powerpc: Add emulation for the addpcis instruction (958465ee) · Commits · e / devices / android_kernel_oneplus_sm7250

The addpcis instruction puts the sum of the next instruction address plus a constant into a register. Since the result depends on the address of the instruction, it will give an incorrect result if it is single-stepped out of line, which is what the *probes subsystem will currently do if a probe is placed on an addpcis instruction. This fixes the problem by adding emulation of it to analyse_instr(). Signed-off-by:

Paul Mackerras <paulus@ozlabs.org> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/lib/sstep.c

+11 −3

Original line number	Diff line number	Diff line
		@@ -1021,9 +1021,6 @@ int analyse_instr(struct instruction_op op, const struct pt_regs regs,
		op->ccval = (regs->ccr & ~(1UL << (31 - rd))) \|
		(val << (31 - rd));
		return 1;
		default:
		op->type = UNKNOWN;
		return 0;
		}
		break;
		case 31:
		@@ -1123,6 +1120,17 @@ int analyse_instr(struct instruction_op op, const struct pt_regs regs,
		op->val = imm;
		goto compute_done;

		case 19:
		if (((instr >> 1) & 0x1f) == 2) {
		/* addpcis */
		imm = (short) (instr & 0xffc1); /* d0 + d2 fields */
		imm \|= (instr >> 15) & 0x3e; /* d1 field */
		op->val = regs->nip + (imm << 16) + 4;
		goto compute_done;
		}
		op->type = UNKNOWN;
		return 0;

		case 20: /* rlwimi */
		mb = (instr >> 6) & 0x1f;
		me = (instr >> 1) & 0x1f;