From b6ec0be73b44b822022406406e89c9da6dfe1a3b Mon Sep 17 00:00:00 2001
From: Anh <zenpoems@gmail.com>
Date: Fri, 14 Jun 2019 02:42:08 +0000
Subject: [PATCH] fix up offset calculation for vldr. now takes into account
the U bit
---
unpin_arm32.cpp | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/unpin_arm32.cpp b/unpin_arm32.cpp
index 56aa56e..b4dcce2 100644
--- a/unpin_arm32.cpp
+++ b/unpin_arm32.cpp
@@ -120,8 +120,9 @@ void UnpinArm32_t::HandlePcrelReloc(Instruction_t* from_insn, Relocation_t* relo
const auto Rm = uint32_t(full_insn >> 0) & mask4;
const auto Rn = uint32_t(full_insn >> 16) & mask4;
const auto Rs = uint32_t(full_insn >> 8) & mask4;
- const auto is_rn_pc = Rn == 0b1111; // rn reg may not be valid for all instructions
+ const auto is_rn_pc = Rn == 0b1111; // rn reg may not be valid for all instructions
const auto is_rd_pc = Rd == 0b1111; // destination register, not valid for all insns
+ const auto is_pos_imm = (bool)((full_insn >> 23) & mask1); // useful only for ldr and vldr
// find a temp_reg if we need one
const auto tmp_reg = allocate_reg({Rd,Rm,Rn,Rs, 13, 15});
@@ -206,7 +207,11 @@ void UnpinArm32_t::HandlePcrelReloc(Instruction_t* from_insn, Relocation_t* relo
zo->applyPatch(L5,FT);
// put the calculated pc-rel offset at L3
- const auto new_offset = int32_t(orig_insn_addr - L2 + reloc_offset);
+ const auto ldr_imm_field = int32_t(full_insn & mask8)*4;
+ const auto ldr_imm = is_pos_imm ? ldr_imm_field : -ldr_imm_field;
+ const auto new_offset = (bo_wrt == nullptr) ?
+ int32_t(orig_insn_addr - L2 + addend) :
+ int32_t(orig_insn_addr - L2 + reloc_offset - (ldr_imm + 8));
ms.plopBytes(L6,reinterpret_cast<const char*>(&new_offset),4); // endianness of host must match target
// should be few enough of these to always print
@@ -243,8 +248,6 @@ void UnpinArm32_t::HandlePcrelReloc(Instruction_t* from_insn, Relocation_t* relo
const auto L2 = tramp_start + 8;
const auto L3 = tramp_start + 12;
- // extract some fields from the orig full_insn
- const auto is_pos_imm = (bool)((full_insn >> 23) & mask1);
const auto is_byte_load = (bool)((full_insn >> 22) & mask1);
assert(Rd!=0xf); // not the program counter.
--
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