Context Navigation

source: trunk/kernel/libk/elf.c @ 321

Last change on this file since 321 was 315, checked in by alain, 7 years ago
Redefine the fuctions ppm_base2page() / ppm_page2base() / ppm_page2ppn() / ppm_ppn2page() / ppm_base2ppn() / ppm_ppn2base(), to use explicitely extended pointers.
File size: 10.6 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	uint32_t count;
89
90	// load .elf header
91	count = vfs_user_move( true, // to_buffer
92	file_xp,
93	buffer,
94	size );
95
96	if( count != size )
97	{
98	printk("\n[ERROR] in %s : cannot read ELF header size : %d / done = %d\n",
99	__FUNCTION__ , size , count );
100	return -1;
101	}
102
103	Elf_Ehdr * header = (Elf_Ehdr *)buffer;
104
105	if( (header->e_ident[EI_MAG0] != ELFMAG0) \|\|
106	(header->e_ident[EI_MAG1] != ELFMAG1) \|\|
107	(header->e_ident[EI_MAG2] != ELFMAG2) \|\|
108	(header->e_ident[EI_MAG3] != ELFMAG3) )
109	{
110	printk("\n[ERROR] in %s : file %s not in ELF format\n", __FUNCTION__ );
111	return -1;
112	}
113
114	if( !(elf_isValidHeader( header ) ) )
115	{
116	printk("\n[ERROR] in %s : not supported Elf\n", __FUNCTION__ );
117	return -1;
118	}
119	return 0;
120
121	} // end elf_header_load()
122
123	///////////////////////////////////////////////////////////////////////////////////////
124	// This function registers in the process VMM the CODE and DATA segments.
125	///////////////////////////////////////////////////////////////////////////////////////
126	// @ file : extended pointer on the remote file descriptor.
127	// @ segs_base : local pointer on buffer containing the segments descriptors array
128	// @ segs_nr : number of segments in segment descriptors array.
129	// @ process : local pointer on process descriptor.
130	///////////////////////////////////////////////////////////////////////////////////////
131	static error_t elf_segments_register( xptr_t file_xp,
132	void * segs_base,
133	uint32_t nb_segs,
134	process_t * process )
135	{
136	uint32_t index;
137	intptr_t file_size;
138	intptr_t mem_size;
139	intptr_t file_offset;
140	intptr_t vbase;
141	uint32_t type;
142	uint32_t flags;
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	vbase = seg_ptr->p_vaddr; // vseg base vaddr
155	mem_size = seg_ptr->p_memsz; // actual vseg size
156	file_offset = seg_ptr->p_offset; // vseg offset in .elf file
157	file_size = seg_ptr->p_filesz; // vseg size in .elf file
158	flags = seg_ptr->p_flags;
159
160	if( flags & PF_X ) // found CODE segment
161	{
162	type = VSEG_TYPE_CODE;
163	process->vmm.code_vpn_base = vbase >> CONFIG_PPM_PAGE_SHIFT;
164
165	elf_dmsg("\n[INFO] %s : found CODE vseg / base = %x / size = %x\n",
166	__FUNCTION__ , vbase , mem_size );
167	}
168	else // found DATA segment
169	{
170	type = VSEG_TYPE_DATA;
171	process->vmm.data_vpn_base = vbase >> CONFIG_PPM_PAGE_SHIFT;
172
173	elf_dmsg("\n[INFO] %s : found DATA vseg / base = %x / size = %x\n",
174	__FUNCTION__, vbase , mem_size );
175	}
176
177	// register vseg in VMM
178	vseg = (vseg_t *)vmm_create_vseg( process,
179	vbase,
180	mem_size,
181	type );
182	if( vseg == NULL )
183	{
184	printk("\n[ERROR] in %s : cannot map segment / base = %x / size = %x\n",
185	__FUNCTION__ , vbase , mem_size );
186	return -1;
187	}
188
189	// get .elf file descriptor cluster and local pointer
190	cxy_t file_cxy = GET_CXY( file_xp );
191	vfs_file_t * file_ptr = (vfs_file_t *)GET_PTR( file_xp );
192
193	// initialize "file_mapper", "file_offset", "file_size" fields in vseg
194	vseg->mapper_xp = (xptr_t)hal_remote_lwd( XPTR( file_cxy , &file_ptr->mapper ) );
195	vseg->file_offset = file_offset;
196	vseg->file_size = file_size;
197
198	// update reference counter in file descriptor
199	vfs_file_count_up( file_xp );
200	}
201
202	return 0;
203
204	} // end elf_segments_register()
205
206	///////////////////////////////////////////////
207	error_t elf_load_process( char * pathname,
208	process_t * process)
209	{
210	kmem_req_t req; // kmem request for program header
211	Elf_Ehdr header; // local buffer for .elf header
212	void * segs_base; // pointer on buffer for segment descriptors array
213	uint32_t segs_size; // size of buffer for segment descriptors array
214	xptr_t file_xp; // extended pointer on created file descriptor
215	uint32_t file_id; // file descriptor index (unused)
216	uint32_t count; // bytes counter
217	error_t error;
218
219	elf_dmsg("\n[INFO] %s : enters for <%s>\n", __FUNCTION__ , pathname );
220
221	// avoid GCC warning
222	file_xp = XPTR_NULL;
223	file_id = -1;
224
225	// open file
226	error = vfs_open( process->vfs_cwd_xp,
227	pathname,
228	O_RDONLY,
229	0,
230	&file_xp,
231	&file_id );
232	if( error )
233	{
234	printk("\n[ERROR] in %s : failed to open file %s\n", __FUNCTION__ , pathname );
235	return -1;
236	}
237
238	elf_dmsg("\n[INFO] %s : file <%s> open\n", __FUNCTION__ , pathname );
239
240	// load header in local buffer
241	error = elf_header_load( file_xp ,
242	&header,
243	sizeof(Elf_Ehdr) );
244	if( error )
245	{
246	printk("\n[ERROR] in %s : cannot get header file %s\n", __FUNCTION__ , pathname );
247	vfs_close( file_xp , file_id );
248	return -1;
249	}
250
251	elf_dmsg("\n[INFO] %s : loaded elf header for %s\n", __FUNCTION__ , pathname );
252
253	if( header.e_phnum == 0 )
254	{
255	printk("\n[ERROR] in %s : no segments found\n", __FUNCTION__ );
256	vfs_close( file_xp , file_id );
257	return -1;
258	}
259
260	// compute buffer size for segment descriptors array
261	segs_size = sizeof(Elf_Phdr) * header.e_phnum;
262
263	// allocate memory for segment descriptors array
264	req.type = KMEM_GENERIC;
265	req.size = segs_size;
266	req.flags = AF_KERNEL;
267	segs_base = kmem_alloc( &req );
268
269	if( segs_base == NULL )
270	{
271	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
272	vfs_close( file_xp , file_id );
273	return -1;
274	}
275
276	// set seek pointer in file descriptor to access segment descriptors array
277	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
278
279	if( error )
280	{
281	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
282	vfs_close( file_xp , file_id );
283	req.ptr = segs_base;
284	kmem_free( &req );
285	return -1;
286	}
287
288	// load seg descriptors array to local buffer
289	count = vfs_user_move( true, // to_buffer
290	file_xp,
291	segs_base,
292	segs_size );
293
294	if( count != segs_size )
295	{
296	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
297	vfs_close( file_xp , file_id );
298	req.ptr = segs_base;
299	kmem_free( &req );
300	return -1;
301	}
302
303	elf_dmsg("\n[INFO] %s loaded segments descriptors for %s \n", __FUNCTION__ , pathname );
304
305	// register loadable segments in process VMM
306	error = elf_segments_register( file_xp,
307	segs_base,
308	header.e_phnum,
309	process );
310	if( error )
311	{
312	vfs_close( file_xp , file_id );
313	req.ptr = segs_base;
314	kmem_free( &req );
315	return -1;
316	}
317
318	// register process entry point in VMM
319	process->vmm.entry_point = (intptr_t)header.e_entry;
320
321	// register extended pointer on .elf file descriptor
322	process->vfs_bin_xp = file_xp;
323
324	// release allocated memory for program header
325	req.ptr = segs_base;
326	kmem_free(&req);
327
328	elf_dmsg("\n[INFO] %s successfully completed / entry point = %x for %s]\n",
329	__FUNCTION__, (uint32_t) header.e_entry , pathname );
330
331	return 0;
332
333	} // end elf_load_process()
334

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

Download in other formats: