source: trunk/kernel/syscalls/sys_exec.c @ 406

Last change on this file since 406 was 406, checked in by alain, 4 years ago

This version executed successfully the user "init" process on a mono-processor TSAR architecture.

File size: 10.1 KB
Line 
1/*
2 * sys_exec.c - Kernel function implementing the "exec" system call.
3 *
4 * Authors   Alain Greiner (2016,2017)
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 <errno.h>
28#include <printk.h>
29#include <core.h>
30#include <vfs.h>
31#include <cluster.h>
32#include <process.h>
33#include <thread.h>
34#include <vmm.h>
35#include <ppm.h>
36#include <rpc.h>
37
38
39////////////////////////////////////////////////i//////////////////////////////////////
40// This static function is called by the sys_exec() function to register the .elf
41// pathname in the exec_info  structure, from a string stored in user space.
42////////////////////////////////////////////////i//////////////////////////////////////
43// @ exec_info : pointer on the exec_info structure.
44// @ pathname  : string containing the path to the .elf file (user space).
45// return 0 if success / non-zero if one string too long, or too many strings.
46///////////////////////////////////////////////////////////////////////////////////////
47static error_t process_exec_get_path( exec_info_t  * exec_info,
48                                      char         * pathname )
49{
50    error_t error;
51
52    // copy string to exec_info
53    error = hal_strcpy_from_uspace( &exec_info->path[0] , pathname ,
54                                    CONFIG_VFS_MAX_PATH_LENGTH );
55    if( error )
56        return EINVAL;
57
58    return 0;
59}
60
61////////////////////////////////////////////////i//////////////////////////////////////
62// This static function is called twice by the sys_exec() function :
63// - to register the main() arguments (args) in the exec_info structure.
64// - to register the environment variables (envs) in the exec_info structure.
65// In both cases the input is an array of string pointers in user space,
66// and a set of strings in user space.
67// We allocate one physical page to store a kernel copy of the array of pointers,
68// we allocate one or several physical pages to store the strings themselve,
69// and register these buffers and the number of strings in the exec_info structure.
70// The max number of strings is 1024 (for both args and envs). The numbers of pages
71// to store the (args) and (envs) strings are configuration parameters.
72///////////////////////////////////////////////////////////////////////////////////////
73// @ exec_info : pointer on the exec_info structure.
74// @ is_args   : true if called for (args) / false if called for (envs).
75// @ pointers  : array of pointers on the strings (in user space).
76// @ return 0 if success / non-zero if too many strings or no more memory.
77///////////////////////////////////////////////////////////////////////////////////////
78static error_t process_exec_get_strings( exec_info_t  * exec_info,
79                                         bool_t         is_args,
80                                         char        ** u_pointers )
81{
82    uint32_t     index;       // string index
83    uint32_t     found_null;  // NULL pointer found in array of pointers
84    uint32_t     length;      // string length
85    kmem_req_t   req;         // kmem request
86    page_t     * page;        // page descriptor
87    xptr_t       base_xp;     // extended pointer on page base
88    uint32_t     order;       // ln2( number of pages to store strings )
89    char      ** k_pointers;  // base of kernel array of pointers
90    char       * k_buf_ptr;   // pointer on first empty slot in kernel strings buffer
91    char       * k_buf_base;  // base address of the kernel strings buffer
92
93    // compute ln2( number of pages for kernel strings buffer )
94    if( is_args ) order = bits_log2( CONFIG_VMM_ARGS_SIZE );
95    else          order = bits_log2( CONFIG_VMM_ENVS_SIZE );
96
97    req.type   = KMEM_PAGE;
98    req.flags  = AF_KERNEL | AF_ZERO;
99
100    // allocate one physical page for kernel array of pointers
101    req.type   = 0;
102    page       = kmem_alloc( &req );
103
104    if( page == NULL ) return ENOMEM;
105
106    base_xp = ppm_page2base( XPTR( local_cxy , page ) );
107    k_pointers = (char **)GET_PTR( base_xp );
108
109    // allocate several physical pages to store the strings themselve
110    req.type   = order;
111    page       = kmem_alloc( &req );
112
113    if( page == NULL ) return ENOMEM;
114
115    base_xp = ppm_page2base( XPTR( local_cxy , page ) );
116    k_buf_base = (char *)GET_PTR( base_xp );
117
118    // copy the array of pointers to kernel buffer
119    hal_copy_from_uspace( k_pointers,
120                          u_pointers,
121                          CONFIG_PPM_PAGE_SIZE );
122
123    // scan kernel array of pointers to copy the strings
124    found_null = 0;
125    k_buf_ptr  = k_buf_base;
126    for( index = 0 ; index < 1024 ; index++ )
127    {
128        if( k_pointers[index] == NULL )
129        {
130            found_null = 1;
131            break;
132        }
133
134        // compute string length
135        length = hal_strlen_from_uspace( k_pointers[index] );
136
137        // copy the user string to kernel buffer
138        hal_copy_from_uspace( k_buf_ptr,
139                              k_pointers[index],
140                              length );
141
142        // update k_pointer[index] entry
143        k_pointers[index] = k_buf_ptr;
144
145        // increment pointer on kernel strings buffer
146        k_buf_ptr += (length + 1);
147    }
148
149    // update into exec_info structure
150    if( found_null && is_args )
151    {
152        exec_info->args_pointers  =  k_pointers;
153        exec_info->args_buf_base  =  k_buf_base;
154        exec_info->args_nr        =  index;
155    }
156    else if( found_null && !is_args )
157    {
158        exec_info->envs_pointers  =  k_pointers;
159        exec_info->envs_buf_base  =  k_buf_base;
160        exec_info->envs_buf_free  =  k_buf_ptr;
161        exec_info->envs_nr        =  index;
162    }
163    else
164    {
165        return EINVAL;
166    }
167
168    return 0;
169} // end process_exec_get_strings()
170
171/////////////////////////////////////////////////////////////////////////////////////////
172// Implementation note:
173// This function build an exec_info_t structure containing all informations
174// required to create the new process descriptor and the associated thread.
175// It calls the static process_exec_get_path() and process_exec_get_strings() functions
176// to copy the .elf pathname, the main() arguments and the environment variables from
177// user buffers to the exec_info_t structure, and call the process_make_exec() function.
178/////////////////////////////////////////////////////////////////////////////////////////
179int sys_exec( char  * filename,     // .elf file pathname
180              char ** args,         // process arguments
181              char ** envs )        // environment variables
182{
183    exec_info_t  exec_info;         // structure to pass to process_make_exec()
184    error_t      error;
185    paddr_t      paddr;
186
187    thread_t   * this    = CURRENT_THREAD;
188    process_t  * process = this->process;
189
190    // check argument fileme
191    error = vmm_v2p_translate( false , filename , &paddr );
192
193    if( error )
194    {
195        printk("\n[ERROR] in %s : filename unmapped\n", __FUNCTION__ );
196        this->errno = EINVAL;
197        return -1;
198    }
199
200    // check argument fileme
201    error = vmm_v2p_translate( false , args , &paddr );
202
203    if( error )
204    {
205        printk("\n[ERROR] in %s : args unmapped\n", __FUNCTION__ );
206        this->errno = EINVAL;
207        return -1;
208    }
209
210    // check argument fileme
211    error = vmm_v2p_translate( false , envs , &paddr );
212
213    if( error )
214    {
215        printk("\n[ERROR] in %s : envs unmapped\n", __FUNCTION__ );
216        this->errno = EINVAL;
217        return -1;
218    }
219
220    // compute client_cxy (local cluster) and server_cxy (target cluster)
221    cxy_t     cxy_server = CXY_FROM_PID( process->pid );
222    cxy_t     cxy_client = local_cxy;
223    bool_t    is_local   = (cxy_server == cxy_client);
224
225    exec_dmsg("\n[DMSG] %s starts for process %x on core %d in cluster %x"
226                 " / target_cluster = %x / cycle %d\n",
227                 __FUNCTION__, process->pid , CURRENT_CORE->lid,
228                 cxy_client, cxy_server, hal_get_cycles());
229
230    // register reference parent process in exec_info
231    exec_info.parent_xp   = process->ref_xp;
232
233    // check pathname and store it in exec_info structure
234    error = process_exec_get_path( &exec_info , filename );
235
236    if ( error )
237    {
238        printk("\n[ERROR] in %s : elf pathname too long\n", __FUNCTION__ );
239        this->errno = error;
240        return -1;
241    }
242
243    // check and store args in exec_info structure
244    error = process_exec_get_strings( &exec_info , true , args );
245
246    if( error )
247    {
248        printk("\n[ERROR] in %s : cannot access args\n", __FUNCTION__ );
249        this->errno = error;
250        return -1;
251    }
252
253    // check and store envs in exec_info structure
254    error = process_exec_get_strings( &exec_info , false , envs );
255
256    if( error )
257    {
258        printk("\n[ERROR] in %s : cannot access envs\n", __FUNCTION__ );
259        this->errno = error;
260        return -1;
261    }
262
263    exec_dmsg("\n[DMSG] %s starts exec for process %x at cycle %d\n",
264              __FUNCTION__, process->pid, hal_get_cycles() );
265
266    if( is_local )  error = process_make_exec( &exec_info );
267    else            rpc_process_exec_client( cxy_server , &exec_info , &error );
268
269    if( error )
270    {
271        printk("\n[ERROR] in %s : cannot create new process %x\n",
272               __FUNCTION__ , process->pid );
273        this->errno = error;
274        return -1;
275    }
276
277    exec_dmsg("\n[DMSG] %s completes exec for process %x at cycle %d\n",
278              __FUNCTION__, process->pid , hal_get_cycles() );
279
280    // delete the calling thread an process
281    thread_kill( CURRENT_THREAD );
282    process_kill( CURRENT_THREAD->process );
283
284    return 0;
285
286} // end sys_exec()
287
Note: See TracBrowser for help on using the repository browser.