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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> 026 028 027 #include "cpu_context.h" 029 #include "cpu_context.h" 028 030 029 031 030 /** 032 /** 031 * Here is the definition of a CPU context for 033 * Here is the definition of a CPU context for IA32 processors. This 032 * is a SOS convention, not a specification gi 034 * is a SOS convention, not a specification given by the IA32 033 * spec. However there is a strong constraint 035 * spec. However there is a strong constraint related to the x86 034 * interrupt handling specification: the top o 036 * interrupt handling specification: the top of the stack MUST be 035 * compatible with the 'iret' instruction, ie 037 * compatible with the 'iret' instruction, ie there must be the 036 * err_code (might be 0), eip, cs and eflags o 038 * err_code (might be 0), eip, cs and eflags of the destination 037 * context in that order (see Intel x86 specs 039 * context in that order (see Intel x86 specs vol 3, figure 5-4). 038 * 040 * 039 * @note IMPORTANT: This definition MUST be co 041 * @note IMPORTANT: This definition MUST be consistent with the way 040 * the registers are stored on the stack in 042 * the registers are stored on the stack in 041 * irq_wrappers.S/exception_wrappers.S !!! Hen 043 * irq_wrappers.S/exception_wrappers.S !!! Hence the constraint above. 042 */ 044 */ 043 struct sos_cpu_state { 045 struct sos_cpu_state { 044 /* (Lower addresses) */ 046 /* (Lower addresses) */ 045 047 046 /* These are SOS convention */ 048 /* These are SOS convention */ 047 sos_ui16_t gs; 049 sos_ui16_t gs; 048 sos_ui16_t fs; 050 sos_ui16_t fs; 049 sos_ui16_t es; 051 sos_ui16_t es; 050 sos_ui16_t ds; 052 sos_ui16_t ds; 051 sos_ui16_t cpl0_ss; /* This is ALWAYS the S 053 sos_ui16_t cpl0_ss; /* This is ALWAYS the Stack Segment of the 052 Kernel context (CPL0 054 Kernel context (CPL0) of the interrupted 053 thread, even for a u 055 thread, even for a user thread */ 054 sos_ui16_t alignment_padding; /* unused */ 056 sos_ui16_t alignment_padding; /* unused */ 055 sos_ui32_t eax; 057 sos_ui32_t eax; 056 sos_ui32_t ebx; 058 sos_ui32_t ebx; 057 sos_ui32_t ecx; 059 sos_ui32_t ecx; 058 sos_ui32_t edx; 060 sos_ui32_t edx; 059 sos_ui32_t esi; 061 sos_ui32_t esi; 060 sos_ui32_t edi; 062 sos_ui32_t edi; 061 sos_ui32_t ebp; 063 sos_ui32_t ebp; 062 064 063 /* MUST NEVER CHANGE (dependent on the IA32 065 /* MUST NEVER CHANGE (dependent on the IA32 iret instruction) */ 064 sos_ui32_t error_code; 066 sos_ui32_t error_code; 065 sos_vaddr_t eip; 067 sos_vaddr_t eip; 066 sos_ui32_t cs; /* 32bits according to the s 068 sos_ui32_t cs; /* 32bits according to the specs ! However, the CS 067 register is really 16bits 069 register is really 16bits long */ 068 sos_ui32_t eflags; 070 sos_ui32_t eflags; 069 071 070 /* (Higher addresses) */ 072 /* (Higher addresses) */ 071 } __attribute__((packed)); 073 } __attribute__((packed)); 072 074 073 075 074 /** 076 /** 075 * The CS value pushed on the stack by the CPU 077 * The CS value pushed on the stack by the CPU upon interrupt, and 076 * needed by the iret instruction, is 32bits l 078 * needed by the iret instruction, is 32bits long while the real CPU 077 * CS register is 16bits only: this macro simp 079 * CS register is 16bits only: this macro simply retrieves the CPU 078 * "CS" register value from the CS value pushe 080 * "CS" register value from the CS value pushed on the stack by the 079 * CPU upon interrupt. 081 * CPU upon interrupt. 080 * 082 * 081 * The remaining 16bits pushed by the CPU shou 083 * The remaining 16bits pushed by the CPU should be considered 082 * "reserved" and architecture dependent. IMHO 084 * "reserved" and architecture dependent. IMHO, the specs don't say 083 * anything about them. Considering that some 085 * anything about them. Considering that some architectures generate 084 * non-zero values for these 16bits (at least 086 * non-zero values for these 16bits (at least Cyrix), we'd better 085 * ignore them. 087 * ignore them. 086 */ 088 */ 087 #define GET_CPU_CS_REGISTER_VALUE(pushed_ui32_ 089 #define GET_CPU_CS_REGISTER_VALUE(pushed_ui32_cs_value) \ 088 ( (pushed_ui32_cs_value) & 0xffff ) 090 ( (pushed_ui32_cs_value) & 0xffff ) 089 091 090 092 091 /** 093 /** 092 * Structure of an interrupted Kernel thread's 094 * Structure of an interrupted Kernel thread's context 093 */ 095 */ 094 struct sos_cpu_kstate 096 struct sos_cpu_kstate 095 { 097 { 096 struct sos_cpu_state regs; 098 struct sos_cpu_state regs; 097 } __attribute__((packed)); 099 } __attribute__((packed)); 098 100 099 101 100 /** 102 /** >> 103 * Structure of an interrupted User thread's context. This is almost >> 104 * the same as a kernel context, except that 2 additional values are >> 105 * pushed on the stack before the eflags/cs/eip of the interrupted >> 106 * context: the stack configuration of the interrupted user context. >> 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 x86 Architecture. >> 123 * >> 124 * @see Intel x86 spec vol 3, figure 6-2 >> 125 * >> 126 * @note Such a data structure should not cross any page boundary (see >> 127 * end of section 6.2.1 of Intel spec vol 3). This is the reason why >> 128 * we tell gcc to align it on a 128B boundary (its size is 104B, which >> 129 * is <= 128). >> 130 */ >> 131 struct x86_tss { >> 132 >> 133 /** >> 134 * Intel provides a way for a task to switch to another in an >> 135 * automatic way (call gates). In this case, the back_link field >> 136 * stores the source TSS of the context switch. This allows to >> 137 * easily implement coroutines, task backtracking, ... In SOS we >> 138 * don't use TSS for the context switch purpouse, so we always >> 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. (+28) */ >> 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 we choose (cpl3 -> cpl0 >> 226 * through a software interrupt), we don't need to initialize a >> 227 * full-fledged TSS. See section 6.4.1 of Intel x86 vol 1. Actually, >> 228 * only a correct value for the kernel esp and ss are required (aka >> 229 * "ss0" and "esp0" fields). Since the esp0 will have to be updated >> 230 * at privilege change time, we don't have to set it up now. >> 231 */ >> 232 kernel_tss.ss0 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); >> 233 >> 234 /* Register this TSS into the gdt */ >> 235 sos_gdt_register_kernel_tss((sos_vaddr_t) &kernel_tss); >> 236 >> 237 return SOS_OK; >> 238 } >> 239 >> 240 >> 241 /** 101 * THE main operation of a kernel thread. This 242 * THE main operation of a kernel thread. This routine calls the 102 * kernel thread function start_func and calls 243 * kernel thread function start_func and calls exit_func when 103 * start_func returns. 244 * start_func returns. 104 */ 245 */ 105 static void core_routine (sos_cpu_kstate_funct 246 static void core_routine (sos_cpu_kstate_function_arg1_t *start_func, 106 sos_ui32_t start_arg 247 sos_ui32_t start_arg, 107 sos_cpu_kstate_funct 248 sos_cpu_kstate_function_arg1_t *exit_func, 108 sos_ui32_t exit_arg) 249 sos_ui32_t exit_arg) 109 __attribute__((noreturn)); 250 __attribute__((noreturn)); 110 251 111 static void core_routine (sos_cpu_kstate_funct 252 static void core_routine (sos_cpu_kstate_function_arg1_t *start_func, 112 sos_ui32_t start_arg 253 sos_ui32_t start_arg, 113 sos_cpu_kstate_funct 254 sos_cpu_kstate_function_arg1_t *exit_func, 114 sos_ui32_t exit_arg) 255 sos_ui32_t exit_arg) 115 { 256 { 116 start_func(start_arg); 257 start_func(start_arg); 117 exit_func(exit_arg); 258 exit_func(exit_arg); 118 259 119 SOS_ASSERT_FATAL(! "The exit function of the 260 SOS_ASSERT_FATAL(! "The exit function of the thread should NOT return !"); 120 for(;;); 261 for(;;); 121 } 262 } 122 263 123 264 124 sos_ret_t sos_cpu_kstate_init(struct sos_cpu_s 265 sos_ret_t sos_cpu_kstate_init(struct sos_cpu_state **ctxt, 125 sos_cpu_kstate_f 266 sos_cpu_kstate_function_arg1_t *start_func, 126 sos_ui32_t star 267 sos_ui32_t start_arg, 127 sos_vaddr_t stac 268 sos_vaddr_t stack_bottom, 128 sos_size_t stac 269 sos_size_t stack_size, 129 sos_cpu_kstate_f 270 sos_cpu_kstate_function_arg1_t *exit_func, 130 sos_ui32_t exit 271 sos_ui32_t exit_arg) 131 { 272 { 132 /* We are initializing a Kernel thread's con 273 /* We are initializing a Kernel thread's context */ 133 struct sos_cpu_kstate *kctxt; 274 struct sos_cpu_kstate *kctxt; 134 275 135 /* This is a critical internal function, so 276 /* This is a critical internal function, so that it is assumed that 136 the caller knows what he does: we legitim 277 the caller knows what he does: we legitimally assume that values 137 for ctxt, start_func, stack_* and exit_fu 278 for ctxt, start_func, stack_* and exit_func are allways VALID ! */ 138 279 139 /* Setup the stack. 280 /* Setup the stack. 140 * 281 * 141 * On x86, the stack goes downward. Each fra 282 * On x86, the stack goes downward. Each frame is configured this 142 * way (higher addresses first): 283 * way (higher addresses first): 143 * 284 * 144 * - (optional unused space. As of gcc 3.3, 285 * - (optional unused space. As of gcc 3.3, this space is 24 bytes) 145 * - arg n 286 * - arg n 146 * - arg n-1 287 * - arg n-1 147 * - ... 288 * - ... 148 * - arg 1 289 * - arg 1 149 * - return instruction address: The addres 290 * - return instruction address: The address the function returns to 150 * once finished 291 * once finished 151 * - local variables 292 * - local variables 152 * 293 * 153 * The remaining of the code should be read 294 * The remaining of the code should be read from the end upward to 154 * understand how the processor will handle 295 * understand how the processor will handle it. 155 */ 296 */ 156 297 157 sos_vaddr_t tmp_vaddr = stack_bottom + stack 298 sos_vaddr_t tmp_vaddr = stack_bottom + stack_size; 158 sos_ui32_t *stack = (sos_ui32_t*)tmp_vaddr; 299 sos_ui32_t *stack = (sos_ui32_t*)tmp_vaddr; 159 300 160 /* If needed, poison the stack */ 301 /* If needed, poison the stack */ 161 #ifdef SOS_CPU_STATE_DETECT_UNINIT_KERNEL_VARS 302 #ifdef SOS_CPU_STATE_DETECT_UNINIT_KERNEL_VARS 162 memset((void*)stack_bottom, SOS_CPU_STATE_ST 303 memset((void*)stack_bottom, SOS_CPU_STATE_STACK_POISON, stack_size); 163 #elif defined(SOS_CPU_STATE_DETECT_KERNEL_STAC 304 #elif defined(SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW) 164 sos_cpu_state_prepare_detect_kernel_stack_ov 305 sos_cpu_state_prepare_detect_kernel_stack_overflow(stack_bottom, stack_size); 165 #endif 306 #endif 166 307 167 /* Simulate a call to the core_routine() fun 308 /* Simulate a call to the core_routine() function: prepare its 168 arguments */ 309 arguments */ 169 *(--stack) = exit_arg; 310 *(--stack) = exit_arg; 170 *(--stack) = (sos_ui32_t)exit_func; 311 *(--stack) = (sos_ui32_t)exit_func; 171 *(--stack) = start_arg; 312 *(--stack) = start_arg; 172 *(--stack) = (sos_ui32_t)start_func; 313 *(--stack) = (sos_ui32_t)start_func; 173 *(--stack) = 0; /* Return address of core_ro 314 *(--stack) = 0; /* Return address of core_routine => force page fault */ 174 315 175 /* 316 /* 176 * Setup the initial context structure, so t 317 * Setup the initial context structure, so that the CPU will execute 177 * the function core_routine() once this new 318 * the function core_routine() once this new context has been 178 * restored on CPU 319 * restored on CPU 179 */ 320 */ 180 321 181 /* Compute the base address of the structure 322 /* Compute the base address of the structure, which must be located 182 below the previous elements */ 323 below the previous elements */ 183 tmp_vaddr = ((sos_vaddr_t)stack) - sizeof(s 324 tmp_vaddr = ((sos_vaddr_t)stack) - sizeof(struct sos_cpu_kstate); 184 kctxt = (struct sos_cpu_kstate*)tmp_vaddr; 325 kctxt = (struct sos_cpu_kstate*)tmp_vaddr; 185 326 186 /* Initialize the CPU context structure */ 327 /* Initialize the CPU context structure */ 187 memset(kctxt, 0x0, sizeof(struct sos_cpu_kst 328 memset(kctxt, 0x0, sizeof(struct sos_cpu_kstate)); 188 329 189 /* Tell the CPU context structure that the f 330 /* Tell the CPU context structure that the first instruction to 190 execute will be that of the core_routine( 331 execute will be that of the core_routine() function */ 191 kctxt->regs.eip = (sos_ui32_t)core_routine; 332 kctxt->regs.eip = (sos_ui32_t)core_routine; 192 333 193 /* Setup the segment registers */ 334 /* Setup the segment registers */ 194 kctxt->regs.cs 335 kctxt->regs.cs 195 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 336 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KCODE); /* Code */ 196 kctxt->regs.ds 337 kctxt->regs.ds 197 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 338 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); /* Data */ 198 kctxt->regs.es 339 kctxt->regs.es 199 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 340 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); /* Data */ 200 kctxt->regs.cpl0_ss 341 kctxt->regs.cpl0_ss 201 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SO 342 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); /* Stack */ 202 /* fs and gs unused for the moment. */ 343 /* fs and gs unused for the moment. */ 203 344 204 /* The newly created context is initially in 345 /* The newly created context is initially interruptible */ 205 kctxt->regs.eflags = (1 << 9); /* set IF bit 346 kctxt->regs.eflags = (1 << 9); /* set IF bit */ 206 347 207 /* Finally, update the generic kernel/user t 348 /* Finally, update the generic kernel/user thread context */ 208 *ctxt = (struct sos_cpu_state*) kctxt; 349 *ctxt = (struct sos_cpu_state*) kctxt; 209 350 210 return SOS_OK; 351 return SOS_OK; 211 } 352 } 212 353 213 354 >> 355 sos_ret_t sos_cpu_ustate_init(struct sos_cpu_state **ctxt, >> 356 sos_uaddr_t user_start_PC, >> 357 sos_ui32_t user_start_arg1, >> 358 sos_ui32_t user_start_arg2, >> 359 sos_uaddr_t user_initial_SP, >> 360 sos_vaddr_t kernel_stack_bottom, >> 361 sos_size_t kernel_stack_size) >> 362 { >> 363 /* We are initializing a User thread's context */ >> 364 struct sos_cpu_ustate *uctxt; >> 365 >> 366 /* This is a critical internal function, so that it is assumed that >> 367 the caller knows what he does: we legitimally assume that values >> 368 for ctxt, etc. are allways VALID ! */ >> 369 >> 370 /* Compute the address of the CPU state to restore on CPU when >> 371 switching to this new user thread */ >> 372 sos_vaddr_t uctxt_vaddr = kernel_stack_bottom >> 373 + kernel_stack_size >> 374 - sizeof(struct sos_cpu_ustate); >> 375 uctxt = (struct sos_cpu_ustate*)uctxt_vaddr; >> 376 >> 377 /* If needed, poison the kernel stack */ >> 378 #ifdef SOS_CPU_STATE_DETECT_UNINIT_KERNEL_VARS >> 379 memset((void*)kernel_stack_bottom, >> 380 SOS_CPU_STATE_STACK_POISON, >> 381 kernel_stack_size); >> 382 #elif defined(SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW) >> 383 sos_cpu_state_prepare_detect_kernel_stack_overflow(kernel_stack_bottom, >> 384 kernel_stack_size); >> 385 #endif >> 386 >> 387 /* >> 388 * Setup the initial context structure, so that the CPU will restore >> 389 * the initial registers' value for the user thread. The >> 390 * user thread argument is passed in the EAX register. >> 391 */ >> 392 >> 393 memset(uctxt, 0x0, sizeof(struct sos_cpu_ustate)); >> 394 >> 395 /* Tell the CPU context structure that the first instruction to >> 396 execute will be located at user_start_PC (in user space) */ >> 397 uctxt->regs.eip = (sos_ui32_t)user_start_PC; >> 398 >> 399 /* Tell the CPU where will be the user stack */ >> 400 uctxt->cpl3_esp = user_initial_SP; >> 401 >> 402 /* The parameter to the start function is not passed by the stack to >> 403 avoid a possible page fault */ >> 404 uctxt->regs.eax = user_start_arg1; >> 405 uctxt->regs.ebx = user_start_arg2; >> 406 >> 407 /* Setup the segment registers */ >> 408 uctxt->regs.cs >> 409 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SOS_SEG_UCODE); /* Code */ >> 410 uctxt->regs.ds >> 411 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SOS_SEG_UDATA); /* Data */ >> 412 uctxt->regs.es >> 413 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SOS_SEG_UDATA); /* Data */ >> 414 uctxt->cpl3_ss >> 415 = SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SOS_SEG_UDATA); /* User Stack */ >> 416 >> 417 /* We need also to update the segment for the kernel stack >> 418 segment. It will be used when this context will be restored on >> 419 CPU: initially it will be executing in kernel mode and will >> 420 switch immediatly to user mode */ >> 421 uctxt->regs.cpl0_ss >> 422 = SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KDATA); /* Kernel Stack */ >> 423 >> 424 /* fs and gs unused for the moment. */ >> 425 >> 426 /* The newly created context is initially interruptible */ >> 427 uctxt->regs.eflags = (1 << 9); /* set IF bit */ >> 428 >> 429 /* Finally, update the generic kernel/user thread context */ >> 430 *ctxt = (struct sos_cpu_state*) uctxt; >> 431 >> 432 return SOS_OK; >> 433 } >> 434 >> 435 >> 436 sos_ret_t >> 437 sos_cpu_context_is_in_user_mode(const struct sos_cpu_state *ctxt) >> 438 { >> 439 /* An interrupted user thread has its CS register set to that of the >> 440 User code segment */ >> 441 switch (GET_CPU_CS_REGISTER_VALUE(ctxt->cs)) >> 442 { >> 443 case SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SOS_SEG_UCODE): >> 444 return TRUE; >> 445 break; >> 446 >> 447 case SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KCODE): >> 448 return FALSE; >> 449 break; >> 450 >> 451 default: >> 452 SOS_FATAL_ERROR("Invalid saved context Code segment register: 0x%x (k=%x, u=%x) !", >> 453 (unsigned) GET_CPU_CS_REGISTER_VALUE(ctxt->cs), >> 454 SOS_BUILD_SEGMENT_REG_VALUE(0, FALSE, SOS_SEG_KCODE), >> 455 SOS_BUILD_SEGMENT_REG_VALUE(3, FALSE, SOS_SEG_UCODE)); >> 456 break; >> 457 } >> 458 >> 459 /* Should never get here */ >> 460 return -SOS_EFATAL; >> 461 } >> 462 >> 463 214 #if defined(SOS_CPU_STATE_DETECT_KERNEL_STACK_ 464 #if defined(SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW) 215 void 465 void 216 sos_cpu_state_prepare_detect_kernel_stack_over 466 sos_cpu_state_prepare_detect_kernel_stack_overflow(const struct sos_cpu_state *ctxt, 217 467 sos_vaddr_t stack_bottom, 218 468 sos_size_t stack_size) 219 { 469 { 220 sos_size_t poison_size = SOS_CPU_STATE_DETEC 470 sos_size_t poison_size = SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW; 221 if (poison_size > stack_size) 471 if (poison_size > stack_size) 222 poison_size = stack_size; 472 poison_size = stack_size; 223 473 224 memset((void*)stack_bottom, SOS_CPU_STATE_ST 474 memset((void*)stack_bottom, SOS_CPU_STATE_STACK_POISON, poison_size); 225 } 475 } 226 476 227 477 228 void 478 void 229 sos_cpu_state_detect_kernel_stack_overflow(con 479 sos_cpu_state_detect_kernel_stack_overflow(const struct sos_cpu_state *ctxt, 230 sos 480 sos_vaddr_t stack_bottom, 231 sos 481 sos_size_t stack_size) 232 { 482 { 233 unsigned char *c; 483 unsigned char *c; 234 int i; 484 int i; 235 485 236 /* On SOS, "ctxt" corresponds to the address 486 /* On SOS, "ctxt" corresponds to the address of the esp register of 237 the saved context in Kernel mode (always, 487 the saved context in Kernel mode (always, even for the interrupted 238 context of a user thread). Here we make s 488 context of a user thread). Here we make sure that this stack 239 pointer is within the allowed stack area 489 pointer is within the allowed stack area */ 240 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) >= stac 490 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) >= stack_bottom); 241 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) + sizeo 491 SOS_ASSERT_FATAL(((sos_vaddr_t)ctxt) + sizeof(struct sos_cpu_kstate) 242 <= stack_bottom + stack_siz 492 <= stack_bottom + stack_size); 243 493 244 /* Check that the bottom of the stack has no 494 /* Check that the bottom of the stack has not been altered */ 245 for (c = (unsigned char*) stack_bottom, i = 495 for (c = (unsigned char*) stack_bottom, i = 0 ; 246 (i < SOS_CPU_STATE_DETECT_KERNEL_STACK_ 496 (i < SOS_CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW) && (i < stack_size) ; 247 c++, i++) 497 c++, i++) 248 { 498 { 249 SOS_ASSERT_FATAL(SOS_CPU_STATE_STACK_POI 499 SOS_ASSERT_FATAL(SOS_CPU_STATE_STACK_POISON == *c); 250 } 500 } 251 } 501 } 252 #endif 502 #endif 253 503 254 504 255 /* =========================================== 505 /* ======================================================================= 256 * Public Accessor functions 506 * Public Accessor functions 257 */ 507 */ 258 508 259 509 260 sos_vaddr_t sos_cpu_context_get_PC(const struc 510 sos_vaddr_t sos_cpu_context_get_PC(const struct sos_cpu_state *ctxt) 261 { 511 { 262 SOS_ASSERT_FATAL(NULL != ctxt); 512 SOS_ASSERT_FATAL(NULL != ctxt); 263 513 264 /* This is the PC of the interrupted context 514 /* This is the PC of the interrupted context (ie kernel or user 265 context). */ 515 context). */ 266 return ctxt->eip; 516 return ctxt->eip; 267 } 517 } 268 518 269 519 270 sos_vaddr_t sos_cpu_context_get_SP(const struc 520 sos_vaddr_t sos_cpu_context_get_SP(const struct sos_cpu_state *ctxt) 271 { 521 { 272 SOS_ASSERT_FATAL(NULL != ctxt); 522 SOS_ASSERT_FATAL(NULL != ctxt); 273 523 >> 524 /* 'ctxt' corresponds to the SP of the interrupted context, in Kernel >> 525 mode. We have to test whether the original interrupted context >> 526 was that of a kernel or user thread */ >> 527 if (TRUE == sos_cpu_context_is_in_user_mode(ctxt)) >> 528 { >> 529 struct sos_cpu_ustate * uctxt = (struct sos_cpu_ustate*)ctxt; >> 530 return uctxt->cpl3_esp; >> 531 } >> 532 274 /* On SOS, "ctxt" corresponds to the address 533 /* On SOS, "ctxt" corresponds to the address of the esp register of 275 the saved context in Kernel mode (always, 534 the saved context in Kernel mode (always, even for the interrupted 276 context of a user thread). */ 535 context of a user thread). */ 277 return (sos_vaddr_t)ctxt; 536 return (sos_vaddr_t)ctxt; 278 } 537 } 279 538 280 539 >> 540 sos_ret_t >> 541 sos_cpu_context_set_EX_return_address(struct sos_cpu_state *ctxt, >> 542 sos_vaddr_t ret_vaddr) >> 543 { >> 544 ctxt->eip = ret_vaddr; >> 545 return SOS_OK; >> 546 } >> 547 >> 548 281 void sos_cpu_context_dump(const struct sos_cpu 549 void sos_cpu_context_dump(const struct sos_cpu_state *ctxt) 282 { 550 { 283 char buf[128]; 551 char buf[128]; >> 552 284 snprintf(buf, sizeof(buf), 553 snprintf(buf, sizeof(buf), 285 "CPU: eip=%x esp=%x eflags=%x cs=%x !! 554 "CPU: eip=%x esp0=%x eflags=%x cs=%x ds=%x ss0=%x err=%x", 286 (unsigned)ctxt->eip, (unsigned)ctxt 555 (unsigned)ctxt->eip, (unsigned)ctxt, (unsigned)ctxt->eflags, 287 (unsigned)GET_CPU_CS_REGISTER_VALUE 556 (unsigned)GET_CPU_CS_REGISTER_VALUE(ctxt->cs), (unsigned)ctxt->ds, 288 (unsigned)ctxt->cpl0_ss, 557 (unsigned)ctxt->cpl0_ss, 289 (unsigned)ctxt->error_code); 558 (unsigned)ctxt->error_code); >> 559 if (TRUE == sos_cpu_context_is_in_user_mode(ctxt)) >> 560 { >> 561 struct sos_cpu_ustate * uctxt = (struct sos_cpu_ustate*)ctxt; >> 562 snprintf(buf, sizeof(buf), >> 563 "%s esp3=%x ss3=%x", >> 564 buf, (unsigned)uctxt->cpl3_esp, (unsigned)uctxt->cpl3_ss); >> 565 } >> 566 else >> 567 snprintf(buf, sizeof(buf), "%s [KERNEL MODE]", buf); >> 568 290 sos_bochs_putstring(buf); sos_bochs_putstrin 569 sos_bochs_putstring(buf); sos_bochs_putstring("\n"); 291 sos_x86_videomem_putstring(23, 0, 570 sos_x86_videomem_putstring(23, 0, 292 SOS_X86_VIDEO_FG_BLA !! 571 SOS_X86_VIDEO_FG_BLACK | SOS_X86_VIDEO_BG_LTGRAY, 293 buf); !! 572 buf); 294 } 573 } 295 574 296 575 297 /* =========================================== 576 /* ======================================================================= 298 * Public Accessor functions TO BE USED ONLY B 577 * Public Accessor functions TO BE USED ONLY BY Exception handlers 299 */ 578 */ 300 579 301 580 302 sos_ui32_t sos_cpu_context_get_EX_info(const s 581 sos_ui32_t sos_cpu_context_get_EX_info(const struct sos_cpu_state *ctxt) 303 { 582 { 304 SOS_ASSERT_FATAL(NULL != ctxt); 583 SOS_ASSERT_FATAL(NULL != ctxt); 305 return ctxt->error_code; 584 return ctxt->error_code; 306 } 585 } 307 586 308 587 309 sos_vaddr_t 588 sos_vaddr_t 310 sos_cpu_context_get_EX_faulting_vaddr(const st 589 sos_cpu_context_get_EX_faulting_vaddr(const struct sos_cpu_state *ctxt) 311 { 590 { 312 sos_ui32_t cr2; 591 sos_ui32_t cr2; 313 592 314 /* 593 /* 315 * See Intel Vol 3 (section 5.14): the addre 594 * See Intel Vol 3 (section 5.14): the address of the faulting 316 * virtual address of a page fault is stored 595 * virtual address of a page fault is stored in the cr2 317 * register. 596 * register. 318 * 597 * 319 * Actually, we do not store the cr2 registe 598 * Actually, we do not store the cr2 register in a saved 320 * kernel thread's context. So we retrieve t 599 * kernel thread's context. So we retrieve the cr2's value directly 321 * from the processor. The value we retrieve 600 * from the processor. The value we retrieve in an exception handler 322 * is actually the correct one because an ex 601 * is actually the correct one because an exception is synchronous 323 * with the code causing the fault, and cann 602 * with the code causing the fault, and cannot be interrupted since 324 * the IDT entries in SOS are "interrupt gat 603 * the IDT entries in SOS are "interrupt gates" (ie IRQ are 325 * disabled). 604 * disabled). 326 */ 605 */ 327 asm volatile ("movl %%cr2, %0" 606 asm volatile ("movl %%cr2, %0" 328 :"=r"(cr2) 607 :"=r"(cr2) 329 : ); 608 : ); 330 609 331 return cr2; 610 return cr2; 332 } 611 } 333 612 334 613 335 /* =========================================== 614 /* ======================================================================= >> 615 * Public Accessor functions TO BE USED ONLY BY the SYSCALL handler >> 616 */ >> 617 >> 618 >> 619 /* >> 620 * By convention, the USER SOS programs always pass 4 arguments to the >> 621 * kernel syscall handler: in eax/../edx. For less arguments, the >> 622 * unused registers are filled with 0s. For more arguments, the 4th >> 623 * syscall parameter gives the address of the array containing the >> 624 * remaining arguments. In any case, eax corresponds to the syscall >> 625 * IDentifier. >> 626 */ >> 627 >> 628 >> 629 inline >> 630 sos_ret_t sos_syscall_get3args(const struct sos_cpu_state *user_ctxt, >> 631 /* out */unsigned int *arg1, >> 632 /* out */unsigned int *arg2, >> 633 /* out */unsigned int *arg3) >> 634 { >> 635 *arg1 = user_ctxt->ebx; >> 636 *arg2 = user_ctxt->ecx; >> 637 *arg3 = user_ctxt->edx; >> 638 return SOS_OK; >> 639 } >> 640 >> 641 >> 642 sos_ret_t sos_syscall_get1arg(const struct sos_cpu_state *user_ctxt, >> 643 /* out */unsigned int *arg1) >> 644 { >> 645 unsigned int unused; >> 646 return sos_syscall_get3args(user_ctxt, arg1, & unused, & unused); >> 647 } >> 648 >> 649 >> 650 sos_ret_t sos_syscall_get2args(const struct sos_cpu_state *user_ctxt, >> 651 /* out */unsigned int *arg1, >> 652 /* out */unsigned int *arg2) >> 653 { >> 654 unsigned int unused; >> 655 return sos_syscall_get3args(user_ctxt, arg1, arg2, & unused); >> 656 } >> 657 >> 658 >> 659 /* >> 660 * sos_syscall_get3args() is defined in cpu_context.c because it needs >> 661 * to know the structure of a struct spu_state >> 662 */ >> 663 >> 664 sos_ret_t sos_syscall_get4args(const struct sos_cpu_state *user_ctxt, >> 665 /* out */unsigned int *arg1, >> 666 /* out */unsigned int *arg2, >> 667 /* out */unsigned int *arg3, >> 668 /* out */unsigned int *arg4) >> 669 { >> 670 sos_uaddr_t uaddr_other_args; >> 671 unsigned int other_args[2]; >> 672 sos_ret_t retval; >> 673 >> 674 /* Retrieve the 3 arguments. The last one is an array containing the >> 675 remaining arguments */ >> 676 retval = sos_syscall_get3args(user_ctxt, arg1, arg2, >> 677 (unsigned int *)& uaddr_other_args); >> 678 if (SOS_OK != retval) >> 679 return retval; >> 680 >> 681 /* Copy the array containing the remaining arguments from user >> 682 space */ >> 683 retval = sos_memcpy_from_user((sos_vaddr_t)other_args, >> 684 (sos_uaddr_t)uaddr_other_args, >> 685 sizeof(other_args)); >> 686 if (sizeof(other_args) != retval) >> 687 return -SOS_EFAULT; >> 688 >> 689 *arg3 = other_args[0]; >> 690 *arg4 = other_args[1]; >> 691 return SOS_OK; >> 692 } >> 693 >> 694 >> 695 sos_ret_t sos_syscall_get5args(const struct sos_cpu_state *user_ctxt, >> 696 /* out */unsigned int *arg1, >> 697 /* out */unsigned int *arg2, >> 698 /* out */unsigned int *arg3, >> 699 /* out */unsigned int *arg4, >> 700 /* out */unsigned int *arg5) >> 701 { >> 702 sos_uaddr_t uaddr_other_args; >> 703 unsigned int other_args[3]; >> 704 sos_ret_t retval; >> 705 >> 706 /* Retrieve the 3 arguments. The last one is an array containing the >> 707 remaining arguments */ >> 708 retval = sos_syscall_get3args(user_ctxt, arg1, arg2, >> 709 (unsigned int *)& uaddr_other_args); >> 710 if (SOS_OK != retval) >> 711 return retval; >> 712 >> 713 /* Copy the array containing the remaining arguments from user >> 714 space */ >> 715 retval = sos_memcpy_from_user((sos_vaddr_t)other_args, >> 716 (sos_uaddr_t)uaddr_other_args, >> 717 sizeof(other_args)); >> 718 if (sizeof(other_args) != retval) >> 719 return -SOS_EFAULT; >> 720 >> 721 *arg3 = other_args[0]; >> 722 *arg4 = other_args[1]; >> 723 *arg5 = other_args[2]; >> 724 return SOS_OK; >> 725 } >> 726 >> 727 >> 728 sos_ret_t sos_syscall_get6args(const struct sos_cpu_state *user_ctxt, >> 729 /* out */unsigned int *arg1, >> 730 /* out */unsigned int *arg2, >> 731 /* out */unsigned int *arg3, >> 732 /* out */unsigned int *arg4, >> 733 /* out */unsigned int *arg5, >> 734 /* out */unsigned int *arg6) >> 735 { >> 736 sos_uaddr_t uaddr_other_args; >> 737 unsigned int other_args[4]; >> 738 sos_ret_t retval; >> 739 >> 740 /* Retrieve the 3 arguments. The last one is an array containing the >> 741 remaining arguments */ >> 742 retval = sos_syscall_get3args(user_ctxt, arg1, arg2, >> 743 (unsigned int *)& uaddr_other_args); >> 744 if (SOS_OK != retval) >> 745 return retval; >> 746 >> 747 /* Copy the array containing the remaining arguments from user >> 748 space */ >> 749 retval = sos_memcpy_from_user((sos_vaddr_t)other_args, >> 750 (sos_uaddr_t)uaddr_other_args, >> 751 sizeof(other_args)); >> 752 if (sizeof(other_args) != retval) >> 753 return -SOS_EFAULT; >> 754 >> 755 *arg3 = other_args[0]; >> 756 *arg4 = other_args[1]; >> 757 *arg5 = other_args[2]; >> 758 *arg6 = other_args[3]; >> 759 return SOS_OK; >> 760 } >> 761 >> 762 >> 763 sos_ret_t sos_syscall_get7args(const struct sos_cpu_state *user_ctxt, >> 764 /* out */unsigned int *arg1, >> 765 /* out */unsigned int *arg2, >> 766 /* out */unsigned int *arg3, >> 767 /* out */unsigned int *arg4, >> 768 /* out */unsigned int *arg5, >> 769 /* out */unsigned int *arg6, >> 770 /* out */unsigned int *arg7) >> 771 { >> 772 sos_uaddr_t uaddr_other_args; >> 773 unsigned int other_args[5]; >> 774 sos_ret_t retval; >> 775 >> 776 /* Retrieve the 3 arguments. The last one is an array containing the >> 777 remaining arguments */ >> 778 retval = sos_syscall_get3args(user_ctxt, arg1, arg2, >> 779 (unsigned int *)& uaddr_other_args); >> 780 if (SOS_OK != retval) >> 781 return retval; >> 782 >> 783 /* Copy the array containing the remaining arguments from user >> 784 space */ >> 785 retval = sos_memcpy_from_user((sos_vaddr_t)other_args, >> 786 (sos_uaddr_t)uaddr_other_args, >> 787 sizeof(other_args)); >> 788 if (sizeof(other_args) != retval) >> 789 return -SOS_EFAULT; >> 790 >> 791 *arg3 = other_args[0]; >> 792 *arg4 = other_args[1]; >> 793 *arg5 = other_args[2]; >> 794 *arg6 = other_args[3]; >> 795 *arg7 = other_args[4]; >> 796 return SOS_OK; >> 797 } >> 798 >> 799 >> 800 sos_ret_t sos_syscall_get8args(const struct sos_cpu_state *user_ctxt, >> 801 /* out */unsigned int *arg1, >> 802 /* out */unsigned int *arg2, >> 803 /* out */unsigned int *arg3, >> 804 /* out */unsigned int *arg4, >> 805 /* out */unsigned int *arg5, >> 806 /* out */unsigned int *arg6, >> 807 /* out */unsigned int *arg7, >> 808 /* out */unsigned int *arg8) >> 809 { >> 810 sos_uaddr_t uaddr_other_args; >> 811 unsigned int other_args[6]; >> 812 sos_ret_t retval; >> 813 >> 814 /* Retrieve the 3 arguments. The last one is an array containing the >> 815 remaining arguments */ >> 816 retval = sos_syscall_get3args(user_ctxt, arg1, arg2, >> 817 (unsigned int *)& uaddr_other_args); >> 818 if (SOS_OK != retval) >> 819 return retval; >> 820 >> 821 /* Copy the array containing the remaining arguments from user >> 822 space */ >> 823 retval = sos_memcpy_from_user((sos_vaddr_t)other_args, >> 824 (sos_uaddr_t)uaddr_other_args, >> 825 sizeof(other_args)); >> 826 if (sizeof(other_args) != retval) >> 827 return -SOS_EFAULT; >> 828 >> 829 *arg3 = other_args[0]; >> 830 *arg4 = other_args[1]; >> 831 *arg5 = other_args[2]; >> 832 *arg6 = other_args[3]; >> 833 *arg7 = other_args[4]; >> 834 *arg8 = other_args[5]; >> 835 return SOS_OK; >> 836 } >> 837 >> 838 >> 839 /* ======================================================================= 336 * Backtrace facility. To be used for DEBUGgin 840 * Backtrace facility. To be used for DEBUGging purpose ONLY. 337 */ 841 */ 338 842 339 843 340 sos_ui32_t sos_backtrace(const struct sos_cpu_ 844 sos_ui32_t sos_backtrace(const struct sos_cpu_state *cpu_state, 341 sos_ui32_t max_depth, 845 sos_ui32_t max_depth, 342 sos_vaddr_t stack_bot 846 sos_vaddr_t stack_bottom, 343 sos_size_t stack_size 847 sos_size_t stack_size, 344 sos_backtrace_callbac 848 sos_backtrace_callback_t * backtracer, 345 void *custom_arg) 849 void *custom_arg) 346 { 850 { 347 int depth; 851 int depth; 348 sos_vaddr_t callee_PC, caller_frame; 852 sos_vaddr_t callee_PC, caller_frame; 349 853 >> 854 /* Cannot backtrace an interrupted user thread ! */ >> 855 if ((NULL != cpu_state) >> 856 && >> 857 (TRUE == sos_cpu_context_is_in_user_mode(cpu_state))) >> 858 { >> 859 return 0; >> 860 } >> 861 350 /* 862 /* 351 * Layout of a frame on the x86 (compiler=gc 863 * Layout of a frame on the x86 (compiler=gcc): 352 * 864 * 353 * funcA calls funcB calls funcC 865 * funcA calls funcB calls funcC 354 * 866 * 355 * .... 867 * .... 356 * funcB Argument 2 868 * funcB Argument 2 357 * funcB Argument 1 869 * funcB Argument 1 358 * funcA Return eip 870 * funcA Return eip 359 * frameB: funcA ebp (ie previous stack fram 871 * frameB: funcA ebp (ie previous stack frame) 360 * .... 872 * .... 361 * (funcB local variables) 873 * (funcB local variables) 362 * .... 874 * .... 363 * funcC Argument 2 875 * funcC Argument 2 364 * funcC Argument 1 876 * funcC Argument 1 365 * funcB Return eip 877 * funcB Return eip 366 * frameC: funcB ebp (ie previous stack fram 878 * frameC: funcB ebp (ie previous stack frame == A0) <---- a frame address 367 * .... 879 * .... 368 * (funcC local variables) 880 * (funcC local variables) 369 * .... 881 * .... 370 * 882 * 371 * The presence of "ebp" on the stack depend 883 * The presence of "ebp" on the stack depends on 2 things: 372 * + the compiler is gcc 884 * + the compiler is gcc 373 * + the source is compiled WITHOUT the -f 885 * + the source is compiled WITHOUT the -fomit-frame-pointer option 374 * In the absence of "ebp", chances are high 886 * In the absence of "ebp", chances are high that the value pushed 375 * at that address is outside the stack boun 887 * at that address is outside the stack boundaries, meaning that the 376 * function will return -SOS_ENOSUP. 888 * function will return -SOS_ENOSUP. 377 */ 889 */ 378 890 379 if (cpu_state) 891 if (cpu_state) 380 { 892 { 381 callee_PC = cpu_state->eip; 893 callee_PC = cpu_state->eip; 382 caller_frame = cpu_state->ebp; 894 caller_frame = cpu_state->ebp; 383 } 895 } 384 else 896 else 385 { 897 { 386 /* Skip the sos_backtrace() frame */ 898 /* Skip the sos_backtrace() frame */ 387 callee_PC = (sos_vaddr_t)__builtin_re 899 callee_PC = (sos_vaddr_t)__builtin_return_address(0); 388 caller_frame = (sos_vaddr_t)__builtin_fr 900 caller_frame = (sos_vaddr_t)__builtin_frame_address(1); 389 } 901 } 390 902 391 for(depth=0 ; depth < max_depth ; depth ++) 903 for(depth=0 ; depth < max_depth ; depth ++) 392 { 904 { 393 /* Call the callback */ 905 /* Call the callback */ 394 backtracer(callee_PC, caller_frame + 8, 906 backtracer(callee_PC, caller_frame + 8, depth, custom_arg); 395 907 396 /* If the frame address is funky, don't 908 /* If the frame address is funky, don't go further */ 397 if ( (caller_frame < stack_bottom) 909 if ( (caller_frame < stack_bottom) 398 || (caller_frame + 4 >= stack_botto 910 || (caller_frame + 4 >= stack_bottom + stack_size) ) 399 return depth; 911 return depth; 400 912 401 /* Go to caller frame */ 913 /* Go to caller frame */ 402 callee_PC = *((sos_vaddr_t*) (caller_ 914 callee_PC = *((sos_vaddr_t*) (caller_frame + 4)); 403 caller_frame = *((sos_vaddr_t*) caller_f 915 caller_frame = *((sos_vaddr_t*) caller_frame); 404 } 916 } 405 917 406 return depth; 918 return depth; >> 919 } >> 920 >> 921 >> 922 /* ************************************************************* >> 923 * Function to manage the TSS. This function is not really "public": >> 924 * it is reserved to the assembler routines defined in >> 925 * cpu_context_switch.S >> 926 * >> 927 * Update the kernel stack address so that the IRQ, syscalls and >> 928 * exception return in a correct stack location when coming back into >> 929 * kernel mode. >> 930 */ >> 931 void >> 932 sos_cpu_context_update_kernel_tss(struct sos_cpu_state *next_ctxt) >> 933 { >> 934 /* next_ctxt corresponds to an interrupted user thread ? */ >> 935 if (sos_cpu_context_is_in_user_mode(next_ctxt)) >> 936 { >> 937 /* >> 938 * Yes: "next_ctxt" is an interrupted user thread => we are >> 939 * going to switch to user mode ! Setup the stack address so >> 940 * that the user thread "next_ctxt" can come back to the correct >> 941 * stack location when returning in kernel mode. >> 942 * >> 943 * This stack location corresponds to the SP of the next user >> 944 * thread once its context has been transferred on the CPU, ie >> 945 * once the CPU has executed all the pop/iret instruction of the >> 946 * context switch with privilege change. >> 947 */ >> 948 kernel_tss.esp0 = ((sos_vaddr_t)next_ctxt) >> 949 + sizeof(struct sos_cpu_ustate); >> 950 /* Note: no need to protect this agains IRQ because IRQs are not >> 951 allowed to update it by themselves, and they are not allowed >> 952 to block */ >> 953 } >> 954 else >> 955 { >> 956 /* No: No need to update kernel TSS when we stay in kernel >> 957 mode */ >> 958 } 407 } 959 }
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