argc <= 1) {
-               fprintf(stderr, "usage: recordmcount file.o...\n");
+       if ((argc - optind) < 1) {
+               fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
                return 0;
        }
 
        /* Process each file in turn, allowing deep failure. */
-       for (--argc, ++argv; 0 < argc; --argc, ++argv) {
+       for (i = optind; i < argc; i++) {
+               char *file = argv[i];
                int const sjval = setjmp(jmpenv);
                int len;
 
@@ -380,29 +526,32 @@ main(int argc, char const *argv[])
                 * function but does not call it. Since ftrace.o should
                 * not be traced anyway, we just skip it.
                 */
-               len = strlen(argv[0]);
+               len = strlen(file);
                if (len >= ftrace_size &&
-                   strcmp(argv[0] + (len - ftrace_size), ftrace) == 0)
+                   strcmp(file + (len - ftrace_size), ftrace) == 0)
                        continue;
 
                switch (sjval) {
-               default: {
-                       fprintf(stderr, "internal error: %s\n", argv[0]);
+               default:
+                       fprintf(stderr, "internal error: %s\n", file);
                        exit(1);
-               } break;
-               case SJ_SETJMP: {  /* normal sequence */
+                       break;
+               case SJ_SETJMP:    /* normal sequence */
                        /* Avoid problems if early cleanup() */
                        fd_map = -1;
-                       ehdr_curr = NULL;
                        mmap_failed = 1;
-                       do_file(argv[0]);
-               } break;
-               case SJ_FAIL: {  /* error in do_file or below */
+                       file_map = NULL;
+                       file_ptr = NULL;
+                       file_updated = 0;
+                       do_file(file);
+                       break;
+               case SJ_FAIL:    /* error in do_file or below */
+                       fprintf(stderr, "%s: failed\n", file);
                        ++n_error;
-               } break;
-               case SJ_SUCCEED: {  /* premature success */
+                       break;
+               case SJ_SUCCEED:    /* premature success */
                        /* do nothing */
-               } break;
+                       break;
                }  /* end switch */
        }
        return !!n_error;