scripts/sortextable: Handle relative entries, and other cleanups

x86 is now using relative rather than absolute addresses in its
exception table, so we add a sorter for these.  If there are
relocations on the __ex_table section, they are redundant and probably
incorrect after the sort, so they are zeroed out leaving them valid
and consistent.

Also use the unaligned safe accessors from tools/{be,le}_byteshift.h

Signed-off-by: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1335291795-26693-2-git-send-email-ddaney.cavm@gmail.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

3 files changed, 164 insertions, 88 deletions

diff --git a/scripts/Makefile b/scripts/Makefile
index 43e19b9fc641..9eace52c64df 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -15,6 +15,8 @@ hostprogs-$(CONFIG_IKCONFIG)     += bin2c
 hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
 hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
 
+HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include
+
 always          := $(hostprogs-y) $(hostprogs-m)
 
 # The following hostprogs-y programs are only build on demand
diff --git a/scripts/sortextable.c b/scripts/sortextable.c
index f51f1d43da63..1ca9ceb95eb6 100644
--- a/scripts/sortextable.c
+++ b/scripts/sortextable.c
@@ -1,7 +1,7 @@
 /*
  * sortextable.c: Sort the kernel's exception table
  *
- * Copyright 2011 Cavium, Inc.
+ * Copyright 2011 - 2012 Cavium, Inc.
  *
  * Based on code taken from recortmcount.c which is:
  *
@@ -28,6 +28,9 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <tools/be_byteshift.h>
+#include <tools/le_byteshift.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 */
@@ -94,109 +97,157 @@ static void *mmap_file(char const *fname)
         return addr;
 }
 
-/* w8rev, w8nat, ...: Handle endianness. */
-
-static uint64_t w8rev(uint64_t const x)
+static uint64_t r8be(const uint64_t *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));
+        return get_unaligned_be64(x);
 }
-
-static uint32_t w4rev(uint32_t const x)
+static uint32_t rbe(const uint32_t *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));
+        return get_unaligned_be32(x);
 }
-
-static uint32_t w2rev(uint16_t const x)
+static uint16_t r2be(const uint16_t *x)
 {
-        return   ((0xff & (x >> (0 * 8))) << (1 * 8))
-               | ((0xff & (x >> (1 * 8))) << (0 * 8));
+        return get_unaligned_be16(x);
 }
-
-static uint64_t w8nat(uint64_t const x)
+static uint64_t r8le(const uint64_t *x)
 {
-        return x;
+        return get_unaligned_le64(x);
 }
-
-static uint32_t w4nat(uint32_t const x)
+static uint32_t rle(const uint32_t *x)
+{
+        return get_unaligned_le32(x);
+}
+static uint16_t r2le(const uint16_t *x)
 {
-        return x;
+        return get_unaligned_le16(x);
 }
 
-static uint32_t w2nat(uint16_t const 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)
 {
-        return x;
+        put_unaligned_le16(val, x);
 }
 
-static uint64_t (*w8)(uint64_t);
-static uint32_t (*w)(uint32_t);
-static uint32_t (*w2)(uint16_t);
+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);
 
 /* 32 bit and 64 bit are very similar */
 #include "sortextable.h"
 #define SORTEXTABLE_64
 #include "sortextable.h"
 
+static int compare_x86_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_x86_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_x86_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)
 {
-        Elf32_Ehdr *const ehdr = mmap_file(fname);
+        table_sort_t custom_sort;
+        Elf32_Ehdr *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;
-                }
+                r = rle;
+                r2 = r2le;
+                r8 = r8le;
+                w = wle;
+                w2 = w2le;
+                w8 = w8le;
                 break;
         case ELFDATA2MSB:
-                if (*(unsigned char const *)&endian != 0) {
-                        /* main() is little endian, file.o is big endian. */
-                        w = w4rev;
-                        w2 = w2rev;
-                        w8 = w8rev;
-                }
+                r = rbe;
+                r2 = r2be;
+                r8 = r8be;
+                w = wbe;
+                w2 = w2be;
+                w8 = w8be;
                 break;
         }  /* end switch */
         if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
-        ||  w2(ehdr->e_type) != ET_EXEC
+        ||  r2(&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)) {
+        custom_sort = NULL;
+        switch (r2(&ehdr->e_machine)) {
         default:
                 fprintf(stderr, "unrecognized e_machine %d %s\n",
-                        w2(ehdr->e_machine), fname);
+                        r2(&ehdr->e_machine), fname);
                 fail_file();
                 break;
         case EM_386:
-        case EM_MIPS:
         case EM_X86_64:
+                custom_sort = sort_x86_table;
+                break;
+        case EM_MIPS:
                 break;
         }  /* end switch */
 
@@ -207,23 +258,23 @@ do_file(char const *const fname)
                 fail_file();
                 break;
         case ELFCLASS32:
-                if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
-                ||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
+                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);
+                do32(ehdr, fname, custom_sort);
                 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)) {
+                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);
+                do64(ghdr, fname, custom_sort);
                 break;
         }
         }  /* end switch */
diff --git a/scripts/sortextable.h b/scripts/sortextable.h
index bb6aaf166002..e4fd45b7e456 100644
--- a/scripts/sortextable.h
+++ b/scripts/sortextable.h
@@ -1,7 +1,7 @@
 /*
  * sortextable.h
  *
- * Copyright 2011 Cavium, Inc.
+ * Copyright 2011 - 2012 Cavium, Inc.
  *
  * Some of this code was taken out of recordmcount.h written by:
  *
@@ -30,6 +30,7 @@
 #undef fn_ELF_R_SYM
 #undef fn_ELF_R_INFO
 #undef uint_t
+#undef _r
 #undef _w
 
 #ifdef SORTEXTABLE_64
@@ -51,6 +52,7 @@
 # define fn_ELF_R_SYM           fn_ELF64_R_SYM
 # define fn_ELF_R_INFO          fn_ELF64_R_INFO
 # define uint_t                 uint64_t
+# define _r                     r8
 # define _w                     w8
 #else
 # define extable_ent_size       8
@@ -71,23 +73,24 @@
 # define fn_ELF_R_SYM           fn_ELF32_R_SYM
 # define fn_ELF_R_INFO          fn_ELF32_R_INFO
 # define uint_t                 uint32_t
+# define _r                     r
 # define _w                     w
 #endif
 
 static int compare_extable(const void *a, const void *b)
 {
-        const uint_t *aa = a;
-        const uint_t *bb = b;
+        Elf_Addr av = _r(a);
+        Elf_Addr bv = _r(b);
 
-        if (_w(*aa) < _w(*bb))
+        if (av < bv)
                 return -1;
-        if (_w(*aa) > _w(*bb))
+        if (av > bv)
                 return 1;
         return 0;
 }
 
 static void
-do_func(Elf_Ehdr *const ehdr, char const *const fname)
+do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
 {
         Elf_Shdr *shdr;
         Elf_Shdr *shstrtab_sec;
@@ -97,19 +100,31 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname)
         Elf_Sym *sym;
         Elf_Sym *sort_needed_sym;
         Elf_Shdr *sort_needed_sec;
+        Elf_Rel *relocs = NULL;
+        int relocs_size;
         uint32_t *sort_done_location;
         const char *secstrtab;
         const char *strtab;
+        char *extab_image;
+        int extab_index = 0;
         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)
+        shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
+        shstrtab_sec = shdr + r2(&ehdr->e_shstrndx);
+        secstrtab = (const char *)ehdr + _r(&shstrtab_sec->sh_offset);
+        for (i = 0; i < r2(&ehdr->e_shnum); i++) {
+                idx = r(&shdr[i].sh_name);
+                if (strcmp(secstrtab + idx, "__ex_table") == 0) {
                         extab_sec = shdr + i;
+                        extab_index = i;
+                }
+                if ((r(&shdr[i].sh_type) == SHT_REL ||
+                     r(&shdr[i].sh_type) == SHT_RELA) &&
+                    r(&shdr[i].sh_info) == extab_index) {
+                        relocs = (void *)ehdr + _r(&shdr[i].sh_offset);
+                        relocs_size = _r(&shdr[i].sh_size);
+                }
                 if (strcmp(secstrtab + idx, ".symtab") == 0)
                         symtab_sec = shdr + i;
                 if (strcmp(secstrtab + idx, ".strtab") == 0)
@@ -127,21 +142,29 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname)
                 fprintf(stderr, "no __ex_table in  file: %s\n", fname);
                 fail_file();
         }
-        strtab = (const char *)ehdr + _w(strtab_sec->sh_offset);
+        strtab = (const char *)ehdr + _r(&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);
+        extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
+
+        if (custom_sort) {
+                custom_sort(extab_image, _r(&extab_sec->sh_size));
+        } else {
+                int num_entries = _r(&extab_sec->sh_size) / extable_ent_size;
+                qsort(extab_image, num_entries,
+                      extable_ent_size, compare_extable);
+        }
+        /* If there were relocations, we no longer need them. */
+        if (relocs)
+                memset(relocs, 0, relocs_size);
 
         /* 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);
+        for (i = 0; i < _r(&symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
+                sym = (void *)ehdr + _r(&symtab_sec->sh_offset);
                 sym += i;
                 if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
                         continue;
-                idx = w(sym->st_name);
+                idx = r(&sym->st_name);
                 if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
                         sort_needed_sym = sym;
                         break;
@@ -153,16 +176,16 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname)
                         fname);
                 fail_file();
         }
-        sort_needed_sec = &shdr[w2(sort_needed_sym->st_shndx)];
+        sort_needed_sec = &shdr[r2(&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);
+                _r(&sort_needed_sec->sh_offset) +
+                _r(&sort_needed_sym->st_value) -
+                _r(&sort_needed_sec->sh_addr);
 
+#if 1
         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)));
+               (unsigned long)((char *)sort_done_location - (char *)ehdr));
+#endif
         /* We sorted it, clear the flag. */
-        *sort_done_location = 0;
+        w(0, sort_done_location);
 }