[Lldb-commits] [lldb] [lldb] Have disassembler show load addresses when using a core file (PR #115453)
Pavel Labath via lldb-commits
lldb-commits at lists.llvm.org
Fri Nov 8 02:15:01 PST 2024
https://github.com/labath created https://github.com/llvm/llvm-project/pull/115453
We got a bug report that the disassember output was not relocated (i.e. a load address) for a core file (like it is for a live process). It turns out this behavior it depends on whether the instructions were read from an executable file or from process memory (a core file will not typically contain the memory image for segments backed by an executable file).
It's unclear whether this behavior is intentional, or if it was just trying to handle the case where we're dissassembling a module without a process, but I think it's undesirable. What makes it particularly confusing is that the instruction addresses are relocated in this case (unlike the when we don't have a process), so with large files and adresses it gets very hard to see whether the relocation has been applied or not.
This patch removes the data_from_file check so that the instruction is relocated regardless of where it was read from. It will still not get relocated for the raw module use case, as those can't be relocated anywhere as they don't have a load address.
>From 55e493a4752a8a31ec1fb970b1d4f821109749b1 Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel at labath.sk>
Date: Fri, 8 Nov 2024 10:44:54 +0100
Subject: [PATCH] [lldb] Have disassembler show load addresses when using a
core file
We got a bug report that the disassember output was not relocated (i.e.
a load address) for a core file (like it is for a live process). It
turns out this behavior it depends on whether the instructions were read
from an executable file or from process memory (a core file will not
typically contain the memory image for segments backed by an executable
file).
It's unclear whether this behavior is intentional, or if it was just
trying to handle the case where we're dissassembling a module without a
process, but I think it's undesirable. What makes it particularly
confusing is that the instruction addresses are relocated in this case
(unlike the when we don't have a process), so with large files and
adresses it gets very hard to see whether the relocation has been
applied or not.
This patch removes the data_from_file check so that the instruction is
relocated regardless of where it was read from. It will still not get
relocated for the raw module use case, as those can't be relocated
anywhere as they don't have a load address.
---
.../Disassembler/LLVMC/DisassemblerLLVMC.cpp | 11 ++++------
.../Commands/command-disassemble-process.yaml | 20 +++++++++----------
.../test/Shell/Commands/command-disassemble.s | 10 +++++-----
3 files changed, 19 insertions(+), 22 deletions(-)
diff --git a/lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp b/lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
index 31edd8d46c444e..08264d837f9c23 100644
--- a/lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
+++ b/lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
@@ -583,7 +583,6 @@ class InstructionLLVMC : public lldb_private::Instruction {
lldb::addr_t pc = m_address.GetFileAddress();
m_using_file_addr = true;
- const bool data_from_file = disasm->m_data_from_file;
bool use_hex_immediates = true;
Disassembler::HexImmediateStyle hex_style = Disassembler::eHexStyleC;
@@ -593,12 +592,10 @@ class InstructionLLVMC : public lldb_private::Instruction {
use_hex_immediates = target->GetUseHexImmediates();
hex_style = target->GetHexImmediateStyle();
- if (!data_from_file) {
- const lldb::addr_t load_addr = m_address.GetLoadAddress(target);
- if (load_addr != LLDB_INVALID_ADDRESS) {
- pc = load_addr;
- m_using_file_addr = false;
- }
+ const lldb::addr_t load_addr = m_address.GetLoadAddress(target);
+ if (load_addr != LLDB_INVALID_ADDRESS) {
+ pc = load_addr;
+ m_using_file_addr = false;
}
}
}
diff --git a/lldb/test/Shell/Commands/command-disassemble-process.yaml b/lldb/test/Shell/Commands/command-disassemble-process.yaml
index 75be1a42fb196d..ce1b37bc8aea7a 100644
--- a/lldb/test/Shell/Commands/command-disassemble-process.yaml
+++ b/lldb/test/Shell/Commands/command-disassemble-process.yaml
@@ -20,7 +20,7 @@
# CHECK: (lldb) disassemble
# CHECK-NEXT: command-disassemble-process.exe`main:
-# CHECK-NEXT: 0x4002 <+0>: addb %al, (%rcx)
+# CHECK-NEXT: 0x4002 <+0>: jmp 0x4004 ; <+2>
# CHECK-NEXT: -> 0x4004 <+2>: addb %al, (%rdx)
# CHECK-NEXT: 0x4006 <+4>: addb %al, (%rbx)
# CHECK-NEXT: 0x4008 <+6>: addb %al, (%rsi)
@@ -32,7 +32,7 @@
# CHECK-NEXT: 0x400a: addb %al, (%rdi)
# CHECK-NEXT: (lldb) disassemble --frame
# CHECK-NEXT: command-disassemble-process.exe`main:
-# CHECK-NEXT: 0x4002 <+0>: addb %al, (%rcx)
+# CHECK-NEXT: 0x4002 <+0>: jmp 0x4004 ; <+2>
# CHECK-NEXT: -> 0x4004 <+2>: addb %al, (%rdx)
# CHECK-NEXT: 0x4006 <+4>: addb %al, (%rbx)
# CHECK-NEXT: 0x4008 <+6>: addb %al, (%rsi)
@@ -44,13 +44,13 @@
# CHECK-NEXT: 0x400a: addb %al, (%rdi)
# CHECK-NEXT: (lldb) disassemble --address 0x4004
# CHECK-NEXT: command-disassemble-process.exe`main:
-# CHECK-NEXT: 0x4002 <+0>: addb %al, (%rcx)
+# CHECK-NEXT: 0x4002 <+0>: jmp 0x4004 ; <+2>
# CHECK-NEXT: -> 0x4004 <+2>: addb %al, (%rdx)
# CHECK-NEXT: 0x4006 <+4>: addb %al, (%rbx)
# CHECK-NEXT: 0x4008 <+6>: addb %al, (%rsi)
# CHECK-NEXT: (lldb) disassemble --count 7
# CHECK-NEXT: command-disassemble-process.exe`main:
-# CHECK-NEXT: 0x4002 <+0>: addb %al, (%rcx)
+# CHECK-NEXT: 0x4002 <+0>: jmp 0x4004 ; <+2>
# CHECK-NEXT: -> 0x4004 <+2>: addb %al, (%rdx)
# CHECK-NEXT: 0x4006 <+4>: addb %al, (%rbx)
# CHECK-NEXT: 0x4008 <+6>: addb %al, (%rsi)
@@ -81,32 +81,32 @@ Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
- Address: 0x0000000000004000
+ Address: 0x0000000000000000
AddressAlign: 0x0000000000001000
- Content: 00000001000200030006000700080009000A000B000E000F00100011001200130016001700180019001A001B001E001F00200021002200230026002700280029002A002B002E002F
+ Content: 0000EB00000200030006000700080009000A000B000E000F00100011001200130016001700180019001A001B001E001F00200021002200230026002700280029002A002B002E002F
Size: 0x10000
- Name: .note.gnu.build-id
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
- Address: 0x0000000000005000
+ Address: 0x0000000000001000
AddressAlign: 0x0000000000001000
Content: 040000000800000003000000474E5500DEADBEEFBAADF00D
Symbols:
- Name: main
Type: STT_FUNC
Section: .text
- Value: 0x0000000000004002
+ Value: 0x0000000000000002
Size: [[MAIN_SIZE]]
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_X, PF_R ]
- VAddr: 0x4000
+ VAddr: 0x0000
Align: 0x1000
FirstSec: .text
LastSec: .text
- Type: PT_LOAD
Flags: [ PF_W, PF_R ]
- VAddr: 0x5000
+ VAddr: 0x1000
Align: 0x1000
FirstSec: .note.gnu.build-id
LastSec: .note.gnu.build-id
diff --git a/lldb/test/Shell/Commands/command-disassemble.s b/lldb/test/Shell/Commands/command-disassemble.s
index 10ce8354025ac5..1625f80468eb17 100644
--- a/lldb/test/Shell/Commands/command-disassemble.s
+++ b/lldb/test/Shell/Commands/command-disassemble.s
@@ -15,7 +15,7 @@
# CHECK-NEXT: error: Cannot disassemble around the current PC without a selected frame: no currently running process.
# CHECK-NEXT: (lldb) disassemble --start-address 0x0
# CHECK-NEXT: command-disassemble.s.tmp`foo:
-# CHECK-NEXT: command-disassemble.s.tmp[0x0] <+0>: int $0x10
+# CHECK-NEXT: command-disassemble.s.tmp[0x0] <+0>: jmp 0x2 ; <+2>
# CHECK-NEXT: command-disassemble.s.tmp[0x2] <+2>: int $0x11
# CHECK-NEXT: command-disassemble.s.tmp[0x4] <+4>: int $0x12
# CHECK-NEXT: command-disassemble.s.tmp[0x6] <+6>: int $0x13
@@ -41,7 +41,7 @@
# CHECK-NEXT: error: End address before start address.
# CHECK-NEXT: (lldb) disassemble --address 0x0
# CHECK-NEXT: command-disassemble.s.tmp`foo:
-# CHECK-NEXT: command-disassemble.s.tmp[0x0] <+0>: int $0x10
+# CHECK-NEXT: command-disassemble.s.tmp[0x0] <+0>: jmp 0x2 ; <+2>
# CHECK-NEXT: command-disassemble.s.tmp[0x2] <+2>: int $0x11
# CHECK-NEXT: command-disassemble.s.tmp[0x4] <+4>: int $0x12
# CHECK-NEXT: command-disassemble.s.tmp[0x6] <+6>: int $0x13
@@ -63,7 +63,7 @@
# CHECK: command-disassemble.s.tmp[0x203e] <+8190>: int $0x2a
# CHECK-NEXT: (lldb) disassemble --start-address 0x0 --count 7
# CHECK-NEXT: command-disassemble.s.tmp`foo:
-# CHECK-NEXT: command-disassemble.s.tmp[0x0] <+0>: int $0x10
+# CHECK-NEXT: command-disassemble.s.tmp[0x0] <+0>: jmp 0x2 ; <+2>
# CHECK-NEXT: command-disassemble.s.tmp[0x2] <+2>: int $0x11
# CHECK-NEXT: command-disassemble.s.tmp[0x4] <+4>: int $0x12
# CHECK-NEXT: command-disassemble.s.tmp[0x6] <+6>: int $0x13
@@ -101,8 +101,8 @@
.text
foo:
- int $0x10
- int $0x11
+ jmp 1f
+1: int $0x11
int $0x12
int $0x13
int $0x14
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