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Currently, lldb's unwinder ignores cfi_restore opcodes for registers
that are not set in the first row of the unwinding info. This prevents
unwinding of failed assertion in Chrome/v8 (https://github.com/v8/v8).
The attached test is an x64 copy of v8's function that failed to unwind
correctly.
This patch changes handling of cfi_restore to reset the location if
the first unwind table row does not map the restored register.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D153043
Files:
lldb/source/Symbol/DWARFCallFrameInfo.cpp
lldb/test/Shell/Unwind/Inputs/eh-frame-dwarf-unwind-abort.s
lldb/test/Shell/Unwind/eh-frame-dwarf-unwind-abort.test
Index: lldb/test/Shell/Unwind/eh-frame-dwarf-unwind-abort.test
===================================================================
--- /dev/null
+++ lldb/test/Shell/Unwind/eh-frame-dwarf-unwind-abort.test
@@ -0,0 +1,21 @@
+# Test restoring of register values.
+
+# UNSUPPORTED: system-windows
+# REQUIRES: target-x86_64, native
+
+# RUN: %clang_host %p/Inputs/call-asm.c
%p/Inputs/eh-frame-dwarf-unwind-abort.s -o %t
+# RUN: %lldb %t -s %s -o exit | FileCheck %s
+
+process launch
+# CHECK: stop reason = signal SIGTRAP
+
+thread backtrace
+# CHECK: frame #0: {{.*}}`asm_main + 23
+# CHECK: frame #1: {{.*}}`main + {{.*}}
+
+target modules show-unwind -n asm_main
+# CHECK: eh_frame UnwindPlan:
+# CHECK: row[0]: 0: CFA=rsp +8 => rip=[CFA-8]
+# CHECK: row[1]: 14: CFA=rsp+16 => rbp=[CFA-16] rip=[CFA-8]
+# CHECK: row[2]: 17: CFA=rbp+16 => rbp=[CFA-16] rip=[CFA-8]
+# CHECK: row[3]: 22: CFA=rsp +8 => rip=[CFA-8]
Index: lldb/test/Shell/Unwind/Inputs/eh-frame-dwarf-unwind-abort.s
===================================================================
--- /dev/null
+++ lldb/test/Shell/Unwind/Inputs/eh-frame-dwarf-unwind-abort.s
@@ -0,0 +1,25 @@
+ .text
+ .globl asm_main
+asm_main:
+ .cfi_startproc
+ cmpb $0x0, g_hard_abort(%rip)
+ jne .L
+
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset 6, -16
+ movq %rsp, %rbp
+ .cfi_def_cfa_register 6
+ callq abort
+.L:
+ .cfi_def_cfa 7, 8
+ .cfi_restore 6
+ int3
+ ud2
+ .cfi_endproc
+
+ .data
+ .globl g_hard_abort
+g_hard_abort:
+ .byte 1
+ .size g_hard_abort, 1
\ No newline at end of file
Index: lldb/source/Symbol/DWARFCallFrameInfo.cpp
===================================================================
--- lldb/source/Symbol/DWARFCallFrameInfo.cpp
+++ lldb/source/Symbol/DWARFCallFrameInfo.cpp
@@ -674,6 +674,8 @@
unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num,
reg_location))
row->SetRegisterInfo(reg_num, reg_location);
+ else
+ row->RemoveRegisterInfo(reg_num);
break;
}
}
Index: lldb/test/Shell/Unwind/eh-frame-dwarf-unwind-abort.test
===================================================================
--- /dev/null
+++ lldb/test/Shell/Unwind/eh-frame-dwarf-unwind-abort.test
@@ -0,0 +1,21 @@
+# Test restoring of register values.
+
+# UNSUPPORTED: system-windows
+# REQUIRES: target-x86_64, native
+
+# RUN: %clang_host %p/Inputs/call-asm.c %p/Inputs/eh-frame-dwarf-unwind-abort.s -o %t
+# RUN: %lldb %t -s %s -o exit | FileCheck %s
+
+process launch
+# CHECK: stop reason = signal SIGTRAP
+
+thread backtrace
+# CHECK: frame #0: {{.*}}`asm_main + 23
+# CHECK: frame #1: {{.*}}`main + {{.*}}
+
+target modules show-unwind -n asm_main
+# CHECK: eh_frame UnwindPlan:
+# CHECK: row[0]: 0: CFA=rsp +8 => rip=[CFA-8]
+# CHECK: row[1]: 14: CFA=rsp+16 => rbp=[CFA-16] rip=[CFA-8]
+# CHECK: row[2]: 17: CFA=rbp+16 => rbp=[CFA-16] rip=[CFA-8]
+# CHECK: row[3]: 22: CFA=rsp +8 => rip=[CFA-8]
Index: lldb/test/Shell/Unwind/Inputs/eh-frame-dwarf-unwind-abort.s
===================================================================
--- /dev/null
+++ lldb/test/Shell/Unwind/Inputs/eh-frame-dwarf-unwind-abort.s
@@ -0,0 +1,25 @@
+ .text
+ .globl asm_main
+asm_main:
+ .cfi_startproc
+ cmpb $0x0, g_hard_abort(%rip)
+ jne .L
+
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset 6, -16
+ movq %rsp, %rbp
+ .cfi_def_cfa_register 6
+ callq abort
+.L:
+ .cfi_def_cfa 7, 8
+ .cfi_restore 6
+ int3
+ ud2
+ .cfi_endproc
+
+ .data
+ .globl g_hard_abort
+g_hard_abort:
+ .byte 1
+ .size g_hard_abort, 1
\ No newline at end of file
Index: lldb/source/Symbol/DWARFCallFrameInfo.cpp
===================================================================
--- lldb/source/Symbol/DWARFCallFrameInfo.cpp
+++ lldb/source/Symbol/DWARFCallFrameInfo.cpp
@@ -674,6 +674,8 @@
unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num,
reg_location))
row->SetRegisterInfo(reg_num, reg_location);
+ else
+ row->RemoveRegisterInfo(reg_num);
break;
}
}
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