kwk created this revision.
kwk added a reviewer: labath.
Herald added subscribers: lldb-commits, MaskRay, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a reviewer: alexshap.
Herald added a project: LLDB.
This change ensures that the .dynsym section will be parsed even when
there's already is a .symtab section.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D67390
Files:
lldb/lit/Modules/ELF/Inputs/load-from-dynsym-alone.c
lldb/lit/Modules/ELF/Inputs/load-symtab-and-dynsym.c
lldb/lit/Modules/ELF/load-from-dynsym-alone.test
lldb/lit/Modules/ELF/load-symtab-and-dynsym.test
lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
Index: lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
===================================================================
--- lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -2649,19 +2649,25 @@
// while the reverse is not necessarily true.
Section *symtab =
section_list->FindSectionByType(eSectionTypeELFSymbolTable, true).get();
- if (!symtab) {
- // The symtab section is non-allocable and can be stripped, so if it
- // doesn't exist then use the dynsym section which should always be
- // there.
- symtab =
- section_list->FindSectionByType(eSectionTypeELFDynamicSymbols, true)
- .get();
- }
if (symtab) {
m_symtab_up.reset(new Symtab(symtab->GetObjectFile()));
symbol_id += ParseSymbolTable(m_symtab_up.get(), symbol_id, symtab);
}
+ // The symtab section is non-allocable and can be stripped. If both, .symtab
+ // and .dynsym exist, we load both. And if only .dymsym exists, we load it
+ // alone.
+ Section *dynsym =
+ section_list->FindSectionByType(eSectionTypeELFDynamicSymbols, true)
+ .get();
+ if (dynsym) {
+ if (!m_symtab_up) {
+ auto sec = symtab ? symtab : dynsym;
+ m_symtab_up.reset(new Symtab(sec->GetObjectFile()));
+ }
+ symbol_id += ParseSymbolTable(m_symtab_up.get(), symbol_id, dynsym);
+ }
+
// DT_JMPREL
// If present, this entry's d_ptr member holds the address of
// relocation
Index: lldb/lit/Modules/ELF/load-symtab-and-dynsym.test
===================================================================
--- /dev/null
+++ lldb/lit/Modules/ELF/load-symtab-and-dynsym.test
@@ -0,0 +1,48 @@
+# REQUIRES: system-linux
+
+# This test ensures that we will load .dynsym even if there's a .symtab section.
+# We do this by compiling a small C program with two functions and we direct the
+# linker where to put the symbols so that in the end the layout is as follows:
+#
+# Symbol table '.dynsym' contains 4 entries:
+# Num: Value Size Type Bind Vis Ndx Name
+# 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
+# 1: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __libc_start_main@GLIBC_2.2.5
+# 2: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
+# 3: 0000000000401120 13 FUNC GLOBAL DEFAULT 10 functionInDynsym
+#
+# Symbol table '.symtab' contains 2 entries:
+# Num: Value Size Type Bind Vis Ndx Name
+# 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
+# 1: 0000000000401110 15 FUNC GLOBAL DEFAULT 10 functionInSymtab
+
+# We want to keep the symbol "functionInDynsym" in the .dynamic section and not
+# have it put the default .symtab section.
+# RUN: echo "{functionInDynsym;};" > %T/dynmic-symbols.txt
+# RUN: %clang -Wl,--dynamic-list=%T/dynmic-symbols.txt -g -o %t.binary %p/Inputs/load-symtab-and-dynsym.c
+
+# Remove not needed symbols
+# RUN: echo "functionInSymtab" > %t.keep_symbols
+# RUN: echo "functionInDynsym" >> %t.keep_symbols
+# RUN: llvm-objcopy --strip-all --remove-section .gdb_index --remove-section .comment --keep-symbols=%t.keep_symbols %t.binary
+
+# Remove functionInDynsym symbol from .symtab (will leave symbol in .dynsym intact)
+# RUN: llvm-strip --strip-symbol=functionInDynsym %t.binary
+
+# RUN: %lldb -b -o 'b functionInSymtab' -o 'b functionInDynsym' -o 'run' -o 'continue' %t.binary | FileCheck %s
+
+# CHECK: (lldb) b functionInSymtab
+# CHECK-NEXT: Breakpoint 1: where = {{.*}}.binary`functionInSymtab, address = 0x{{.*}}
+
+# CHECK: (lldb) b functionInDynsym
+# CHECK-NEXT: Breakpoint 2: where = {{.*}}.binary`functionInDynsym, address = 0x{{.*}}
+
+# CHECK: (lldb) run
+# CHECK-NEXT: Process {{.*}} stopped
+# CHECK-NEXT: * thread #1, name = 'load-symtab-and', stop reason = breakpoint 1.1
+
+# CHECK: (lldb) continue
+# CHECK-NEXT: Process {{.*}} resuming
+# CHECK-NEXT: Process {{.*}} stopped
+# CHECK-NEXT: * thread #1, name = 'load-symtab-and', stop reason = breakpoint 2.1
+
Index: lldb/lit/Modules/ELF/load-from-dynsym-alone.test
===================================================================
--- /dev/null
+++ lldb/lit/Modules/ELF/load-from-dynsym-alone.test
@@ -0,0 +1,33 @@
+# REQUIRES: system-linux
+
+# This test ensures that we will load .dynsym even if there's no .symtab section.
+# We do this by compiling a small C program with a function and we direct the
+# linker where to put the symbols so that in the end the layout is as follows:
+#
+# Symbol table '.dynsym' contains 4 entries:
+# Num: Value Size Type Bind Vis Ndx Name
+# 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
+# 1: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __libc_start_main@GLIBC_2.2.5
+# 2: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
+# 3: 0000000000401110 13 FUNC GLOBAL DEFAULT 10 functionInDynsym
+
+# We want to keep the symbol "functionInDynsym" in the .dynamic section and not
+# have it put the default .symtab section.
+# RUN: echo "{functionInDynsym;};" > %T/dynmic-symbols.txt
+# RUN: %clang -Wl,--dynamic-list=%T/dynmic-symbols.txt -g -o %t.binary %p/Inputs/load-from-dynsym-alone.c
+
+# Remove not needed symbols
+# RUN: echo "functionInDynsym" > %t.keep_symbols
+# RUN: llvm-objcopy --strip-all --remove-section .gdb_index --remove-section .comment --keep-symbols=%t.keep_symbols %t.binary
+
+# Remove functionInDynsym symbol from .symtab (will leave symbol in .dynsym intact)
+# RUN: llvm-strip --strip-symbol=functionInDynsym %t.binary
+
+# RUN: %lldb -b -o 'b functionInDynsym' -o 'run' -o 'continue' %t.binary | FileCheck %s
+
+# CHECK: (lldb) b functionInDynsym
+# CHECK-NEXT: Breakpoint 1: where = {{.*}}.binary`functionInDynsym, address = 0x{{.*}}
+
+# CHECK: (lldb) run
+# CHECK-NEXT: Process {{.*}} stopped
+# CHECK-NEXT: * thread #1, name = 'load-from-dynsy', stop reason = breakpoint 1.1
Index: lldb/lit/Modules/ELF/Inputs/load-symtab-and-dynsym.c
===================================================================
--- /dev/null
+++ lldb/lit/Modules/ELF/Inputs/load-symtab-and-dynsym.c
@@ -0,0 +1,12 @@
+// This function will be embedded within the .symtab section of the
+// .gnu_debugdata section.
+int functionInSymtab(int num) { return num * 4; }
+
+// This function will be embedded within the .dynsym section of the main binary.
+int functionInDynsym(int num) { return num * 3; }
+
+int main(int argc, char *argv[]) {
+ int x = functionInSymtab(argc);
+ int y = functionInDynsym(x);
+ return y;
+}
Index: lldb/lit/Modules/ELF/Inputs/load-from-dynsym-alone.c
===================================================================
--- /dev/null
+++ lldb/lit/Modules/ELF/Inputs/load-from-dynsym-alone.c
@@ -0,0 +1,7 @@
+// This function will be embedded within the .dynsym section of the main binary.
+int functionInDynsym(int num) { return num * 3; }
+
+int main(int argc, char *argv[]) {
+ int y = functionInDynsym(argc);
+ return y;
+}
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