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001 /* Copyright (C) 2005 David Decotigny 001 /* Copyright (C) 2005 David Decotigny 002 Copyright (C) 2000-2004, The KOS team 002 Copyright (C) 2000-2004, The KOS team 003 003 004 This program is free software; you can redi 004 This program is free software; you can redistribute it and/or 005 modify it under the terms of the GNU Genera 005 modify it under the terms of the GNU General Public License 006 as published by the Free Software Foundatio 006 as published by the Free Software Foundation; either version 2 007 of the License, or (at your option) any lat 007 of the License, or (at your option) any later version. 008 008 009 This program is distributed in the hope tha 009 This program is distributed in the hope that it will be useful, 010 but WITHOUT ANY WARRANTY; without even the 010 but WITHOUT ANY WARRANTY; without even the implied warranty of 011 MERCHANTABILITY or FITNESS FOR A PARTICULAR 011 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 012 GNU General Public License for more details 012 GNU General Public License for more details. 013 013 014 You should have received a copy of the GNU 014 You should have received a copy of the GNU General Public License 015 along with this program; if not, write to t 015 along with this program; if not, write to the Free Software 016 Foundation, Inc., 59 Temple Place - Suite 3 016 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 017 USA. 017 USA. 018 */ 018 */ 019 019 020 020 021 #include <sos/assert.h> 021 #include <sos/assert.h> 022 #include <sos/klibc.h> 022 #include <sos/klibc.h> 023 #include <drivers/bochs.h> 023 #include <drivers/bochs.h> 024 #include <drivers/x86_videomem.h> 024 #include <drivers/x86_videomem.h> 025 #include <hwcore/segment.h> 025 #include <hwcore/segment.h> 026 #include <hwcore/gdt.h> << 027 #include <sos/uaccess.h> << 028 026 029 #include "cpu_context.h" 027 #include "cpu_context.h" 030 028 031 029 032 /** 030 /** 033 * Here is the definition of a CPU context for 031 * Here is the definition of a CPU context for IA32 processors. This 034 * is a SOS convention, not a specification gi 032 * is a SOS convention, not a specification given by the IA32 035 * spec. However there is a strong constraint 033 * spec. However there is a strong constraint related to the x86 036 * interrupt handling specification: the top o 034 * interrupt handling specification: the top of the stack MUST be 037 * compatible with the 'iret' instruction, ie 035 * compatible with the 'iret' instruction, ie there must be the 038 * err_code (might be 0), eip, cs and eflags o 036 * err_code (might be 0), eip, cs and eflags of the destination 039 * context in that order (see Intel x86 specs 037 * context in that order (see Intel x86 specs vol 3, figure 5-4). 040 * 038 * 041 * @note IMPORTANT: This definition MUST be co 039 * @note IMPORTANT: This definition MUST be consistent with the way 042 * the registers are stored on the stack in 040 * the registers are stored on the stack in 043 * irq_wrappers.S/exception_wrappers.S !!! Hen 041 * irq_wrappers.S/exception_wrappers.S !!! Hence the constraint above. 044 */ 042 */ 045 struct sos_cpu_state { 043 struct sos_cpu_state { 046 /* (Lower addresses) */ 044 /* (Lower addresses) */ 047 045 048 /* These are SOS convention */ 046 /* These are SOS convention */ 049 sos_ui16_t gs; 047 sos_ui16_t gs; 050 sos_ui16_t fs; 048 sos_ui16_t fs; 051 sos_ui16_t es; 049 sos_ui16_t es; 052 sos_ui16_t ds; 050 sos_ui16_t ds; 053 sos_ui16_t cpl0_ss; /* This is ALWAYS the S 051 sos_ui16_t cpl0_ss; /* This is ALWAYS the Stack Segment of the 054 Kernel context (CPL0 052 Kernel context (CPL0) of the interrupted 055 thread, even for a u 053 thread, even for a user thread */ 056 sos_ui16_t alignment_padding; /* unused */ 054 sos_ui16_t alignment_padding; /* unused */ 057 sos_ui32_t eax; 055 sos_ui32_t eax; 058 sos_ui32_t ebx; 056 sos_ui32_t ebx; 059 sos_ui32_t ecx; 057 sos_ui32_t ecx; 060 sos_ui32_t edx; 058 sos_ui32_t edx; 061 sos_ui32_t esi; 059 sos_ui32_t esi; 062 sos_ui32_t edi; 060 sos_ui32_t edi; 063 sos_ui32_t ebp; 061 sos_ui32_t ebp; 064 062 065 /* MUST NEVER CHANGE (dependent on the IA32 063 /* MUST NEVER CHANGE (dependent on the IA32 iret instruction) */ 066 sos_ui32_t error_code; 064 sos_ui32_t error_code; 067 sos_vaddr_t eip; 065 sos_vaddr_t eip; 068 sos_ui32_t cs; /* 32bits according to the s 066 sos_ui32_t cs; /* 32bits according to the specs ! However, the CS 069 register is really 16bits 067 register is really 16bits long */ 070 sos_ui32_t eflags; 068 sos_ui32_t eflags; 071 069 072 /* (Higher addresses) */ 070 /* (Higher addresses) */ 073 } __attribute__((packed)); 071 } __attribute__((packed)); 074 072 075 073 076 /** 074 /** 077 * The CS value pushed on the stack by the CPU 075 * The CS value pushed on the stack by the CPU upon interrupt, and 078 * needed by the iret instruction, is 32bits l 076 * needed by the iret instruction, is 32bits long while the real CPU 079 * CS register is 16bits only: this macro simp 077 * CS register is 16bits only: this macro simply retrieves the CPU 080 * "CS" register value from the CS value pushe 078 * "CS" register value from the CS value pushed on the stack by the 081 * CPU upon interrupt. 079 * CPU upon interrupt. 082 * 080 * 083 * The remaining 16bits pushed by the CPU shou 081 * The remaining 16bits pushed by the CPU should be considered 084 * "reserved" and architecture dependent. IMHO 082 * "reserved" and architecture dependent. IMHO, the specs don't say 085 * anything about them. Considering that some 083 * anything about them. Considering that some architectures generate 086 * non-zero values for these 16bits (at least 084 * non-zero values for these 16bits (at least Cyrix), we'd better 087 * ignore them. 085 * ignore them. 088 */ 086 */ 089 #define GET_CPU_CS_REGISTER_VALUE(pushed_ui32_ 087 #define GET_CPU_CS_REGISTER_VALUE(pushed_ui32_cs_value) \ 090 ( (pushed_ui32_cs_value) & 0xffff ) 088 ( (pushed_ui32_cs_value) & 0xffff ) 091 089 092 090 093 /** 091 /** 094 * Structure of an interrupted Kernel thread's 092 * Structure of an interrupted Kernel thread's context 095 */ 093 */ 096 struct sos_cpu_kstate 094 struct sos_cpu_kstate 097 { 095 { 098 struct sos_cpu_state regs; 096 struct sos_cpu_state regs; 099 } __attribute__((packed)); 097 } __attribute__((packed)); 100 098 101 099 102 /** 100 /** 103 * Structure of an interrupted User thread's c << 104 * the same as a kernel context, except that 2 << 105 * pushed on the stack before the eflags/cs/ei << 106 * context: the stack configuration of the int << 107 * << 108 * @see Section 6.4.1 of Intel x86 vol 1 << 109 */ << 110 struct sos_cpu_ustate << 111 { << 112 struct sos_cpu_state regs; << 113 struct << 114 { << 115 sos_ui32_t cpl3_esp; << 116 sos_ui16_t cpl3_ss; << 117 }; << 118 } __attribute__((packed)); << 119 << 120 << 121 /* << 122 * Structure of a Task State Segment on the x8 << 123 * << 124 * @see Intel x86 spec vol 3, figure 6-2 << 125 * << 126 * @note Such a data structure should not cros << 127 * end of section 6.2.1 of Intel spec vol 3). << 128 * we tell gcc to align it on a 128B boundary << 129 * is <= 128). << 130 */ << 131 struct x86_tss { << 132 << 133 /** << 134 * Intel provides a way for a task to switch << 135 * automatic way (call gates). In this case, << 136 * stores the source TSS of the context swit << 137 * easily implement coroutines, task backtra << 138 * don't use TSS for the context switch purp << 139 * ignore this field. << 140 * (+0) << 141 */ << 142 sos_ui16_t back_link; << 143 << 144 sos_ui16_t reserved1; << 145 << 146 /* CPL0 saved context. (+4) */ << 147 sos_vaddr_t esp0; << 148 sos_ui16_t ss0; << 149 << 150 sos_ui16_t reserved2; << 151 << 152 /* CPL1 saved context. (+12) */ << 153 sos_vaddr_t esp1; << 154 sos_ui16_t ss1; << 155 << 156 sos_ui16_t reserved3; << 157 << 158 /* CPL2 saved context. (+20) */ << 159 sos_vaddr_t esp2; << 160 sos_ui16_t ss2; << 161 << 162 sos_ui16_t reserved4; << 163 << 164 /* Interrupted context's saved registers. (+ << 165 sos_vaddr_t cr3; << 166 sos_vaddr_t eip; << 167 sos_ui32_t eflags; << 168 sos_ui32_t eax; << 169 sos_ui32_t ecx; << 170 sos_ui32_t edx; << 171 sos_ui32_t ebx; << 172 sos_ui32_t esp; << 173 sos_ui32_t ebp; << 174 sos_ui32_t esi; << 175 sos_ui32_t edi; << 176 << 177 /* +72 */ << 178 sos_ui16_t es; << 179 sos_ui16_t reserved5; << 180 << 181 /* +76 */ << 182 sos_ui16_t cs; << 183 sos_ui16_t reserved6; << 184 << 185 /* +80 */ << 186 sos_ui16_t ss; << 187 sos_ui16_t reserved7; << 188 << 189 /* +84 */ << 190 sos_ui16_t ds; << 191 sos_ui16_t reserved8; << 192 << 193 /* +88 */ << 194 sos_ui16_t fs; << 195 sos_ui16_t reserved9; << 196 << 197 /* +92 */ << 198 sos_ui16_t gs; << 199 sos_ui16_t reserved10; << 200 << 201 /* +96 */ << 202 sos_ui16_t ldtr; << 203 sos_ui16_t reserved11; << 204 << 205 /* +100 */ << 206 sos_ui16_t debug_trap_flag :1; << 207 sos_ui16_t reserved12 :15; << 208 sos_ui16_t iomap_base_addr; << 209 << 210 /* 104 */ << 211 } __attribute__((packed, aligned(128))); << 212 << 213 << 214 static struct x86_tss kernel_tss; << 215 << 216 << 217 sos_ret_t sos_cpu_context_subsystem_setup() << 218 { << 219 /* Reset the kernel TSS */ << 220 memset(&kernel_tss, 0x0, sizeof(kernel_tss)) << 221 << 222 /** << 223 * Now setup the kernel TSS. << 224 * << 225 * Considering the privilege change method w << 226 * through a software interrupt), we don't n << 227 * full-fledged TSS. See section 6.4.1 of In << 228 * only a correct value for the kernel esp a << 229 * "ss0" and "esp0" fields). Since the esp0 << 230 * at privilege change time, we don't have t << 231 */ << 232 kernel_tss.ss0 = SOS_BUILD_SEGMENT_REG_VALUE << 233 << 234 /* Register this TSS into the gdt */ << 235 sos_gdt_register_kernel_tss((sos_vaddr_t) &k << 236 << 237 return SOS_OK; << 238 } << 239 << 240 << 241 /** << 242 * THE main operation of a kernel thread. This 101 * THE main operation of a kernel thread. This routine calls the 243 * kernel thread function start_func and calls 102 * kernel thread function start_func and calls exit_func when 244 * start_func returns. 103 * start_func returns. 245 */ 104 */ 246 static void core_routine (sos_cpu_kstate_funct 105 static void core_routine (sos_cpu_kstate_function_arg1_t *start_func, 247 sos_ui32_t start_arg 106 sos_ui32_t start_arg, 248 sos_cpu_kstate_funct 107 sos_cpu_kstate_function_arg1_t *exit_func, 249 sos_ui32_t exit_arg) 108 sos_ui32_t exit_arg) 250 __attribute__((noreturn)); 109 __attribute__((noreturn)); 251 110 252 static void core_routine (sos_cpu_kstate_funct 111 static void core_routine (sos_cpu_kstate_function_arg1_t *start_func, 253 sos_ui32_t start_arg 112 sos_ui32_t start_arg, 254 sos_cpu_kstate_funct 113 sos_cpu_kstate_function_arg1_t *exit_func, 255 sos_ui32_t exit_arg) 114 sos_ui32_t exit_arg) 256 { 115 { 257 start_func(start_arg); 116 start_func(start_arg); 258 exit_func(exit_arg); 117 exit_func(exit_arg); 259 118 260 SOS_ASSERT_FATAL(! "The exit function of the 119 SOS_ASSERT_FATAL(! "The exit function of the thread should NOT return !"); 261 for(;;); 120 for(;;); 262 } 121 } 263 122 264 123 265 sos_ret_t sos_cpu_kstate_init(struct sos_cpu_s 124 sos_ret_t sos_cpu_kstate_init(struct sos_cpu_state **ctxt, 266 sos_cpu_kstate_f 125 sos_cpu_kstate_function_arg1_t *start_func, 267 sos_ui32_t star 126 sos_ui32_t start_arg, 268 sos_vaddr_t stac 127 sos_vaddr_t stack_bottom, 269 sos_size_t stac 128 sos_size_t stack_size, 270 sos_cpu_kstate_f 129 sos_cpu_kstate_function_arg1_t *exit_func, 271 sos_ui32_t exit 130 sos_ui32_t exit_arg) 272 { 131 { 273 /* We are initializing a Kernel thread's con 132 /* We are initializing a Kernel thread's context */ 274 struct sos_cpu_kstate *kctxt; 133 struct sos_cpu_kstate *kctxt; 275 134 276 /* This is a critical internal function, so 135 /* This is a critical internal function, so that it is assumed that 277 the caller knows what he does: we legitim 136 the caller knows what he does: we legitimally assume that values 278 for ctxt, start_func, stack_* and exit_fu 137 for ctxt, start_func, stack_* and exit_func are allways VALID ! */ 279 138 280 /* Setup the stack. 139 /* Setup the stack. 281 * 140 * 282 * On x86, the stack goes downward. Each fra 141 * On x86, the stack goes downward. Each frame is configured this 283 * way (higher addresses first): 142 * way (higher addresses first): 284 * 143 * 285 * - (optional unused space. As of gcc 3.3, 144 * - (optional unused space. As of gcc 3.3, this space is 24 bytes) 286 * - arg n 145 * - arg n 287 * - arg n-1 146 * - arg n-1 288 * - ... 147 * - ... 289 * - arg 1 148 * - arg 1 290 * - return instruction address: The addres 149 * - return instruction address: The address the function returns to 291 * once finished 150 * once finished 292 * - local variables 151 * - local variables 293 * 152 * 294 * The remaining of the code should be read 153 * The remaining of the code should be read from the end upward to 295 * understand how the processor will handle 154 * understand how the processor will handle it. 296 */ 155 */ 297 156 298 sos_vaddr_t tmp_vaddr = stack_bottom + stack 157 sos_vaddr_t tmp_vaddr = stack_bottom + stack_size; 299 sos_ui32_t *stack = (sos_ui32_t*)tmp_vaddr; 158 sos_ui32_t *stack = (sos_ui32_t*)tmp_vaddr; 300 159 301 /* If needed, poison the stack */ 160 /* If needed, poison the stack */ 302 #ifdef SOS_CPU_STATE_DETECT_UNINIT_KERNEL_VARS 161 #ifdef SOS_CPU_STATE_DETECT_UNINIT_KERNEL_VARS 303 memset((void*)stack_bottom, SOS_CPU_STATE_ST 162 memset((void*)stack_bottom, SOS_CPU_STATE_STACK_POISON, stack_size); 304 #elif defined(SOS_CPU_STATE_DETECT_KERNEL_STAC 163 #elif defined(SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW) 305 sos_cpu_state_prepare_detect_kernel_stack_ov 164 sos_cpu_state_prepare_detect_kernel_stack_overflow(stack_bottom, stack_size); 306 #endif 165 #endif 307 166 308 /* Simulate a call to the core_routine() fun 167 /* Simulate a call to the core_routine() function: prepare its 309 arguments */ 168 arguments */ 310 *(--stack) = exit_arg; 169 *(--stack) = exit_arg; 311 *(--stack) = (sos_ui32_t)exit_func; 170 *(--stack) = (sos_ui32_t)exit_func; 312 *(--stack) = start_arg; 171 *(--stack) = start_arg; 313 *(--stack) = (sos_ui32_t)start_func; 172 *(--stack) = (sos_ui32_t)start_func; 314 *(--stack) = 0; /* Return address of core_ro 173 *(--stack) = 0; /* Return address of core_routine => force page fault */ 315 174 316 /* 175 /* 317 * Setup the initial context structure, so t 176 * Setup the initial context structure, so that the CPU will execute 318 * the function core_routine() once this new 177 * the function core_routine() once this new context has been 319 * restored on CPU 178 * restored on CPU 320 */ 179 */ 321 180 322 /* Compute the base address of the structure 181 /* Compute the base address of the structure, which must be located 323 below the previous elements */ 182 below the previous elements */ 324 tmp_vaddr = ((sos_vaddr_t)stack) - sizeof(s 183 tmp_vaddr = ((sos_vaddr_t)stack) - sizeof(struct sos_cpu_kstate); 325 kctxt = (struct sos_cpu_kstate*)tmp_vaddr; 184 kctxt = (struct sos_cpu_kstate*)tmp_vaddr; 326 185 327 /* Initialize the CPU context structure */ 186 /* Initialize the CPU context structure */ 328 memset(kctxt, 0x0, sizeof(struct sos_cpu_kst 187 memset(kctxt, 0x0, sizeof(struct sos_cpu_kstate)); 329 188 330 /* Tell the CPU context structure that the f 189 /* Tell the CPU context structure that the first instruction to 331 execute will be that of the core_routine( 190 execute will be that of the core_routine() function */ 332 kctxt->regs.eip = (sos_ui32_t)core_routine; 191 kctxt->regs.eip = (sos_ui32_t)core_routine; 333 192 334 /* Setup the segment registers */ 193 /* Setup the segment registers */ 335 kctxt->regs.cs 194 kctxt->regs.cs 336 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 195 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KCODE); /* Code */ 337 kctxt->regs.ds 196 kctxt->regs.ds 338 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 197 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); /* Data */ 339 kctxt->regs.es 198 kctxt->regs.es 340 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 199 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); /* Data */ 341 kctxt->regs.cpl0_ss 200 kctxt->regs.cpl0_ss 342 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 201 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); /* Stack */ 343 /* fs and gs unused for the moment. */ 202 /* fs and gs unused for the moment. */ 344 203 345 /* The newly created context is initially in 204 /* The newly created context is initially interruptible */ 346 kctxt->regs.eflags = (1 << 9); /* set IF bit 205 kctxt->regs.eflags = (1 << 9); /* set IF bit */ 347 206 348 /* Finally, update the generic kernel/user t 207 /* Finally, update the generic kernel/user thread context */ 349 *ctxt = (struct sos_cpu_state*) kctxt; 208 *ctxt = (struct sos_cpu_state*) kctxt; 350 209 351 return SOS_OK; 210 return SOS_OK; 352 } 211 } 353 212 354 213 355 /** << 356 * Helper function to create a new user thread << 357 * model_uctxt is NON NULL, the new user conte << 358 * model_uctxt, otherwise the SP/PC registers << 359 * user_initial_SP/PC arguments << 360 */ << 361 static sos_ret_t cpu_ustate_init(struct sos_cp << 362 const struct << 363 sos_uaddr_t << 364 sos_ui32_t << 365 sos_ui32_t << 366 sos_uaddr_t << 367 sos_vaddr_t << 368 sos_size_t << 369 { << 370 /* We are initializing a User thread's conte << 371 struct sos_cpu_ustate *uctxt; << 372 << 373 /* This is a critical internal function, so << 374 the caller knows what he does: we legitim << 375 for ctxt, etc. are allways VALID ! */ << 376 << 377 /* Compute the address of the CPU state to r << 378 switching to this new user thread */ << 379 sos_vaddr_t uctxt_vaddr = kernel_stack_botto << 380 + kernel_stack_si << 381 - sizeof(struct s << 382 uctxt = (struct sos_cpu_ustate*)uctxt_vaddr; << 383 << 384 if (model_uctxt && !sos_cpu_context_is_in_us << 385 return -SOS_EINVAL; << 386 << 387 /* If needed, poison the kernel stack */ << 388 #ifdef SOS_CPU_STATE_DETECT_UNINIT_KERNEL_VARS << 389 memset((void*)kernel_stack_bottom, << 390 SOS_CPU_STATE_STACK_POISON, << 391 kernel_stack_size); << 392 #elif defined(SOS_CPU_STATE_DETECT_KERNEL_STAC << 393 sos_cpu_state_prepare_detect_kernel_stack_ov << 394 << 395 #endif << 396 << 397 /* << 398 * Setup the initial context structure, so t << 399 * the initial registers' value for the user << 400 * user thread argument is passed in the EAX << 401 */ << 402 << 403 /* Initialize the CPU context structure */ << 404 if (! model_uctxt) << 405 { << 406 memset(uctxt, 0x0, sizeof(struct sos_cpu << 407 << 408 /* Tell the CPU context structure that t << 409 execute will be located at user_start << 410 uctxt->regs.eip = (sos_ui32_t)user_start << 411 << 412 /* Tell the CPU where will be the user s << 413 uctxt->cpl3_esp = user_initial_SP; << 414 } << 415 else << 416 memcpy(uctxt, model_uctxt, sizeof(struct s << 417 << 418 /* The parameter to the start function is no << 419 avoid a possible page fault */ << 420 uctxt->regs.eax = user_start_arg1; << 421 << 422 /* Optional additional argument for non-dupl << 423 if (! model_uctxt) << 424 uctxt->regs.ebx = user_start_arg2; << 425 << 426 /* Setup the segment registers */ << 427 uctxt->regs.cs << 428 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SO << 429 uctxt->regs.ds << 430 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SO << 431 uctxt->regs.es << 432 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SO << 433 uctxt->cpl3_ss << 434 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SO << 435 << 436 /* We need also to update the segment for th << 437 segment. It will be used when this contex << 438 CPU: initially it will be executing in ke << 439 switch immediatly to user mode */ << 440 uctxt->regs.cpl0_ss << 441 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO << 442 << 443 /* fs and gs unused for the moment. */ << 444 << 445 /* The newly created context is initially in << 446 uctxt->regs.eflags = (1 << 9); /* set IF bit << 447 << 448 /* Finally, update the generic kernel/user t << 449 *ctxt = (struct sos_cpu_state*) uctxt; << 450 << 451 return SOS_OK; << 452 } << 453 << 454 << 455 sos_ret_t sos_cpu_ustate_init(struct sos_cpu_s << 456 sos_uaddr_t use << 457 sos_ui32_t use << 458 sos_ui32_t use << 459 sos_uaddr_t use << 460 sos_vaddr_t ker << 461 sos_size_t ker << 462 { << 463 return cpu_ustate_init(ctxt, NULL, << 464 user_start_PC, << 465 user_start_arg1, user << 466 user_initial_SP, << 467 kernel_stack_bottom, << 468 } << 469 << 470 << 471 sos_ret_t sos_cpu_ustate_duplicate(struct sos_ << 472 const struc << 473 sos_ui32_t << 474 sos_vaddr_t << 475 sos_size_t << 476 { << 477 return cpu_ustate_init(ctxt, model_uctxt, << 478 /* ignored */0, << 479 user_retval, /* ignor << 480 /* ignored */0, << 481 kernel_stack_bottom, << 482 } << 483 << 484 << 485 sos_ret_t << 486 sos_cpu_context_is_in_user_mode(const struct s << 487 { << 488 /* An interrupted user thread has its CS reg << 489 User code segment */ << 490 switch (GET_CPU_CS_REGISTER_VALUE(ctxt->cs)) << 491 { << 492 case SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, << 493 return TRUE; << 494 break; << 495 << 496 case SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, << 497 return FALSE; << 498 break; << 499 << 500 default: << 501 SOS_FATAL_ERROR("Invalid saved context C << 502 (unsigned) GET_CPU_CS_RE << 503 SOS_BUILD_SEGMENT_REG_VA << 504 SOS_BUILD_SEGMENT_REG_VA << 505 break; << 506 } << 507 << 508 /* Should never get here */ << 509 return -SOS_EFATAL; << 510 } << 511 << 512 << 513 #if defined(SOS_CPU_STATE_DETECT_KERNEL_STACK_ 214 #if defined(SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW) 514 void 215 void 515 sos_cpu_state_prepare_detect_kernel_stack_over 216 sos_cpu_state_prepare_detect_kernel_stack_overflow(const struct sos_cpu_state *ctxt, 516 217 sos_vaddr_t stack_bottom, 517 218 sos_size_t stack_size) 518 { 219 { 519 sos_size_t poison_size = SOS_CPU_STATE_DETEC 220 sos_size_t poison_size = SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW; 520 if (poison_size > stack_size) 221 if (poison_size > stack_size) 521 poison_size = stack_size; 222 poison_size = stack_size; 522 223 523 memset((void*)stack_bottom, SOS_CPU_STATE_ST 224 memset((void*)stack_bottom, SOS_CPU_STATE_STACK_POISON, poison_size); 524 } 225 } 525 226 526 227 527 void 228 void 528 sos_cpu_state_detect_kernel_stack_overflow(con 229 sos_cpu_state_detect_kernel_stack_overflow(const struct sos_cpu_state *ctxt, 529 sos 230 sos_vaddr_t stack_bottom, 530 sos 231 sos_size_t stack_size) 531 { 232 { 532 unsigned char *c; 233 unsigned char *c; 533 int i; 234 int i; 534 235 535 /* On SOS, "ctxt" corresponds to the address 236 /* On SOS, "ctxt" corresponds to the address of the esp register of 536 the saved context in Kernel mode (always, 237 the saved context in Kernel mode (always, even for the interrupted 537 context of a user thread). Here we make s 238 context of a user thread). Here we make sure that this stack 538 pointer is within the allowed stack area 239 pointer is within the allowed stack area */ 539 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) >= stac 240 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) >= stack_bottom); 540 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) + sizeo 241 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) + sizeof(struct sos_cpu_kstate) 541 <= stack_bottom + stack_siz 242 <= stack_bottom + stack_size); 542 243 543 /* Check that the bottom of the stack has no 244 /* Check that the bottom of the stack has not been altered */ 544 for (c = (unsigned char*) stack_bottom, i = 245 for (c = (unsigned char*) stack_bottom, i = 0 ; 545 (i < SOS_CPU_STATE_DETECT_KERNEL_STACK_ 246 (i < SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW) && (i < stack_size) ; 546 c++, i++) 247 c++, i++) 547 { 248 { 548 SOS_ASSERT_FATAL(SOS_CPU_STATE_STACK_POI 249 SOS_ASSERT_FATAL(SOS_CPU_STATE_STACK_POISON == *c); 549 } 250 } 550 } 251 } 551 #endif 252 #endif 552 253 553 254 554 /* =========================================== 255 /* ======================================================================= 555 * Public Accessor functions 256 * Public Accessor functions 556 */ 257 */ 557 258 558 259 559 sos_vaddr_t sos_cpu_context_get_PC(const struc 260 sos_vaddr_t sos_cpu_context_get_PC(const struct sos_cpu_state *ctxt) 560 { 261 { 561 SOS_ASSERT_FATAL(NULL != ctxt); 262 SOS_ASSERT_FATAL(NULL != ctxt); 562 263 563 /* This is the PC of the interrupted context 264 /* This is the PC of the interrupted context (ie kernel or user 564 context). */ 265 context). */ 565 return ctxt->eip; 266 return ctxt->eip; 566 } 267 } 567 268 568 269 569 sos_vaddr_t sos_cpu_context_get_SP(const struc 270 sos_vaddr_t sos_cpu_context_get_SP(const struct sos_cpu_state *ctxt) 570 { 271 { 571 SOS_ASSERT_FATAL(NULL != ctxt); 272 SOS_ASSERT_FATAL(NULL != ctxt); 572 273 573 /* 'ctxt' corresponds to the SP of the inter << 574 mode. We have to test whether the origina << 575 was that of a kernel or user thread */ << 576 if (TRUE == sos_cpu_context_is_in_user_mode( << 577 { << 578 struct sos_cpu_ustate * uctxt = (struct << 579 return uctxt->cpl3_esp; << 580 } << 581 << 582 /* On SOS, "ctxt" corresponds to the address 274 /* On SOS, "ctxt" corresponds to the address of the esp register of 583 the saved context in Kernel mode (always, 275 the saved context in Kernel mode (always, even for the interrupted 584 context of a user thread). */ 276 context of a user thread). */ 585 return (sos_vaddr_t)ctxt; 277 return (sos_vaddr_t)ctxt; 586 } 278 } 587 279 588 280 589 sos_ret_t << 590 sos_cpu_context_set_EX_return_address(struct s << 591 sos_vadd << 592 { << 593 ctxt->eip = ret_vaddr; << 594 return SOS_OK; << 595 } << 596 << 597 << 598 void sos_cpu_context_dump(const struct sos_cpu 281 void sos_cpu_context_dump(const struct sos_cpu_state *ctxt) 599 { 282 { 600 char buf[128]; 283 char buf[128]; 601 << 602 snprintf(buf, sizeof(buf), 284 snprintf(buf, sizeof(buf), 603 "CPU: eip=%x esp0=%x eflags=%x cs=% !! 285 "CPU: eip=%x esp=%x eflags=%x cs=%x ds=%x ss=%x err=%x", 604 (unsigned)ctxt->eip, (unsigned)ctxt 286 (unsigned)ctxt->eip, (unsigned)ctxt, (unsigned)ctxt->eflags, 605 (unsigned)GET_CPU_CS_REGISTER_VALUE 287 (unsigned)GET_CPU_CS_REGISTER_VALUE(ctxt->cs), (unsigned)ctxt->ds, 606 (unsigned)ctxt->cpl0_ss, 288 (unsigned)ctxt->cpl0_ss, 607 (unsigned)ctxt->error_code); 289 (unsigned)ctxt->error_code); 608 if (TRUE == sos_cpu_context_is_in_user_mode( << 609 { << 610 struct sos_cpu_ustate * uctxt = (struct << 611 snprintf(buf, sizeof(buf), << 612 "%s esp3=%x ss3=%x", << 613 buf, (unsigned)uctxt->cpl3_esp, << 614 } << 615 else << 616 snprintf(buf, sizeof(buf), "%s [KERNEL MOD << 617 << 618 sos_bochs_putstring(buf); sos_bochs_putstrin 290 sos_bochs_putstring(buf); sos_bochs_putstring("\n"); 619 sos_x86_videomem_putstring(23, 0, 291 sos_x86_videomem_putstring(23, 0, 620 SOS_X86_VIDEO_FG_ !! 292 SOS_X86_VIDEO_FG_BLACK | SOS_X86_VIDEO_BG_LTGRAY, 621 buf); !! 293 buf); 622 } 294 } 623 295 624 296 625 /* =========================================== 297 /* ======================================================================= 626 * Public Accessor functions TO BE USED ONLY B 298 * Public Accessor functions TO BE USED ONLY BY Exception handlers 627 */ 299 */ 628 300 629 301 630 sos_ui32_t sos_cpu_context_get_EX_info(const s 302 sos_ui32_t sos_cpu_context_get_EX_info(const struct sos_cpu_state *ctxt) 631 { 303 { 632 SOS_ASSERT_FATAL(NULL != ctxt); 304 SOS_ASSERT_FATAL(NULL != ctxt); 633 return ctxt->error_code; 305 return ctxt->error_code; 634 } 306 } 635 307 636 308 637 sos_vaddr_t 309 sos_vaddr_t 638 sos_cpu_context_get_EX_faulting_vaddr(const st 310 sos_cpu_context_get_EX_faulting_vaddr(const struct sos_cpu_state *ctxt) 639 { 311 { 640 sos_ui32_t cr2; 312 sos_ui32_t cr2; 641 313 642 /* 314 /* 643 * See Intel Vol 3 (section 5.14): the addre 315 * See Intel Vol 3 (section 5.14): the address of the faulting 644 * virtual address of a page fault is stored 316 * virtual address of a page fault is stored in the cr2 645 * register. 317 * register. 646 * 318 * 647 * Actually, we do not store the cr2 registe 319 * Actually, we do not store the cr2 register in a saved 648 * kernel thread's context. So we retrieve t 320 * kernel thread's context. So we retrieve the cr2's value directly 649 * from the processor. The value we retrieve 321 * from the processor. The value we retrieve in an exception handler 650 * is actually the correct one because an ex 322 * is actually the correct one because an exception is synchronous 651 * with the code causing the fault, and cann 323 * with the code causing the fault, and cannot be interrupted since 652 * the IDT entries in SOS are "interrupt gat 324 * the IDT entries in SOS are "interrupt gates" (ie IRQ are 653 * disabled). 325 * disabled). 654 */ 326 */ 655 asm volatile ("movl %%cr2, %0" 327 asm volatile ("movl %%cr2, %0" 656 :"=r"(cr2) 328 :"=r"(cr2) 657 : ); 329 : ); 658 330 659 return cr2; 331 return cr2; 660 } 332 } 661 333 662 334 663 /* =========================================== 335 /* ======================================================================= 664 * Public Accessor functions TO BE USED ONLY B << 665 */ << 666 << 667 << 668 /* << 669 * By convention, the USER SOS programs always << 670 * kernel syscall handler: in eax/../edx. For << 671 * unused registers are filled with 0s. For mo << 672 * syscall parameter gives the address of the << 673 * remaining arguments. In any case, eax corre << 674 * IDentifier. << 675 */ << 676 << 677 << 678 inline << 679 sos_ret_t sos_syscall_get3args(const struct so << 680 /* out */unsign << 681 /* out */unsign << 682 /* out */unsign << 683 { << 684 *arg1 = user_ctxt->ebx; << 685 *arg2 = user_ctxt->ecx; << 686 *arg3 = user_ctxt->edx; << 687 return SOS_OK; << 688 } << 689 << 690 << 691 sos_ret_t sos_syscall_get1arg(const struct sos << 692 /* out */unsigne << 693 { << 694 unsigned int unused; << 695 return sos_syscall_get3args(user_ctxt, arg1, << 696 } << 697 << 698 << 699 sos_ret_t sos_syscall_get2args(const struct so << 700 /* out */unsign << 701 /* out */unsign << 702 { << 703 unsigned int unused; << 704 return sos_syscall_get3args(user_ctxt, arg1, << 705 } << 706 << 707 << 708 /* << 709 * sos_syscall_get3args() is defined in cpu_co << 710 * to know the structure of a struct spu_state << 711 */ << 712 << 713 sos_ret_t sos_syscall_get4args(const struct so << 714 /* out */unsign << 715 /* out */unsign << 716 /* out */unsign << 717 /* out */unsign << 718 { << 719 sos_uaddr_t uaddr_other_args; << 720 unsigned int other_args[2]; << 721 sos_ret_t retval; << 722 << 723 /* Retrieve the 3 arguments. The last one is << 724 remaining arguments */ << 725 retval = sos_syscall_get3args(user_ctxt, arg << 726 (unsigned int << 727 if (SOS_OK != retval) << 728 return retval; << 729 << 730 /* Copy the array containing the remaining a << 731 space */ << 732 retval = sos_memcpy_from_user((sos_vaddr_t)o << 733 (sos_uaddr_t)u << 734 sizeof(other_a << 735 if (sizeof(other_args) != retval) << 736 return -SOS_EFAULT; << 737 << 738 *arg3 = other_args[0]; << 739 *arg4 = other_args[1]; << 740 return SOS_OK; << 741 } << 742 << 743 << 744 sos_ret_t sos_syscall_get5args(const struct so << 745 /* out */unsign << 746 /* out */unsign << 747 /* out */unsign << 748 /* out */unsign << 749 /* out */unsign << 750 { << 751 sos_uaddr_t uaddr_other_args; << 752 unsigned int other_args[3]; << 753 sos_ret_t retval; << 754 << 755 /* Retrieve the 3 arguments. The last one is << 756 remaining arguments */ << 757 retval = sos_syscall_get3args(user_ctxt, arg << 758 (unsigned int << 759 if (SOS_OK != retval) << 760 return retval; << 761 << 762 /* Copy the array containing the remaining a << 763 space */ << 764 retval = sos_memcpy_from_user((sos_vaddr_t)o << 765 (sos_uaddr_t)u << 766 sizeof(other_a << 767 if (sizeof(other_args) != retval) << 768 return -SOS_EFAULT; << 769 << 770 *arg3 = other_args[0]; << 771 *arg4 = other_args[1]; << 772 *arg5 = other_args[2]; << 773 return SOS_OK; << 774 } << 775 << 776 << 777 sos_ret_t sos_syscall_get6args(const struct so << 778 /* out */unsign << 779 /* out */unsign << 780 /* out */unsign << 781 /* out */unsign << 782 /* out */unsign << 783 /* out */unsign << 784 { << 785 sos_uaddr_t uaddr_other_args; << 786 unsigned int other_args[4]; << 787 sos_ret_t retval; << 788 << 789 /* Retrieve the 3 arguments. The last one is << 790 remaining arguments */ << 791 retval = sos_syscall_get3args(user_ctxt, arg << 792 (unsigned int << 793 if (SOS_OK != retval) << 794 return retval; << 795 << 796 /* Copy the array containing the remaining a << 797 space */ << 798 retval = sos_memcpy_from_user((sos_vaddr_t)o << 799 (sos_uaddr_t)u << 800 sizeof(other_a << 801 if (sizeof(other_args) != retval) << 802 return -SOS_EFAULT; << 803 << 804 *arg3 = other_args[0]; << 805 *arg4 = other_args[1]; << 806 *arg5 = other_args[2]; << 807 *arg6 = other_args[3]; << 808 return SOS_OK; << 809 } << 810 << 811 << 812 sos_ret_t sos_syscall_get7args(const struct so << 813 /* out */unsign << 814 /* out */unsign << 815 /* out */unsign << 816 /* out */unsign << 817 /* out */unsign << 818 /* out */unsign << 819 /* out */unsign << 820 { << 821 sos_uaddr_t uaddr_other_args; << 822 unsigned int other_args[5]; << 823 sos_ret_t retval; << 824 << 825 /* Retrieve the 3 arguments. The last one is << 826 remaining arguments */ << 827 retval = sos_syscall_get3args(user_ctxt, arg << 828 (unsigned int << 829 if (SOS_OK != retval) << 830 return retval; << 831 << 832 /* Copy the array containing the remaining a << 833 space */ << 834 retval = sos_memcpy_from_user((sos_vaddr_t)o << 835 (sos_uaddr_t)u << 836 sizeof(other_a << 837 if (sizeof(other_args) != retval) << 838 return -SOS_EFAULT; << 839 << 840 *arg3 = other_args[0]; << 841 *arg4 = other_args[1]; << 842 *arg5 = other_args[2]; << 843 *arg6 = other_args[3]; << 844 *arg7 = other_args[4]; << 845 return SOS_OK; << 846 } << 847 << 848 << 849 sos_ret_t sos_syscall_get8args(const struct so << 850 /* out */unsign << 851 /* out */unsign << 852 /* out */unsign << 853 /* out */unsign << 854 /* out */unsign << 855 /* out */unsign << 856 /* out */unsign << 857 /* out */unsign << 858 { << 859 sos_uaddr_t uaddr_other_args; << 860 unsigned int other_args[6]; << 861 sos_ret_t retval; << 862 << 863 /* Retrieve the 3 arguments. The last one is << 864 remaining arguments */ << 865 retval = sos_syscall_get3args(user_ctxt, arg << 866 (unsigned int << 867 if (SOS_OK != retval) << 868 return retval; << 869 << 870 /* Copy the array containing the remaining a << 871 space */ << 872 retval = sos_memcpy_from_user((sos_vaddr_t)o << 873 (sos_uaddr_t)u << 874 sizeof(other_a << 875 if (sizeof(other_args) != retval) << 876 return -SOS_EFAULT; << 877 << 878 *arg3 = other_args[0]; << 879 *arg4 = other_args[1]; << 880 *arg5 = other_args[2]; << 881 *arg6 = other_args[3]; << 882 *arg7 = other_args[4]; << 883 *arg8 = other_args[5]; << 884 return SOS_OK; << 885 } << 886 << 887 << 888 /* =========================================== << 889 * Backtrace facility. To be used for DEBUGgin 336 * Backtrace facility. To be used for DEBUGging purpose ONLY. 890 */ 337 */ 891 338 892 339 893 sos_ui32_t sos_backtrace(const struct sos_cpu_ 340 sos_ui32_t sos_backtrace(const struct sos_cpu_state *cpu_state, 894 sos_ui32_t max_depth, 341 sos_ui32_t max_depth, 895 sos_vaddr_t stack_bot 342 sos_vaddr_t stack_bottom, 896 sos_size_t stack_size 343 sos_size_t stack_size, 897 sos_backtrace_callbac 344 sos_backtrace_callback_t * backtracer, 898 void *custom_arg) 345 void *custom_arg) 899 { 346 { 900 int depth; 347 int depth; 901 sos_vaddr_t callee_PC, caller_frame; 348 sos_vaddr_t callee_PC, caller_frame; 902 349 903 /* Cannot backtrace an interrupted user thre << 904 if ((NULL != cpu_state) << 905 && << 906 (TRUE == sos_cpu_context_is_in_user_mode << 907 { << 908 return 0; << 909 } << 910 << 911 /* 350 /* 912 * Layout of a frame on the x86 (compiler=gc 351 * Layout of a frame on the x86 (compiler=gcc): 913 * 352 * 914 * funcA calls funcB calls funcC 353 * funcA calls funcB calls funcC 915 * 354 * 916 * .... 355 * .... 917 * funcB Argument 2 356 * funcB Argument 2 918 * funcB Argument 1 357 * funcB Argument 1 919 * funcA Return eip 358 * funcA Return eip 920 * frameB: funcA ebp (ie previous stack fram 359 * frameB: funcA ebp (ie previous stack frame) 921 * .... 360 * .... 922 * (funcB local variables) 361 * (funcB local variables) 923 * .... 362 * .... 924 * funcC Argument 2 363 * funcC Argument 2 925 * funcC Argument 1 364 * funcC Argument 1 926 * funcB Return eip 365 * funcB Return eip 927 * frameC: funcB ebp (ie previous stack fram 366 * frameC: funcB ebp (ie previous stack frame == A0) <---- a frame address 928 * .... 367 * .... 929 * (funcC local variables) 368 * (funcC local variables) 930 * .... 369 * .... 931 * 370 * 932 * The presence of "ebp" on the stack depend 371 * The presence of "ebp" on the stack depends on 2 things: 933 * + the compiler is gcc 372 * + the compiler is gcc 934 * + the source is compiled WITHOUT the -f 373 * + the source is compiled WITHOUT the -fomit-frame-pointer option 935 * In the absence of "ebp", chances are high 374 * In the absence of "ebp", chances are high that the value pushed 936 * at that address is outside the stack boun 375 * at that address is outside the stack boundaries, meaning that the 937 * function will return -SOS_ENOSUP. 376 * function will return -SOS_ENOSUP. 938 */ 377 */ 939 378 940 if (cpu_state) 379 if (cpu_state) 941 { 380 { 942 callee_PC = cpu_state->eip; 381 callee_PC = cpu_state->eip; 943 caller_frame = cpu_state->ebp; 382 caller_frame = cpu_state->ebp; 944 } 383 } 945 else 384 else 946 { 385 { 947 /* Skip the sos_backtrace() frame */ 386 /* Skip the sos_backtrace() frame */ 948 callee_PC = (sos_vaddr_t)__builtin_re 387 callee_PC = (sos_vaddr_t)__builtin_return_address(0); 949 caller_frame = (sos_vaddr_t)__builtin_fr 388 caller_frame = (sos_vaddr_t)__builtin_frame_address(1); 950 } 389 } 951 390 952 for(depth=0 ; depth < max_depth ; depth ++) 391 for(depth=0 ; depth < max_depth ; depth ++) 953 { 392 { 954 /* Call the callback */ 393 /* Call the callback */ 955 backtracer(callee_PC, caller_frame + 8, 394 backtracer(callee_PC, caller_frame + 8, depth, custom_arg); 956 395 957 /* If the frame address is funky, don't 396 /* If the frame address is funky, don't go further */ 958 if ( (caller_frame < stack_bottom) 397 if ( (caller_frame < stack_bottom) 959 || (caller_frame + 4 >= stack_botto 398 || (caller_frame + 4 >= stack_bottom + stack_size) ) 960 return depth; 399 return depth; 961 400 962 /* Go to caller frame */ 401 /* Go to caller frame */ 963 callee_PC = *((sos_vaddr_t*) (caller_ 402 callee_PC = *((sos_vaddr_t*) (caller_frame + 4)); 964 caller_frame = *((sos_vaddr_t*) caller_f 403 caller_frame = *((sos_vaddr_t*) caller_frame); 965 } 404 } 966 405 967 return depth; 406 return depth; 968 } << 969 << 970 << 971 /* ******************************************* << 972 * Function to manage the TSS. This function << 973 * it is reserved to the assembler routines de << 974 * cpu_context_switch.S << 975 * << 976 * Update the kernel stack address so that the << 977 * exception return in a correct stack locatio << 978 * kernel mode. << 979 */ << 980 void << 981 sos_cpu_context_update_kernel_tss(struct sos_c << 982 { << 983 /* next_ctxt corresponds to an interrupted u << 984 if (sos_cpu_context_is_in_user_mode(next_ctx << 985 { << 986 /* << 987 * Yes: "next_ctxt" is an interrupted us << 988 * going to switch to user mode ! Setup << 989 * that the user thread "next_ctxt" can << 990 * stack location when returning in kern << 991 * << 992 * This stack location corresponds to th << 993 * thread once its context has been tran << 994 * once the CPU has executed all the pop << 995 * context switch with privilege change. << 996 */ << 997 kernel_tss.esp0 = ((sos_vaddr_t)next_ctx << 998 + sizeof(struct sos_cp << 999 /* Note: no need to protect this agains << 1000 allowed to update it by themselves, << 1001 to block */ << 1002 } << 1003 else << 1004 { << 1005 /* No: No need to update kernel TSS whe << 1006 mode */ << 1007 } << 1008 } 407 }
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