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>

4 files changed, 441 insertions, 0 deletions

diff --git a/scripts/.gitignore b/scripts/.gitignore
index 105b21f08185..65f362d931b5 100644
--- a/scripts/.gitignore
+++ b/scripts/.gitignore
@@ -9,3 +9,4 @@ unifdef
 ihex2fw
 recordmcount
 docproc
+sortextable
diff --git a/scripts/Makefile b/scripts/Makefile
index df7678febf27..43e19b9fc641 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -13,6 +13,7 @@ hostprogs-$(CONFIG_LOGO)         += pnmtologo
 hostprogs-$(CONFIG_VT)           += conmakehash
 hostprogs-$(CONFIG_IKCONFIG)     += bin2c
 hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
+hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
 
 always          := $(hostprogs-y) $(hostprogs-m)
 
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;
+}
diff --git a/scripts/sortextable.h b/scripts/sortextable.h
new file mode 100644
index 000000000000..bb6aaf166002
--- /dev/null
+++ b/scripts/sortextable.h
@@ -0,0 +1,168 @@
+/*
+ * sortextable.h
+ *
+ * Copyright 2011 Cavium, Inc.
+ *
+ * Some of this code was taken out of recordmcount.h written by:
+ *
+ * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
+ * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
+ *
+ *
+ * Licensed under the GNU General Public License, version 2 (GPLv2).
+ */
+
+#undef extable_ent_size
+#undef compare_extable
+#undef do_func
+#undef Elf_Addr
+#undef Elf_Ehdr
+#undef Elf_Shdr
+#undef Elf_Rel
+#undef Elf_Rela
+#undef Elf_Sym
+#undef ELF_R_SYM
+#undef Elf_r_sym
+#undef ELF_R_INFO
+#undef Elf_r_info
+#undef ELF_ST_BIND
+#undef ELF_ST_TYPE
+#undef fn_ELF_R_SYM
+#undef fn_ELF_R_INFO
+#undef uint_t
+#undef _w
+
+#ifdef SORTEXTABLE_64
+# define extable_ent_size       16
+# define compare_extable        compare_extable_64
+# define do_func                do64
+# define Elf_Addr               Elf64_Addr
+# define Elf_Ehdr               Elf64_Ehdr
+# define Elf_Shdr               Elf64_Shdr
+# define Elf_Rel                Elf64_Rel
+# define Elf_Rela               Elf64_Rela
+# define Elf_Sym                Elf64_Sym
+# define ELF_R_SYM              ELF64_R_SYM
+# define Elf_r_sym              Elf64_r_sym
+# define ELF_R_INFO             ELF64_R_INFO
+# define Elf_r_info             Elf64_r_info
+# define ELF_ST_BIND            ELF64_ST_BIND
+# define ELF_ST_TYPE            ELF64_ST_TYPE
+# define fn_ELF_R_SYM           fn_ELF64_R_SYM
+# define fn_ELF_R_INFO          fn_ELF64_R_INFO
+# define uint_t                 uint64_t
+# define _w                     w8
+#else
+# define extable_ent_size       8
+# define compare_extable        compare_extable_32
+# define do_func                do32
+# define Elf_Addr               Elf32_Addr
+# define Elf_Ehdr               Elf32_Ehdr
+# define Elf_Shdr               Elf32_Shdr
+# define Elf_Rel                Elf32_Rel
+# define Elf_Rela               Elf32_Rela
+# define Elf_Sym                Elf32_Sym
+# define ELF_R_SYM              ELF32_R_SYM
+# define Elf_r_sym              Elf32_r_sym
+# define ELF_R_INFO             ELF32_R_INFO
+# define Elf_r_info             Elf32_r_info
+# define ELF_ST_BIND            ELF32_ST_BIND
+# define ELF_ST_TYPE            ELF32_ST_TYPE
+# define fn_ELF_R_SYM           fn_ELF32_R_SYM
+# define fn_ELF_R_INFO          fn_ELF32_R_INFO
+# define uint_t                 uint32_t
+# define _w                     w
+#endif
+
+static int compare_extable(const void *a, const void *b)
+{
+        const uint_t *aa = a;
+        const uint_t *bb = b;
+
+        if (_w(*aa) < _w(*bb))
+                return -1;
+        if (_w(*aa) > _w(*bb))
+                return 1;
+        return 0;
+}
+
+static void
+do_func(Elf_Ehdr *const ehdr, char const *const fname)
+{
+        Elf_Shdr *shdr;
+        Elf_Shdr *shstrtab_sec;
+        Elf_Shdr *strtab_sec = NULL;
+        Elf_Shdr *symtab_sec = NULL;
+        Elf_Shdr *extab_sec = NULL;
+        Elf_Sym *sym;
+        Elf_Sym *sort_needed_sym;
+        Elf_Shdr *sort_needed_sec;
+        uint32_t *sort_done_location;
+        const char *secstrtab;
+        const char *strtab;
+        int i;
+        int idx;
+
+        shdr = (Elf_Shdr *)((void *)ehdr + _w(ehdr->e_shoff));
+        shstrtab_sec = shdr + w2(ehdr->e_shstrndx);
+        secstrtab = (const char *)ehdr + _w(shstrtab_sec->sh_offset);
+        for (i = 0; i < w2(ehdr->e_shnum); i++) {
+                idx = w(shdr[i].sh_name);
+                if (strcmp(secstrtab + idx, "__ex_table") == 0)
+                        extab_sec = shdr + i;
+                if (strcmp(secstrtab + idx, ".symtab") == 0)
+                        symtab_sec = shdr + i;
+                if (strcmp(secstrtab + idx, ".strtab") == 0)
+                        strtab_sec = shdr + i;
+        }
+        if (strtab_sec == NULL) {
+                fprintf(stderr, "no .strtab in  file: %s\n", fname);
+                fail_file();
+        }
+        if (symtab_sec == NULL) {
+                fprintf(stderr, "no .symtab in  file: %s\n", fname);
+                fail_file();
+        }
+        if (extab_sec == NULL) {
+                fprintf(stderr, "no __ex_table in  file: %s\n", fname);
+                fail_file();
+        }
+        strtab = (const char *)ehdr + _w(strtab_sec->sh_offset);
+
+        /* Sort the table in place */
+        qsort((void *)ehdr + _w(extab_sec->sh_offset),
+              (_w(extab_sec->sh_size) / extable_ent_size),
+              extable_ent_size, compare_extable);
+
+        /* find main_extable_sort_needed */
+        sort_needed_sym = NULL;
+        for (i = 0; i < _w(symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
+                sym = (void *)ehdr + _w(symtab_sec->sh_offset);
+                sym += i;
+                if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
+                        continue;
+                idx = w(sym->st_name);
+                if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
+                        sort_needed_sym = sym;
+                        break;
+                }
+        }
+        if (sort_needed_sym == NULL) {
+                fprintf(stderr,
+                        "no main_extable_sort_needed symbol in  file: %s\n",
+                        fname);
+                fail_file();
+        }
+        sort_needed_sec = &shdr[w2(sort_needed_sym->st_shndx)];
+        sort_done_location = (void *)ehdr +
+                _w(sort_needed_sec->sh_offset) +
+                _w(sort_needed_sym->st_value) -
+                _w(sort_needed_sec->sh_addr);
+
+        printf("sort done marker at %lx\n",
+                (unsigned long) (_w(sort_needed_sec->sh_offset) +
+                                 _w(sort_needed_sym->st_value) -
+                                 _w(sort_needed_sec->sh_addr)));
+        /* We sorted it, clear the flag. */
+        *sort_done_location = 0;
+}