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, 168 insertions, 0 deletions

diff --git a/scripts/sortextable.h b/scripts/sortextable.h
new file mode 100644
index 0000000..bb6aaf1
--- /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;
+}