ObjectFileELF: Add support for arbitrarily named code sections

ObjectFileELF assumes that code section has ".text" name. There is an
exception for kalimba toolchain that can use arbitrary names, but other
toolchains also could use arbitrary names for code sections. For
example, corert uses separate section for compiled managed code. As lldb
doesn't recognize such section it leads to problem with breakpoints on
arm, because debugger cannot determine instruction set (arm/thumb) and
uses incorrect breakpoint opcode that breaks program execution.

This change allows debugger to correctly handle such code sections. We
assume that section is a code section if it has SHF_EXECINSTR flag set
and has SHT_PROGBITS type.

Patch by Konstantin Baladurin <k.baladurin@partner.samsung.com>.
Differential Revision: https://reviews.llvm.org/D44998

llvm-svn: 331173

5 files changed, 73 insertions, 0 deletions

diff --git a/lldb/lit/Modules/dwarf-gnu-debugaltlink.yaml b/lldb/lit/Modules/elf-section-types.yaml
index 65f8cc7a3a3..a331917f6b7 100644
--- a/lldb/lit/Modules/dwarf-gnu-debugaltlink.yaml
+++ b/lldb/lit/Modules/elf-section-types.yaml
@@ -1,11 +1,17 @@
 # RUN: yaml2obj %s > %t
 # RUN: lldb-test module-sections %t | FileCheck %s
 
+# CHECK: Name: .text
+# CHECK-NEXT: Type: code
+
 # CHECK: Name: .gnu_debugaltlink
 # CHECK-NEXT: Type: dwarf-gnu-debugaltlink
 # CHECK-NEXT: VM size: 0
 # CHECK-NEXT: File size: 8
 
+# CHECK: Name: __codesection
+# CHECK-NEXT: Type: code
+
 --- !ELF
 FileHeader:      
   Class:           ELFCLASS64
@@ -14,6 +20,10 @@ FileHeader:
   Machine:         EM_X86_64
   Entry:           0x00000000000007A0
 Sections:        
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Content:         DEADBEEFBAADF00D
   - Name:            .debug_info
     Type:            SHT_PROGBITS
     AddressAlign:    0x0000000000000001
@@ -22,4 +32,8 @@ Sections:
     Type:            SHT_PROGBITS
     AddressAlign:    0x0000000000000001
     Content:         DEADBEEFBAADF00D
+  - Name:            __codesection
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Content:         DEADBEEFBAADF00D
 ...
diff --git a/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/Makefile b/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/Makefile
new file mode 100644
index 00000000000..ea79c55cd4a
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/Makefile
@@ -0,0 +1,6 @@
+LEVEL = ../../make
+
+C_SOURCES := main.c
+CFLAGS_EXTRAS = -mthumb
+
+include $(LEVEL)/Makefile.rules
\ No newline at end of file
diff --git a/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/TestBreakpointThumbCodesection.py b/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/TestBreakpointThumbCodesection.py
new file mode 100644
index 00000000000..f020a653852
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/TestBreakpointThumbCodesection.py
@@ -0,0 +1,35 @@
+"""
+Test that breakpoints correctly work in an thumb function in an arbitrary
+named codesection.
+"""
+from __future__ import print_function
+
+
+import lldb
+import os
+import time
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestBreakpointThumbCodesection(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @skipIf(archs=no_match(["arm"]))
+    def test_breakpoint(self):
+        self.build()
+        exe = self.getBuildArtifact("a.out")
+        line = line_number('main.c', '// Set break point at this line.')
+
+        self.runCmd("target create %s" % exe)
+        bpid = lldbutil.run_break_set_by_file_and_line(self, "main.c", line)
+
+        self.runCmd("run")
+
+        self.assertIsNotNone(lldbutil.get_one_thread_stopped_at_breakpoint_id(
+            self.process(), bpid), "Process is not stopped at breakpoint")
+
+        self.process().Continue()
+        self.assertEqual(self.process().GetState(), lldb.eStateExited, PROCESS_EXITED)
diff --git a/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/main.c b/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/main.c
new file mode 100644
index 00000000000..38ea7be6bfc
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/main.c
@@ -0,0 +1,8 @@
+__attribute__((section("__codesection")))
+int f(int a) {
+  return a + 1; // Set break point at this line.
+}
+
+int main() {
+  return f(10);
+}
diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
index a5f577f653c..61186aebfc6 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -1950,6 +1950,16 @@ void ObjectFileELF::CreateSections(SectionList &unified_section_list) {
         sect_type = kalimbaSectionType(m_header, header);
       }
 
+      // In common case ELF code section can have arbitrary name (for example,
+      // we can specify it using section attribute for particular function) so
+      // assume that section is a code section if it has SHF_EXECINSTR flag set
+      // and has SHT_PROGBITS type.
+      if (eSectionTypeOther == sect_type &&
+          llvm::ELF::SHT_PROGBITS == header.sh_type &&
+          (header.sh_flags & SHF_EXECINSTR)) {
+        sect_type = eSectionTypeCode;
+      }
+
       const uint32_t target_bytes_size =
           (eSectionTypeData == sect_type || eSectionTypeZeroFill == sect_type)
               ? m_arch_spec.GetDataByteSize()