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 <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: H. Peter Anvin <[email protected]>

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

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 */