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@ -6,9 +6,9 @@ |
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* License, v. 2.0. If a copy of the MPL was not distributed with this |
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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* |
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* This library was modified and adapted to be used in Marlin 3D printer |
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* firmware as backtracer for exceptions for debugging purposes in 2018 |
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* by Eduardo José Tagle. |
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* This library was modified, some bugs fixed, stack address validated |
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* and adapted to be used in Marlin 3D printer firmware as backtracer |
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* for exceptions for debugging purposes in 2018 by Eduardo José Tagle. |
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*/ |
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#ifdef ARDUINO_ARCH_SAM |
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@ -43,10 +43,30 @@ void __aeabi_unwind_cpp_pr2(void) {}; |
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extern const int _sstack; |
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extern const int _estack; |
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/* Validate stack pointer */ |
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/* These symbols point to the start and end of the code section */ |
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extern const int _sfixed; |
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extern const int _efixed; |
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/* These symbols point to the start and end of initialized data (could be SRAM functions!) */ |
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extern const int _srelocate; |
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extern const int _erelocate; |
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/* Validate stack pointer (SP): It must be in the stack area */ |
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static inline __attribute__((always_inline)) int validate_sp(const void* sp) { |
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if ((uint32_t)sp < (uint32_t)&_sstack || (uint32_t)sp > (uint32_t)&_estack) |
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return -1; |
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// SP must point into the allocated stack area
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if ((uint32_t)sp >= (uint32_t)&_sstack && (uint32_t)sp <= (uint32_t)&_estack) |
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return 0; |
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return -1; |
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} |
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/* Validate code pointer (PC): It must be either in TEXT or in SRAM */ |
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static inline __attribute__((always_inline)) int validate_pc(const void* pc) { |
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// PC must point into the text (CODE) area
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if ((uint32_t)pc >= (uint32_t)&_sfixed && (uint32_t)pc <= (uint32_t)&_efixed) |
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return 0; |
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// Or into the SRAM function area
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if ((uint32_t)pc >= (uint32_t)&_srelocate && (uint32_t)pc <= (uint32_t)&_erelocate) |
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return 0; |
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return 0; |
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} |
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@ -103,11 +123,11 @@ static int unwind_control_block_init(unwind_control_block_t *ucb, const uint32_t |
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memset(ucb, 0, sizeof(unwind_control_block_t)); |
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ucb->current = instructions; |
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/* Is the a short unwind description */ |
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/* Is a short unwind description */ |
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if ((*instructions & 0xff000000) == 0x80000000) { |
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ucb->remaining = 3; |
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ucb->byte = 2; |
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/* Is the a long unwind description */ |
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/* Is a long unwind description */ |
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} else if ((*instructions & 0xff000000) == 0x81000000) { |
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ucb->remaining = ((*instructions & 0x00ff0000) >> 14) + 2; |
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ucb->byte = 1; |
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@ -115,12 +135,10 @@ static int unwind_control_block_init(unwind_control_block_t *ucb, const uint32_t |
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return -1; |
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/* Initialize the virtual register set */ |
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if (frame) { |
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ucb->vrs[7] = frame->fp; |
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ucb->vrs[13] = frame->sp; |
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ucb->vrs[14] = frame->lr; |
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ucb->vrs[15] = 0; |
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} |
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ucb->vrs[7] = frame->fp; |
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ucb->vrs[13] = frame->sp; |
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ucb->vrs[14] = frame->lr; |
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ucb->vrs[15] = 0; |
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/* All good */ |
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return 0; |
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@ -136,46 +154,49 @@ static int unwind_execute_instruction(unwind_control_block_t *ucb) { |
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/* Consume all instruction byte */ |
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while ((instruction = unwind_get_next_byte(ucb)) != -1) { |
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if ((instruction & 0xc0) == 0x00) { |
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if ((instruction & 0xc0) == 0x00) { // ARM_EXIDX_CMD_DATA_POP
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/* vsp = vsp + (xxxxxx << 2) + 4 */ |
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ucb->vrs[13] += ((instruction & 0x3f) << 2) + 4; |
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} else if ((instruction & 0xc0) == 0x40) { |
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} else |
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if ((instruction & 0xc0) == 0x40) { // ARM_EXIDX_CMD_DATA_PUSH
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/* vsp = vsp - (xxxxxx << 2) - 4 */ |
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ucb->vrs[13] -= ((instruction & 0x3f) << 2) - 4; |
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} else if ((instruction & 0xf0) == 0x80) { |
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} else |
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if ((instruction & 0xf0) == 0x80) { |
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/* pop under mask {r15-r12},{r11-r4} or refuse to unwind */ |
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instruction = instruction << 8 | unwind_get_next_byte(ucb); |
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/* Check for refuse to unwind */ |
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if (instruction == 0x8000) |
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if (instruction == 0x8000) // ARM_EXIDX_CMD_REFUSED
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return 0; |
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/* Pop registers using mask */ |
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/* Pop registers using mask */ // ARM_EXIDX_CMD_REG_POP
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vsp = (uint32_t *)ucb->vrs[13]; |
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mask = instruction & 0xfff; |
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reg = 4; |
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while (mask != 0) { |
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if ((mask & 0x001) != 0) { |
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while (mask) { |
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if ((mask & 1) != 0) { |
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if (validate_sp(vsp)) |
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return -1; |
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ucb->vrs[reg] = *vsp++; |
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} |
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mask = mask >> 1; |
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mask >>= 1; |
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++reg; |
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} |
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/* Patch up the vrs sp if it was in the mask */ |
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if ((mask & (1 << (13 - 4))) != 0) |
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if ((instruction & (1 << (13 - 4))) != 0) |
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ucb->vrs[13] = (uint32_t)vsp; |
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} else if ((instruction & 0xf0) == 0x90 && instruction != 0x9d && instruction != 0x9f) { |
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} else |
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if ((instruction & 0xf0) == 0x90 && // ARM_EXIDX_CMD_REG_TO_SP
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instruction != 0x9d && |
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instruction != 0x9f) { |
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/* vsp = r[nnnn] */ |
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ucb->vrs[13] = ucb->vrs[instruction & 0x0f]; |
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} else if ((instruction & 0xf0) == 0xa0) { |
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} else |
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if ((instruction & 0xf0) == 0xa0) { // ARM_EXIDX_CMD_REG_POP
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/* pop r4-r[4+nnn] or pop r4-r[4+nnn], r14*/ |
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vsp = (uint32_t *)ucb->vrs[13]; |
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@ -185,7 +206,7 @@ static int unwind_execute_instruction(unwind_control_block_t *ucb) { |
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ucb->vrs[reg] = *vsp++; |
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} |
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if (instruction & 0x80) { |
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if (instruction & 0x08) { // ARM_EXIDX_CMD_REG_POP
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if (validate_sp(vsp)) |
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return -1; |
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ucb->vrs[14] = *vsp++; |
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@ -193,7 +214,8 @@ static int unwind_execute_instruction(unwind_control_block_t *ucb) { |
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ucb->vrs[13] = (uint32_t)vsp; |
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} else if (instruction == 0xb0) { |
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} else |
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if (instruction == 0xb0) { // ARM_EXIDX_CMD_FINISH
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/* finished */ |
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if (ucb->vrs[15] == 0) |
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ucb->vrs[15] = ucb->vrs[14]; |
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@ -201,28 +223,34 @@ static int unwind_execute_instruction(unwind_control_block_t *ucb) { |
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/* All done unwinding */ |
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return 0; |
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} else if (instruction == 0xb1) { |
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} else |
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if (instruction == 0xb1) { // ARM_EXIDX_CMD_REG_POP
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/* pop register under mask {r3,r2,r1,r0} */ |
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vsp = (uint32_t *)ucb->vrs[13]; |
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mask = unwind_get_next_byte(ucb); |
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reg = 0; |
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while (mask != 0) { |
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if ((mask & 0x01) != 0) { |
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while (mask) { |
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if ((mask & 1) != 0) { |
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if (validate_sp(vsp)) |
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return -1; |
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ucb->vrs[reg] = *vsp++; |
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} |
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mask = mask >> 1; |
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mask >>= 1; |
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++reg; |
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} |
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ucb->vrs[13] = (uint32_t)vsp; |
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} else if (instruction == 0xb2) { |
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} else |
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if (instruction == 0xb2) { // ARM_EXIDX_CMD_DATA_POP
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/* vps = vsp + 0x204 + (uleb128 << 2) */ |
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ucb->vrs[13] += 0x204 + (unwind_get_next_byte(ucb) << 2); |
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} else if (instruction == 0xb3 || instruction == 0xc8 || instruction == 0xc9) { |
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} else |
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if (instruction == 0xb3 || // ARM_EXIDX_CMD_VFP_POP
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instruction == 0xc8 || |
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instruction == 0xc9) { |
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/* pop VFP double-precision registers */ |
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vsp = (uint32_t *)ucb->vrs[13]; |
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@ -243,7 +271,10 @@ static int unwind_execute_instruction(unwind_control_block_t *ucb) { |
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ucb->vrs[13] = (uint32_t)vsp; |
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} else if ((instruction & 0xf8) == 0xb8 || (instruction & 0xf8) == 0xd0) { |
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} else |
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if ((instruction & 0xf8) == 0xb8 || |
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(instruction & 0xf8) == 0xd0) { |
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/* Pop VFP double precision registers D[8]-D[8+nnn] */ |
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ucb->vrs[14] = 0x80 | (instruction & 0x07); |
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@ -296,7 +327,7 @@ static int unwind_frame(backtrace_frame_t *frame) { |
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if (unwind_control_block_init(&ucb, instructions, frame) < 0) |
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return -1; |
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/* Execute the unwind instructions TODO range check the stack pointer */ |
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/* Execute the unwind instructions */ |
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while ((execution_result = unwind_execute_instruction(&ucb)) > 0); |
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if (execution_result == -1) |
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return -1; |
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@ -332,8 +363,7 @@ static int unwind_frame(backtrace_frame_t *frame) { |
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stack -= 2; |
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/* If there was a VFP exception (0xffffffe1), the PC is located another 18 words down */ |
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if ((ucb.vrs[15] & 0xf0) == 0xe0) |
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{ |
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if ((ucb.vrs[15] & 0xf0) == 0xe0) { |
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stack -= 18; |
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} |
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} |
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@ -366,47 +396,146 @@ static int unwind_frame(backtrace_frame_t *frame) { |
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return 1; |
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} |
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// Detect if function names are available
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static int __attribute__ ((noinline)) has_function_names(void) { |
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uint32_t flag_word = ((uint32_t*)&has_function_names)[-1]; |
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return ((flag_word & 0xff000000) == 0xff000000) ? 1 : 0; |
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} |
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// Detect if unwind information is present or not
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static int has_unwind_info(void) { |
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return ((char*)(&__exidx_end) - (char*)(&__exidx_start)) > 16 ? 1 : 0; // 16 because there are default entries we can´t supress
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} |
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int backtrace_dump(backtrace_frame_t *frame, backtrace_dump_fn_t dump_entry, void* ctx ) |
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{ |
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backtrace_t entry; |
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int count = 1; |
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/* Unwind all frames */ |
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do { |
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if (frame->pc == 0) { |
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/* Reached __exidx_end. */ |
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entry.name = "<reached end of unwind table>"; |
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entry.address = 0; |
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entry.function = 0; |
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dump_entry(count, &entry, ctx); |
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break; |
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} |
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/* If there is no unwind information, perform a RAW try at it. Idea was taken from
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* https://stackoverflow.com/questions/3398664/how-to-get-a-call-stack-backtrace-deeply-embedded-no-library-support
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* |
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* And requires code to be compiled with the following flags: |
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* -mtpcs-frame -mtpcs-leaf-frame -fno-omit-frame-pointer |
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* With these options, the Stack pointer is automatically |
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* pushed to the stack at the beginning of each function. |
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*/ |
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if (!has_unwind_info()) { |
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/*
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* We basically iterate through the current stack finding the |
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* following combination of values: |
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* - <Frame Address> |
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* - <Link Address> |
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* This combination will occur for each function in the call stack |
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*/ |
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uint32_t previous_frame_address = (uint32_t)frame->sp; |
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uint32_t* stack_pointer = (uint32_t*)frame->sp; |
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// loop following stack frames
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while (1) { |
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// Validate stack address
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if (validate_sp(stack_pointer)) |
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break; |
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// Attempt to obtain next stack pointer
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// The link address should come immediately after
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const uint32_t possible_frame_address = *stack_pointer; |
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const uint32_t possible_link_address = *(stack_pointer+1); |
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// Next check that the frame addresss (i.e. stack pointer for the function)
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// and Link address are within an acceptable range
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if(possible_frame_address > previous_frame_address && |
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validate_sp((const void *)possible_frame_address) == 0 && |
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(possible_link_address & 1) != 0 && // in THUMB mode the address will be odd
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validate_pc((const void *)possible_link_address) == 0) { |
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// We found two acceptable values.
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entry.name = "unknown"; |
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entry.address = (void*)possible_link_address; |
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entry.function = 0; |
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// If there are function names, try to solve name
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if (has_function_names()) { |
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// Lets find the function name, if possible
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// Align address to 4 bytes
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uint32_t* pf = (uint32_t*) (((uint32_t)possible_link_address) & (-4)); |
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// Scan backwards until we find the function name
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while(validate_pc(pf-1) == 0) { |
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// Get name descriptor value
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uint32_t v = pf[-1]; |
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// Check if name descriptor is valid and name is terminated in 0.
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if ((v & 0xffffff00) == 0xff000000 && |
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(v & 0xff) > 1) { |
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// Assume the name was found!
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entry.name = ((const char*)pf) - 4 - (v & 0xff); |
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entry.function = (void*)pf; |
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break; |
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} |
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// Go backwards to the previous word
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--pf; |
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} |
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} |
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dump_entry(count, &entry, ctx); |
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++count; |
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if (frame->pc == 0x00000001) { |
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/* Reached .cantunwind instruction. */ |
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entry.name = "<reached .cantunwind>"; |
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entry.address = 0; |
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entry.function = 0; |
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dump_entry(count, &entry, ctx); |
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break; |
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// Update the book-keeping registers for the next search
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previous_frame_address = possible_frame_address; |
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stack_pointer = (uint32_t*)(possible_frame_address + 4); |
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} else { |
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// Keep iterating through the stack until we find an acceptable combination
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++stack_pointer; |
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} |
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} |
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|
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/* Find the unwind index of the current frame pc */ |
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const unwind_index_t *index = unwind_search_index(__exidx_start, __exidx_end, frame->pc); |
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} else { |
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/* Otherwise, unwind information is present. Use it to unwind frames */ |
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|
do { |
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|
|
if (frame->pc == 0) { |
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|
/* Reached __exidx_end. */ |
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|
|
entry.name = "<reached end of unwind table>"; |
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|
|
entry.address = 0; |
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|
entry.function = 0; |
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|
|
dump_entry(count, &entry, ctx); |
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break; |
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} |
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|
|
|
|
|
|
/* Clear last bit (Thumb indicator) */ |
|
|
|
frame->pc &= 0xfffffffeU; |
|
|
|
if (frame->pc == 0x00000001) { |
|
|
|
/* Reached .cantunwind instruction. */ |
|
|
|
entry.name = "<reached .cantunwind>"; |
|
|
|
entry.address = 0; |
|
|
|
entry.function = 0; |
|
|
|
dump_entry(count, &entry, ctx); |
|
|
|
break; |
|
|
|
} |
|
|
|
|
|
|
|
/* Generate the backtrace information */ |
|
|
|
entry.address = (void *)frame->pc; |
|
|
|
entry.function = (void *)prel31_to_addr(&index->addr_offset); |
|
|
|
entry.name = unwind_get_function_name(entry.function); |
|
|
|
dump_entry(count, &entry, ctx); |
|
|
|
/* Find the unwind index of the current frame pc */ |
|
|
|
const unwind_index_t *index = unwind_search_index(__exidx_start, __exidx_end, frame->pc); |
|
|
|
|
|
|
|
/* Next backtrace frame */ |
|
|
|
++count; |
|
|
|
/* Clear last bit (Thumb indicator) */ |
|
|
|
frame->pc &= 0xfffffffeU; |
|
|
|
|
|
|
|
} while (unwind_frame(frame) == 1); |
|
|
|
/* Generate the backtrace information */ |
|
|
|
entry.address = (void *)frame->pc; |
|
|
|
entry.function = (void *)prel31_to_addr(&index->addr_offset); |
|
|
|
entry.name = unwind_get_function_name(entry.function); |
|
|
|
dump_entry(count, &entry, ctx); |
|
|
|
|
|
|
|
/* Next backtrace frame */ |
|
|
|
++count; |
|
|
|
|
|
|
|
} while (unwind_frame(frame) == 1); |
|
|
|
} |
|
|
|
|
|
|
|
/* All done */ |
|
|
|
return count; |
|
|
|