[v2,1/2] scripts: Add a recorduidiv program

diff --git a/scripts/Makefile b/scripts/Makefile
index fd0d53d4a234..26b9ebd8be31 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -15,6 +15,7 @@  hostprogs-$(CONFIG_KALLSYMS)     += kallsyms
 hostprogs-$(CONFIG_LOGO)         += pnmtologo
 hostprogs-$(CONFIG_VT)           += conmakehash
 hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
+hostprogs-$(CONFIG_ARM_PATCH_UIDIV) += recorduidiv
 hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
 hostprogs-$(CONFIG_ASN1)	 += asn1_compiler
 hostprogs-$(CONFIG_MODULE_SIG)	 += sign-file
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 01df30af4d4a..142e5db29d3b 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -241,12 +241,25 @@  cmd_record_mcount =						\
 	fi;
 endif
 
+ifdef CONFIG_ARM_PATCH_UIDIV
+# Due to recursion, we must skip empty.o.
+# The empty.o file is created in the make process in order to determine
+#  the target endianness and word size. It is made before all other C
+#  files, including recorduidiv.
+cmd_record_uidiv =					\
+	if [ $(@) != "scripts/mod/empty.o" ]; then	\
+		$(objtree)/scripts/recorduidiv "$(@)";	\
+	fi;
+recorduidiv_source := $(srctree)/scripts/recorduidiv.c
+endif
+
 define rule_cc_o_c
 	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
 	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);				  \
 	$(cmd_modversions)						  \
 	$(call echo-cmd,record_mcount)					  \
 	$(cmd_record_mcount)						  \
+	$(call echo-cmd,record_uidiv) $(cmd_record_uidiv)		  \
 	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
 	                                              $(dot-target).tmp;  \
 	rm -f $(depfile);						  \
@@ -254,13 +267,13 @@  define rule_cc_o_c
 endef
 
 # Built-in and composite module parts
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(recorduidiv_source) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
 
 # Single-part modules are special since we need to mark them in $(MODVERDIR)
 
-$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(recorduidiv_source) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
 	@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
diff --git a/scripts/recorduidiv.c b/scripts/recorduidiv.c
new file mode 100644
index 000000000000..a2af5c46cb6d
--- /dev/null
+++ b/scripts/recorduidiv.c
@@ -0,0 +1,745 @@ 
+/*
+ * recorduidiv.c: construct a table of the locations of calls to '__aeabi_uidiv'
+ * and '__aeabi_idiv' so that the kernel can replace them with idiv and sdiv
+ * instructions.
+ *
+ * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
+ * Licensed under the GNU General Public License, version 2 (GPLv2).
+ *
+ * Restructured to fit Linux format, as well as other updates:
+ *  Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
+ *
+ * Copyright (c) 2015 The Linux Foundation. All rights reserved.
+ */
+
+/*
+ * Strategy: alter the .o file in-place.
+ *
+ * Append a new STRTAB that has the new section names, followed by a new array
+ * ElfXX_Shdr[] that has the new section headers, followed by the section
+ * contents for __udiv_loc and __idiv_loc and their relocations. The old
+ * shstrtab strings, and the old ElfXX_Shdr[] array, remain as "garbage"
+ * (commonly, a couple kilobytes.) Subsequent processing by /bin/ld (or the
+ * kernel module loader) will ignore the garbage regions, because they are not
+ * designated by the new .e_shoff nor the new ElfXX_Shdr[].  [In order to
+ * remove the garbage, then use "ld -r" to create a new file that omits the
+ * garbage.]
+ */
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <elf.h>
+#include <fcntl.h>
+#include <setjmp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+# define _align			3u
+# define _size			4
+
+#ifndef R_ARM_CALL
+#define R_ARM_CALL		28
+#endif
+
+#ifndef R_ARM_JUMP24
+#define R_ARM_JUMP24		29
+#endif
+
+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 */
+static struct stat sb;	/* Remember .st_size, etc. */
+static jmp_buf jmpenv;	/* setjmp/longjmp per-file error escape */
+
+/* setjmp() return values */
+enum {
+	SJ_SETJMP = 0,  /* hardwired first return */
+	SJ_FAIL,
+	SJ_SUCCEED
+};
+
+/* Per-file resource cleanup when multiple files. */
+static void
+cleanup(void)
+{
+	if (!mmap_failed)
+		munmap(ehdr_curr, sb.st_size);
+	else
+		free(ehdr_curr);
+	close(fd_map);
+}
+
+static void __attribute__((noreturn))
+fail_file(void)
+{
+	cleanup();
+	longjmp(jmpenv, SJ_FAIL);
+}
+
+static void __attribute__((noreturn))
+succeed_file(void)
+{
+	cleanup();
+	longjmp(jmpenv, SJ_SUCCEED);
+}
+
+/* ulseek, uread, ...:  Check return value for errors. */
+
+static off_t
+ulseek(int const fd, off_t const offset, int const whence)
+{
+	off_t const w = lseek(fd, offset, whence);
+	if (w == (off_t)-1) {
+		perror("lseek");
+		fail_file();
+	}
+	return w;
+}
+
+static size_t
+uread(int const fd, void *const buf, size_t const count)
+{
+	size_t const n = read(fd, buf, count);
+	if (n != count) {
+		perror("read");
+		fail_file();
+	}
+	return n;
+}
+
+static size_t
+uwrite(int const fd, void const *const buf, size_t const count)
+{
+	size_t const n = write(fd, buf, count);
+	if (n != count) {
+		perror("write");
+		fail_file();
+	}
+	return n;
+}
+
+static void *
+umalloc(size_t size)
+{
+	void *const addr = malloc(size);
+	if (addr == 0) {
+		fprintf(stderr, "malloc failed: %zu bytes\n", size);
+		fail_file();
+	}
+	return addr;
+}
+
+/*
+ * Get the whole file as a programming convenience in order to avoid
+ * malloc+lseek+read+free of many pieces.  If successful, then mmap
+ * avoids copying unused pieces; else just read the whole file.
+ * Open for both read and write; new info will be appended to the file.
+ * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
+ * do not propagate to the file until an explicit overwrite at the last.
+ * This preserves most aspects of consistency (all except .st_size)
+ * for simultaneous readers of the file while we are appending to it.
+ * However, multiple writers still are bad.  We choose not to use
+ * locking because it is expensive and the use case of kernel build
+ * makes multiple writers unlikely.
+ */
+static void *mmap_file(char const *fname)
+{
+	void *addr;
+
+	fd_map = open(fname, O_RDWR);
+	if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
+		perror(fname);
+		fail_file();
+	}
+	if (!S_ISREG(sb.st_mode)) {
+		fprintf(stderr, "not a regular file: %s\n", fname);
+		fail_file();
+	}
+	addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
+		    fd_map, 0);
+	mmap_failed = 0;
+	if (addr == MAP_FAILED) {
+		mmap_failed = 1;
+		addr = umalloc(sb.st_size);
+		uread(fd_map, addr, sb.st_size);
+	}
+	return addr;
+}
+
+/* w8rev, w8nat, ...: Handle endianness. */
+
+static uint64_t w8rev(uint64_t const 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));
+}
+
+static uint32_t w4rev(uint32_t const 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));
+}
+
+static uint32_t w2rev(uint16_t const x)
+{
+	return   ((0xff & (x >> (0 * 8))) << (1 * 8))
+	       | ((0xff & (x >> (1 * 8))) << (0 * 8));
+}
+
+static uint64_t w8nat(uint64_t const x)
+{
+	return x;
+}
+
+static uint32_t w4nat(uint32_t const x)
+{
+	return x;
+}
+
+static uint32_t w2nat(uint16_t const x)
+{
+	return x;
+}
+
+static uint64_t (*w8)(uint64_t);
+static uint32_t (*w)(uint32_t);
+static uint32_t (*w2)(uint16_t);
+
+/* Names of the sections that could contain calls to __aeabi_{u}idiv() */
+static int is_valid_section_name(char const *const txtname)
+{
+	return strcmp(".text",           txtname) == 0 ||
+		strcmp(".ref.text",      txtname) == 0 ||
+		strcmp(".sched.text",    txtname) == 0 ||
+		strcmp(".spinlock.text", txtname) == 0 ||
+		strcmp(".irqentry.text", txtname) == 0 ||
+		strcmp(".kprobes.text",  txtname) == 0 ||
+		strcmp(".text.unlikely", txtname) == 0 ||
+		strcmp(".init.text",     txtname) == 0;
+}
+
+static uint32_t Elf32_r_sym(Elf32_Rel const *rp)
+{
+	return ELF32_R_SYM(w(rp->r_info));
+}
+
+static void append_section(uint32_t const *const mloc0,
+			   uint32_t const *const mlocp,
+			   Elf32_Rel const *const mrel0,
+			   Elf32_Rel const *const mrelp,
+			   char const *name,
+			   unsigned int const rel_entsize,
+			   unsigned int const symsec_sh_link,
+			   uint32_t *name_offp,
+			   uint32_t *tp,
+			   unsigned *shnump
+		)
+{
+	Elf32_Shdr mcsec;
+	uint32_t name_off = *name_offp;
+	uint32_t t = *tp;
+	uint32_t loc_diff = (void *)mlocp - (void *)mloc0;
+	uint32_t rel_diff = (void *)mrelp - (void *)mrel0;
+	unsigned shnum = *shnump;
+
+	mcsec.sh_name = w((sizeof(Elf32_Rela) == rel_entsize) + strlen(".rel")
+		+ name_off);
+	mcsec.sh_type = w(SHT_PROGBITS);
+	mcsec.sh_flags = w(SHF_ALLOC);
+	mcsec.sh_addr = 0;
+	mcsec.sh_offset = w(t);
+	mcsec.sh_size = w(loc_diff);
+	mcsec.sh_link = 0;
+	mcsec.sh_info = 0;
+	mcsec.sh_addralign = w(_size);
+	mcsec.sh_entsize = w(_size);
+	uwrite(fd_map, &mcsec, sizeof(mcsec));
+	t += loc_diff;
+
+	mcsec.sh_name = w(name_off);
+	mcsec.sh_type = (sizeof(Elf32_Rela) == rel_entsize)
+		? w(SHT_RELA)
+		: w(SHT_REL);
+	mcsec.sh_flags = 0;
+	mcsec.sh_addr = 0;
+	mcsec.sh_offset = w(t);
+	mcsec.sh_size   = w(rel_diff);
+	mcsec.sh_link = w(symsec_sh_link);
+	mcsec.sh_info = w(shnum);
+	mcsec.sh_addralign = w(_size);
+	mcsec.sh_entsize = w(rel_entsize);
+	uwrite(fd_map, &mcsec, sizeof(mcsec));
+	t += rel_diff;
+
+	shnum += 2;
+	name_off += strlen(name) + 1;
+
+	*tp = t;
+	*shnump = shnum;
+	*name_offp = name_off;
+}
+
+/*
+ * Append the new shstrtab, Elf32_Shdr[], __{udiv,idiv}_loc and their
+ * relocations.
+ */
+static void append_func(Elf32_Ehdr *const ehdr,
+			Elf32_Shdr *const shstr,
+			uint32_t const *const mloc0_u,
+			uint32_t const *const mlocp_u,
+			Elf32_Rel const *const mrel0_u,
+			Elf32_Rel const *const mrelp_u,
+			uint32_t const *const mloc0_i,
+			uint32_t const *const mlocp_i,
+			Elf32_Rel const *const mrel0_i,
+			Elf32_Rel const *const mrelp_i,
+			unsigned int const rel_entsize,
+			unsigned int const symsec_sh_link)
+{
+	/* Begin constructing output file */
+	char const *udiv_name = (sizeof(Elf32_Rela) == rel_entsize)
+		? ".rela__udiv_loc"
+		:  ".rel__udiv_loc";
+	char const *idiv_name = (sizeof(Elf32_Rela) == rel_entsize)
+		? ".rela__idiv_loc"
+		:  ".rel__idiv_loc";
+	unsigned old_shnum = w2(ehdr->e_shnum);
+	uint32_t const old_shoff = w(ehdr->e_shoff);
+	uint32_t const old_shstr_sh_size   = w(shstr->sh_size);
+	uint32_t const old_shstr_sh_offset = w(shstr->sh_offset);
+	uint32_t new_e_shoff;
+	uint32_t t = w(shstr->sh_size);
+	uint32_t name_off = old_shstr_sh_size;
+	int udiv = 0, idiv = 0;
+	int num_sections;
+
+	if (mlocp_u != mloc0_u) {
+		t += 1 + strlen(udiv_name);
+		udiv = 1;
+	}
+	if (mlocp_i != mloc0_i) {
+		t += 1 + strlen(idiv_name);
+		idiv = 1;
+	}
+	num_sections = (udiv * 2) + (idiv * 2);
+
+	shstr->sh_size = w(t);
+	shstr->sh_offset = w(sb.st_size);
+	t += sb.st_size;
+	t += (_align & -t);  /* word-byte align */
+	new_e_shoff = t;
+
+	/* body for new shstrtab */
+	ulseek(fd_map, sb.st_size, SEEK_SET);
+	uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, name_off);
+	if (udiv)
+		uwrite(fd_map, udiv_name, 1 + strlen(udiv_name));
+	if (idiv)
+		uwrite(fd_map, idiv_name, 1 + strlen(idiv_name));
+
+	/* old(modified) Elf32_Shdr table, word-byte aligned */
+	ulseek(fd_map, t, SEEK_SET);
+	t += sizeof(Elf32_Shdr) * old_shnum;
+	uwrite(fd_map, old_shoff + (void *)ehdr,
+	       sizeof(Elf32_Shdr) * old_shnum);
+
+	t += num_sections * sizeof(Elf32_Shdr);
+
+	/* new sections __udiv_loc and .rel__udiv_loc */
+	if (udiv)
+		append_section(mloc0_u, mlocp_u, mrel0_u, mrelp_u, udiv_name,
+			       rel_entsize, symsec_sh_link, &name_off, &t,
+			       &old_shnum);
+
+	/* new sections __idiv_loc and .rel__idiv_loc */
+	if (idiv)
+		append_section(mloc0_i, mlocp_i, mrel0_i, mrelp_i, idiv_name,
+			       rel_entsize, symsec_sh_link, &name_off, &t,
+			       &old_shnum);
+
+	if (udiv) {
+		uwrite(fd_map, mloc0_u, (void *)mlocp_u - (void *)mloc0_u);
+		uwrite(fd_map, mrel0_u, (void *)mrelp_u - (void *)mrel0_u);
+	}
+	if (idiv) {
+		uwrite(fd_map, mloc0_i, (void *)mlocp_i - (void *)mloc0_i);
+		uwrite(fd_map, mrel0_i, (void *)mrelp_i - (void *)mrel0_i);
+	}
+
+	ehdr->e_shoff = w(new_e_shoff);
+	ehdr->e_shnum = w2(num_sections + w2(ehdr->e_shnum));
+	ulseek(fd_map, 0, SEEK_SET);
+	uwrite(fd_map, ehdr, sizeof(*ehdr));
+}
+
+static unsigned get_sym(Elf32_Sym const *const sym0,
+			      Elf32_Rel const *relp,
+			      char const *const str0, const char *find)
+{
+	unsigned sym = 0;
+	Elf32_Sym const *const symp = &sym0[Elf32_r_sym(relp)];
+	char const *symname = &str0[w(symp->st_name)];
+
+	if (strcmp(find, symname) == 0)
+		sym = Elf32_r_sym(relp);
+
+	return sym;
+}
+
+static void get_sym_str_and_relp(Elf32_Shdr const *const relhdr,
+				 Elf32_Ehdr const *const ehdr,
+				 Elf32_Sym const **sym0,
+				 char const **str0,
+				 Elf32_Rel const **relp)
+{
+	Elf32_Shdr *const shdr0 = (Elf32_Shdr *)(w(ehdr->e_shoff)
+		+ (void *)ehdr);
+	unsigned const symsec_sh_link = w(relhdr->sh_link);
+	Elf32_Shdr const *const symsec = &shdr0[symsec_sh_link];
+	Elf32_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
+	Elf32_Rel const *const rel0 = (Elf32_Rel const *)(w(relhdr->sh_offset)
+		+ (void *)ehdr);
+
+	*sym0 = (Elf32_Sym const *)(w(symsec->sh_offset)
+				  + (void *)ehdr);
+
+	*str0 = (char const *)(w(strsec->sh_offset)
+			       + (void *)ehdr);
+
+	*relp = rel0;
+}
+
+static void add_relocation(Elf32_Rel const *relp, uint32_t *mloc0, uint32_t **mlocpp,
+			   uint32_t const recval, unsigned const recsym,
+			   Elf32_Rel **const mrelpp, unsigned offbase,
+			   unsigned rel_entsize)
+{
+	uint32_t *mlocp = *mlocpp;
+	Elf32_Rel *mrelp = *mrelpp;
+	uint32_t const addend = w(w(relp->r_offset) - recval);
+	mrelp->r_offset = w(offbase + ((void *)mlocp - (void *)mloc0));
+	mrelp->r_info = w(ELF32_R_INFO(recsym, R_ARM_ABS32));
+	if (rel_entsize == sizeof(Elf32_Rela)) {
+		((Elf32_Rela *)mrelp)->r_addend = addend;
+		*mlocp++ = 0;
+	} else
+		*mlocp++ = addend;
+
+	*mlocpp = mlocp;
+	*mrelpp = (Elf32_Rel *)(rel_entsize + (void *)mrelp);
+}
+
+/*
+ * Look at the relocations in order to find the calls to __aeabi_{u}idiv.
+ * Accumulate the section offsets that are found, and their relocation info,
+ * onto the end of the existing arrays.
+ */
+static void sift_relocations(uint32_t **mlocpp_u, uint32_t *mloc_base_u,
+			     Elf32_Rel **const mrelpp_u,
+			     uint32_t **mlocpp_i,
+			     uint32_t *mloc_base_i,
+			     Elf32_Rel **const mrelpp_i,
+			     Elf32_Shdr const *const relhdr,
+			     Elf32_Ehdr const *const ehdr,
+			     unsigned const recsym, uint32_t const recval)
+{
+	uint32_t *mlocp_u = *mlocpp_u;
+	unsigned const offbase_u = (void *)mlocp_u - (void *)mloc_base_u;
+	uint32_t *const mloc0_u = mlocp_u;
+	Elf32_Rel *mrelp_u = *mrelpp_u;
+	uint32_t *mlocp_i = *mlocpp_i;
+	unsigned const offbase_i = (void *)mlocp_i - (void *)mloc_base_i;
+	uint32_t *const mloc0_i = mlocp_i;
+	Elf32_Rel *mrelp_i = *mrelpp_i;
+	Elf32_Sym const *sym0;
+	char const *str0;
+	Elf32_Rel const *relp;
+	unsigned rel_entsize = w(relhdr->sh_entsize);
+	unsigned const nrel = w(relhdr->sh_size) / rel_entsize;
+	unsigned udiv_sym = 0, idiv_sym = 0;
+	unsigned t;
+
+	get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
+
+	for (t = nrel; t; --t) {
+		if (!udiv_sym)
+			udiv_sym = get_sym(sym0, relp, str0,
+					       "__aeabi_uidiv");
+		if (!idiv_sym)
+			idiv_sym = get_sym(sym0, relp, str0,
+						 "__aeabi_idiv");
+
+		switch (relp->r_info & 0xff) {
+		case R_ARM_PC24:
+		case R_ARM_CALL:
+		case R_ARM_JUMP24:
+			if (udiv_sym == Elf32_r_sym(relp)) {
+				add_relocation(relp, mloc0_u, &mlocp_u, recval,
+					       recsym, &mrelp_u, offbase_u,
+					       rel_entsize);
+			} else if (idiv_sym == Elf32_r_sym(relp)) {
+				add_relocation(relp, mloc0_i, &mlocp_i, recval,
+					       recsym, &mrelp_i, offbase_i,
+					       rel_entsize);
+			}
+		}
+
+		relp = (Elf32_Rel const *)(rel_entsize + (void *)relp);
+	}
+	*mrelpp_i = mrelp_i;
+	*mrelpp_u = mrelp_u;
+	*mlocpp_i = mlocp_i;
+	*mlocpp_u = mlocp_u;
+}
+
+/*
+ * Find a symbol in the given section, to be used as the base for relocating
+ * the table of offsets of calls.  A local or global symbol suffices,
+ * but avoid a Weak symbol because it may be overridden; the change in value
+ * would invalidate the relocations of the offsets of the calls.
+ * Often the found symbol will be the unnamed local symbol generated by
+ * GNU 'as' for the start of each section.  For example:
+ *    Num:    Value  Size Type    Bind   Vis      Ndx Name
+ *      2: 00000000     0 SECTION LOCAL  DEFAULT    1
+ */
+static unsigned find_secsym_ndx(unsigned const txtndx,
+				char const *const txtname,
+				uint32_t *const recvalp,
+				Elf32_Shdr const *const symhdr,
+				Elf32_Ehdr const *const ehdr)
+{
+	Elf32_Sym const *const sym0 = (Elf32_Sym const *)(w(symhdr->sh_offset)
+		+ (void *)ehdr);
+	unsigned const nsym = w(symhdr->sh_size) / w(symhdr->sh_entsize);
+	Elf32_Sym const *symp;
+	unsigned t;
+
+	for (symp = sym0, t = nsym; t; --t, ++symp) {
+		unsigned int const st_bind = ELF32_ST_BIND(symp->st_info);
+
+		if (txtndx == w2(symp->st_shndx)
+			/* avoid STB_WEAK */
+		    && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
+			/* function symbols on ARM have quirks, avoid them */
+			if (ELF32_ST_TYPE(symp->st_info) == STT_FUNC)
+				continue;
+
+			*recvalp = w(symp->st_value);
+			return symp - sym0;
+		}
+	}
+	fprintf(stderr, "Cannot find symbol for section %d: %s.\n",
+		txtndx, txtname);
+	fail_file();
+}
+
+
+/* Evade ISO C restriction: no declaration after statement in has_rel. */
+static char const *
+__has_rel(Elf32_Shdr const *const relhdr,  /* is SHT_REL or SHT_RELA */
+	  Elf32_Shdr const *const shdr0,
+	  char const *const shstrtab,
+	  char const *const fname)
+{
+	/* .sh_info depends on .sh_type == SHT_REL[,A] */
+	Elf32_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
+	char const *const txtname = &shstrtab[w(txthdr->sh_name)];
+
+	if (strcmp("__idiv_loc", txtname) == 0 ||
+	    strcmp("__udiv_loc", txtname) == 0)
+		succeed_file();
+	if (w(txthdr->sh_type) != SHT_PROGBITS ||
+	    !(w(txthdr->sh_flags) & SHF_EXECINSTR))
+		return NULL;
+	return txtname;
+}
+
+static char const *has_rel(Elf32_Shdr const *const relhdr,
+				  Elf32_Shdr const *const shdr0,
+				  char const *const shstrtab,
+				  char const *const fname)
+{
+	if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
+		return NULL;
+	return __has_rel(relhdr, shdr0, shstrtab, fname);
+}
+
+
+static unsigned tot_relsize(Elf32_Shdr const *const shdr0,
+			    unsigned nhdr,
+			    const char *const shstrtab,
+			    const char *const fname)
+{
+	unsigned totrelsz = 0;
+	Elf32_Shdr const *shdrp = shdr0;
+	char const *txtname;
+
+	for (; nhdr; --nhdr, ++shdrp) {
+		txtname = has_rel(shdrp, shdr0, shstrtab, fname);
+		if (txtname && is_valid_section_name(txtname))
+			totrelsz += w(shdrp->sh_size);
+	}
+	return totrelsz;
+}
+
+
+/* Overall supervision for Elf32 ET_REL file. */
+static void
+do_func(Elf32_Ehdr *const ehdr, char const *const fname)
+{
+	Elf32_Shdr *const shdr0 = (Elf32_Shdr *)(w(ehdr->e_shoff)
+		+ (void *)ehdr);
+	unsigned const nhdr = w2(ehdr->e_shnum);
+	Elf32_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
+	char const *const shstrtab = (char const *)(w(shstr->sh_offset)
+		+ (void *)ehdr);
+
+	Elf32_Shdr const *relhdr;
+	unsigned k;
+
+	/* Upper bound on space: assume all relevant relocs are valid. */
+	unsigned const totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
+	Elf32_Rel *const mrel0_u = umalloc(totrelsz);
+	Elf32_Rel *      mrelp_u = mrel0_u;
+
+	/* 2*sizeof(address) <= sizeof(Elf32_Rel) */
+	uint32_t *const mloc0_u = umalloc(totrelsz>>1);
+	uint32_t *      mlocp_u = mloc0_u;
+
+	Elf32_Rel *const mrel0_i = umalloc(totrelsz);
+	Elf32_Rel *      mrelp_i = mrel0_i;
+
+	/* 2*sizeof(address) <= sizeof(Elf32_Rel) */
+	uint32_t *const mloc0_i = umalloc(totrelsz>>1);
+	uint32_t *      mlocp_i = mloc0_i;
+
+	unsigned rel_entsize = 0;
+	unsigned symsec_sh_link = 0;
+
+	for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
+		char const *const txtname = has_rel(relhdr, shdr0, shstrtab,
+						    fname);
+		if (txtname && is_valid_section_name(txtname)) {
+			uint32_t recval = 0;
+			unsigned const recsym = find_secsym_ndx(
+				w(relhdr->sh_info), txtname, &recval,
+				&shdr0[symsec_sh_link = w(relhdr->sh_link)],
+				ehdr);
+
+			rel_entsize = w(relhdr->sh_entsize);
+			sift_relocations(&mlocp_u, mloc0_u, &mrelp_u,
+					&mlocp_i, mloc0_i, &mrelp_i,
+					relhdr, ehdr, recsym, recval);
+		}
+	}
+	if (mloc0_u != mlocp_u || mloc0_i != mlocp_i) {
+		append_func(ehdr, shstr, mloc0_u, mlocp_u, mrel0_u, mrelp_u,
+			    mloc0_i, mlocp_i, mrel0_i, mrelp_i,
+			    rel_entsize, symsec_sh_link);
+	}
+	free(mrel0_u);
+	free(mloc0_u);
+	free(mrel0_i);
+	free(mloc0_i);
+}
+
+static void
+do_file(char const *const fname)
+{
+	Elf32_Ehdr *const 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;
+		}
+		break;
+	case ELFDATA2MSB:
+		if (*(unsigned char const *)&endian != 0) {
+			/* main() is little endian, file.o is big endian. */
+			w = w4rev;
+			w2 = w2rev;
+			w8 = w8rev;
+		}
+		break;
+	}  /* end switch */
+	if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
+	||  w2(ehdr->e_type) != ET_REL
+	||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
+		fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
+		fail_file();
+	}
+
+	if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
+	||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
+		fprintf(stderr,
+			"unrecognized ET_REL file: %s\n", fname);
+		fail_file();
+	}
+	do_func(ehdr, fname);
+
+	cleanup();
+}
+
+int
+main(int argc, char *argv[])
+{
+	int n_error = 0;  /* gcc-4.3.0 false positive complaint */
+	int i;
+
+	if (argc < 2) {
+		fprintf(stderr, "usage: recorduidiv file.o...\n");
+		return 0;
+	}
+
+	/* Process each file in turn, allowing deep failure. */
+	for (i = 1; i < argc; i++) {
+		char *file = argv[i];
+		int const sjval = setjmp(jmpenv);
+
+		switch (sjval) {
+		default:
+			fprintf(stderr, "internal error: %s\n", file);
+			exit(1);
+			break;
+		case SJ_SETJMP:    /* normal sequence */
+			/* Avoid problems if early cleanup() */
+			fd_map = -1;
+			ehdr_curr = NULL;
+			mmap_failed = 1;
+			do_file(file);
+			break;
+		case SJ_FAIL:    /* error in do_file or below */
+			++n_error;
+			break;
+		case SJ_SUCCEED:    /* premature success */
+			/* do nothing */
+			break;
+		}  /* end switch */
+	}
+	return !!n_error;
+}