Context Navigation

source: trunk/kernel/libk/elf.c @ 265

Last change on this file since 265 was 265, checked in by alain, 7 years ago
Fix several bugs in VFS.
File size: 10.7 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
[265]	89	count = vfs_move( true, // to_buffer
	90	false, // is_user
[156]	91	file_xp,
	92	buffer,
	93	size );
[1]	94
	95	if( count != size )
	96	{
[265]	97	printk("\n[ERROR] in %s : cannot read ELF header size : %d / done = %d\n",
	98	__FUNCTION__ , size , count );
[1]	99	return -1;
	100	}
	101
[227]	102	Elf_Ehdr * header = (Elf_Ehdr *)buffer;
[156]	103
[1]	104	if( (header->e_ident[EI_MAG0] != ELFMAG0) \|\|
	105	(header->e_ident[EI_MAG1] != ELFMAG1) \|\|
	106	(header->e_ident[EI_MAG2] != ELFMAG2) \|\|
	107	(header->e_ident[EI_MAG3] != ELFMAG3) )
	108	{
	109	printk("\n[ERROR] in %s : file %s not in ELF format\n", __FUNCTION__ );
	110	return -1;
	111	}
	112
	113	if( !(elf_isValidHeader( header ) ) )
	114	{
	115	printk("\n[ERROR] in %s : not supported Elf\n", __FUNCTION__ );
	116	return -1;
	117	}
	118	return 0;
	119
[204]	120	} // end elf_header_load()
	121
[1]	122	///////////////////////////////////////////////////////////////////////////////////////
	123	// This function registers in the process VMM the CODE and DATA segments.
[204]	124	///////////////////////////////////////////////////////////////////////////////////////
[1]	125	// @ file : extended pointer on the remote file descriptor.
	126	// @ segs_base : local pointer on buffer containing the segments descriptors array
	127	// @ segs_nr : number of segments in segment descriptors array.
	128	// @ process : local pointer on process descriptor.
	129	///////////////////////////////////////////////////////////////////////////////////////
	130	static error_t elf_segments_load( xptr_t file_xp,
[156]	131	void * segs_base,
[1]	132	uint32_t nb_segs,
[156]	133	process_t * process )
[1]	134	{
	135	error_t error;
	136	uint32_t index;
	137	uint32_t file_size;
[156]	138	uint32_t mem_size;
[1]	139	intptr_t start;
	140	uint32_t type;
	141	uint32_t flags;
	142	uint32_t offset;
[156]	143	vseg_t * vseg;
[1]	144
[227]	145	Elf_Phdr * seg_ptr = (Elf_Phdr *)segs_base;
[1]	146
[156]	147	// loop on segments
	148	for( index = 0 ; index < nb_segs ; index++ , seg_ptr++ )
	149	{
	150	if( seg_ptr->p_type != PT_LOAD)
	151	continue;
	152
	153	// get segment attributes
[1]	154	start = seg_ptr->p_vaddr;
[156]	155	offset = seg_ptr->p_offset;
	156	file_size = seg_ptr->p_filesz;
	157	mem_size = seg_ptr->p_memsz;
	158	flags = seg_ptr->p_flags;
[1]	159
[156]	160	// check alignment
[1]	161	if( start & CONFIG_PPM_PAGE_MASK )
	162	{
	163	printk("\n[WARNING] in %s : segment base not aligned = %x\n",
	164	__FUNCTION__, start );
	165	}
	166
[156]	167	// check size
	168	if( file_size != mem_size )
[1]	169	{
	170	printk("\n[WARNING] in %s : base = %x / mem_size = %x / file_size = %x\n",
	171	__FUNCTION__, start , mem_size , file_size);
	172	}
	173
[156]	174	// set seek on segment base in file
[23]	175	error = vfs_lseek( file_xp,
[156]	176	offset,
	177	SEEK_SET,
	178	NULL );
[1]	179
	180	if( error )
	181	{
	182	printk("\n[ERROR] in %s : failed to seek\n", __FUNCTION__ );
	183	return -1;
	184	}
	185
	186	if( flags & PF_X ) // found CODE segment
	187	{
[156]	188	type = VSEG_TYPE_CODE;
[1]	189	process->vmm.code_vpn_base = start >> CONFIG_PPM_PAGE_SHIFT;
	190
	191	elf_dmsg("\n[INFO] %s found CODE vseg / base = %x / size = %x\n",
[156]	192	__FUNCTION__ , start , mem_size );
[1]	193	}
[156]	194	else // found DATA segment
[1]	195	{
[156]	196	type = VSEG_TYPE_DATA;
[1]	197	process->vmm.data_vpn_base = start >> CONFIG_PPM_PAGE_SHIFT;
	198
	199	elf_dmsg("\n[INFO] %s found DATA vseg / base = %x / size = %x\n",
[156]	200	__FUNCTION__, start , mem_size );
[1]	201	}
	202
[156]	203	// register vseg in VMM
	204	vseg = (vseg_t *)vmm_create_vseg( process,
	205	start,
	206	mem_size,
	207	type );
[1]	208	if( vseg == NULL )
	209	{
	210	printk("\n[ERROR] in %s : cannot map segment / base = %x / size = %x\n",
	211	__FUNCTION__ , start , mem_size );
	212	return -1;
	213	}
	214
	215	vfs_file_count_up( file_xp );
	216	}
	217
	218	return 0;
	219
[204]	220	} // end elf_segments_load()
	221
[1]	222	///////////////////////////////////////////////
	223	error_t elf_load_process( char * pathname,
	224	process_t * process)
	225	{
	226	kmem_req_t req; // kmem request for program header
[227]	227	Elf_Ehdr header; // local buffer for .elf header
[1]	228	void * segs_base; // pointer on buffer for segment descriptors array
[156]	229	uint32_t segs_size; // size of buffer for segment descriptors array
[1]	230	xptr_t file_xp; // extended pointer on created file descriptor
[156]	231	uint32_t file_id; // file descriptor index (unused)
	232	uint32_t count; // bytes counter
[1]	233	error_t error;
	234
[265]	235	elf_dmsg("\n[INFO] %s : enters for <%s>\n", __FUNCTION__ , pathname );
[1]	236
[204]	237	// avoid GCC warning
	238	file_xp = XPTR_NULL;
	239	file_id = -1;
[1]	240
[156]	241	// open file
	242	error = vfs_open( process->vfs_cwd_xp,
[204]	243	pathname,
[156]	244	O_RDONLY,
	245	0,
	246	&file_xp,
	247	&file_id );
[1]	248	if( error )
	249	{
[204]	250	printk("\n[ERROR] in %s : failed to open file %s\n", __FUNCTION__ , pathname );
[1]	251	return -1;
	252	}
	253
[265]	254	elf_dmsg("\n[INFO] %s : file <%s> open\n", __FUNCTION__ , pathname );
[204]	255
[156]	256	// load header in local buffer
[204]	257	error = elf_header_load( file_xp ,
[156]	258	&header,
[227]	259	sizeof(Elf_Ehdr) );
[156]	260	if( error )
	261	{
[204]	262	printk("\n[ERROR] in %s : cannot get header file %s\n", __FUNCTION__ , pathname );
[156]	263	vfs_close( file_xp , file_id );
	264	return -1;
	265	}
[1]	266
[204]	267	elf_dmsg("\n[INFO] %s : loaded elf header for %s\n", __FUNCTION__ , pathname );
[1]	268
	269	if( header.e_phnum == 0 )
	270	{
	271	printk("\n[ERROR] in %s : no segments found\n", __FUNCTION__ );
[156]	272	vfs_close( file_xp , file_id );
[1]	273	return -1;
	274	}
	275
[156]	276	// compute buffer size for segment descriptors array
[227]	277	segs_size = sizeof(Elf_Phdr) * header.e_phnum;
[156]	278
	279	// allocate memory for segment descriptors array
[1]	280	req.type = KMEM_GENERIC;
	281	req.size = segs_size;
	282	req.flags = AF_KERNEL;
	283	segs_base = kmem_alloc( &req );
	284
	285	if( segs_base == NULL )
[156]	286	{
[1]	287	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
[156]	288	vfs_close( file_xp , file_id );
	289	return -1;
	290	}
[1]	291
[156]	292	// set seek pointer in file descriptor to access segment descriptors array
[23]	293	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
[1]	294
	295	if( error )
	296	{
	297	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
[156]	298	vfs_close( file_xp , file_id );
	299	req.ptr = segs_base;
	300	kmem_free( &req );
[1]	301	return -1;
	302	}
	303
[156]	304	// load seg descriptors array to local buffer
[265]	305	count = vfs_move( true, // to_buffer
	306	false, // is_user
[156]	307	file_xp,
	308	segs_base,
	309	segs_size );
[1]	310
	311	if( count != segs_size )
	312	{
	313	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
[156]	314	vfs_close( file_xp , file_id );
	315	req.ptr = segs_base;
	316	kmem_free( &req );
[1]	317	return -1;
	318	}
	319
[204]	320	elf_dmsg("\n[INFO] %s loaded segments descriptors for %s \n", __FUNCTION__ , pathname );
[1]	321
[156]	322	// register loadable segments in process VMM
	323	error = elf_segments_load( file_xp,
	324	segs_base,
	325	header.e_phnum,
	326	process );
[1]	327	if( error )
[156]	328	{
	329	vfs_close( file_xp , file_id );
	330	req.ptr = segs_base;
	331	kmem_free( &req );
[1]	332	return -1;
[156]	333	}
[1]	334
[156]	335	// register process entry point in VMM
[1]	336	process->vmm.entry_point = (intptr_t)header.e_entry;
	337
[156]	338	// register extended pointer on .elf file descriptor
	339	process->vfs_bin_xp = file_xp;
[1]	340
[156]	341	// release allocated memory for program header
[1]	342	req.ptr = segs_base;
	343	kmem_free(&req);
	344
[156]	345	elf_dmsg("\n[INFO] %s successfully completed / entry point = %x for %s]\n",
[204]	346	__FUNCTION__, (uint32_t) header.e_entry , pathname );
[1]	347
	348	return 0;
	349
[204]	350	} // end elf_load_process()
	351

Note: See TracBrowser for help on using the repository browser.

Download in other formats: