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source: trunk/kernel/libk/elf.c @ 434

Last change on this file since 434 was 433, checked in by alain, 7 years ago
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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_special.h>
27	#include <hal_uspace.h>
28	#include <printk.h>
29	#include <process.h>
30	#include <thread.h>
31	#include <mapper.h>
32	#include <vseg.h>
33	#include <kmem.h>
34	#include <vfs.h>
35	#include <elf.h>
36	#include <syscalls.h>
37
38	///////////////////////////////////////////////////////////////////
39	// This static function checks the .elf header.
40	// - return true if legal header.
41	// - return false with an error message if illegal header.
42	///////////////////////////////////////////////////////////////////
43	static bool_t elf_isValidHeader(Elf_Ehdr *header)
44	{
45	if((header->e_ident[EI_CLASS] == ELFCLASS)
46	&& (header->e_ident[EI_DATA] == ELFDATA2LSB)
47	&& (header->e_ident[EI_VERSION] == EV_CURRENT)
48	/*
49	&& (header->e_ident[EI_OSABI] == ELFOSABI_NONE)
50	*/
51	&& ((header->e_machine == EM_MIPS) \|\|
52	(header->e_machine == EM_MIPS_RS3_LE) \|\|
53	(header->e_machine == EM_X86_64))
54	&& (header->e_type == ET_EXEC))
55	return true;
56
57	if( header->e_ident[EI_CLASS] != ELFCLASS )
58	printk("\n[ERROR] in %s : Elf is not 32/64-Binary\n", __FUNCTION__ );
59
60	if( header->e_ident[EI_DATA] != ELFDATA2LSB )
61	printk("\n[ERROR] in %s : Elf is not 2's complement, little endian\n", __FUNCTION__ );
62
63	if( header->e_ident[EI_VERSION] != EV_CURRENT )
64	printk("\n[ERROR] in %s : Elf is not in Current Version\n", __FUNCTION__);
65	/*
66	if( header->e_ident[EI_OSABI] != ELFOSABI_NONE )
67	printk("\n[ERROR] in %s : Unexpected Elf ABI, need UNIX System V ABI\n", __FUNCTION__ );
68	*/
69	if( (header->e_machine != EM_MIPS) &&
70	(header->e_machine != EM_MIPS_RS3_LE) &&
71	(header->e_machine != EM_X86_64) )
72	printk("\n[ERROR] in %s : unexpected core / accept only MIPS or x86_64\n", __FUNCTION__ );
73
74	if( header->e_type != ET_EXEC )
75	printk("\n[ERROR] in %s : Elf is not executable binary\n", __FUNCTION__ );
76
77	return false;
78	}
79
80	///////////////////////////////////////////////////////////////////////////////////////
81	// This function loads the .elf header in the buffer allocated by the caller.
82	///////////////////////////////////////////////////////////////////////////////////////
83	// @ file : extended pointer on the remote file descriptor.
84	// @ buffer : pointer on buffer allocated by the caller.
85	// @ size : number of bytes to read.
86	///////////////////////////////////////////////////////////////////////////////////////
87	static error_t elf_header_load( xptr_t file_xp,
88	void * buffer,
89	uint32_t size )
90	{
91	error_t error;
92	xptr_t buf_xp;
93
94	buf_xp = XPTR( local_cxy , buffer );
95
96	// load .elf header
97	error = vfs_kernel_move( true, // to_buffer
98	file_xp,
99	buf_xp,
100	size );
101
102	if( error )
103	{
104	printk("\n[ERROR] in %s : cannot read ELF header size : %d\n",
105	__FUNCTION__ , size );
106	return -1;
107	}
108
109	Elf_Ehdr * header = (Elf_Ehdr *)buffer;
110
111	if( (header->e_ident[EI_MAG0] != ELFMAG0) \|\|
112	(header->e_ident[EI_MAG1] != ELFMAG1) \|\|
113	(header->e_ident[EI_MAG2] != ELFMAG2) \|\|
114	(header->e_ident[EI_MAG3] != ELFMAG3) )
115	{
116	printk("\n[ERROR] in %s : file not in ELF format\n", __FUNCTION__ );
117	return -1;
118	}
119
120	if( !(elf_isValidHeader( header ) ) )
121	{
122	printk("\n[ERROR] in %s : not supported Elf\n", __FUNCTION__ );
123	return -1;
124	}
125	return 0;
126
127	} // end elf_header_load()
128
129	///////////////////////////////////////////////////////////////////////////////////////
130	// This function registers in the process VMM the CODE and DATA segments.
131	///////////////////////////////////////////////////////////////////////////////////////
132	// @ file : extended pointer on the remote file descriptor.
133	// @ segs_base : local pointer on buffer containing the segments descriptors array
134	// @ segs_nr : number of segments in segment descriptors array.
135	// @ process : local pointer on process descriptor.
136	///////////////////////////////////////////////////////////////////////////////////////
137	static error_t elf_segments_register( xptr_t file_xp,
138	void * segs_base,
139	uint32_t nb_segs,
140	process_t * process )
141	{
142	uint32_t index;
143	intptr_t file_size;
144	intptr_t mem_size;
145	intptr_t file_offset;
146	intptr_t vbase;
147	uint32_t type;
148	uint32_t flags;
149	vseg_t * vseg;
150
151	Elf_Phdr * seg_ptr = (Elf_Phdr *)segs_base;
152
153	// loop on segments
154	for( index = 0 ; index < nb_segs ; index++ , seg_ptr++ )
155	{
156	if( seg_ptr->p_type != PT_LOAD)
157	continue;
158
159	// get segment attributes
160	vbase = seg_ptr->p_vaddr; // vseg base vaddr
161	mem_size = seg_ptr->p_memsz; // actual vseg size
162	file_offset = seg_ptr->p_offset; // vseg offset in .elf file
163	file_size = seg_ptr->p_filesz; // vseg size in .elf file
164	flags = seg_ptr->p_flags;
165
166	if( flags & PF_X ) // found CODE segment
167	{
168	type = VSEG_TYPE_CODE;
169	process->vmm.code_vpn_base = vbase >> CONFIG_PPM_PAGE_SHIFT;
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
177	// get .elf file descriptor cluster and local pointer
178	cxy_t file_cxy = GET_CXY( file_xp );
179	vfs_file_t * file_ptr = (vfs_file_t *)GET_PTR( file_xp );
180
181	// get local pointer on .elf file mapper
182	mapper_t * mapper_ptr = (mapper_t *)hal_remote_lpt( XPTR( file_cxy ,
183	&file_ptr->mapper ) );
184	// register vseg in VMM
185	vseg = (vseg_t *)vmm_create_vseg( process,
186	type,
187	vbase,
188	mem_size,
189	file_offset,
190	file_size,
191	XPTR( file_cxy , mapper_ptr ),
192	local_cxy );
193	if( vseg == NULL )
194	{
195	printk("\n[ERROR] in %s : cannot map segment / base = %x / size = %x\n",
196	__FUNCTION__ , vbase , mem_size );
197	return -1;
198	}
199
200	// update reference counter in file descriptor
201	vfs_file_count_up( file_xp );
202
203	#if CONFIG_DEBUG_ELF_LOAD
204	uint32_t cycle = (uint32_t)hal_get_cycles();
205	if( CONFIG_DEBUG_ELF_LOAD < cycle )
206	printk("\n[DBG] %s : found %s vseg / base %x / size %x\n"
207	" file_size %x / file_offset %x / mapper_xp %l / cycle %d\n",
208	__FUNCTION__ , vseg_type_str(vseg->type) , vseg->min , vseg->max - vseg->min ,
209	vseg->file_size , vseg->file_offset , vseg->mapper_xp );
210	#endif
211
212	}
213
214	return 0;
215
216	} // end elf_segments_register()
217
218	///////////////////////////////////////////////
219	error_t elf_load_process( char * pathname,
220	process_t * process)
221	{
222	kmem_req_t req; // kmem request for program header
223	Elf_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	error_t error;
229
230	#if CONFIG_DEBUG_ELF_LOAD
231	uint32_t cycle = (uint32_t)hal_get_cycles();
232	if( CONFIG_DEBUG_ELF_LOAD < cycle )
233	printk("\n[DBG] %s : thread %d enter for <%s> / cycle %d\n",
234	__FUNCTION__, CURRENT_THREAD, pathname, cycle );
235	#endif
236
237	// avoid GCC warning
238	file_xp = XPTR_NULL;
239	file_id = -1;
240
241	// open file
242	error = vfs_open( process,
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	#if (CONFIG_DEBUG_ELF_LOAD & 1)
255	if( CONFIG_DEBUG_ELF_LOAD < cycle )
256	printk("\n[DBG] %s : open file <%s>\n", __FUNCTION__, pathname );
257	#endif
258
259	// load header in local buffer
260	error = elf_header_load( file_xp ,
261	&header,
262	sizeof(Elf_Ehdr) );
263	if( error )
264	{
265	printk("\n[ERROR] in %s : cannot get header file %s\n", __FUNCTION__ , pathname );
266	vfs_close( file_xp , file_id );
267	return -1;
268	}
269
270	#if (CONFIG_DEBUG_ELF_LOAD & 1)
271	if( CONFIG_DEBUG_ELF_LOAD < cycle )
272	printk("\n[DBG] %s : loaded elf header for %s\n", __FUNCTION__ , pathname );
273	#endif
274
275	if( header.e_phnum == 0 )
276	{
277	printk("\n[ERROR] in %s : no segments found\n", __FUNCTION__ );
278	vfs_close( file_xp , file_id );
279	return -1;
280	}
281
282	// compute buffer size for segment descriptors array
283	segs_size = sizeof(Elf_Phdr) * header.e_phnum;
284
285	// allocate memory for segment descriptors array
286	req.type = KMEM_GENERIC;
287	req.size = segs_size;
288	req.flags = AF_KERNEL;
289	segs_base = kmem_alloc( &req );
290
291	if( segs_base == NULL )
292	{
293	printk("\n[ERROR] in %s : no memory for segment descriptors\n", __FUNCTION__ );
294	vfs_close( file_xp , file_id );
295	return -1;
296	}
297
298	// set seek pointer in file descriptor to access segment descriptors array
299	error = vfs_lseek( file_xp , header.e_phoff, SEEK_SET , NULL );
300
301	if( error )
302	{
303	printk("\n[ERROR] in %s : cannot seek for descriptors array\n", __FUNCTION__ );
304	vfs_close( file_xp , file_id );
305	req.ptr = segs_base;
306	kmem_free( &req );
307	return -1;
308	}
309
310	#if (CONFIG_DEBUG_ELF_LOAD & 1)
311	if( CONFIG_DEBUG_ELF_LOAD < cycle )
312	printk("\n[DBG] %s : segments array allocated for %s\n", __FUNCTION__ , pathname );
313	#endif
314
315	// load seg descriptors array to local buffer
316	error = vfs_kernel_move( true, // to_buffer
317	file_xp,
318	XPTR( local_cxy , segs_base ),
319	segs_size );
320
321	if( error )
322	{
323	printk("\n[ERROR] in %s : cannot read segments descriptors\n", __FUNCTION__ );
324	vfs_close( file_xp , file_id );
325	req.ptr = segs_base;
326	kmem_free( &req );
327	return -1;
328	}
329
330	#if (CONFIG_DEBUG_ELF_LOAD & 1)
331	if( CONFIG_DEBUG_ELF_LOAD < cycle )
332	printk("\n[DBG] %s loaded segments descriptors for %s \n", __FUNCTION__ , pathname );
333	#endif
334
335	// register loadable segments in process VMM
336	error = elf_segments_register( file_xp,
337	segs_base,
338	header.e_phnum,
339	process );
340	if( error )
341	{
342	vfs_close( file_xp , file_id );
343	req.ptr = segs_base;
344	kmem_free( &req );
345	return -1;
346	}
347
348	// register process entry point in VMM
349	process->vmm.entry_point = (intptr_t)header.e_entry;
350
351	// register extended pointer on .elf file descriptor
352	process->vfs_bin_xp = file_xp;
353
354	// release allocated memory for program header
355	req.ptr = segs_base;
356	kmem_free(&req);
357
358	#if CONFIG_DEBUG_ELF_LOAD
359	cycle = (uint32_t)hal_get_cycles();
360	if( CONFIG_DEBUG_ELF_LOAD < cycle )
361	printk("\n[DBG] %s : thread %d exit for <%s> / entry_point %x / cycle %d\n",
362	__FUNCTION__, CURRENT_THREAD, pathname, header.e_entry, cycle );
363	#endif
364
365	return 0;
366
367	} // end elf_load_process()
368

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