piegen: Implement tool building, v2

Here we simply build piegen tool which gonna be used
to generate parasite code safe to rellocate. The tool
is taking object file as an argument, parses it and
generates C file with rellocations encoded in form
suitable for fast appliance.

Currently only x86-32 x86-64 is supported.

v2 (by ldufour@):
 - Filter PIEGEN
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Makefile

@@ -142,6 +142,9 @@ ARCH-LIB	:= $(ARCH_DIR)/crtools.built-in.o
 CRIU-SO		:= libcriu
 CRIU-LIB	:= lib/$(CRIU-SO).so
 CRIU-INC	:= lib/criu.h include/criu-plugin.h include/criu-log.h protobuf/rpc.proto
+ifneq ($(filter i386 ia32 x86_64, $(ARCH)),)
+PIEGEN		:= pie/piegen/piegen
+endif
 
 export CC MAKE CFLAGS LIBS SRCARCH DEFINES MAKEFLAGS CRIU-SO
 export SRC_DIR SYSCALL-LIB SH RM ARCH_DIR OBJCOPY LDARCH LD
@@ -184,9 +187,20 @@ $(ARCH_DIR)/%:: protobuf config
 $(ARCH_DIR): protobuf config
 	$(Q) $(MAKE) $(build)=$(ARCH_DIR) all
 
-pie/%:: $(ARCH_DIR)
+ifneq ($(filter i386 ia32 x86_64, $(ARCH)),)
+pie/piegen/%:
+	$(Q) $(MAKE) $(build)=pie/piegen $@
+pie/piegen:
+	$(Q) $(MAKE) $(build)=pie/piegen all
+$(PIEGEN): pie/piegen/built-in.o
+	$(E) "  LINK    " $@
+	$(Q) $(CC) $(CFLAGS) $^ $(LDFLAGS) -o $@
+.PHONY: pie/piegen
+endif
+
+pie/%:: $(ARCH_DIR) $(PIEGEN)
 	$(Q) $(MAKE) $(build)=pie $@
-pie: $(ARCH_DIR)
+pie: $(ARCH_DIR) $(PIEGEN)
 	$(Q) $(MAKE) $(build)=pie all
 
 %.o %.i %.s %.d: $(VERSION_HEADER) pie
@@ -235,6 +249,7 @@ clean-built:
 	$(Q) $(RM) $(VERSION_HEADER)
 	$(Q) $(MAKE) $(build)=$(ARCH_DIR) clean
 	$(Q) $(MAKE) $(build)=protobuf clean
+	$(Q) $(MAKE) $(build)=pie/piegen clean
 	$(Q) $(MAKE) $(build)=pie clean
 	$(Q) $(MAKE) $(build)=lib clean
 	$(Q) $(MAKE) $(build-crtools)=. clean

pie/piegen/Makefile

+CFLAGS += -iquote pie/piegen
+
+obj-y += main.o
+ifneq ($(filter i386 ia32 x86_64, $(ARCH)),)
+obj-y += elf-x86-32.o
+obj-y += elf-x86-64.o
+endif
+
+cleanup-y += $(obj)/piegen
+cleanup-y += $(obj)/*.o
+
+ifneq ($(MAKECMDGOALS),clean)
+incdeps := y
+endif

pie/piegen/elf-x86-32.c

+#define ELF_X86_32
+#define handle_elf	handle_elf_x86_32
+
+#define Ehdr_t		Elf32_Ehdr
+#define Shdr_t		Elf32_Shdr
+#define Sym_t		Elf32_Sym
+#define Rel_t		Elf32_Rel
+#define Rela_t		Elf32_Rela
+
+#define ELF_ST_TYPE	ELF32_ST_TYPE
+#define ELF_ST_BIND	ELF32_ST_BIND
+
+#define ELF_R_SYM	ELF32_R_SYM
+#define ELF_R_TYPE	ELF32_R_TYPE
+
+#include "elf.c"

pie/piegen/elf-x86-64.c

+#define ELF_X86_64
+#define handle_elf	handle_elf_x86_64
+
+#define Ehdr_t		Elf64_Ehdr
+#define Shdr_t		Elf64_Shdr
+#define Sym_t		Elf64_Sym
+#define Rel_t		Elf64_Rel
+#define Rela_t		Elf64_Rela
+
+#define ELF_ST_TYPE	ELF64_ST_TYPE
+#define ELF_ST_BIND	ELF64_ST_BIND
+
+#define ELF_R_SYM	ELF64_R_SYM
+#define ELF_R_TYPE	ELF64_R_TYPE
+
+#include "elf.c"

pie/piegen/main.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <getopt.h>
+#include <string.h>
+
+#include <fcntl.h>
+#include <elf.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#include "compiler.h"
+#include "config.h"
+#include "piegen.h"
+
+piegen_opt_t opts = {
+	.input_filename		= "file.o",
+	.stream_name		= "stream",
+	.type_name		= "elf_reloc_t",
+	.prefix_name		= "__",
+	.var_name		= "elf_relocs",
+	.nrgotpcrel_name	= "nr_gotpcrel",
+};
+
+static int handle_elf(const piegen_opt_t *opts, void *mem, size_t size)
+{
+#if defined(CONFIG_X86_32) || defined(CONFIG_X86_64)
+	unsigned char elf_ident_x86_32[EI_NIDENT] = {
+		0x7f, 0x45, 0x4c, 0x46, 0x01, 0x01, 0x01, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	};
+
+	unsigned char elf_ident_x86_64[EI_NIDENT] = {
+		0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	};
+
+	if (memcmp(mem, elf_ident_x86_32, sizeof(elf_ident_x86_32)) == 0)
+		return handle_elf_x86_32(opts, mem, size);
+	else if (memcmp(mem, elf_ident_x86_64, sizeof(elf_ident_x86_64)) == 0)
+		return handle_elf_x86_64(opts, mem, size);
+#endif
+
+	pr_err("Unsupported Elf format detected\n");
+	return -1;
+}
+
+/*
+ * That;s the tool to generate patches object files.
+ */
+int main(int argc, char *argv[])
+{
+	struct stat st;
+	int opt, idx;
+	void *mem;
+	int fd;
+
+	static const char short_opts[] = "f:s:t:p:v:h";
+	static struct option long_opts[] = {
+		{ "file",	required_argument,	0, 'f' },
+		{ "stream",	required_argument,	0, 's' },
+		{ "type",	required_argument,	0, 't' },
+		{ "sym-prefix",	required_argument,	0, 'p' },
+		{ "variable",	required_argument,	0, 'v' },
+		{ "help",	required_argument,	0, 'h' },
+		{ },
+	};
+
+	if (argc < 3)
+		goto usage;
+
+	while (1) {
+		idx = -1;
+		opt = getopt_long(argc, argv, short_opts, long_opts, &idx);
+		if (opt == -1)
+			break;
+		switch (opt) {
+		case 'f':
+			opts.input_filename = optarg;
+			break;
+		case 's':
+			opts.stream_name = optarg;
+			break;
+		case 'p':
+			opts.prefix_name = optarg;
+			break;
+		case 't':
+			opts.type_name = optarg;
+			break;
+		case 'v':
+			opts.var_name = optarg;
+			break;
+		case 'h':
+		default:
+			goto usage;
+		}
+	}
+
+	fd = open(opts.input_filename, O_RDONLY);
+	if (fd < 0) {
+		pr_perror("Can't open file %s", opts.input_filename);
+		goto err;
+	}
+
+	if (fstat(fd, &st)) {
+		pr_perror("Can't stat file %s", opts.input_filename);
+		goto err;
+	}
+
+	mem = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FILE, fd, 0);
+	if (mem == MAP_FAILED) {
+		pr_perror("Can't mmap file %s", opts.input_filename);
+		goto err;
+	}
+
+	if (handle_elf(&opts, mem, st.st_size))
+		goto err;
+	return 1;
+usage:
+	printf("Usage: %s -f filename\n", argv[0]);
+err:
+	return 0;
+}

pie/piegen/piegen.h

+#ifndef __ELFTIL_H__
+#define __ELFTIL_H__
+
+#include <stdio.h>
+#include <unistd.h>
+
+typedef struct {
+	char		*input_filename;
+	char		*stream_name;
+	char		*type_name;
+	char		*prefix_name;
+	char		*var_name;
+	char		*nrgotpcrel_name;
+} piegen_opt_t;
+
+extern piegen_opt_t opts;
+
+#if defined(CONFIG_X86_32) || defined(CONFIG_X86_64)
+extern int handle_elf_x86_32(const piegen_opt_t *opts, void *mem, size_t size);
+extern int handle_elf_x86_64(const piegen_opt_t *opts, void *mem, size_t size);
+#endif
+
+#define pr_out(fmt, ...)	fprintf(stdout, fmt, ##__VA_ARGS__)
+
+#if 0
+# define pr_debug(fmt, ...)	fprintf(stderr, fmt, ##__VA_ARGS__)
+#else
+# define pr_debug(fmt, ...)
+#endif
+
+#define pr_err(fmt, ...)	fprintf(stderr, "Error (%s:%d): "fmt, __FILE__, __LINE__, ##__VA_ARGS__)
+#define pr_perror(fmt, ...)	fprintf(stderr, "Error (%s:%d): "fmt "%m\n", __FILE__, __LINE__, ##__VA_ARGS__)
+
+#endif /* __ELFTIL_H__ */