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source: trunk/kernel/libk/elf.c @ 374

Last change on this file since 374 was 367, checked in by alain, 7 years ago
Change Time unit from cycle to TICK (in millisecond). Fix several bugs in VFS.
File size: 10.7 KB

Line
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
24	#include <kernel_config.h>
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>
33	#include <syscalls.h>
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(Elf_Ehdr *header)
41	{
42	if((header->e_ident[EI_CLASS] == ELFCLASS)
43	&& (header->e_ident[EI_DATA] == ELFDATA2LSB)
44	&& (header->e_ident[EI_VERSION] == EV_CURRENT)
45	/*
46	&& (header->e_ident[EI_OSABI] == ELFOSABI_NONE)
47	*/
48	&& ((header->e_machine == EM_MIPS) \|\|
49	(header->e_machine == EM_MIPS_RS3_LE) \|\|
50	(header->e_machine == EM_X86_64))
51	&& (header->e_type == ET_EXEC))
52	return true;
53
54	if( header->e_ident[EI_CLASS] != ELFCLASS )
55	printk("\n[ERROR] in %s : Elf is not 32/64-Binary\n", __FUNCTION__ );
56
57	if( header->e_ident[EI_DATA] != ELFDATA2LSB )
58	printk("\n[ERROR] in %s : Elf is not 2's complement, little endian\n", __FUNCTION__ );
59
60	if( header->e_ident[EI_VERSION] != EV_CURRENT )
61	printk("\n[ERROR] in %s : Elf is not in Current Version\n", __FUNCTION__);
62	/*
63	if( header->e_ident[EI_OSABI] != ELFOSABI_NONE )
64	printk("\n[ERROR] in %s : Unexpected Elf ABI, need UNIX System V ABI\n", __FUNCTION__ );
65	*/
66	if( (header->e_machine != EM_MIPS) &&
67	(header->e_machine != EM_MIPS_RS3_LE) &&
68	(header->e_machine != EM_X86_64) )
69	printk("\n[ERROR] in %s : unexpected core / accept only MIPS or x86_64\n", __FUNCTION__ );
70
71	if( header->e_type != ET_EXEC )
72	printk("\n[ERROR] in %s : Elf is not executable binary\n", __FUNCTION__ );
73
74	return false;
75	}
76
77	///////////////////////////////////////////////////////////////////////////////////////
78	// This function loads the .elf header in the buffer allocated by the caller.
79	///////////////////////////////////////////////////////////////////////////////////////
80	// @ file : extended pointer on the remote file descriptor.
81	// @ buffer : pointer on buffer allocated by the caller.
82	// @ size : number of bytes to read.
83	///////////////////////////////////////////////////////////////////////////////////////
84	static error_t elf_header_load( xptr_t file_xp,
85	void * buffer,
86	uint32_t size )
87	{
88	error_t error;
89	xptr_t buf_xp;
90
91	buf_xp = XPTR( local_cxy , buffer );
92
93	// load .elf header
94	error = vfs_kernel_move( true, // to_buffer
95	file_xp,
96	buf_xp,
97	size );
98
99	if( error )
100	{
101	printk("\n[ERROR] in %s : cannot read ELF header size : %d\n",
102	__FUNCTION__ , size );
103	return -1;
104	}
105
106	Elf_Ehdr * header = (Elf_Ehdr *)buffer;
107
108	if( (header->e_ident[EI_MAG0] != ELFMAG0) \|\|
109	(header->e_ident[EI_MAG1] != ELFMAG1) \|\|
110	(header->e_ident[EI_MAG2] != ELFMAG2) \|\|
111	(header->e_ident[EI_MAG3] != ELFMAG3) )
112	{
113	printk("\n[ERROR] in %s : file not in ELF format\n", __FUNCTION__ );
114	return -1;
115	}
116
117	if( !(elf_isValidHeader( header ) ) )
118	{
119	printk("\n[ERROR] in %s : not supported Elf\n", __FUNCTION__ );
120	return -1;
121	}
122	return 0;
123
124	} // end elf_header_load()
125
126	///////////////////////////////////////////////////////////////////////////////////////
127	// This function registers in the process VMM the CODE and DATA segments.
128	///////////////////////////////////////////////////////////////////////////////////////
129	// @ file : extended pointer on the remote file descriptor.
130	// @ segs_base : local pointer on buffer containing the segments descriptors array
131	// @ segs_nr : number of segments in segment descriptors array.
132	// @ process : local pointer on process descriptor.
133	///////////////////////////////////////////////////////////////////////////////////////
134	static error_t elf_segments_register( xptr_t file_xp,
135	void * segs_base,
136	uint32_t nb_segs,
137	process_t * process )
138	{
139	uint32_t index;
140	intptr_t file_size;
141	intptr_t mem_size;
142	intptr_t file_offset;
143	intptr_t vbase;
144	uint32_t type;
145	uint32_t flags;
146	vseg_t * vseg;
147
148	Elf_Phdr * seg_ptr = (Elf_Phdr *)segs_base;
149
150	// loop on segments
151	for( index = 0 ; index < nb_segs ; index++ , seg_ptr++ )
152	{
153	if( seg_ptr->p_type != PT_LOAD)
154	continue;
155
156	// get segment attributes
157	vbase = seg_ptr->p_vaddr; // vseg base vaddr
158	mem_size = seg_ptr->p_memsz; // actual vseg size
159	file_offset = seg_ptr->p_offset; // vseg offset in .elf file
160	file_size = seg_ptr->p_filesz; // vseg size in .elf file
161	flags = seg_ptr->p_flags;
162
163	if( flags & PF_X ) // found CODE segment
164	{
165	type = VSEG_TYPE_CODE;
166	process->vmm.code_vpn_base = vbase >> CONFIG_PPM_PAGE_SHIFT;
167
168	elf_dmsg("\n[INFO] %s : found CODE vseg / base = %x / size = %x\n",
169	__FUNCTION__ , vbase , mem_size );
170	}
171	else // found DATA segment
172	{
173	type = VSEG_TYPE_DATA;
174	process->vmm.data_vpn_base = vbase >> CONFIG_PPM_PAGE_SHIFT;
175
176	elf_dmsg("\n[INFO] %s : found DATA vseg / base = %x / size = %x\n",
177	__FUNCTION__, vbase , mem_size );
178	}
179
180	// register vseg in VMM
181	vseg = (vseg_t *)vmm_create_vseg( process,
182	vbase,
183	mem_size,
184	type );
185	if( vseg == NULL )
186	{
187	printk("\n[ERROR] in %s : cannot map segment / base = %x / size = %x\n",
188	__FUNCTION__ , vbase , mem_size );
189	return -1;
190	}
191
192	// get .elf file descriptor cluster and local pointer
193	cxy_t file_cxy = GET_CXY( file_xp );
194	vfs_file_t * file_ptr = (vfs_file_t *)GET_PTR( file_xp );
195
196	// initialize "file_mapper", "file_offset", "file_size" fields in vseg
197	vseg->mapper_xp = (xptr_t)hal_remote_lwd( XPTR( file_cxy , &file_ptr->mapper ) );
198	vseg->file_offset = file_offset;
199	vseg->file_size = file_size;
200
201	// update reference counter in file descriptor
202	vfs_file_count_up( file_xp );
203	}
204
205	return 0;
206
207	} // end elf_segments_register()
208
209	///////////////////////////////////////////////
210	error_t elf_load_process( char * pathname,
211	process_t * process)
212	{
213	kmem_req_t req; // kmem request for program header
214	Elf_Ehdr header; // local buffer for .elf header
215	void * segs_base; // pointer on buffer for segment descriptors array
216	uint32_t segs_size; // size of buffer for segment descriptors array
217	xptr_t file_xp; // extended pointer on created file descriptor
218	uint32_t file_id; // file descriptor index (unused)
219	error_t error;
220
221	elf_dmsg("\n[INFO] %s : enters for <%s>\n", __FUNCTION__ , pathname );
222
223	// avoid GCC warning
224	file_xp = XPTR_NULL;
225	file_id = -1;
226
227	// open file
228	error = vfs_open( process->vfs_cwd_xp,
229	pathname,
230	O_RDONLY,
231	0,
232	&file_xp,
233	&file_id );
234	if( error )
235	{
236	printk("\n[ERROR] in %s : failed to open file %s\n", __FUNCTION__ , pathname );
237	return -1;
238	}
239
240	elf_dmsg("\n[INFO] %s : open file <%s>\n", __FUNCTION__ , pathname );
241
242	// load header in local buffer
243	error = elf_header_load( file_xp ,
244	&header,
245	sizeof(Elf_Ehdr) );
246	if( error )
247	{
248	printk("\n[ERROR] in %s : cannot get header file %s\n", __FUNCTION__ , pathname );
249	vfs_close( file_xp , file_id );
250	return -1;
251	}
252
253	elf_dmsg("\n[INFO] %s : loaded elf header for %s\n", __FUNCTION__ , pathname );
254
255	if( header.e_phnum == 0 )
256	{
257	printk("\n[ERROR] in %s : no segments found\n", __FUNCTION__ );
258	vfs_close( file_xp , file_id );
259	return -1;
260	}
261
262	// compute buffer size for segment descriptors array
263	segs_size = sizeof(Elf_Phdr) * header.e_phnum;
264
265	// allocate memory for segment descriptors array
266	req.type = KMEM_GENERIC;
267	req.size = segs_size;
268	req.flags = AF_KERNEL;
269	segs_base = kmem_alloc( &req );
270
271	if( segs_base == NULL )
272	{
273	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
274	vfs_close( file_xp , file_id );
275	return -1;
276	}
277
278	// set seek pointer in file descriptor to access segment descriptors array
279	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
280
281	if( error )
282	{
283	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
284	vfs_close( file_xp , file_id );
285	req.ptr = segs_base;
286	kmem_free( &req );
287	return -1;
288	}
289
290	elf_dmsg("\n[INFO] %s : segments array allocated for %s\n", __FUNCTION__ , pathname );
291
292	// load seg descriptors array to local buffer
293	error = vfs_kernel_move( true, // to_buffer
294	file_xp,
295	XPTR( local_cxy , segs_base ),
296	segs_size );
297
298	if( error )
299	{
300	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
301	vfs_close( file_xp , file_id );
302	req.ptr = segs_base;
303	kmem_free( &req );
304	return -1;
305	}
306
307	elf_dmsg("\n[INFO] %s loaded segments descriptors for %s \n", __FUNCTION__ , pathname );
308
309	// register loadable segments in process VMM
310	error = elf_segments_register( file_xp,
311	segs_base,
312	header.e_phnum,
313	process );
314	if( error )
315	{
316	vfs_close( file_xp , file_id );
317	req.ptr = segs_base;
318	kmem_free( &req );
319	return -1;
320	}
321
322	// register process entry point in VMM
323	process->vmm.entry_point = (intptr_t)header.e_entry;
324
325	// register extended pointer on .elf file descriptor
326	process->vfs_bin_xp = file_xp;
327
328	// release allocated memory for program header
329	req.ptr = segs_base;
330	kmem_free(&req);
331
332	elf_dmsg("\n[INFO] %s successfully completed / entry point = %x for %s]\n",
333	__FUNCTION__, (uint32_t) header.e_entry , pathname );
334
335	return 0;
336
337	} // end elf_load_process()
338

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