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ee9f8fce99
Add the new ORC unwinder which is enabled by CONFIG_ORC_UNWINDER=y. It plugs into the existing x86 unwinder framework. It relies on objtool to generate the needed .orc_unwind and .orc_unwind_ip sections. For more details on why ORC is used instead of DWARF, see Documentation/x86/orc-unwinder.txt - but the short version is that it's a simplified, fundamentally more robust debugninfo data structure, which also allows up to two orders of magnitude faster lookups than the DWARF unwinder - which matters to profiling workloads like perf. Thanks to Andy Lutomirski for the performance improvement ideas: splitting the ORC unwind table into two parallel arrays and creating a fast lookup table to search a subset of the unwind table. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/0a6cbfb40f8da99b7a45a1a8302dc6aef16ec812.1500938583.git.jpoimboe@redhat.com [ Extended the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
107 lines
3.5 KiB
C
107 lines
3.5 KiB
C
/*
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* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _ORC_TYPES_H
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#define _ORC_TYPES_H
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#include <linux/types.h>
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#include <linux/compiler.h>
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/*
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* The ORC_REG_* registers are base registers which are used to find other
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* registers on the stack.
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*
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* ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the
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* address of the previous frame: the caller's SP before it called the current
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* function.
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*
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* ORC_REG_UNDEFINED means the corresponding register's value didn't change in
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* the current frame.
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*
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* The most commonly used base registers are SP and BP -- which the previous SP
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* is usually based on -- and PREV_SP and UNDEFINED -- which the previous BP is
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* usually based on.
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*
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* The rest of the base registers are needed for special cases like entry code
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* and GCC realigned stacks.
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*/
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#define ORC_REG_UNDEFINED 0
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#define ORC_REG_PREV_SP 1
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#define ORC_REG_DX 2
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#define ORC_REG_DI 3
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#define ORC_REG_BP 4
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#define ORC_REG_SP 5
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#define ORC_REG_R10 6
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#define ORC_REG_R13 7
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#define ORC_REG_BP_INDIRECT 8
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#define ORC_REG_SP_INDIRECT 9
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#define ORC_REG_MAX 15
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/*
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* ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the
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* caller's SP right before it made the call). Used for all callable
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* functions, i.e. all C code and all callable asm functions.
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*
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* ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points
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* to a fully populated pt_regs from a syscall, interrupt, or exception.
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*
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* ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset
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* points to the iret return frame.
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*
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* The UNWIND_HINT macros are used only for the unwind_hint struct. They
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* aren't used in struct orc_entry due to size and complexity constraints.
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* Objtool converts them to real types when it converts the hints to orc
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* entries.
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*/
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#define ORC_TYPE_CALL 0
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#define ORC_TYPE_REGS 1
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#define ORC_TYPE_REGS_IRET 2
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#define UNWIND_HINT_TYPE_SAVE 3
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#define UNWIND_HINT_TYPE_RESTORE 4
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#ifndef __ASSEMBLY__
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/*
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* This struct is more or less a vastly simplified version of the DWARF Call
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* Frame Information standard. It contains only the necessary parts of DWARF
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* CFI, simplified for ease of access by the in-kernel unwinder. It tells the
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* unwinder how to find the previous SP and BP (and sometimes entry regs) on
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* the stack for a given code address. Each instance of the struct corresponds
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* to one or more code locations.
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*/
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struct orc_entry {
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s16 sp_offset;
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s16 bp_offset;
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unsigned sp_reg:4;
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unsigned bp_reg:4;
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unsigned type:2;
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} __packed;
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/*
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* This struct is used by asm and inline asm code to manually annotate the
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* location of registers on the stack for the ORC unwinder.
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*
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* Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*.
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*/
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struct unwind_hint {
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u32 ip;
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s16 sp_offset;
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u8 sp_reg;
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u8 type;
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};
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#endif /* __ASSEMBLY__ */
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#endif /* _ORC_TYPES_H */
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