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https://github.com/JakeHillion/drgn.git
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185a5bf66d
It's difficult to automatically detect calling an invalid, non-NULL
pointer when getting a stack trace. This manually recreates what we do
for calls to NULL since commit 412ce956b0 ("libdrgn: x86_64: unwind
call when pc is 0"). This was used to debug the issue fixed by "net:
tcp: fix crashes trying to free half-baked MTU probes" [1].
1: https://lore.kernel.org/all/20231010173651.3990234-1-kuba@kernel.org/T/
Signed-off-by: Omar Sandoval <osandov@osandov.com>
47 lines
1.3 KiB
Python
47 lines
1.3 KiB
Python
#!/usr/bin/env drgn
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# Copyright (c) Meta Platforms, Inc. and affiliates.
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# SPDX-License-Identifier: LGPL-2.1-or-later
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"""
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Get a stack trace from a call to an invalid address on x86-64. drgn should do
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this automatically eventually.
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"""
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from drgn import Object
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def pt_regs_members_from_stack_frame(frame):
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regs = frame.registers()
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return {
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"r15": regs.get("r15", 0),
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"r14": regs.get("r14", 0),
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"r13": regs.get("r13", 0),
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"r12": regs.get("r12", 0),
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"bp": regs.get("rbp", 0),
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"bx": regs.get("rbx", 0),
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"r11": regs.get("r11", 0),
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"r10": regs.get("r10", 0),
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"r9": regs.get("r9", 0),
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"r8": regs.get("r8", 0),
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"ax": regs.get("rax", 0),
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"cx": regs.get("rcx", 0),
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"dx": regs.get("rdx", 0),
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"si": regs.get("rsi", 0),
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"di": regs.get("rdi", 0),
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"orig_ax": -1,
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"ip": regs.get("rip", 0),
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"cs": regs.get("cs", 0),
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"flags": regs.get("rflags", 0),
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"sp": regs.get("rsp", 0),
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"ss": regs.get("ss", 0),
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}
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pt_regs_members = pt_regs_members_from_stack_frame(
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prog.crashed_thread().stack_trace()[0]
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)
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pt_regs_members["ip"] = prog.read_word(pt_regs_members["sp"]) - 1
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pt_regs_members["sp"] += 8
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trace = prog.stack_trace(Object(prog, "struct pt_regs", pt_regs_members))
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print(trace)
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