[PATCH v3 08/17] powerpc: Add emulation for the addpcis instruction
From: Paul Mackerras <hidden>
Date: 2017-08-30 04:12:51
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted> --- 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 114e597..ed2bc4c 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c@@ -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;
--
2.7.4