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source: trunk/kernel/libk/elf.c @ 255

Last change on this file since 255 was 227, checked in by max@…, 7 years ago
use Elf64 for 64bit architectures (x86_64)
File size: 10.5 KB

Rev	Line
[1]	1	/*
	2	* elf.c - elf parser: find and map process CODE and DATA segments
	3	*
	4	* Authors Alain Greiner (2016)
	5	*
	6	* Copyright (c) UPMC Sorbonne Universites
	7	*
	8	* This file is part of ALMOS-MKH.
	9	*
	10	* ALMOS-MKH is free software; you can redistribute it and/or modify it
	11	* under the terms of the GNU General Public License as published by
	12	* the Free Software Foundation; version 2.0 of the License.
	13	*
	14	* ALMOS-MKH is distributed in the hope that it will be useful, but
	15	* WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU General Public License
	20	* along with ALMOS-MKH; if not, write to the Free Software Foundation,
	21	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	22	*/
	23
[14]	24	#include <kernel_config.h>
[1]	25	#include <hal_types.h>
	26	#include <hal_uspace.h>
	27	#include <printk.h>
	28	#include <process.h>
	29	#include <vseg.h>
	30	#include <kmem.h>
	31	#include <vfs.h>
	32	#include <elf.h>
[23]	33	#include <syscalls.h>
[1]	34
	35	///////////////////////////////////////////////////////////////////
	36	// This static function checks the .elf header.
	37	// - return true if legal header.
	38	// - return false with an error message if illegal header.
	39	///////////////////////////////////////////////////////////////////
[227]	40	static bool_t elf_isValidHeader(Elf_Ehdr *header)
[1]	41	{
[156]	42	if((header->e_ident[EI_CLASS] == ELFCLASS32)
	43	&& (header->e_ident[EI_DATA] == ELFDATA2LSB)
[1]	44	&& (header->e_ident[EI_VERSION] == EV_CURRENT)
	45	&& (header->e_ident[EI_OSABI] == ELFOSABI_NONE)
[156]	46	&& ((header->e_machine == EM_MIPS) \|\|
[1]	47	(header->e_machine == EM_MIPS_RS3_LE) \|\|
[157]	48	(header->e_machine == EM_X86_64))
[156]	49	&& (header->e_type == ET_EXEC))
	50	return true;
	51
[1]	52	if( header->e_ident[EI_CLASS] != ELFCLASS32 )
[156]	53	printk("\n[ERROR] in %s : Elf is not 32-Binary\n", __FUNCTION__ );
[1]	54
	55	if( header->e_ident[EI_DATA] != ELFDATA2LSB )
[156]	56	printk("\n[ERROR] in %s : Elf is not 2's complement, little endian\n", __FUNCTION__ );
[1]	57
[156]	58	if( header->e_ident[EI_VERSION] != EV_CURRENT )
	59	printk("\n[ERROR] in %s : Elf is not in Current Version\n", __FUNCTION__);
[1]	60
	61	if( header->e_ident[EI_OSABI] != ELFOSABI_NONE )
[156]	62	printk("\n[ERROR] in %s : Unexpected Elf ABI, need UNIX System V ABI\n", __FUNCTION__ );
[1]	63
[156]	64	if( (header->e_machine == EM_MIPS) \|\|
	65	(header->e_machine == EM_MIPS_RS3_LE) \|\|
[157]	66	(header->e_machine == EM_X86_64) )
	67	printk("\n[ERROR] in %s : unexpected core / accept only MIPS or x86_64\n", __FUNCTION__ );
[1]	68
	69	if( header->e_type == ET_EXEC )
[156]	70	printk("\n[ERROR] in %s : Elf is not executable binary\n", __FUNCTION__ );
[1]	71
	72	return false;
	73	}
	74
	75	///////////////////////////////////////////////////////////////////////////////////////
[156]	76	// This function loads the .elf header in the buffer allocated by the caller.
[204]	77	///////////////////////////////////////////////////////////////////////////////////////
[1]	78	// @ file : extended pointer on the remote file descriptor.
	79	// @ buffer : pointer on buffer allocated by the caller.
	80	// @ size : number of bytes to read.
	81	///////////////////////////////////////////////////////////////////////////////////////
[204]	82	static error_t elf_header_load( xptr_t file_xp,
[1]	83	void * buffer,
	84	uint32_t size )
[156]	85	{
	86	uint32_t count;
[1]	87
[156]	88	// load .elf header
[23]	89	count = vfs_move( true ,
[156]	90	file_xp,
	91	buffer,
	92	size );
[1]	93
	94	if( count != size )
	95	{
	96	printk("\n[ERROR] in %s : failed to read ELF header\n", __FUNCTION__ );
	97	return -1;
	98	}
	99
[227]	100	Elf_Ehdr * header = (Elf_Ehdr *)buffer;
[156]	101
[1]	102	if( (header->e_ident[EI_MAG0] != ELFMAG0) \|\|
	103	(header->e_ident[EI_MAG1] != ELFMAG1) \|\|
	104	(header->e_ident[EI_MAG2] != ELFMAG2) \|\|
	105	(header->e_ident[EI_MAG3] != ELFMAG3) )
	106	{
	107	printk("\n[ERROR] in %s : file %s not in ELF format\n", __FUNCTION__ );
	108	return -1;
	109	}
	110
	111	if( !(elf_isValidHeader( header ) ) )
	112	{
	113	printk("\n[ERROR] in %s : not supported Elf\n", __FUNCTION__ );
	114	return -1;
	115	}
	116	return 0;
	117
[204]	118	} // end elf_header_load()
	119
[1]	120	///////////////////////////////////////////////////////////////////////////////////////
	121	// This function registers in the process VMM the CODE and DATA segments.
[204]	122	///////////////////////////////////////////////////////////////////////////////////////
[1]	123	// @ file : extended pointer on the remote file descriptor.
	124	// @ segs_base : local pointer on buffer containing the segments descriptors array
	125	// @ segs_nr : number of segments in segment descriptors array.
	126	// @ process : local pointer on process descriptor.
	127	///////////////////////////////////////////////////////////////////////////////////////
	128	static error_t elf_segments_load( xptr_t file_xp,
[156]	129	void * segs_base,
[1]	130	uint32_t nb_segs,
[156]	131	process_t * process )
[1]	132	{
	133	error_t error;
	134	uint32_t index;
	135	uint32_t file_size;
[156]	136	uint32_t mem_size;
[1]	137	intptr_t start;
	138	uint32_t type;
	139	uint32_t flags;
	140	uint32_t offset;
[156]	141	vseg_t * vseg;
[1]	142
[227]	143	Elf_Phdr * seg_ptr = (Elf_Phdr *)segs_base;
[1]	144
[156]	145	// loop on segments
	146	for( index = 0 ; index < nb_segs ; index++ , seg_ptr++ )
	147	{
	148	if( seg_ptr->p_type != PT_LOAD)
	149	continue;
	150
	151	// get segment attributes
[1]	152	start = seg_ptr->p_vaddr;
[156]	153	offset = seg_ptr->p_offset;
	154	file_size = seg_ptr->p_filesz;
	155	mem_size = seg_ptr->p_memsz;
	156	flags = seg_ptr->p_flags;
[1]	157
[156]	158	// check alignment
[1]	159	if( start & CONFIG_PPM_PAGE_MASK )
	160	{
	161	printk("\n[WARNING] in %s : segment base not aligned = %x\n",
	162	__FUNCTION__, start );
	163	}
	164
[156]	165	// check size
	166	if( file_size != mem_size )
[1]	167	{
	168	printk("\n[WARNING] in %s : base = %x / mem_size = %x / file_size = %x\n",
	169	__FUNCTION__, start , mem_size , file_size);
	170	}
	171
[156]	172	// set seek on segment base in file
[23]	173	error = vfs_lseek( file_xp,
[156]	174	offset,
	175	SEEK_SET,
	176	NULL );
[1]	177
	178	if( error )
	179	{
	180	printk("\n[ERROR] in %s : failed to seek\n", __FUNCTION__ );
	181	return -1;
	182	}
	183
	184	if( flags & PF_X ) // found CODE segment
	185	{
[156]	186	type = VSEG_TYPE_CODE;
[1]	187	process->vmm.code_vpn_base = start >> CONFIG_PPM_PAGE_SHIFT;
	188
	189	elf_dmsg("\n[INFO] %s found CODE vseg / base = %x / size = %x\n",
[156]	190	__FUNCTION__ , start , mem_size );
[1]	191	}
[156]	192	else // found DATA segment
[1]	193	{
[156]	194	type = VSEG_TYPE_DATA;
[1]	195	process->vmm.data_vpn_base = start >> CONFIG_PPM_PAGE_SHIFT;
	196
	197	elf_dmsg("\n[INFO] %s found DATA vseg / base = %x / size = %x\n",
[156]	198	__FUNCTION__, start , mem_size );
[1]	199	}
	200
[156]	201	// register vseg in VMM
	202	vseg = (vseg_t *)vmm_create_vseg( process,
	203	start,
	204	mem_size,
	205	type );
[1]	206	if( vseg == NULL )
	207	{
	208	printk("\n[ERROR] in %s : cannot map segment / base = %x / size = %x\n",
	209	__FUNCTION__ , start , mem_size );
	210	return -1;
	211	}
	212
	213	vfs_file_count_up( file_xp );
	214	}
	215
	216	return 0;
	217
[204]	218	} // end elf_segments_load()
	219
[1]	220	///////////////////////////////////////////////
	221	error_t elf_load_process( char * pathname,
	222	process_t * process)
	223	{
	224	kmem_req_t req; // kmem request for program header
[227]	225	Elf_Ehdr header; // local buffer for .elf header
[1]	226	void * segs_base; // pointer on buffer for segment descriptors array
[156]	227	uint32_t segs_size; // size of buffer for segment descriptors array
[1]	228	xptr_t file_xp; // extended pointer on created file descriptor
[156]	229	uint32_t file_id; // file descriptor index (unused)
	230	uint32_t count; // bytes counter
[1]	231	error_t error;
	232
[204]	233	elf_dmsg("\n[INFO] %s : enter for %s\n", __FUNCTION__ , pathname );
[1]	234
[204]	235	// avoid GCC warning
	236	file_xp = XPTR_NULL;
	237	file_id = -1;
[1]	238
[156]	239	// open file
	240	error = vfs_open( process->vfs_cwd_xp,
[204]	241	pathname,
[156]	242	O_RDONLY,
	243	0,
	244	&file_xp,
	245	&file_id );
[1]	246	if( error )
	247	{
[204]	248	printk("\n[ERROR] in %s : failed to open file %s\n", __FUNCTION__ , pathname );
[1]	249	return -1;
	250	}
	251
[204]	252	elf_dmsg("\n[INFO] %s : file %s open\n", __FUNCTION__ , pathname );
	253
[156]	254	// load header in local buffer
[204]	255	error = elf_header_load( file_xp ,
[156]	256	&header,
[227]	257	sizeof(Elf_Ehdr) );
[156]	258	if( error )
	259	{
[204]	260	printk("\n[ERROR] in %s : cannot get header file %s\n", __FUNCTION__ , pathname );
[156]	261	vfs_close( file_xp , file_id );
	262	return -1;
	263	}
[1]	264
[204]	265	elf_dmsg("\n[INFO] %s : loaded elf header for %s\n", __FUNCTION__ , pathname );
[1]	266
	267	if( header.e_phnum == 0 )
	268	{
	269	printk("\n[ERROR] in %s : no segments found\n", __FUNCTION__ );
[156]	270	vfs_close( file_xp , file_id );
[1]	271	return -1;
	272	}
	273
[156]	274	// compute buffer size for segment descriptors array
[227]	275	segs_size = sizeof(Elf_Phdr) * header.e_phnum;
[156]	276
	277	// allocate memory for segment descriptors array
[1]	278	req.type = KMEM_GENERIC;
	279	req.size = segs_size;
	280	req.flags = AF_KERNEL;
	281	segs_base = kmem_alloc( &req );
	282
	283	if( segs_base == NULL )
[156]	284	{
[1]	285	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
[156]	286	vfs_close( file_xp , file_id );
	287	return -1;
	288	}
[1]	289
[156]	290	// set seek pointer in file descriptor to access segment descriptors array
[23]	291	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
[1]	292
	293	if( error )
	294	{
	295	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
[156]	296	vfs_close( file_xp , file_id );
	297	req.ptr = segs_base;
	298	kmem_free( &req );
[1]	299	return -1;
	300	}
	301
[156]	302	// load seg descriptors array to local buffer
[23]	303	count = vfs_move( true,
[156]	304	file_xp,
	305	segs_base,
	306	segs_size );
[1]	307
	308	if( count != segs_size )
	309	{
	310	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
[156]	311	vfs_close( file_xp , file_id );
	312	req.ptr = segs_base;
	313	kmem_free( &req );
[1]	314	return -1;
	315	}
	316
[204]	317	elf_dmsg("\n[INFO] %s loaded segments descriptors for %s \n", __FUNCTION__ , pathname );
[1]	318
[156]	319	// register loadable segments in process VMM
	320	error = elf_segments_load( file_xp,
	321	segs_base,
	322	header.e_phnum,
	323	process );
[1]	324	if( error )
[156]	325	{
	326	vfs_close( file_xp , file_id );
	327	req.ptr = segs_base;
	328	kmem_free( &req );
[1]	329	return -1;
[156]	330	}
[1]	331
[156]	332	// register process entry point in VMM
[1]	333	process->vmm.entry_point = (intptr_t)header.e_entry;
	334
[156]	335	// register extended pointer on .elf file descriptor
	336	process->vfs_bin_xp = file_xp;
[1]	337
[156]	338	// release allocated memory for program header
[1]	339	req.ptr = segs_base;
	340	kmem_free(&req);
	341
[156]	342	elf_dmsg("\n[INFO] %s successfully completed / entry point = %x for %s]\n",
[204]	343	__FUNCTION__, (uint32_t) header.e_entry , pathname );
[1]	344
	345	return 0;
	346
[204]	347	} // end elf_load_process()
	348

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