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[PATCH 1/2] scripts/sortextable: Handle relative entries, and other clea

To: Ralf Baechle <ralf@linux-mips.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>, Michal Marek <mmarek@suse.cz>
Subject: [PATCH 1/2] scripts/sortextable: Handle relative entries, and other cleanups.
From: David Daney <ddaney.cavm@gmail.com>
Date: Tue, 24 Apr 2012 11:23:14 -0700
Cc: linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Andrew Morton <akpm@linux-foundation.org>, David Daney <david.daney@cavium.com>
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In-reply-to: <1335291795-26693-1-git-send-email-ddaney.cavm@gmail.com>
References: <1335291795-26693-1-git-send-email-ddaney.cavm@gmail.com>
Sender: linux-mips-bounce@linux-mips.org
From: David Daney <david.daney@cavium.com>

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 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>
---
 scripts/Makefile      |    2 +
 scripts/sortextable.c |  171 ++++++++++++++++++++++++++++++++-----------------
 scripts/sortextable.h |   79 +++++++++++++++--------
 3 files changed, 164 insertions(+), 88 deletions(-)

diff --git a/scripts/Makefile b/scripts/Makefile
index 43e19b9..9eace52 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 f51f1d4..1ca9ceb 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 bb6aaf1..e4fd45b 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);
 }
-- 
1.7.7.6


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