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 <pau...@ozlabs.org>
---
arch/powerpc/lib/sstep.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 7921b2a..d9b3b63 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1024,9 +1024,6 @@ 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:
@@ -1126,6 +1123,17 @@ 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;
--
2.7.4
