https://github.com/labath created
https://github.com/llvm/llvm-project/pull/125839
PR #86603 broke unwinding in for unwind info added via "target symbols add".
#86770 attempted to fix this, but the fix was only partial -- it accepted new
sources of unwind information, but didn't take into account that the symbol
file can alter what lldb percieves as function boundaries.
A stripped file will not contain information about private (non-exported)
symbols, which will make the public symbols appear very large. If lldb tries to
unwind from such a function before symbols are added, then the cached unwind
plan will prevent new (correct) unwind plans from being created.
target-symbols-add-unwind.test might have caught this, were it not for the fact
that the "image show-unwind" command does *not* use cached unwind information
(it recomputes it from scratch).
The changes in this patch come in three pieces:
- Clear cached unwind plans when adding symbols. Since the symbol boundaries
can change, we cannot trust anything we've computed previously.
- Add a flag to "image show-unwind" to display the cached unwind information
(mainly for the use in the test, but I think it's also generally useful).
- Rewrite the test to better and more reliably simulate the real-world
scenario: I've swapped the running process for a core (minidump) file so it can
run anywhere; used the caching version of the show-unwind command; and swapped
C for assembly to better control the placement of symbols
>From 82e0ee5bf53dd6b886327021f5b145c942b43ff6 Mon Sep 17 00:00:00 2001
From: Pavel Labath <pa...@labath.sk>
Date: Wed, 5 Feb 2025 11:28:48 +0100
Subject: [PATCH] [lldb] Clear cached unwind plans when adding symbols
PR #86603 broke unwinding in for unwind info added via "target symbols
add". #86770 attempted to fix this, but the fix was only partial -- it
accepted new sources of unwind information, but didn't take into account
that the symbol file can alter what lldb percieves as function
boundaries.
A stripped file will not contain information about private
(non-exported) symbols, which will make the public symbols appear very
large. If lldb tries to unwind from such a function before symbols are
added, then the cached unwind plan will prevent new (correct) unwind
plans from being created.
target-symbols-add-unwind.test might have caught this, were it not for
the fact that the "image show-unwind" command does *not* use cached
unwind information (it recomputes it from scratch).
The changes in this patch come in three pieces:
- Clear cached unwind plans when adding symbols. Since the symbol
boundaries can change, we cannot trust anything we've computed
previously.
- Add a flag to "image show-unwind" to display the cached unwind
information (mainly for the use in the test, but I think it's also
generally useful).
- Rewrite the test to better and more reliably simulate the real-world
scenario: I've swapped the running process for a core (minidump) file
so it can run anywhere; used the caching version of the show-unwind
command; and swapped C for assembly to better control the placement of
symbols
---
lldb/include/lldb/Symbol/UnwindTable.h | 5 +-
lldb/source/Commands/CommandObjectTarget.cpp | 22 +++-
lldb/source/Commands/Options.td | 2 +
lldb/source/Symbol/UnwindTable.cpp | 3 +-
.../Inputs/target-symbols-add-unwind.c | 1 -
.../SymbolFile/target-symbols-add-unwind.test | 118 +++++++++++++++---
6 files changed, 125 insertions(+), 26 deletions(-)
delete mode 100644
lldb/test/Shell/SymbolFile/Inputs/target-symbols-add-unwind.c
diff --git a/lldb/include/lldb/Symbol/UnwindTable.h
b/lldb/include/lldb/Symbol/UnwindTable.h
index 29b7fa61b4849e0..3166fdec6ebaa77 100644
--- a/lldb/include/lldb/Symbol/UnwindTable.h
+++ b/lldb/include/lldb/Symbol/UnwindTable.h
@@ -38,8 +38,9 @@ class UnwindTable {
ArmUnwindInfo *GetArmUnwindInfo();
SymbolFile *GetSymbolFile();
- lldb::FuncUnwindersSP GetFuncUnwindersContainingAddress(const Address &addr,
- SymbolContext &sc);
+ lldb::FuncUnwindersSP
+ GetFuncUnwindersContainingAddress(const Address &addr,
+ const SymbolContext &sc);
bool GetAllowAssemblyEmulationUnwindPlans();
diff --git a/lldb/source/Commands/CommandObjectTarget.cpp
b/lldb/source/Commands/CommandObjectTarget.cpp
index d8265e41a7384eb..db142e8f0eaee77 100644
--- a/lldb/source/Commands/CommandObjectTarget.cpp
+++ b/lldb/source/Commands/CommandObjectTarget.cpp
@@ -3471,6 +3471,17 @@ class CommandObjectTargetModulesShowUnwind : public
CommandObjectParsed {
m_type = eLookupTypeFunctionOrSymbol;
break;
+ case 'c':
+ bool value, success;
+ value = OptionArgParser::ToBoolean(option_arg, false, &success);
+ if (success) {
+ m_cached = value;
+ } else {
+ return Status::FromErrorStringWithFormatv(
+ "invalid boolean value '%s' passed for -G option", option_arg);
+ }
+ break;
+
default:
llvm_unreachable("Unimplemented option");
}
@@ -3482,6 +3493,7 @@ class CommandObjectTargetModulesShowUnwind : public
CommandObjectParsed {
m_type = eLookupTypeInvalid;
m_str.clear();
m_addr = LLDB_INVALID_ADDRESS;
+ m_cached = false;
}
llvm::ArrayRef<OptionDefinition> GetDefinitions() override {
@@ -3494,6 +3506,7 @@ class CommandObjectTargetModulesShowUnwind : public
CommandObjectParsed {
// parsing options
std::string m_str; // Holds name lookup
lldb::addr_t m_addr = LLDB_INVALID_ADDRESS; // Holds the address to lookup
+ bool m_cached = false;
};
CommandObjectTargetModulesShowUnwind(CommandInterpreter &interpreter)
@@ -3583,9 +3596,12 @@ class CommandObjectTargetModulesShowUnwind : public
CommandObjectParsed {
if (abi)
start_addr = abi->FixCodeAddress(start_addr);
- FuncUnwindersSP func_unwinders_sp(
- sc.module_sp->GetUnwindTable()
- .GetUncachedFuncUnwindersContainingAddress(start_addr, sc));
+ UnwindTable &uw_table = sc.module_sp->GetUnwindTable();
+ FuncUnwindersSP func_unwinders_sp =
+ m_options.m_cached
+ ? uw_table.GetFuncUnwindersContainingAddress(start_addr, sc)
+ : uw_table.GetUncachedFuncUnwindersContainingAddress(start_addr,
+ sc);
if (!func_unwinders_sp)
continue;
diff --git a/lldb/source/Commands/Options.td b/lldb/source/Commands/Options.td
index 777f8c36c4916ca..8831fed38435b54 100644
--- a/lldb/source/Commands/Options.td
+++ b/lldb/source/Commands/Options.td
@@ -965,6 +965,8 @@ let Command = "target modules show unwind" in {
def target_modules_show_unwind_address : Option<"address", "a">, Group<2>,
Arg<"AddressOrExpression">, Desc<"Show unwind instructions for a function "
"or symbol containing an address">;
+ def target_modules_show_unwind_cached : Option<"cached", "c">,
+ Arg<"Boolean">, Desc<"Show cached unwind information">;
}
let Command = "target modules lookup" in {
diff --git a/lldb/source/Symbol/UnwindTable.cpp
b/lldb/source/Symbol/UnwindTable.cpp
index da88b0c9c4ea191..61d51192bf3d1e4 100644
--- a/lldb/source/Symbol/UnwindTable.cpp
+++ b/lldb/source/Symbol/UnwindTable.cpp
@@ -86,6 +86,7 @@ void UnwindTable::Initialize() {
void UnwindTable::ModuleWasUpdated() {
std::lock_guard<std::mutex> guard(m_mutex);
m_scanned_all_unwind_sources = false;
+ m_unwinds.clear();
}
UnwindTable::~UnwindTable() = default;
@@ -118,7 +119,7 @@ UnwindTable::GetAddressRange(const Address &addr, const
SymbolContext &sc) {
FuncUnwindersSP
UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
- SymbolContext &sc) {
+ const SymbolContext &sc) {
Initialize();
std::lock_guard<std::mutex> guard(m_mutex);
diff --git a/lldb/test/Shell/SymbolFile/Inputs/target-symbols-add-unwind.c
b/lldb/test/Shell/SymbolFile/Inputs/target-symbols-add-unwind.c
deleted file mode 100644
index 237c8ce181774d9..000000000000000
--- a/lldb/test/Shell/SymbolFile/Inputs/target-symbols-add-unwind.c
+++ /dev/null
@@ -1 +0,0 @@
-int main() {}
diff --git a/lldb/test/Shell/SymbolFile/target-symbols-add-unwind.test
b/lldb/test/Shell/SymbolFile/target-symbols-add-unwind.test
index 5420213d405e868..249d2ef79a891c4 100644
--- a/lldb/test/Shell/SymbolFile/target-symbols-add-unwind.test
+++ b/lldb/test/Shell/SymbolFile/target-symbols-add-unwind.test
@@ -1,27 +1,107 @@
-# TODO: When it's possible to run "image show-unwind" without a running
-# process, we can remove the unsupported line below, and hard-code an ELF
-# triple in the test.
-# UNSUPPORTED: system-windows, system-darwin
-
-# RUN: cd %T
-# RUN: %clang_host %S/Inputs/target-symbols-add-unwind.c -g \
-# RUN: -fno-unwind-tables -fno-asynchronous-unwind-tables \
-# RUN: -o target-symbols-add-unwind.debug
-# RUN: llvm-objcopy --strip-debug target-symbols-add-unwind.debug \
-# RUN: target-symbols-add-unwind.stripped
-# RUN: %lldb target-symbols-add-unwind.stripped -s %s -o quit | FileCheck %s
-
-process launch --stop-at-entry
-image show-unwind -n main
-# CHECK-LABEL: image show-unwind -n main
+# NB: The minidump core file exists only because "image show-unwind" currently
+# requires a process to exist. If that changes, it can be removed.
+
+# REQUIRES: x86, lld
+
+# RUN: split-file %s %t
+# RUN: yaml2obj %t/a.core.yaml -o %t/a.core
+# RUN: %clang -c --target=x86_64-pc-linux %t/a.s -o %t/a.o
+# RUN: ld.lld --shared %t/a.o -o %t/a.debug --build-id=0xdeadbeef \
+# RUN: --image-base=0x10000
+# RUN: llvm-objcopy --strip-all %t/a.debug %t/a.stripped
+# RUN: cd %t
+# RUN: %lldb -c %t/a.core \
+# RUN: -o "settings set interpreter.stop-command-source-on-error false" \
+# RUN: -s %t/commands -o quit | FileCheck %s
+
+#--- commands
+
+image add a.stripped
+image load --file a.stripped --slide 0
+image list
+# CHECK-LABEL: image list
+# CHECK: [ 0] DEADBEEF 0x0000000000010000 a.stripped
+
+## Due to missing symbol information this (incorrectly) prints the unwind
+## information for public_fn1
+image show-unwind -n public_fn1 --cached true
+# CHECK-LABEL: image show-unwind -n public_fn1
+# CHECK-NEXT: UNWIND PLANS for a.stripped`public_fn1 (start addr 0x12000)
# CHECK-NOT: debug_frame UnwindPlan:
-target symbols add -s target-symbols-add-unwind.stripped
target-symbols-add-unwind.debug
+target symbols add -s a.stripped a.debug
# CHECK-LABEL: target symbols add
# CHECK: symbol file {{.*}} has been added to {{.*}}
-image show-unwind -n main
-# CHECK-LABEL: image show-unwind -n main
+image show-unwind -n private_fn --cached true
+# CHECK-LABEL: image show-unwind -n private_fn
+# CHECK-NEXT: UNWIND PLANS for a.stripped`private_fn (start addr 0x12010)
# CHECK: debug_frame UnwindPlan:
# CHECK-NEXT: This UnwindPlan originally sourced from DWARF CFI
# CHECK-NEXT: This UnwindPlan is sourced from the compiler: yes.
+# CHECK-NEXT: This UnwindPlan is valid at all instruction locations: no.
+# CHECK-NEXT: This UnwindPlan is for a trap handler function: no.
+# CHECK-NEXT: Address range of this UnwindPlan: [a.stripped.PT_LOAD[1]..text +
16-0x0000000000000013)
+
+
+#--- a.s
+
+ .text
+ .cfi_sections .debug_frame
+ .globl public_fn1, public_fn2
+
+ .p2align 12
+public_fn1:
+ .cfi_startproc
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset %rbp, -16
+ popq %rbp
+ .cfi_def_cfa %rsp, 8
+ retq
+ .cfi_endproc
+
+ .p2align 4
+private_fn:
+ .cfi_startproc
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset %rbp, -16
+ popq %rbp
+ .cfi_def_cfa %rsp, 8
+ retq
+ .cfi_endproc
+
+ .p2align 4
+public_fn2:
+ .cfi_startproc
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset %rbp, -16
+ popq %rbp
+ .cfi_def_cfa %rsp, 8
+ retq
+ .cfi_endproc
+
+#--- a.core.yaml
+--- !minidump
+Streams:
+ - Type: SystemInfo
+ Processor Arch: AMD64
+ Platform ID: Linux
+ CPU:
+ Vendor ID: GenuineIntel
+ Version Info: 0x00000000
+ Feature Info: 0x00000000
+ - Type: ThreadList
+ Threads:
+ - Thread Id: 0x000074F3
+ Context:
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000B001000000000006CAE000000006B7FC05A0000C81D415A0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000A2BF9E5A6B7F0000000000000000000000000000000000008850C14BFD7F00009850C14BFD7F00000100000000000000B04AC14BFD7F0000000000000000000060812D01000000000800000000000000B065E05A6B7F00008004400000000000E050C14BFD7F00000000000000000000000000000000000004400000000000007F03FFFF0000FFFFFFFFFFFF000000000000000000000000801F00006B7F00000400000000000000B84CC14BFD7F0000304D405A6B7F0000C84DC14BFD7F0000C0AA405A6B7F00004F033D0000000000B84DC14BFD7F0000E84DC14BFD7F0000000000000000000000000000000000000070E05A6B7F000078629E5A6B7F0000C81D415A6B7F0000804F9E5A6B7F00000000000001000000E603000001000000E093115A6B7F0000804EC14BFD7F0000584EC14BFD7F000099ADC05A6B7F00000100000000000000AAAAD77D0000000002000000000000000800000000000000B065E05A6B7F0000E6B7C05A6B7F0000010000006B7F0000884DC14BFD7F0000106F7C5A6B7F0000984EC14BFD7F0000488B7C5A6B7F0000C4A71CB90000000001000000000000000800000000000000B065E05A6B7F000048B6C05A6B7F0000702AE25A6B7F0000D84DC14BFD7F000030489E5A6B7F0000E84EC14BFD7F0000E05E9E5A6B7F00000991F0460000000001000000000000000800000000000000B065E05A6B7F000048B6C05A6B7F00000100000000000000284EC14BFD7F00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ Stack:
+ Start of Memory Range: 0x00007FFD4BC15080
+ Content: 30044000000000000000000000000000
+ - Type: MemoryList
+ Memory Ranges:
+ - Start of Memory Range: 0x00007FFD4BC15080
+ Content: 30044000000000000000000000000000
+...
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