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91ede0c6a4
The ORC format changed twice recently:
- Linux kernel commit ffb1b4a41016 ("x86/unwind/orc: Add 'signal' field
to ORC metadata") (in v6.3).
- Linux kernel commit fb799447ae29 ("x86,objtool: Split
UNWIND_HINT_EMPTY in two") (in v6.4).
The former went unnoticed because the change was subtle, and the latter
completely broke x86-64 kernel stack traces.
To handle this, let's "upgrade" the format to the latest version when we
load and sort the ORC information. This is more work upfront but avoids
needing to handle the version differences every time we use ORC to
unwind.
Unfortunately, ORC currently doesn't have any sort of versioning, so we
have to break the rule of not checking kernel versions. However, I have
a kernel patch pending merging that should fix this for the future.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
84 lines
2.3 KiB
C
84 lines
2.3 KiB
C
// 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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* @file
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*
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* ORC unwinder definitions.
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*
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* As of Linux v6.4, ORC is only defined for x86-64. This file assumes that the
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* overall format would be the same for other architectures other than
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* architecture-specific register numbers, but this may require reorganization
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* if that isn't the case.
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*
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* There are multiple versions of the ORC format:
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*
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* - Version 3 since since Linux kernel commit fb799447ae29 ("x86,objtool: Split
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* UNWIND_HINT_EMPTY in two") (in v6.4).
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* - Version 2 between that and Linux kernel commit ffb1b4a41016
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* ("x86/unwind/orc: Add 'signal' field to ORC metadata") (in v6.3).
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* - Version 1 before that, introduced in Linux kernel commit ee9f8fce9964
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* ("x86/unwind: Add the ORC unwinder") (in v4.14).
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*
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* (The version numbers are our own invention and aren't used upstream.)
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*
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* So far, the format changes only affect the interpretation of @ref
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* drgn_orc_entry::flags. The getters assume the latest version.
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*/
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#ifndef DRGN_ORC_H
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#define DRGN_ORC_H
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#include <stdbool.h>
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#include <stdint.h>
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struct drgn_orc_entry {
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int16_t sp_offset;
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int16_t bp_offset;
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/**
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* Bit layout by version:
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*
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* |Version| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10| 11|
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* |-------|---|---|---|---|---|---|---|---|---|---|---|---|
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* | 3| sp_reg |||| bp_reg |||| type ||| S |
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* | 2| sp_reg |||| bp_reg |||| type || S | E |
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* | 1| sp_reg |||| bp_reg |||| type || E | |
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*
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* S = signal
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* E = end
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*/
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uint16_t flags;
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};
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enum {
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// In versions 1 and 2, UNDEFINED and END_OF_STACK didn't exist, and
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// CALL = 0, REGS = 1, and REGS_PARTIAL = 2.
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DRGN_ORC_TYPE_UNDEFINED = 0,
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DRGN_ORC_TYPE_END_OF_STACK = 1,
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DRGN_ORC_TYPE_CALL = 2,
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DRGN_ORC_TYPE_REGS = 3,
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DRGN_ORC_TYPE_REGS_PARTIAL = 4,
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};
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static inline int drgn_orc_sp_reg(const struct drgn_orc_entry *orc)
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{
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return orc->flags & 0xf;
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}
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static inline int drgn_orc_bp_reg(const struct drgn_orc_entry *orc)
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{
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return (orc->flags >> 4) & 0xf;
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}
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static inline int drgn_orc_type(const struct drgn_orc_entry *orc)
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{
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return (orc->flags >> 8) & 0x7;
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}
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static inline bool drgn_orc_signal(const struct drgn_orc_entry *orc)
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{
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return orc->flags & 0x800;
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}
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#endif /* DRGN_ORC_H */
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