| 44 | #define VALID_PC(addr) ((addr) >= (uintptr_t)btext && (addr) % 4 == 0) |
| 45 | |
| 46 | static void |
| 47 | stack_capture(struct stack *st, struct thread *td, uintptr_t pc, uintptr_t sp) |
| 48 | { |
| 49 | u_register_t ra; |
| 50 | uintptr_t i, ra_addr; |
| 51 | int ra_stack_pos, stacksize; |
| 52 | InstFmt insn; |
| 53 | |
| 54 | stack_zero(st); |
| 55 | |
| 56 | for (;;) { |
| 57 | if (!VALID_PC(pc)) |
| 58 | break; |
| 59 | |
| 60 | /* |
| 61 | * Walk backward from the PC looking for the function |
| 62 | * start. Assume a subtraction from SP is the start |
| 63 | * of a function. Hope that we find the store of RA |
| 64 | * into the stack frame along the way and save the |
| 65 | * offset of the saved RA relative to SP. |
| 66 | */ |
| 67 | ra_stack_pos = -1; |
| 68 | stacksize = 0; |
| 69 | for (i = pc; VALID_PC(i); i -= sizeof(insn)) { |
| 70 | bcopy((void *)i, &insn, sizeof(insn)); |
| 71 | switch (insn.IType.op) { |
| 72 | case OP_ADDI: |
| 73 | case OP_ADDIU: |
| 74 | case OP_DADDI: |
| 75 | case OP_DADDIU: |
| 76 | if (insn.IType.rs != SP || insn.IType.rt != SP) |
| 77 | break; |
| 78 | |
| 79 | /* |
| 80 | * Ignore stack fixups in "early" |
| 81 | * returns in a function, or if the |
| 82 | * call was from an unlikely branch |
| 83 | * moved after the end of the normal |
| 84 | * return. |
| 85 | */ |
| 86 | if ((short)insn.IType.imm > 0) |
| 87 | break; |
| 88 | |
| 89 | stacksize = -(short)insn.IType.imm; |
| 90 | break; |
| 91 | |
| 92 | case OP_SW: |
| 93 | case OP_SD: |
| 94 | if (insn.IType.rs != SP || insn.IType.rt != RA) |
| 95 | break; |
| 96 | ra_stack_pos = (short)insn.IType.imm; |
| 97 | break; |
| 98 | default: |
| 99 | break; |
| 100 | } |
| 101 | |
| 102 | if (stacksize != 0) |
| 103 | break; |
no test coverage detected