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source: trunk/kernel/libk/elf.c @ 267

Last change on this file since 267 was 265, checked in by alain, 7 years ago
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] == 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	///////////////////////////////////////////////////////////////////////////////////////
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	///////////////////////////////////////////////////////////////////////////////////////
82	static error_t elf_header_load( xptr_t file_xp,
83	void * buffer,
84	uint32_t size )
85	{
86	uint32_t count;
87
88	// load .elf header
89	count = vfs_move( true, // to_buffer
90	false, // is_user
91	file_xp,
92	buffer,
93	size );
94
95	if( count != size )
96	{
97	printk("\n[ERROR] in %s : cannot read ELF header size : %d / done = %d\n",
98	__FUNCTION__ , size , count );
99	return -1;
100	}
101
102	Elf_Ehdr * header = (Elf_Ehdr *)buffer;
103
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
120	} // end elf_header_load()
121
122	///////////////////////////////////////////////////////////////////////////////////////
123	// This function registers in the process VMM the CODE and DATA segments.
124	///////////////////////////////////////////////////////////////////////////////////////
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,
131	void * segs_base,
132	uint32_t nb_segs,
133	process_t * process )
134	{
135	error_t error;
136	uint32_t index;
137	uint32_t file_size;
138	uint32_t mem_size;
139	intptr_t start;
140	uint32_t type;
141	uint32_t flags;
142	uint32_t offset;
143	vseg_t * vseg;
144
145	Elf_Phdr * seg_ptr = (Elf_Phdr *)segs_base;
146
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
154	start = seg_ptr->p_vaddr;
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;
159
160	// check alignment
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
167	// check size
168	if( file_size != mem_size )
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
174	// set seek on segment base in file
175	error = vfs_lseek( file_xp,
176	offset,
177	SEEK_SET,
178	NULL );
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	{
188	type = VSEG_TYPE_CODE;
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",
192	__FUNCTION__ , start , mem_size );
193	}
194	else // found DATA segment
195	{
196	type = VSEG_TYPE_DATA;
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",
200	__FUNCTION__, start , mem_size );
201	}
202
203	// register vseg in VMM
204	vseg = (vseg_t *)vmm_create_vseg( process,
205	start,
206	mem_size,
207	type );
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
220	} // end elf_segments_load()
221
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	Elf_Ehdr header; // local buffer for .elf header
228	void * segs_base; // pointer on buffer for segment descriptors array
229	uint32_t segs_size; // size of buffer for segment descriptors array
230	xptr_t file_xp; // extended pointer on created file descriptor
231	uint32_t file_id; // file descriptor index (unused)
232	uint32_t count; // bytes counter
233	error_t error;
234
235	elf_dmsg("\n[INFO] %s : enters for <%s>\n", __FUNCTION__ , pathname );
236
237	// avoid GCC warning
238	file_xp = XPTR_NULL;
239	file_id = -1;
240
241	// open file
242	error = vfs_open( process->vfs_cwd_xp,
243	pathname,
244	O_RDONLY,
245	0,
246	&file_xp,
247	&file_id );
248	if( error )
249	{
250	printk("\n[ERROR] in %s : failed to open file %s\n", __FUNCTION__ , pathname );
251	return -1;
252	}
253
254	elf_dmsg("\n[INFO] %s : file <%s> open\n", __FUNCTION__ , pathname );
255
256	// load header in local buffer
257	error = elf_header_load( file_xp ,
258	&header,
259	sizeof(Elf_Ehdr) );
260	if( error )
261	{
262	printk("\n[ERROR] in %s : cannot get header file %s\n", __FUNCTION__ , pathname );
263	vfs_close( file_xp , file_id );
264	return -1;
265	}
266
267	elf_dmsg("\n[INFO] %s : loaded elf header for %s\n", __FUNCTION__ , pathname );
268
269	if( header.e_phnum == 0 )
270	{
271	printk("\n[ERROR] in %s : no segments found\n", __FUNCTION__ );
272	vfs_close( file_xp , file_id );
273	return -1;
274	}
275
276	// compute buffer size for segment descriptors array
277	segs_size = sizeof(Elf_Phdr) * header.e_phnum;
278
279	// allocate memory for segment descriptors array
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 )
286	{
287	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
288	vfs_close( file_xp , file_id );
289	return -1;
290	}
291
292	// set seek pointer in file descriptor to access segment descriptors array
293	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
294
295	if( error )
296	{
297	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
298	vfs_close( file_xp , file_id );
299	req.ptr = segs_base;
300	kmem_free( &req );
301	return -1;
302	}
303
304	// load seg descriptors array to local buffer
305	count = vfs_move( true, // to_buffer
306	false, // is_user
307	file_xp,
308	segs_base,
309	segs_size );
310
311	if( count != segs_size )
312	{
313	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
314	vfs_close( file_xp , file_id );
315	req.ptr = segs_base;
316	kmem_free( &req );
317	return -1;
318	}
319
320	elf_dmsg("\n[INFO] %s loaded segments descriptors for %s \n", __FUNCTION__ , pathname );
321
322	// register loadable segments in process VMM
323	error = elf_segments_load( file_xp,
324	segs_base,
325	header.e_phnum,
326	process );
327	if( error )
328	{
329	vfs_close( file_xp , file_id );
330	req.ptr = segs_base;
331	kmem_free( &req );
332	return -1;
333	}
334
335	// register process entry point in VMM
336	process->vmm.entry_point = (intptr_t)header.e_entry;
337
338	// register extended pointer on .elf file descriptor
339	process->vfs_bin_xp = file_xp;
340
341	// release allocated memory for program header
342	req.ptr = segs_base;
343	kmem_free(&req);
344
345	elf_dmsg("\n[INFO] %s successfully completed / entry point = %x for %s]\n",
346	__FUNCTION__, (uint32_t) header.e_entry , pathname );
347
348	return 0;
349
350	} // end elf_load_process()
351

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