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source: trunk/kernel/libk/elf.c @ 174

Last change on this file since 174 was 157, checked in by max@…, 7 years ago
add the x86_64 flag
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	///////////////////////////////////////////////////////////////////
	40	static bool_t elf_isValidHeader(Elf32_Ehdr *header)
	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.
[1]	77	// @ file : extended pointer on the remote file descriptor.
	78	// @ buffer : pointer on buffer allocated by the caller.
	79	// @ size : number of bytes to read.
	80	///////////////////////////////////////////////////////////////////////////////////////
	81	static error_t elf_header_read( xptr_t file_xp,
	82	void * buffer,
	83	uint32_t size )
[156]	84	{
	85	uint32_t count;
[1]	86
[156]	87	// load .elf header
[23]	88	count = vfs_move( true ,
[156]	89	file_xp,
	90	buffer,
	91	size );
[1]	92
	93	if( count != size )
	94	{
	95	printk("\n[ERROR] in %s : failed to read ELF header\n", __FUNCTION__ );
	96	return -1;
	97	}
	98
[156]	99	Elf32_Ehdr * header = (Elf32_Ehdr *)buffer;
	100
[1]	101	if( (header->e_ident[EI_MAG0] != ELFMAG0) \|\|
	102	(header->e_ident[EI_MAG1] != ELFMAG1) \|\|
	103	(header->e_ident[EI_MAG2] != ELFMAG2) \|\|
	104	(header->e_ident[EI_MAG3] != ELFMAG3) )
	105	{
	106	printk("\n[ERROR] in %s : file %s not in ELF format\n", __FUNCTION__ );
	107	return -1;
	108	}
	109
	110	if( !(elf_isValidHeader( header ) ) )
	111	{
	112	printk("\n[ERROR] in %s : not supported Elf\n", __FUNCTION__ );
	113	return -1;
	114	}
	115	return 0;
[156]	116	}
[1]	117
	118	///////////////////////////////////////////////////////////////////////////////////////
	119	// This function registers in the process VMM the CODE and DATA segments.
	120	// @ file : extended pointer on the remote file descriptor.
	121	// @ segs_base : local pointer on buffer containing the segments descriptors array
	122	// @ segs_nr : number of segments in segment descriptors array.
	123	// @ process : local pointer on process descriptor.
	124	///////////////////////////////////////////////////////////////////////////////////////
	125	static error_t elf_segments_load( xptr_t file_xp,
[156]	126	void * segs_base,
[1]	127	uint32_t nb_segs,
[156]	128	process_t * process )
[1]	129	{
	130	error_t error;
	131	uint32_t index;
	132	uint32_t file_size;
[156]	133	uint32_t mem_size;
[1]	134	intptr_t start;
	135	uint32_t type;
	136	uint32_t flags;
	137	uint32_t offset;
[156]	138	vseg_t * vseg;
[1]	139
[156]	140	Elf32_Phdr * seg_ptr = (Elf32_Phdr *)segs_base;
[1]	141
[156]	142	// loop on segments
	143	for( index = 0 ; index < nb_segs ; index++ , seg_ptr++ )
	144	{
	145	if( seg_ptr->p_type != PT_LOAD)
	146	continue;
	147
	148	// get segment attributes
[1]	149	start = seg_ptr->p_vaddr;
[156]	150	offset = seg_ptr->p_offset;
	151	file_size = seg_ptr->p_filesz;
	152	mem_size = seg_ptr->p_memsz;
	153	flags = seg_ptr->p_flags;
[1]	154
[156]	155	// check alignment
[1]	156	if( start & CONFIG_PPM_PAGE_MASK )
	157	{
	158	printk("\n[WARNING] in %s : segment base not aligned = %x\n",
	159	__FUNCTION__, start );
	160	}
	161
[156]	162	// check size
	163	if( file_size != mem_size )
[1]	164	{
	165	printk("\n[WARNING] in %s : base = %x / mem_size = %x / file_size = %x\n",
	166	__FUNCTION__, start , mem_size , file_size);
	167	}
	168
[156]	169	// set seek on segment base in file
[23]	170	error = vfs_lseek( file_xp,
[156]	171	offset,
	172	SEEK_SET,
	173	NULL );
[1]	174
	175	if( error )
	176	{
	177	printk("\n[ERROR] in %s : failed to seek\n", __FUNCTION__ );
	178	return -1;
	179	}
	180
	181	if( flags & PF_X ) // found CODE segment
	182	{
[156]	183	type = VSEG_TYPE_CODE;
[1]	184	process->vmm.code_vpn_base = start >> CONFIG_PPM_PAGE_SHIFT;
	185
	186	elf_dmsg("\n[INFO] %s found CODE vseg / base = %x / size = %x\n",
[156]	187	__FUNCTION__ , start , mem_size );
[1]	188	}
[156]	189	else // found DATA segment
[1]	190	{
[156]	191	type = VSEG_TYPE_DATA;
[1]	192	process->vmm.data_vpn_base = start >> CONFIG_PPM_PAGE_SHIFT;
	193
	194	elf_dmsg("\n[INFO] %s found DATA vseg / base = %x / size = %x\n",
[156]	195	__FUNCTION__, start , mem_size );
[1]	196	}
	197
[156]	198	// register vseg in VMM
	199	vseg = (vseg_t *)vmm_create_vseg( process,
	200	start,
	201	mem_size,
	202	type );
[1]	203	if( vseg == NULL )
	204	{
	205	printk("\n[ERROR] in %s : cannot map segment / base = %x / size = %x\n",
	206	__FUNCTION__ , start , mem_size );
	207	return -1;
	208	}
	209
	210	vfs_file_count_up( file_xp );
	211	}
	212
	213	return 0;
[156]	214	}
[1]	215
	216	///////////////////////////////////////////////
	217	error_t elf_load_process( char * pathname,
	218	process_t * process)
	219	{
[156]	220	char path_copy[CONFIG_VFS_MAX_PATH_LENGTH];
[1]	221	kmem_req_t req; // kmem request for program header
	222	uint32_t length; // actual path length
	223	Elf32_Ehdr header; // local buffer for .elf header
	224	void * segs_base; // pointer on buffer for segment descriptors array
[156]	225	uint32_t segs_size; // size of buffer for segment descriptors array
[1]	226	xptr_t file_xp; // extended pointer on created file descriptor
[156]	227	uint32_t file_id; // file descriptor index (unused)
	228	uint32_t count; // bytes counter
[1]	229	error_t error;
	230
[156]	231	// get path length from user space
[1]	232	length = hal_strlen_from_uspace( pathname );
	233
[156]	234	if( length >= CONFIG_VFS_MAX_PATH_LENGTH )
	235	{
	236	printk("\n[ERROR] in %s : pathname length too long\n", __FUNCTION__ );
	237	return -1;
	238	}
[1]	239
[156]	240	// make a local copy for pathname
	241	hal_copy_from_uspace( path_copy , pathname , length+1 );
[1]	242
[156]	243	// open file
	244	file_xp = XPTR_NULL; // avoid GCC warning
	245	file_id = -1;
[1]	246
[156]	247	error = vfs_open( process->vfs_cwd_xp,
	248	path_copy,
	249	O_RDONLY,
	250	0,
	251	&file_xp,
	252	&file_id );
[1]	253	if( error )
	254	{
	255	printk("\n[ERROR] in %s : failed to open executable file %s\n",
[156]	256	__FUNCTION__ , path_copy );
[1]	257	return -1;
	258	}
	259
[156]	260	// load header in local buffer
	261	error = elf_header_read( file_xp ,
	262	&header,
	263	sizeof(Elf32_Ehdr) );
	264	if( error )
	265	{
	266	vfs_close( file_xp , file_id );
	267	return -1;
	268	}
[1]	269
	270	elf_dmsg("\n[INFO] %s loaded elf header for %s\n", __FUNCTION__ , path_copy );
	271
	272	if( header.e_phnum == 0 )
	273	{
	274	printk("\n[ERROR] in %s : no segments found\n", __FUNCTION__ );
[156]	275	vfs_close( file_xp , file_id );
[1]	276	return -1;
	277	}
	278
[156]	279	// compute buffer size for segment descriptors array
[1]	280	segs_size = sizeof(Elf32_Phdr) * header.e_phnum;
[156]	281
	282	// allocate memory for segment descriptors array
[1]	283	req.type = KMEM_GENERIC;
	284	req.size = segs_size;
	285	req.flags = AF_KERNEL;
	286	segs_base = kmem_alloc( &req );
	287
	288	if( segs_base == NULL )
[156]	289	{
[1]	290	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
[156]	291	vfs_close( file_xp , file_id );
	292	return -1;
	293	}
[1]	294
[156]	295	// set seek pointer in file descriptor to access segment descriptors array
[23]	296	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
[1]	297
	298	if( error )
	299	{
	300	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
[156]	301	vfs_close( file_xp , file_id );
	302	req.ptr = segs_base;
	303	kmem_free( &req );
[1]	304	return -1;
	305	}
	306
[156]	307	// load seg descriptors array to local buffer
[23]	308	count = vfs_move( true,
[156]	309	file_xp,
	310	segs_base,
	311	segs_size );
[1]	312
	313	if( count != segs_size )
	314	{
	315	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
[156]	316	vfs_close( file_xp , file_id );
	317	req.ptr = segs_base;
	318	kmem_free( &req );
[1]	319	return -1;
	320	}
	321
	322	elf_dmsg("\n[INFO] %s loaded segments descriptors for %s \n", __FUNCTION__ , path_copy );
	323
[156]	324	// register loadable segments in process VMM
	325	error = elf_segments_load( file_xp,
	326	segs_base,
	327	header.e_phnum,
	328	process );
[1]	329	if( error )
[156]	330	{
	331	vfs_close( file_xp , file_id );
	332	req.ptr = segs_base;
	333	kmem_free( &req );
[1]	334	return -1;
[156]	335	}
[1]	336
[156]	337	// register process entry point in VMM
[1]	338	process->vmm.entry_point = (intptr_t)header.e_entry;
	339
[156]	340	// register extended pointer on .elf file descriptor
	341	process->vfs_bin_xp = file_xp;
[1]	342
[156]	343	// release allocated memory for program header
[1]	344	req.ptr = segs_base;
	345	kmem_free(&req);
	346
[156]	347	elf_dmsg("\n[INFO] %s successfully completed / entry point = %x for %s]\n",
[1]	348	__FUNCTION__, (uint32_t) header.e_entry , path_copy );
	349
	350	return 0;
[156]	351	}
[1]	352

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