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powerpc: Add emulation for the addpcis instruction

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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>
This commit is contained in:
Paul Mackerras 2017-08-30 14:12:31 +10:00 committed by Michael Ellerman
parent 5762e08344
commit 958465ee54
1 changed files with 11 additions and 3 deletions
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14
arch/powerpc/lib/sstep.c
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@ -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;