[Lldb-commits] [lldb] Add support for reading the dynamic symbol table from PT_DYNAMIC (PR #112596)

[Greg Clayton via lldb-commits]

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@@ -0,0 +1,631 @@
+## This test verifies that loading an ELF file that has no section headers can
+## load the dynamic symbol table using the DT_SYMTAB, DT_SYMENT, DT_HASH or
+## the DT_GNU_HASH .dynamic key/value pairs that are loaded via the PT_DYNAMIC
+## segment.
+##
+## This test will convert a shared library from yaml, strip its section headers,
+## and varify that LLDB can load the dynamic symbol table. We must manually
+## strip the section headers from a full shared library because our ELF YAML
+## support in obj2yaml/yaml2obj doesn't support ELF files with program headers
+## only, they must have sections or the file doesn't get recreated correctlty.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-strip --strip-sections %t -o %t.noshdrs
+
+# RUN: %lldb -b \
+# RUN:   -o "target create -d '%t.noshdrs'" \
+# RUN:   -o "image dump objfile" \
+# RUN:   | FileCheck %s --dump-input=always
+# CHECK: (lldb) image dump objfile
+# CHECK: Dumping headers for 1 module(s).
+# CHECK: ObjectFileELF, file =
+# CHECK: ELF Header
+# Make sure there are no section headers
+# CHECK: e_shnum = 0x00000000
+# Make sure we were able to load the symbols
+# CHECK: elf-dynsym.yaml.tmp.noshdrs, num_symbols = 9:
+# CHECK: [ 0] 1 Undefined 0x0000000000000000 0x0000000000000000 0x00000022 __cxa_finalize
+# CHECK: [ 1] 2 X Undefined 0x0000000000000000 0x0000000000000000 0x00000012 puts
+# CHECK: [ 2] 3 Undefined 0x0000000000000000 0x0000000000000000 0x00000020 _ITM_deregisterTMCloneTable
+# CHECK: [ 3] 4 Undefined 0x0000000000000000 0x0000000000000000 0x00000020 __gmon_start__
+# CHECK: [ 4] 5 Undefined 0x0000000000000000 0x0000000000000000 0x00000020 _ITM_registerTMCloneTable
+# CHECK: [ 5] 6 X Code 0x0000000000001135 0x0000000000000016 0x00000012 baz()
+# CHECK: [ 6] 7 X Code 0x000000000000111f 0x0000000000000016 0x00000012 bar()
+# CHECK: [ 7] 8 X Code 0x000000000000114b 0x0000000000000016 0x00000012 biz()
+# CHECK: [ 8] 9 X Code 0x0000000000001109 0x0000000000000016 0x00000012 foo()
+
+--- !ELF
----------------
clayborg wrote:

I am happy to use the llvm-mc + ld.lld trick, bit I need:
- the output file to have a .dynamic section or PT_DYNAMIC (above example doesn't)
- it needs to have a dynamic symbol table (SHT_DYNSYM or .dynamic section needs to have `DT_SYMTAB` and `DT_SYMENT` entries
- Needs to have a DT_HASH or DT_GNU_HASH

I don't know much about the `llvm-mc` tool, but if you can get it to generate a file that i can use I will use it.

https://github.com/llvm/llvm-project/pull/112596