jasonmolenda created this revision.
jasonmolenda added a project: LLDB.
Herald added subscribers: omjavaid, danielkiss, JDevlieghere, kristof.beyls.
jasonmolenda requested review of this revision.
lldb's disassembler for arm64 / aarch64 doesn't recognize the ADRP+ADD
instruction pair often used to calculate pc-relative addresses, and symbolicate
what is being pointed to, making it hard to understand the assembly; doing the
computation manually is annoying. This patch adds a bit of arm64-specific
knowledge to the disassembly symbolicator to remember the state and compute the
address being specified when the target is aarch64.
I'm fixing the other thing that I dislike the most about lldb's arm64
disassembly in the llvm aarch64 instruction printer, via
https://reviews.llvm.org/D107196 .
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D107213
Files:
lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.h
lldb/test/API/functionalities/disassemble/aarch64-adrp-add/TestAArch64AdrpAdd.py
lldb/test/API/functionalities/disassemble/aarch64-adrp-add/a.out.yaml
lldb/test/API/functionalities/disassemble/aarch64-adrp-add/main.c
Index: lldb/test/API/functionalities/disassemble/aarch64-adrp-add/main.c
===================================================================
--- /dev/null
+++ lldb/test/API/functionalities/disassemble/aarch64-adrp-add/main.c
@@ -0,0 +1,5 @@
+#include <stdio.h>
+int main() {
+ puts("HI");
+ return 0;
+}
Index: lldb/test/API/functionalities/disassemble/aarch64-adrp-add/a.out.yaml
===================================================================
--- /dev/null
+++ lldb/test/API/functionalities/disassemble/aarch64-adrp-add/a.out.yaml
@@ -0,0 +1,387 @@
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Index: lldb/test/API/functionalities/disassemble/aarch64-adrp-add/TestAArch64AdrpAdd.py
===================================================================
--- /dev/null
+++ lldb/test/API/functionalities/disassemble/aarch64-adrp-add/TestAArch64AdrpAdd.py
@@ -0,0 +1,41 @@
+"""
+Test that the arm64 ADRP + ADD pc-relative addressing pair is symbolicated.
+"""
+
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+class TestCase(TestBase):
+
+ mydir = TestBase.compute_mydir(__file__)
+
+ @no_debug_info_test
+ def test(self):
+ src_dir = self.getSourceDir()
+ yaml_path = os.path.join(src_dir, "a.out.yaml")
+ yaml_base, ext = os.path.splitext(yaml_path)
+ obj_path = self.getBuildArtifact("a.out")
+ self.yaml2obj(yaml_path, obj_path)
+
+ target = self.dbg.CreateTarget(obj_path)
+ self.assertTrue(target, VALID_TARGET)
+
+ mains = target.FindFunctions("main")
+ for f in mains.symbols:
+ if f.GetStartAddress().GetModule().GetFileSpec().GetFilename() == "a.out":
+ insns = f.GetInstructions(target)
+ found_hi_string = False
+
+ # The binary has an ADRP + ADD instruction pair which load
+ # the pc-relative address of a c-string. lldb should show
+ # that c-string in the disassembly in the comment field.
+ for i in insns:
+ if "HI" in i.GetComment(target):
+ found_hi_string = True
+ if found_hi_string == False and self.TraceOn():
+ strm = lldb.SBStream()
+ insns.GetDescription(strm)
+ print('Disassembly of main(), looking for "HI" in comments:')
+ print(strm.GetData())
+ self.assertTrue(found_hi_string)
Index: lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.h
===================================================================
--- lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.h
+++ lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.h
@@ -73,6 +73,8 @@
InstructionLLVMC *m_inst;
std::mutex m_mutex;
bool m_data_from_file;
+ lldb::addr_t m_adrp_address;
+ uint32_t m_adrp_insn;
// Since we need to make two actual MC Disassemblers for ARM (ARM & THUMB),
// and there's a bit of goo to set up and own in the MC disassembler world,
Index: lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
===================================================================
--- lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
+++ lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
@@ -1030,7 +1030,8 @@
DisassemblerLLVMC::DisassemblerLLVMC(const ArchSpec &arch,
const char *flavor_string)
: Disassembler(arch, flavor_string), m_exe_ctx(nullptr), m_inst(nullptr),
- m_data_from_file(false) {
+ m_data_from_file(false), m_adrp_address(LLDB_INVALID_ADDRESS),
+ m_adrp_insn(0) {
if (!FlavorValidForArchSpec(arch, m_flavor.c_str())) {
m_flavor.assign("default");
}
@@ -1310,6 +1311,40 @@
Target *target = m_exe_ctx ? m_exe_ctx->GetTargetPtr() : nullptr;
Address value_so_addr;
Address pc_so_addr;
+ if (target->GetArchitecture().GetMachine() == llvm::Triple::aarch64 ||
+ target->GetArchitecture().GetMachine() == llvm::Triple::aarch64_32) {
+ if (*type_ptr == LLVMDisassembler_ReferenceType_In_ARM64_ADRP) {
+ m_adrp_address = pc;
+ m_adrp_insn = value;
+ *name = nullptr;
+ *type_ptr = LLVMDisassembler_ReferenceType_InOut_None;
+ return nullptr;
+ }
+ // If previous instruction was ADRP and this is ADD, and it's to
+ // the same register, this is pc-relative address calculation.
+ if (*type_ptr == LLVMDisassembler_ReferenceType_In_ARM64_ADDXri &&
+ m_adrp_address == pc - 4 &&
+ (m_adrp_insn & 0x9f000000) == 0x90000000 &&
+ (m_adrp_insn & 0x1f) == ((value >> 5) & 0x1f)) {
+ // Bitmasking lifted from MachODump.cpp's SymbolizerSymbolLookUp.
+ uint32_t addxri_inst;
+ uint64_t adrp_imm, addxri_imm;
+ adrp_imm =
+ ((m_adrp_insn & 0x00ffffe0) >> 3) | ((m_adrp_insn >> 29) & 0x3);
+ if (m_adrp_insn & 0x0200000)
+ adrp_imm |= 0xfffffffffc000000LL;
+
+ addxri_inst = value;
+ addxri_imm = (addxri_inst >> 10) & 0xfff;
+ if (((addxri_inst >> 22) & 0x3) == 1)
+ addxri_imm <<= 12;
+ value = (m_adrp_address & 0xfffffffffffff000LL) + (adrp_imm << 12) +
+ addxri_imm;
+ }
+ m_adrp_address = LLDB_INVALID_ADDRESS;
+ m_adrp_insn = 0;
+ }
+
if (m_inst->UsingFileAddress()) {
ModuleSP module_sp(m_inst->GetAddress().GetModule());
if (module_sp) {
@@ -1371,6 +1406,12 @@
}
}
+ // TODO: llvm-objdump sets the type_ptr to the
+ // LLVMDisassembler_ReferenceType_Out_* values
+ // based on where value_so_addr is pointing, with
+ // Mach-O specific augmentations in MachODump.cpp. e.g.
+ // see what AArch64ExternalSymbolizer::tryAddingSymbolicOperand
+ // handles.
*type_ptr = LLVMDisassembler_ReferenceType_InOut_None;
*name = nullptr;
return nullptr;
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