source: trunk/kernel/syscalls/sys_exec.c @ 569

Last change on this file since 569 was 566, checked in by alain, 6 years ago

Complete restructuration of kernel locks.

File size: 9.0 KB
RevLine 
[1]1/*
[23]2 * sys_exec.c - Kernel function implementing the "exec" system call.
[302]3 *
[23]4 * Authors   Alain Greiner (2016,2017)
[1]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
[14]24#include <kernel_config.h>
[457]25#include <hal_kernel_types.h>
[23]26#include <hal_uspace.h>
[1]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
[506]38#include <syscalls.h>
[1]39
[302]40////////////////////////////////////////////////i//////////////////////////////////////
[1]41// This static function is called twice by the sys_exec() function :
42// - to register the main() arguments (args) in the exec_info structure.
43// - to register the environment variables (envs) in the exec_info structure.
44// In both cases the input is an array of string pointers in user space,
[302]45// and a set of strings in user space.
[1]46// We allocate one physical page to store a kernel copy of the array of pointers,
47// we allocate one or several physical pages to store the strings themselve,
48// and register these buffers and the number of strings in the exec_info structure.
[302]49// The max number of strings is 1024 (for both args and envs). The numbers of pages
[1]50// to store the (args) and (envs) strings are configuration parameters.
[302]51///////////////////////////////////////////////////////////////////////////////////////
[407]52// @ exec_info   : pointer on the exec_info structure.
53// @ is_args     : true if called for (args) / false if called for (envs).
54// @ u_pointers  : array of pointers on the strings (in user space).
[302]55// @ return 0 if success / non-zero if too many strings or no more memory.
[1]56///////////////////////////////////////////////////////////////////////////////////////
57static error_t process_exec_get_strings( exec_info_t  * exec_info,
58                                         bool_t         is_args,
[302]59                                         char        ** u_pointers )
[1]60{
61    uint32_t     index;       // string index
62    uint32_t     found_null;  // NULL pointer found in array of pointers
63    uint32_t     length;      // string length
64    kmem_req_t   req;         // kmem request
65    page_t     * page;        // page descriptor
[315]66    xptr_t       base_xp;     // extended pointer on page base
[1]67    uint32_t     order;       // ln2( number of pages to store strings )
[23]68    char      ** k_pointers;  // base of kernel array of pointers
69    char       * k_buf_ptr;   // pointer on first empty slot in kernel strings buffer
70    char       * k_buf_base;  // base address of the kernel strings buffer
[1]71
72    // compute ln2( number of pages for kernel strings buffer )
[23]73    if( is_args ) order = bits_log2( CONFIG_VMM_ARGS_SIZE );
74    else          order = bits_log2( CONFIG_VMM_ENVS_SIZE );
[1]75
[302]76    req.type   = KMEM_PAGE;
77    req.flags  = AF_KERNEL | AF_ZERO;
[1]78
79    // allocate one physical page for kernel array of pointers
80    req.type   = 0;
81    page       = kmem_alloc( &req );
[23]82
83    if( page == NULL ) return ENOMEM;
84
[315]85    base_xp = ppm_page2base( XPTR( local_cxy , page ) );
86    k_pointers = (char **)GET_PTR( base_xp );
[302]87
[1]88    // allocate several physical pages to store the strings themselve
89    req.type   = order;
90    page       = kmem_alloc( &req );
[23]91
92    if( page == NULL ) return ENOMEM;
93
[315]94    base_xp = ppm_page2base( XPTR( local_cxy , page ) );
95    k_buf_base = (char *)GET_PTR( base_xp );
[302]96
97    // copy the array of pointers to kernel buffer
98    hal_copy_from_uspace( k_pointers,
[1]99                          u_pointers,
100                          CONFIG_PPM_PAGE_SIZE );
101
[23]102    // scan kernel array of pointers to copy the strings
[1]103    found_null = 0;
[23]104    k_buf_ptr  = k_buf_base;
[1]105    for( index = 0 ; index < 1024 ; index++ )
106    {
[302]107        if( k_pointers[index] == NULL )
[1]108        {
109            found_null = 1;
110            break;
111        }
112
113        // compute string length
[302]114        length = hal_strlen_from_uspace( k_pointers[index] );
115
[1]116        // copy the user string to kernel buffer
[23]117        hal_copy_from_uspace( k_buf_ptr,
118                              k_pointers[index],
[1]119                              length );
120
121        // update k_pointer[index] entry
[23]122        k_pointers[index] = k_buf_ptr;
[1]123
124        // increment pointer on kernel strings buffer
[23]125        k_buf_ptr += (length + 1);
[1]126    }
127
[302]128    // update into exec_info structure
[1]129    if( found_null && is_args )
130    {
131        exec_info->args_pointers  =  k_pointers;
[23]132        exec_info->args_buf_base  =  k_buf_base;
[1]133        exec_info->args_nr        =  index;
134    }
135    else if( found_null && !is_args )
136    {
137        exec_info->envs_pointers  =  k_pointers;
[23]138        exec_info->envs_buf_base  =  k_buf_base;
139        exec_info->envs_buf_free  =  k_buf_ptr;
[1]140        exec_info->envs_nr        =  index;
141    }
[302]142    else
[1]143    {
144        return EINVAL;
145    }
146
147    return 0;
148} // end process_exec_get_strings()
149
150/////////////////////////////////////////////////////////////////////////////////////////
151// Implementation note:
[433]152// This function must be called by the main thread (thread 0 in owner cluster).
[441]153// It build an exec_info_t structure containing all informations
[408]154// required to initialize the new process descriptor and the associated thread.
[457]155// It includes the new process main() arguments, the environment variables,
[408]156// and the pathname to the new process .elf file.
[407]157// It calls the process_exec_get_strings() functions to copy the main() arguments and
158// the environment variables from user buffers to the exec_info_t structure, allocate
159// and call the process_make_exec() function.
[566]160// As it must destroy all process copies, and all other threads in all clusters,
[457]161// the process_make_exec() function must be executed in the owner cluster.
[408]162//
[416]163// TODO : the args & envs arguments are not supported yet : both must be NULL  [AG]
[1]164/////////////////////////////////////////////////////////////////////////////////////////
[566]165int sys_exec( char  * pathname,       // .elf file pathname
[506]166              char ** args,           // process arguments
167              char ** envs )          // environment variables
[1]168{
[566]169    exec_info_t   exec_info;          // structure to pass to process_make_exec()
[407]170    error_t       error;
[1]171
[433]172    // get calling thread, process, & pid
[421]173    thread_t    * this    = CURRENT_THREAD;
174    process_t   * process = this->process;
175    pid_t         pid     = process->pid;
[23]176
[566]177#if DEBUG_SYS_EXEC
178uint64_t     tm_start = hal_get_cycles();
179#endif
180
[492]181    assert( (CXY_FROM_PID( pid ) == local_cxy) ,
[433]182    "must be called in the owner cluster\n");
[23]183
[492]184    assert( (LTID_FROM_TRDID( this->trdid ) == 0) ,
[433]185    "must be called by the main thread\n");
186
[492]187    assert( (args == NULL) ,
[433]188    "args not supported yet\n" );
189
[492]190    assert( (envs == NULL) ,
[433]191    "args not supported yet\n" );
192
[407]193    // check pathname length
194    if( hal_strlen_from_uspace( pathname ) >= CONFIG_VFS_MAX_PATH_LENGTH )
[23]195    {
[433]196
[438]197#if DEBUG_SYSCALLS_ERROR
[433]198printk("\n[ERROR] in %s : pathname too long\n", __FUNCTION__ );
199#endif
[407]200        this->errno = ENFILE;
[23]201        return -1;
202    }
203
[407]204    // copy pathname in exec_info structure (kernel space)
205    hal_strcpy_from_uspace( exec_info.path , pathname , CONFIG_VFS_MAX_PATH_LENGTH );
[408]206
[438]207#if DEBUG_SYS_EXEC
208if( DEBUG_SYS_EXEC < tm_start )
[441]209printk("\n[DBG] %s : thread %x in process %x enter for path <%s> / cycle = %d\n",
[457]210__FUNCTION__, this->trdid, pid, exec_info.path, (uint32_t)tm_start );
[433]211#endif
[23]212
[407]213    // check and store args in exec_info structure if required
214    if( args != NULL )
[1]215    {
[407]216        if( process_exec_get_strings( &exec_info , true , args ) )
217        {
[433]218
[438]219#if DEBUG_SYSCALLS_ERROR
[441]220printk("\n[ERROR] in %s : thread %x in process %x cannot access args\n",
[457]221__FUNCTION__ , this->trdid, pid );
[433]222#endif
[435]223            this->errno = EINVAL;
[407]224            return -1;
225        }
[23]226    }
[1]227
[407]228    // check and store envs in exec_info structure if required
229    if( envs != NULL )
[23]230    {
[407]231        if( process_exec_get_strings( &exec_info , false , envs ) )
232        {
[433]233
[509]234#if DEBUG_SYSCALLS_ERROR
[441]235printk("\n[ERROR] in %s : thread %x in process %x cannot access envs\n",
[457]236__FUNCTION__ , this->trdid, pid );
[433]237#endif
[435]238            this->errno = EINVAL;
[407]239            return -1;
240        }
[1]241    }
[23]242
[433]243    // call relevant kernel function
244    error = process_make_exec( &exec_info );
[408]245
[433]246    if( error )
[1]247    {
[302]248
[438]249#if DEBUG_SYSCALLS_ERROR
[441]250printk("\n[ERROR] in %s : thread %x in process %x cannot create process for <%s>\n",
[457]251__FUNCTION__, this->trdid, pid, exec_info.path );
[433]252#endif
[23]253        this->errno = error;
254        return -1;
[1]255    }
256
[492]257    assert( false , "we should not execute this code" );
[1]258
[433]259    return 0; 
260
[1]261} // end sys_exec()
262
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