Commit d59a1683 authored by David Daney's avatar David Daney Committed by H. Peter Anvin
Browse files

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: default avatarDavid Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1335291795-26693-2-git-send-email-ddaney.cavm@gmail.com


Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 70627654

scripts/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -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

+111 −60
Original line number Diff line number Diff line 
/*

 * 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)

{

	return 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)

{

	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 */

scripts/sortextable.h

+51 −28
Original line number Diff line number Diff line 
/*

 * 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);



	extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);



	/* Sort the table in place */

	qsort((void *)ehdr + _w(extab_sec->sh_offset),

	      (_w(extab_sec->sh_size) / extable_ent_size),

	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);

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE