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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

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(Elf32_Ehdr *header)
41	{
42	if((header->e_ident[EI_CLASS] == ELFCLASS32)
43	&& (header->e_ident[EI_DATA] == ELFDATA2LSB)
44	&& (header->e_ident[EI_VERSION] == EV_CURRENT)
45	&& (header->e_ident[EI_OSABI] == ELFOSABI_NONE)
46	&& ((header->e_machine == EM_MIPS) \|\|
47	(header->e_machine == EM_MIPS_RS3_LE) \|\|
48	(header->e_machine == EM_X86_64))
49	&& (header->e_type == ET_EXEC))
50	return true;
51
52	if( header->e_ident[EI_CLASS] != ELFCLASS32 )
53	printk("\n[ERROR] in %s : Elf is not 32-Binary\n", __FUNCTION__ );
54
55	if( header->e_ident[EI_DATA] != ELFDATA2LSB )
56	printk("\n[ERROR] in %s : Elf is not 2's complement, little endian\n", __FUNCTION__ );
57
58	if( header->e_ident[EI_VERSION] != EV_CURRENT )
59	printk("\n[ERROR] in %s : Elf is not in Current Version\n", __FUNCTION__);
60
61	if( header->e_ident[EI_OSABI] != ELFOSABI_NONE )
62	printk("\n[ERROR] in %s : Unexpected Elf ABI, need UNIX System V ABI\n", __FUNCTION__ );
63
64	if( (header->e_machine == EM_MIPS) \|\|
65	(header->e_machine == EM_MIPS_RS3_LE) \|\|
66	(header->e_machine == EM_X86_64) )
67	printk("\n[ERROR] in %s : unexpected core / accept only MIPS or x86_64\n", __FUNCTION__ );
68
69	if( header->e_type == ET_EXEC )
70	printk("\n[ERROR] in %s : Elf is not executable binary\n", __FUNCTION__ );
71
72	return false;
73	}
74
75	///////////////////////////////////////////////////////////////////////////////////////
76	// This function loads the .elf header in the buffer allocated by the caller.
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 )
84	{
85	uint32_t count;
86
87	// load .elf header
88	count = vfs_move( true ,
89	file_xp,
90	buffer,
91	size );
92
93	if( count != size )
94	{
95	printk("\n[ERROR] in %s : failed to read ELF header\n", __FUNCTION__ );
96	return -1;
97	}
98
99	Elf32_Ehdr * header = (Elf32_Ehdr *)buffer;
100
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;
116	}
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,
126	void * segs_base,
127	uint32_t nb_segs,
128	process_t * process )
129	{
130	error_t error;
131	uint32_t index;
132	uint32_t file_size;
133	uint32_t mem_size;
134	intptr_t start;
135	uint32_t type;
136	uint32_t flags;
137	uint32_t offset;
138	vseg_t * vseg;
139
140	Elf32_Phdr * seg_ptr = (Elf32_Phdr *)segs_base;
141
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
149	start = seg_ptr->p_vaddr;
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;
154
155	// check alignment
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
162	// check size
163	if( file_size != mem_size )
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
169	// set seek on segment base in file
170	error = vfs_lseek( file_xp,
171	offset,
172	SEEK_SET,
173	NULL );
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	{
183	type = VSEG_TYPE_CODE;
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",
187	__FUNCTION__ , start , mem_size );
188	}
189	else // found DATA segment
190	{
191	type = VSEG_TYPE_DATA;
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",
195	__FUNCTION__, start , mem_size );
196	}
197
198	// register vseg in VMM
199	vseg = (vseg_t *)vmm_create_vseg( process,
200	start,
201	mem_size,
202	type );
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;
214	}
215
216	///////////////////////////////////////////////
217	error_t elf_load_process( char * pathname,
218	process_t * process)
219	{
220	char path_copy[CONFIG_VFS_MAX_PATH_LENGTH];
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
225	uint32_t segs_size; // size of buffer for segment descriptors array
226	xptr_t file_xp; // extended pointer on created file descriptor
227	uint32_t file_id; // file descriptor index (unused)
228	uint32_t count; // bytes counter
229	error_t error;
230
231	// get path length from user space
232	length = hal_strlen_from_uspace( pathname );
233
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	}
239
240	// make a local copy for pathname
241	hal_copy_from_uspace( path_copy , pathname , length+1 );
242
243	// open file
244	file_xp = XPTR_NULL; // avoid GCC warning
245	file_id = -1;
246
247	error = vfs_open( process->vfs_cwd_xp,
248	path_copy,
249	O_RDONLY,
250	0,
251	&file_xp,
252	&file_id );
253	if( error )
254	{
255	printk("\n[ERROR] in %s : failed to open executable file %s\n",
256	__FUNCTION__ , path_copy );
257	return -1;
258	}
259
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	}
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__ );
275	vfs_close( file_xp , file_id );
276	return -1;
277	}
278
279	// compute buffer size for segment descriptors array
280	segs_size = sizeof(Elf32_Phdr) * header.e_phnum;
281
282	// allocate memory for segment descriptors array
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 )
289	{
290	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
291	vfs_close( file_xp , file_id );
292	return -1;
293	}
294
295	// set seek pointer in file descriptor to access segment descriptors array
296	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
297
298	if( error )
299	{
300	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
301	vfs_close( file_xp , file_id );
302	req.ptr = segs_base;
303	kmem_free( &req );
304	return -1;
305	}
306
307	// load seg descriptors array to local buffer
308	count = vfs_move( true,
309	file_xp,
310	segs_base,
311	segs_size );
312
313	if( count != segs_size )
314	{
315	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
316	vfs_close( file_xp , file_id );
317	req.ptr = segs_base;
318	kmem_free( &req );
319	return -1;
320	}
321
322	elf_dmsg("\n[INFO] %s loaded segments descriptors for %s \n", __FUNCTION__ , path_copy );
323
324	// register loadable segments in process VMM
325	error = elf_segments_load( file_xp,
326	segs_base,
327	header.e_phnum,
328	process );
329	if( error )
330	{
331	vfs_close( file_xp , file_id );
332	req.ptr = segs_base;
333	kmem_free( &req );
334	return -1;
335	}
336
337	// register process entry point in VMM
338	process->vmm.entry_point = (intptr_t)header.e_entry;
339
340	// register extended pointer on .elf file descriptor
341	process->vfs_bin_xp = file_xp;
342
343	// release allocated memory for program header
344	req.ptr = segs_base;
345	kmem_free(&req);
346
347	elf_dmsg("\n[INFO] %s successfully completed / entry point = %x for %s]\n",
348	__FUNCTION__, (uint32_t) header.e_entry , path_copy );
349
350	return 0;
351	}
352

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