scripts: Add sortextable to sort the kernel's exception table.

Using this build-time sort saves time booting as we don't have to burn
cycles sorting the exception table.

Signed-off-by: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1334872799-14589-2-git-send-email-ddaney.cavm@gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 271 insertions, 0 deletions

diff --git a/scripts/sortextable.c b/scripts/sortextable.c
new file mode 100644
index 000000000000..f51f1d43da63
--- /dev/null
+++ b/scripts/sortextable.c
@@ -0,0 +1,271 @@
+/*
+ * sortextable.c: Sort the kernel's exception table
+ *
+ * Copyright 2011 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>
+
+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);
+}
+
+static void __attribute__((noreturn))
+succeed_file(void)
+{
+        cleanup();
+        longjmp(jmpenv, SJ_SUCCEED);
+}
+
+
+/*
+ * 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;
+}
+
+/* w8rev, w8nat, ...: Handle endianness. */
+
+static uint64_t w8rev(uint64_t const x)
+{
+        return   ((0xff & (x >> (0 * 8))) << (7 * 8))
+               | ((0xff & (x >> (1 * 8))) << (6 * 8))
+               | ((0xff & (x >> (2 * 8))) << (5 * 8))
+               | ((0xff & (x >> (3 * 8))) << (4 * 8))
+               | ((0xff & (x >> (4 * 8))) << (3 * 8))
+               | ((0xff & (x >> (5 * 8))) << (2 * 8))
+               | ((0xff & (x >> (6 * 8))) << (1 * 8))
+               | ((0xff & (x >> (7 * 8))) << (0 * 8));
+}
+
+static uint32_t w4rev(uint32_t const x)
+{
+        return   ((0xff & (x >> (0 * 8))) << (3 * 8))
+               | ((0xff & (x >> (1 * 8))) << (2 * 8))
+               | ((0xff & (x >> (2 * 8))) << (1 * 8))
+               | ((0xff & (x >> (3 * 8))) << (0 * 8));
+}
+
+static uint32_t w2rev(uint16_t const x)
+{
+        return   ((0xff & (x >> (0 * 8))) << (1 * 8))
+               | ((0xff & (x >> (1 * 8))) << (0 * 8));
+}
+
+static uint64_t w8nat(uint64_t const x)
+{
+        return x;
+}
+
+static uint32_t w4nat(uint32_t const x)
+{
+        return x;
+}
+
+static uint32_t w2nat(uint16_t const x)
+{
+        return x;
+}
+
+static uint64_t (*w8)(uint64_t);
+static uint32_t (*w)(uint32_t);
+static uint32_t (*w2)(uint16_t);
+
+
+/* 32 bit and 64 bit are very similar */
+#include "sortextable.h"
+#define SORTEXTABLE_64
+#include "sortextable.h"
+
+
+static void
+do_file(char const *const fname)
+{
+        Elf32_Ehdr *const ehdr = mmap_file(fname);
+
+        ehdr_curr = ehdr;
+        w = w4nat;
+        w2 = w2nat;
+        w8 = w8nat;
+        switch (ehdr->e_ident[EI_DATA]) {
+                static unsigned int const endian = 1;
+        default:
+                fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
+                        ehdr->e_ident[EI_DATA], fname);
+                fail_file();
+                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 (*(unsigned char const *)&endian != 0) {
+                        /* main() is little endian, file.o is big endian. */
+                        w = w4rev;
+                        w2 = w2rev;
+                        w8 = w8rev;
+                }
+                break;
+        }  /* end switch */
+        if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
+        ||  w2(ehdr->e_type) != ET_EXEC
+        ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
+                fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
+                fail_file();
+        }
+
+        switch (w2(ehdr->e_machine)) {
+        default:
+                fprintf(stderr, "unrecognized e_machine %d %s\n",
+                        w2(ehdr->e_machine), fname);
+                fail_file();
+                break;
+        case EM_386:
+        case EM_MIPS:
+        case EM_X86_64:
+                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 (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
+                ||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
+                        fprintf(stderr,
+                                "unrecognized ET_EXEC file: %s\n", fname);
+                        fail_file();
+                }
+                do32(ehdr, fname);
+                break;
+        case ELFCLASS64: {
+                Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
+                if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
+                ||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
+                        fprintf(stderr,
+                                "unrecognized ET_EXEC file: %s\n", fname);
+                        fail_file();
+                }
+                do64(ghdr, fname);
+                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;
+}