-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Josh Poimboeuf <jpoimboe@redhat.com>
-Date: Mon, 24 Jul 2017 18:36:57 -0500
-Subject: [PATCH] x86/unwind: Add the ORC unwinder
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-CVE-2017-5754
-
-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>
-(cherry picked from commit ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67)
-Signed-off-by: Andy Whitcroft <apw@canonical.com>
-Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
-(cherry picked from commit dccbf63d7a6cc431af23a86e28275a74904545cd)
-Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
----
- Documentation/x86/orc-unwinder.txt | 179 ++++++++++++
- arch/x86/kernel/Makefile | 8 +-
- scripts/Makefile.build | 14 +-
- arch/um/include/asm/unwind.h | 8 +
- arch/x86/include/asm/module.h | 9 +
- arch/x86/include/asm/orc_lookup.h | 46 +++
- arch/x86/include/asm/orc_types.h | 2 +-
- arch/x86/include/asm/unwind.h | 76 +++--
- include/asm-generic/vmlinux.lds.h | 27 +-
- arch/x86/kernel/module.c | 11 +-
- arch/x86/kernel/setup.c | 3 +
- arch/x86/kernel/unwind_frame.c | 39 +--
- arch/x86/kernel/unwind_guess.c | 5 +
- arch/x86/kernel/unwind_orc.c | 582 +++++++++++++++++++++++++++++++++++++
- arch/x86/Kconfig | 1 +
- arch/x86/Kconfig.debug | 25 ++
- arch/x86/kernel/vmlinux.lds.S | 3 +
- lib/Kconfig.debug | 3 +
- 18 files changed, 977 insertions(+), 64 deletions(-)
- create mode 100644 Documentation/x86/orc-unwinder.txt
- create mode 100644 arch/um/include/asm/unwind.h
- create mode 100644 arch/x86/include/asm/orc_lookup.h
- create mode 100644 arch/x86/kernel/unwind_orc.c
-
-diff --git a/Documentation/x86/orc-unwinder.txt b/Documentation/x86/orc-unwinder.txt
-new file mode 100644
-index 000000000000..af0c9a4c65a6
---- /dev/null
-+++ b/Documentation/x86/orc-unwinder.txt
-@@ -0,0 +1,179 @@
-+ORC unwinder
-+============
-+
-+Overview
-+--------
-+
-+The kernel CONFIG_ORC_UNWINDER option enables the ORC unwinder, which is
-+similar in concept to a DWARF unwinder. The difference is that the
-+format of the ORC data is much simpler than DWARF, which in turn allows
-+the ORC unwinder to be much simpler and faster.
-+
-+The ORC data consists of unwind tables which are generated by objtool.
-+They contain out-of-band data which is used by the in-kernel ORC
-+unwinder. Objtool generates the ORC data by first doing compile-time
-+stack metadata validation (CONFIG_STACK_VALIDATION). After analyzing
-+all the code paths of a .o file, it determines information about the
-+stack state at each instruction address in the file and outputs that
-+information to the .orc_unwind and .orc_unwind_ip sections.
-+
-+The per-object ORC sections are combined at link time and are sorted and
-+post-processed at boot time. The unwinder uses the resulting data to
-+correlate instruction addresses with their stack states at run time.
-+
-+
-+ORC vs frame pointers
-+---------------------
-+
-+With frame pointers enabled, GCC adds instrumentation code to every
-+function in the kernel. The kernel's .text size increases by about
-+3.2%, resulting in a broad kernel-wide slowdown. Measurements by Mel
-+Gorman [1] have shown a slowdown of 5-10% for some workloads.
-+
-+In contrast, the ORC unwinder has no effect on text size or runtime
-+performance, because the debuginfo is out of band. So if you disable
-+frame pointers and enable the ORC unwinder, you get a nice performance
-+improvement across the board, and still have reliable stack traces.
-+
-+Ingo Molnar says:
-+
-+ "Note that it's not just a performance improvement, but also an
-+ instruction cache locality improvement: 3.2% .text savings almost
-+ directly transform into a similarly sized reduction in cache
-+ footprint. That can transform to even higher speedups for workloads
-+ whose cache locality is borderline."
-+
-+Another benefit of ORC compared to frame pointers is that it can
-+reliably unwind across interrupts and exceptions. Frame pointer based
-+unwinds can sometimes skip the caller of the interrupted function, if it
-+was a leaf function or if the interrupt hit before the frame pointer was
-+saved.
-+
-+The main disadvantage of the ORC unwinder compared to frame pointers is
-+that it needs more memory to store the ORC unwind tables: roughly 2-4MB
-+depending on the kernel config.
-+
-+
-+ORC vs DWARF
-+------------
-+
-+ORC debuginfo's advantage over DWARF itself is that it's much simpler.
-+It gets rid of the complex DWARF CFI state machine and also gets rid of
-+the tracking of unnecessary registers. This allows the unwinder to be
-+much simpler, meaning fewer bugs, which is especially important for
-+mission critical oops code.
-+
-+The simpler debuginfo format also enables the unwinder to be much faster
-+than DWARF, which is important for perf and lockdep. In a basic
-+performance test by Jiri Slaby [2], the ORC unwinder was about 20x
-+faster than an out-of-tree DWARF unwinder. (Note: That measurement was
-+taken before some performance tweaks were added, which doubled
-+performance, so the speedup over DWARF may be closer to 40x.)
-+
-+The ORC data format does have a few downsides compared to DWARF. ORC
-+unwind tables take up ~50% more RAM (+1.3MB on an x86 defconfig kernel)
-+than DWARF-based eh_frame tables.
-+
-+Another potential downside is that, as GCC evolves, it's conceivable
-+that the ORC data may end up being *too* simple to describe the state of
-+the stack for certain optimizations. But IMO this is unlikely because
-+GCC saves the frame pointer for any unusual stack adjustments it does,
-+so I suspect we'll really only ever need to keep track of the stack
-+pointer and the frame pointer between call frames. But even if we do
-+end up having to track all the registers DWARF tracks, at least we will
-+still be able to control the format, e.g. no complex state machines.
-+
-+
-+ORC unwind table generation
-+---------------------------
-+
-+The ORC data is generated by objtool. With the existing compile-time
-+stack metadata validation feature, objtool already follows all code
-+paths, and so it already has all the information it needs to be able to
-+generate ORC data from scratch. So it's an easy step to go from stack
-+validation to ORC data generation.
-+
-+It should be possible to instead generate the ORC data with a simple
-+tool which converts DWARF to ORC data. However, such a solution would
-+be incomplete due to the kernel's extensive use of asm, inline asm, and
-+special sections like exception tables.
-+
-+That could be rectified by manually annotating those special code paths
-+using GNU assembler .cfi annotations in .S files, and homegrown
-+annotations for inline asm in .c files. But asm annotations were tried
-+in the past and were found to be unmaintainable. They were often
-+incorrect/incomplete and made the code harder to read and keep updated.
-+And based on looking at glibc code, annotating inline asm in .c files
-+might be even worse.
-+
-+Objtool still needs a few annotations, but only in code which does
-+unusual things to the stack like entry code. And even then, far fewer
-+annotations are needed than what DWARF would need, so they're much more
-+maintainable than DWARF CFI annotations.
-+
-+So the advantages of using objtool to generate ORC data are that it
-+gives more accurate debuginfo, with very few annotations. It also
-+insulates the kernel from toolchain bugs which can be very painful to
-+deal with in the kernel since we often have to workaround issues in
-+older versions of the toolchain for years.
-+
-+The downside is that the unwinder now becomes dependent on objtool's
-+ability to reverse engineer GCC code flow. If GCC optimizations become
-+too complicated for objtool to follow, the ORC data generation might
-+stop working or become incomplete. (It's worth noting that livepatch
-+already has such a dependency on objtool's ability to follow GCC code
-+flow.)
-+
-+If newer versions of GCC come up with some optimizations which break
-+objtool, we may need to revisit the current implementation. Some
-+possible solutions would be asking GCC to make the optimizations more
-+palatable, or having objtool use DWARF as an additional input, or
-+creating a GCC plugin to assist objtool with its analysis. But for now,
-+objtool follows GCC code quite well.
-+
-+
-+Unwinder implementation details
-+-------------------------------
-+
-+Objtool generates the ORC data by integrating with the compile-time
-+stack metadata validation feature, which is described in detail in
-+tools/objtool/Documentation/stack-validation.txt. After analyzing all
-+the code paths of a .o file, it creates an array of orc_entry structs,
-+and a parallel array of instruction addresses associated with those
-+structs, and writes them to the .orc_unwind and .orc_unwind_ip sections
-+respectively.
-+
-+The ORC data is split into the two arrays for performance reasons, to
-+make the searchable part of the data (.orc_unwind_ip) more compact. The
-+arrays are sorted in parallel at boot time.
-+
-+Performance is further improved by the use of a fast lookup table which
-+is created at runtime. The fast lookup table associates a given address
-+with a range of indices for the .orc_unwind table, so that only a small
-+subset of the table needs to be searched.
-+
-+
-+Etymology
-+---------
-+
-+Orcs, fearsome creatures of medieval folklore, are the Dwarves' natural
-+enemies. Similarly, the ORC unwinder was created in opposition to the
-+complexity and slowness of DWARF.
-+
-+"Although Orcs rarely consider multiple solutions to a problem, they do
-+excel at getting things done because they are creatures of action, not
-+thought." [3] Similarly, unlike the esoteric DWARF unwinder, the
-+veracious ORC unwinder wastes no time or siloconic effort decoding
-+variable-length zero-extended unsigned-integer byte-coded
-+state-machine-based debug information entries.
-+
-+Similar to how Orcs frequently unravel the well-intentioned plans of
-+their adversaries, the ORC unwinder frequently unravels stacks with
-+brutal, unyielding efficiency.
-+
-+ORC stands for Oops Rewind Capability.
-+
-+
-+[1] https://lkml.kernel.org/r/20170602104048.jkkzssljsompjdwy@suse.de
-+[2] https://lkml.kernel.org/r/d2ca5435-6386-29b8-db87-7f227c2b713a@suse.cz
-+[3] http://dustin.wikidot.com/half-orcs-and-orcs
-diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
-index a01892bdd61a..287eac7d207f 100644
---- a/arch/x86/kernel/Makefile
-+++ b/arch/x86/kernel/Makefile
-@@ -126,11 +126,9 @@ obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
- obj-$(CONFIG_TRACING) += tracepoint.o
- obj-$(CONFIG_SCHED_MC_PRIO) += itmt.o
-
--ifdef CONFIG_FRAME_POINTER
--obj-y += unwind_frame.o
--else
--obj-y += unwind_guess.o
--endif
-+obj-$(CONFIG_ORC_UNWINDER) += unwind_orc.o
-+obj-$(CONFIG_FRAME_POINTER_UNWINDER) += unwind_frame.o
-+obj-$(CONFIG_GUESS_UNWINDER) += unwind_guess.o
-
- ###
- # 64 bit specific files
-diff --git a/scripts/Makefile.build b/scripts/Makefile.build
-index 273bc2228307..ab2c8ef43cdb 100644
---- a/scripts/Makefile.build
-+++ b/scripts/Makefile.build
-@@ -258,7 +258,8 @@ ifneq ($(SKIP_STACK_VALIDATION),1)
-
- __objtool_obj := $(objtree)/tools/objtool/objtool
-
--objtool_args = check
-+objtool_args = $(if $(CONFIG_ORC_UNWINDER),orc generate,check)
-+
- ifndef CONFIG_FRAME_POINTER
- objtool_args += --no-fp
- endif
-@@ -276,6 +277,11 @@ objtool_obj = $(if $(patsubst y%,, \
- endif # SKIP_STACK_VALIDATION
- endif # CONFIG_STACK_VALIDATION
-
-+# Rebuild all objects when objtool changes, or is enabled/disabled.
-+objtool_dep = $(objtool_obj) \
-+ $(wildcard include/config/orc/unwinder.h \
-+ include/config/stack/validation.h)
-+
- define rule_cc_o_c
- $(call echo-cmd,checksrc) $(cmd_checksrc) \
- $(call cmd_and_fixdep,cc_o_c) \
-@@ -298,14 +304,14 @@ cmd_undef_syms = echo
- endif
-
- # Built-in and composite module parts
--$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
-+$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
- $(call cmd,force_checksrc)
- $(call cmd,force_check_kmsg)
- $(call if_changed_rule,cc_o_c)
-
- # Single-part modules are special since we need to mark them in $(MODVERDIR)
-
--$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
-+$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
- $(call cmd,force_checksrc)
- $(call cmd,force_check_kmsg)
- $(call if_changed_rule,cc_o_c)
-@@ -401,7 +407,7 @@ cmd_modversions_S = \
- endif
- endif
-
--$(obj)/%.o: $(src)/%.S $(objtool_obj) FORCE
-+$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
- $(call if_changed_rule,as_o_S)
-
- targets += $(real-objs-y) $(real-objs-m) $(lib-y)
-diff --git a/arch/um/include/asm/unwind.h b/arch/um/include/asm/unwind.h
-new file mode 100644
-index 000000000000..7ffa5437b761
---- /dev/null
-+++ b/arch/um/include/asm/unwind.h
-@@ -0,0 +1,8 @@
-+#ifndef _ASM_UML_UNWIND_H
-+#define _ASM_UML_UNWIND_H
-+
-+static inline void
-+unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
-+ void *orc, size_t orc_size) {}
-+
-+#endif /* _ASM_UML_UNWIND_H */
-diff --git a/arch/x86/include/asm/module.h b/arch/x86/include/asm/module.h
-index e3b7819caeef..9eb7c718aaf8 100644
---- a/arch/x86/include/asm/module.h
-+++ b/arch/x86/include/asm/module.h
-@@ -2,6 +2,15 @@
- #define _ASM_X86_MODULE_H
-
- #include <asm-generic/module.h>
-+#include <asm/orc_types.h>
-+
-+struct mod_arch_specific {
-+#ifdef CONFIG_ORC_UNWINDER
-+ unsigned int num_orcs;
-+ int *orc_unwind_ip;
-+ struct orc_entry *orc_unwind;
-+#endif
-+};
-
- #ifdef CONFIG_X86_64
- /* X86_64 does not define MODULE_PROC_FAMILY */
-diff --git a/arch/x86/include/asm/orc_lookup.h b/arch/x86/include/asm/orc_lookup.h
-new file mode 100644
-index 000000000000..91c8d868424d
---- /dev/null
-+++ b/arch/x86/include/asm/orc_lookup.h
-@@ -0,0 +1,46 @@
-+/*
-+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
-+ *
-+ * This program is free software; you can redistribute it and/or
-+ * modify it under the terms of the GNU General Public License
-+ * as published by the Free Software Foundation; either version 2
-+ * of the License, or (at your option) any later version.
-+ *
-+ * This program is distributed in the hope that it will be useful,
-+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
-+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-+ * GNU General Public License for more details.
-+ *
-+ * You should have received a copy of the GNU General Public License
-+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
-+ */
-+#ifndef _ORC_LOOKUP_H
-+#define _ORC_LOOKUP_H
-+
-+/*
-+ * This is a lookup table for speeding up access to the .orc_unwind table.
-+ * Given an input address offset, the corresponding lookup table entry
-+ * specifies a subset of the .orc_unwind table to search.
-+ *
-+ * Each block represents the end of the previous range and the start of the
-+ * next range. An extra block is added to give the last range an end.
-+ *
-+ * The block size should be a power of 2 to avoid a costly 'div' instruction.
-+ *
-+ * A block size of 256 was chosen because it roughly doubles unwinder
-+ * performance while only adding ~5% to the ORC data footprint.
-+ */
-+#define LOOKUP_BLOCK_ORDER 8
-+#define LOOKUP_BLOCK_SIZE (1 << LOOKUP_BLOCK_ORDER)
-+
-+#ifndef LINKER_SCRIPT
-+
-+extern unsigned int orc_lookup[];
-+extern unsigned int orc_lookup_end[];
-+
-+#define LOOKUP_START_IP (unsigned long)_stext
-+#define LOOKUP_STOP_IP (unsigned long)_etext
-+
-+#endif /* LINKER_SCRIPT */
-+
-+#endif /* _ORC_LOOKUP_H */
-diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h
-index 7dc777a6cb40..9c9dc579bd7d 100644
---- a/arch/x86/include/asm/orc_types.h
-+++ b/arch/x86/include/asm/orc_types.h
-@@ -88,7 +88,7 @@ struct orc_entry {
- unsigned sp_reg:4;
- unsigned bp_reg:4;
- unsigned type:2;
--};
-+} __packed;
-
- /*
- * This struct is used by asm and inline asm code to manually annotate the
-diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
-index e6676495b125..25b8d31a007d 100644
---- a/arch/x86/include/asm/unwind.h
-+++ b/arch/x86/include/asm/unwind.h
-@@ -12,11 +12,14 @@ struct unwind_state {
- struct task_struct *task;
- int graph_idx;
- bool error;
--#ifdef CONFIG_FRAME_POINTER
-+#if defined(CONFIG_ORC_UNWINDER)
-+ bool signal, full_regs;
-+ unsigned long sp, bp, ip;
-+ struct pt_regs *regs;
-+#elif defined(CONFIG_FRAME_POINTER)
- bool got_irq;
-- unsigned long *bp, *orig_sp;
-+ unsigned long *bp, *orig_sp, ip;
- struct pt_regs *regs;
-- unsigned long ip;
- #else
- unsigned long *sp;
- #endif
-@@ -24,41 +27,30 @@ struct unwind_state {
-
- void __unwind_start(struct unwind_state *state, struct task_struct *task,
- struct pt_regs *regs, unsigned long *first_frame);
--
- bool unwind_next_frame(struct unwind_state *state);
--
- unsigned long unwind_get_return_address(struct unwind_state *state);
-+unsigned long *unwind_get_return_address_ptr(struct unwind_state *state);
-
- static inline bool unwind_done(struct unwind_state *state)
- {
- return state->stack_info.type == STACK_TYPE_UNKNOWN;
- }
-
--static inline
--void unwind_start(struct unwind_state *state, struct task_struct *task,
-- struct pt_regs *regs, unsigned long *first_frame)
--{
-- first_frame = first_frame ? : get_stack_pointer(task, regs);
--
-- __unwind_start(state, task, regs, first_frame);
--}
--
- static inline bool unwind_error(struct unwind_state *state)
- {
- return state->error;
- }
-
--#ifdef CONFIG_FRAME_POINTER
--
- static inline
--unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
-+void unwind_start(struct unwind_state *state, struct task_struct *task,
-+ struct pt_regs *regs, unsigned long *first_frame)
- {
-- if (unwind_done(state))
-- return NULL;
-+ first_frame = first_frame ? : get_stack_pointer(task, regs);
-
-- return state->regs ? &state->regs->ip : state->bp + 1;
-+ __unwind_start(state, task, regs, first_frame);
- }
-
-+#if defined(CONFIG_ORC_UNWINDER) || defined(CONFIG_FRAME_POINTER)
- static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
- {
- if (unwind_done(state))
-@@ -66,20 +58,46 @@ static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
-
- return state->regs;
- }
--
--#else /* !CONFIG_FRAME_POINTER */
--
--static inline
--unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
-+#else
-+static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
- {
- return NULL;
- }
-+#endif
-
--static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
-+#ifdef CONFIG_ORC_UNWINDER
-+void unwind_init(void);
-+void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
-+ void *orc, size_t orc_size);
-+#else
-+static inline void unwind_init(void) {}
-+static inline
-+void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
-+ void *orc, size_t orc_size) {}
-+#endif
-+
-+/*
-+ * This disables KASAN checking when reading a value from another task's stack,
-+ * since the other task could be running on another CPU and could have poisoned
-+ * the stack in the meantime.
-+ */
-+#define READ_ONCE_TASK_STACK(task, x) \
-+({ \
-+ unsigned long val; \
-+ if (task == current) \
-+ val = READ_ONCE(x); \
-+ else \
-+ val = READ_ONCE_NOCHECK(x); \
-+ val; \
-+})
-+
-+static inline bool task_on_another_cpu(struct task_struct *task)
- {
-- return NULL;
-+#ifdef CONFIG_SMP
-+ return task != current && task->on_cpu;
-+#else
-+ return false;
-+#endif
- }
-
--#endif /* CONFIG_FRAME_POINTER */
--
- #endif /* _ASM_X86_UNWIND_H */
-diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
-index e7e955d4ab9e..9fdb54a95976 100644
---- a/include/asm-generic/vmlinux.lds.h
-+++ b/include/asm-generic/vmlinux.lds.h
-@@ -686,6 +686,31 @@
- #define BUG_TABLE
- #endif
-
-+#ifdef CONFIG_ORC_UNWINDER
-+#define ORC_UNWIND_TABLE \
-+ . = ALIGN(4); \
-+ .orc_unwind_ip : AT(ADDR(.orc_unwind_ip) - LOAD_OFFSET) { \
-+ VMLINUX_SYMBOL(__start_orc_unwind_ip) = .; \
-+ KEEP(*(.orc_unwind_ip)) \
-+ VMLINUX_SYMBOL(__stop_orc_unwind_ip) = .; \
-+ } \
-+ . = ALIGN(6); \
-+ .orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \
-+ VMLINUX_SYMBOL(__start_orc_unwind) = .; \
-+ KEEP(*(.orc_unwind)) \
-+ VMLINUX_SYMBOL(__stop_orc_unwind) = .; \
-+ } \
-+ . = ALIGN(4); \
-+ .orc_lookup : AT(ADDR(.orc_lookup) - LOAD_OFFSET) { \
-+ VMLINUX_SYMBOL(orc_lookup) = .; \
-+ . += (((SIZEOF(.text) + LOOKUP_BLOCK_SIZE - 1) / \
-+ LOOKUP_BLOCK_SIZE) + 1) * 4; \
-+ VMLINUX_SYMBOL(orc_lookup_end) = .; \
-+ }
-+#else
-+#define ORC_UNWIND_TABLE
-+#endif
-+
- #ifdef CONFIG_PM_TRACE
- #define TRACEDATA \
- . = ALIGN(4); \
-@@ -872,7 +897,7 @@
- DATA_DATA \
- CONSTRUCTORS \
- } \
-- BUG_TABLE
-+ BUG_TABLE \
-
- #define INIT_TEXT_SECTION(inittext_align) \
- . = ALIGN(inittext_align); \
-diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
-index f67bd3205df7..62e7d70aadd5 100644
---- a/arch/x86/kernel/module.c
-+++ b/arch/x86/kernel/module.c
-@@ -35,6 +35,7 @@
- #include <asm/page.h>
- #include <asm/pgtable.h>
- #include <asm/setup.h>
-+#include <asm/unwind.h>
-
- #if 0
- #define DEBUGP(fmt, ...) \
-@@ -213,7 +214,7 @@ int module_finalize(const Elf_Ehdr *hdr,
- struct module *me)
- {
- const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
-- *para = NULL;
-+ *para = NULL, *orc = NULL, *orc_ip = NULL;
- char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
-
- for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
-@@ -225,6 +226,10 @@ int module_finalize(const Elf_Ehdr *hdr,
- locks = s;
- if (!strcmp(".parainstructions", secstrings + s->sh_name))
- para = s;
-+ if (!strcmp(".orc_unwind", secstrings + s->sh_name))
-+ orc = s;
-+ if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
-+ orc_ip = s;
- }
-
- if (alt) {
-@@ -248,6 +253,10 @@ int module_finalize(const Elf_Ehdr *hdr,
- /* make jump label nops */
- jump_label_apply_nops(me);
-
-+ if (orc && orc_ip)
-+ unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
-+ (void *)orc->sh_addr, orc->sh_size);
-+
- return 0;
- }
-
-diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
-index f964bfddfefd..dd6e8707e969 100644
---- a/arch/x86/kernel/setup.c
-+++ b/arch/x86/kernel/setup.c
-@@ -121,6 +121,7 @@
- #include <asm/microcode.h>
- #include <asm/mmu_context.h>
- #include <asm/kaslr.h>
-+#include <asm/unwind.h>
-
- /*
- * max_low_pfn_mapped: highest direct mapped pfn under 4GB
-@@ -1325,6 +1326,8 @@ void __init setup_arch(char **cmdline_p)
- if (efi_enabled(EFI_BOOT))
- efi_apply_memmap_quirks();
- #endif
-+
-+ unwind_init();
- }
-
- #ifdef CONFIG_X86_32
-diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
-index c29e5bc7e9c9..d145a0b1f529 100644
---- a/arch/x86/kernel/unwind_frame.c
-+++ b/arch/x86/kernel/unwind_frame.c
-@@ -10,20 +10,22 @@
-
- #define FRAME_HEADER_SIZE (sizeof(long) * 2)
-
--/*
-- * This disables KASAN checking when reading a value from another task's stack,
-- * since the other task could be running on another CPU and could have poisoned
-- * the stack in the meantime.
-- */
--#define READ_ONCE_TASK_STACK(task, x) \
--({ \
-- unsigned long val; \
-- if (task == current) \
-- val = READ_ONCE(x); \
-- else \
-- val = READ_ONCE_NOCHECK(x); \
-- val; \
--})
-+unsigned long unwind_get_return_address(struct unwind_state *state)
-+{
-+ if (unwind_done(state))
-+ return 0;
-+
-+ return __kernel_text_address(state->ip) ? state->ip : 0;
-+}
-+EXPORT_SYMBOL_GPL(unwind_get_return_address);
-+
-+unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
-+{
-+ if (unwind_done(state))
-+ return NULL;
-+
-+ return state->regs ? &state->regs->ip : state->bp + 1;
-+}
-
- static void unwind_dump(struct unwind_state *state)
- {
-@@ -66,15 +68,6 @@ static void unwind_dump(struct unwind_state *state)
- }
- }
-
--unsigned long unwind_get_return_address(struct unwind_state *state)
--{
-- if (unwind_done(state))
-- return 0;
--
-- return __kernel_text_address(state->ip) ? state->ip : 0;
--}
--EXPORT_SYMBOL_GPL(unwind_get_return_address);
--
- static size_t regs_size(struct pt_regs *regs)
- {
- /* x86_32 regs from kernel mode are two words shorter: */
-diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c
-index 039f36738e49..4f0e17b90463 100644
---- a/arch/x86/kernel/unwind_guess.c
-+++ b/arch/x86/kernel/unwind_guess.c
-@@ -19,6 +19,11 @@ unsigned long unwind_get_return_address(struct unwind_state *state)
- }
- EXPORT_SYMBOL_GPL(unwind_get_return_address);
-
-+unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
-+{
-+ return NULL;
-+}
-+
- bool unwind_next_frame(struct unwind_state *state)
- {
- struct stack_info *info = &state->stack_info;
-diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
-new file mode 100644
-index 000000000000..570b70d3f604
---- /dev/null
-+++ b/arch/x86/kernel/unwind_orc.c
-@@ -0,0 +1,582 @@
-+#include <linux/module.h>
-+#include <linux/sort.h>
-+#include <asm/ptrace.h>
-+#include <asm/stacktrace.h>
-+#include <asm/unwind.h>
-+#include <asm/orc_types.h>
-+#include <asm/orc_lookup.h>
-+#include <asm/sections.h>
-+
-+#define orc_warn(fmt, ...) \
-+ printk_deferred_once(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__)
-+
-+extern int __start_orc_unwind_ip[];
-+extern int __stop_orc_unwind_ip[];
-+extern struct orc_entry __start_orc_unwind[];
-+extern struct orc_entry __stop_orc_unwind[];
-+
-+static DEFINE_MUTEX(sort_mutex);
-+int *cur_orc_ip_table = __start_orc_unwind_ip;
-+struct orc_entry *cur_orc_table = __start_orc_unwind;
-+
-+unsigned int lookup_num_blocks;
-+bool orc_init;
-+
-+static inline unsigned long orc_ip(const int *ip)
-+{
-+ return (unsigned long)ip + *ip;
-+}
-+
-+static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
-+ unsigned int num_entries, unsigned long ip)
-+{
-+ int *first = ip_table;
-+ int *last = ip_table + num_entries - 1;
-+ int *mid = first, *found = first;
-+
-+ if (!num_entries)
-+ return NULL;
-+
-+ /*
-+ * Do a binary range search to find the rightmost duplicate of a given
-+ * starting address. Some entries are section terminators which are
-+ * "weak" entries for ensuring there are no gaps. They should be
-+ * ignored when they conflict with a real entry.
-+ */
-+ while (first <= last) {
-+ mid = first + ((last - first) / 2);
-+
-+ if (orc_ip(mid) <= ip) {
-+ found = mid;
-+ first = mid + 1;
-+ } else
-+ last = mid - 1;
-+ }
-+
-+ return u_table + (found - ip_table);
-+}
-+
-+#ifdef CONFIG_MODULES
-+static struct orc_entry *orc_module_find(unsigned long ip)
-+{
-+ struct module *mod;
-+
-+ mod = __module_address(ip);
-+ if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip)
-+ return NULL;
-+ return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind,
-+ mod->arch.num_orcs, ip);
-+}
-+#else
-+static struct orc_entry *orc_module_find(unsigned long ip)
-+{
-+ return NULL;
-+}
-+#endif
-+
-+static struct orc_entry *orc_find(unsigned long ip)
-+{
-+ if (!orc_init)
-+ return NULL;
-+
-+ /* For non-init vmlinux addresses, use the fast lookup table: */
-+ if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
-+ unsigned int idx, start, stop;
-+
-+ idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
-+
-+ if (unlikely((idx >= lookup_num_blocks-1))) {
-+ orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%lx\n",
-+ idx, lookup_num_blocks, ip);
-+ return NULL;
-+ }
-+
-+ start = orc_lookup[idx];
-+ stop = orc_lookup[idx + 1] + 1;
-+
-+ if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) ||
-+ (__start_orc_unwind + stop > __stop_orc_unwind))) {
-+ orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%lx\n",
-+ idx, lookup_num_blocks, start, stop, ip);
-+ return NULL;
-+ }
-+
-+ return __orc_find(__start_orc_unwind_ip + start,
-+ __start_orc_unwind + start, stop - start, ip);
-+ }
-+
-+ /* vmlinux .init slow lookup: */
-+ if (ip >= (unsigned long)_sinittext && ip < (unsigned long)_einittext)
-+ return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
-+ __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
-+
-+ /* Module lookup: */
-+ return orc_module_find(ip);
-+}
-+
-+static void orc_sort_swap(void *_a, void *_b, int size)
-+{
-+ struct orc_entry *orc_a, *orc_b;
-+ struct orc_entry orc_tmp;
-+ int *a = _a, *b = _b, tmp;
-+ int delta = _b - _a;
-+
-+ /* Swap the .orc_unwind_ip entries: */
-+ tmp = *a;
-+ *a = *b + delta;
-+ *b = tmp - delta;
-+
-+ /* Swap the corresponding .orc_unwind entries: */
-+ orc_a = cur_orc_table + (a - cur_orc_ip_table);
-+ orc_b = cur_orc_table + (b - cur_orc_ip_table);
-+ orc_tmp = *orc_a;
-+ *orc_a = *orc_b;
-+ *orc_b = orc_tmp;
-+}
-+
-+static int orc_sort_cmp(const void *_a, const void *_b)
-+{
-+ struct orc_entry *orc_a;
-+ const int *a = _a, *b = _b;
-+ unsigned long a_val = orc_ip(a);
-+ unsigned long b_val = orc_ip(b);
-+
-+ if (a_val > b_val)
-+ return 1;
-+ if (a_val < b_val)
-+ return -1;
-+
-+ /*
-+ * The "weak" section terminator entries need to always be on the left
-+ * to ensure the lookup code skips them in favor of real entries.
-+ * These terminator entries exist to handle any gaps created by
-+ * whitelisted .o files which didn't get objtool generation.
-+ */
-+ orc_a = cur_orc_table + (a - cur_orc_ip_table);
-+ return orc_a->sp_reg == ORC_REG_UNDEFINED ? -1 : 1;
-+}
-+
-+#ifdef CONFIG_MODULES
-+void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
-+ void *_orc, size_t orc_size)
-+{
-+ int *orc_ip = _orc_ip;
-+ struct orc_entry *orc = _orc;
-+ unsigned int num_entries = orc_ip_size / sizeof(int);
-+
-+ WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 ||
-+ orc_size % sizeof(*orc) != 0 ||
-+ num_entries != orc_size / sizeof(*orc));
-+
-+ /*
-+ * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
-+ * associate an .orc_unwind_ip table entry with its corresponding
-+ * .orc_unwind entry so they can both be swapped.
-+ */
-+ mutex_lock(&sort_mutex);
-+ cur_orc_ip_table = orc_ip;
-+ cur_orc_table = orc;
-+ sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
-+ mutex_unlock(&sort_mutex);
-+
-+ mod->arch.orc_unwind_ip = orc_ip;
-+ mod->arch.orc_unwind = orc;
-+ mod->arch.num_orcs = num_entries;
-+}
-+#endif
-+
-+void __init unwind_init(void)
-+{
-+ size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
-+ size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
-+ size_t num_entries = orc_ip_size / sizeof(int);
-+ struct orc_entry *orc;
-+ int i;
-+
-+ if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
-+ orc_size % sizeof(struct orc_entry) != 0 ||
-+ num_entries != orc_size / sizeof(struct orc_entry)) {
-+ orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n");
-+ return;
-+ }
-+
-+ /* Sort the .orc_unwind and .orc_unwind_ip tables: */
-+ sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp,
-+ orc_sort_swap);
-+
-+ /* Initialize the fast lookup table: */
-+ lookup_num_blocks = orc_lookup_end - orc_lookup;
-+ for (i = 0; i < lookup_num_blocks-1; i++) {
-+ orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
-+ num_entries,
-+ LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
-+ if (!orc) {
-+ orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
-+ return;
-+ }
-+
-+ orc_lookup[i] = orc - __start_orc_unwind;
-+ }
-+
-+ /* Initialize the ending block: */
-+ orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries,
-+ LOOKUP_STOP_IP);
-+ if (!orc) {
-+ orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
-+ return;
-+ }
-+ orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
-+
-+ orc_init = true;
-+}
-+
-+unsigned long unwind_get_return_address(struct unwind_state *state)
-+{
-+ if (unwind_done(state))
-+ return 0;
-+
-+ return __kernel_text_address(state->ip) ? state->ip : 0;
-+}
-+EXPORT_SYMBOL_GPL(unwind_get_return_address);
-+
-+unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
-+{
-+ if (unwind_done(state))
-+ return NULL;
-+
-+ if (state->regs)
-+ return &state->regs->ip;
-+
-+ if (state->sp)
-+ return (unsigned long *)state->sp - 1;
-+
-+ return NULL;
-+}
-+
-+static bool stack_access_ok(struct unwind_state *state, unsigned long addr,
-+ size_t len)
-+{
-+ struct stack_info *info = &state->stack_info;
-+
-+ /*
-+ * If the address isn't on the current stack, switch to the next one.
-+ *
-+ * We may have to traverse multiple stacks to deal with the possibility
-+ * that info->next_sp could point to an empty stack and the address
-+ * could be on a subsequent stack.
-+ */
-+ while (!on_stack(info, (void *)addr, len))
-+ if (get_stack_info(info->next_sp, state->task, info,
-+ &state->stack_mask))
-+ return false;
-+
-+ return true;
-+}
-+
-+static bool deref_stack_reg(struct unwind_state *state, unsigned long addr,
-+ unsigned long *val)
-+{
-+ if (!stack_access_ok(state, addr, sizeof(long)))
-+ return false;
-+
-+ *val = READ_ONCE_TASK_STACK(state->task, *(unsigned long *)addr);
-+ return true;
-+}
-+
-+#define REGS_SIZE (sizeof(struct pt_regs))
-+#define SP_OFFSET (offsetof(struct pt_regs, sp))
-+#define IRET_REGS_SIZE (REGS_SIZE - offsetof(struct pt_regs, ip))
-+#define IRET_SP_OFFSET (SP_OFFSET - offsetof(struct pt_regs, ip))
-+
-+static bool deref_stack_regs(struct unwind_state *state, unsigned long addr,
-+ unsigned long *ip, unsigned long *sp, bool full)
-+{
-+ size_t regs_size = full ? REGS_SIZE : IRET_REGS_SIZE;
-+ size_t sp_offset = full ? SP_OFFSET : IRET_SP_OFFSET;
-+ struct pt_regs *regs = (struct pt_regs *)(addr + regs_size - REGS_SIZE);
-+
-+ if (IS_ENABLED(CONFIG_X86_64)) {
-+ if (!stack_access_ok(state, addr, regs_size))
-+ return false;
-+
-+ *ip = regs->ip;
-+ *sp = regs->sp;
-+
-+ return true;
-+ }
-+
-+ if (!stack_access_ok(state, addr, sp_offset))
-+ return false;
-+
-+ *ip = regs->ip;
-+
-+ if (user_mode(regs)) {
-+ if (!stack_access_ok(state, addr + sp_offset,
-+ REGS_SIZE - SP_OFFSET))
-+ return false;
-+
-+ *sp = regs->sp;
-+ } else
-+ *sp = (unsigned long)®s->sp;
-+
-+ return true;
-+}
-+
-+bool unwind_next_frame(struct unwind_state *state)
-+{
-+ unsigned long ip_p, sp, orig_ip, prev_sp = state->sp;
-+ enum stack_type prev_type = state->stack_info.type;
-+ struct orc_entry *orc;
-+ struct pt_regs *ptregs;
-+ bool indirect = false;
-+
-+ if (unwind_done(state))
-+ return false;
-+
-+ /* Don't let modules unload while we're reading their ORC data. */
-+ preempt_disable();
-+
-+ /* Have we reached the end? */
-+ if (state->regs && user_mode(state->regs))
-+ goto done;
-+
-+ /*
-+ * Find the orc_entry associated with the text address.
-+ *
-+ * Decrement call return addresses by one so they work for sibling
-+ * calls and calls to noreturn functions.
-+ */
-+ orc = orc_find(state->signal ? state->ip : state->ip - 1);
-+ if (!orc || orc->sp_reg == ORC_REG_UNDEFINED)
-+ goto done;
-+ orig_ip = state->ip;
-+
-+ /* Find the previous frame's stack: */
-+ switch (orc->sp_reg) {
-+ case ORC_REG_SP:
-+ sp = state->sp + orc->sp_offset;
-+ break;
-+
-+ case ORC_REG_BP:
-+ sp = state->bp + orc->sp_offset;
-+ break;
-+
-+ case ORC_REG_SP_INDIRECT:
-+ sp = state->sp + orc->sp_offset;
-+ indirect = true;
-+ break;
-+
-+ case ORC_REG_BP_INDIRECT:
-+ sp = state->bp + orc->sp_offset;
-+ indirect = true;
-+ break;
-+
-+ case ORC_REG_R10:
-+ if (!state->regs || !state->full_regs) {
-+ orc_warn("missing regs for base reg R10 at ip %p\n",
-+ (void *)state->ip);
-+ goto done;
-+ }
-+ sp = state->regs->r10;
-+ break;
-+
-+ case ORC_REG_R13:
-+ if (!state->regs || !state->full_regs) {
-+ orc_warn("missing regs for base reg R13 at ip %p\n",
-+ (void *)state->ip);
-+ goto done;
-+ }
-+ sp = state->regs->r13;
-+ break;
-+
-+ case ORC_REG_DI:
-+ if (!state->regs || !state->full_regs) {
-+ orc_warn("missing regs for base reg DI at ip %p\n",
-+ (void *)state->ip);
-+ goto done;
-+ }
-+ sp = state->regs->di;
-+ break;
-+
-+ case ORC_REG_DX:
-+ if (!state->regs || !state->full_regs) {
-+ orc_warn("missing regs for base reg DX at ip %p\n",
-+ (void *)state->ip);
-+ goto done;
-+ }
-+ sp = state->regs->dx;
-+ break;
-+
-+ default:
-+ orc_warn("unknown SP base reg %d for ip %p\n",
-+ orc->sp_reg, (void *)state->ip);
-+ goto done;
-+ }
-+
-+ if (indirect) {
-+ if (!deref_stack_reg(state, sp, &sp))
-+ goto done;
-+ }
-+
-+ /* Find IP, SP and possibly regs: */
-+ switch (orc->type) {
-+ case ORC_TYPE_CALL:
-+ ip_p = sp - sizeof(long);
-+
-+ if (!deref_stack_reg(state, ip_p, &state->ip))
-+ goto done;
-+
-+ state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-+ state->ip, (void *)ip_p);
-+
-+ state->sp = sp;
-+ state->regs = NULL;
-+ state->signal = false;
-+ break;
-+
-+ case ORC_TYPE_REGS:
-+ if (!deref_stack_regs(state, sp, &state->ip, &state->sp, true)) {
-+ orc_warn("can't dereference registers at %p for ip %p\n",
-+ (void *)sp, (void *)orig_ip);
-+ goto done;
-+ }
-+
-+ state->regs = (struct pt_regs *)sp;
-+ state->full_regs = true;
-+ state->signal = true;
-+ break;
-+
-+ case ORC_TYPE_REGS_IRET:
-+ if (!deref_stack_regs(state, sp, &state->ip, &state->sp, false)) {
-+ orc_warn("can't dereference iret registers at %p for ip %p\n",
-+ (void *)sp, (void *)orig_ip);
-+ goto done;
-+ }
-+
-+ ptregs = container_of((void *)sp, struct pt_regs, ip);
-+ if ((unsigned long)ptregs >= prev_sp &&
-+ on_stack(&state->stack_info, ptregs, REGS_SIZE)) {
-+ state->regs = ptregs;
-+ state->full_regs = false;
-+ } else
-+ state->regs = NULL;
-+
-+ state->signal = true;
-+ break;
-+
-+ default:
-+ orc_warn("unknown .orc_unwind entry type %d\n", orc->type);
-+ break;
-+ }
-+
-+ /* Find BP: */
-+ switch (orc->bp_reg) {
-+ case ORC_REG_UNDEFINED:
-+ if (state->regs && state->full_regs)
-+ state->bp = state->regs->bp;
-+ break;
-+
-+ case ORC_REG_PREV_SP:
-+ if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp))
-+ goto done;
-+ break;
-+
-+ case ORC_REG_BP:
-+ if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp))
-+ goto done;
-+ break;
-+
-+ default:
-+ orc_warn("unknown BP base reg %d for ip %p\n",
-+ orc->bp_reg, (void *)orig_ip);
-+ goto done;
-+ }
-+
-+ /* Prevent a recursive loop due to bad ORC data: */
-+ if (state->stack_info.type == prev_type &&
-+ on_stack(&state->stack_info, (void *)state->sp, sizeof(long)) &&
-+ state->sp <= prev_sp) {
-+ orc_warn("stack going in the wrong direction? ip=%p\n",
-+ (void *)orig_ip);
-+ goto done;
-+ }
-+
-+ preempt_enable();
-+ return true;
-+
-+done:
-+ preempt_enable();
-+ state->stack_info.type = STACK_TYPE_UNKNOWN;
-+ return false;
-+}
-+EXPORT_SYMBOL_GPL(unwind_next_frame);
-+
-+void __unwind_start(struct unwind_state *state, struct task_struct *task,
-+ struct pt_regs *regs, unsigned long *first_frame)
-+{
-+ memset(state, 0, sizeof(*state));
-+ state->task = task;
-+
-+ /*
-+ * Refuse to unwind the stack of a task while it's executing on another
-+ * CPU. This check is racy, but that's ok: the unwinder has other
-+ * checks to prevent it from going off the rails.
-+ */
-+ if (task_on_another_cpu(task))
-+ goto done;
-+
-+ if (regs) {
-+ if (user_mode(regs))
-+ goto done;
-+
-+ state->ip = regs->ip;
-+ state->sp = kernel_stack_pointer(regs);
-+ state->bp = regs->bp;
-+ state->regs = regs;
-+ state->full_regs = true;
-+ state->signal = true;
-+
-+ } else if (task == current) {
-+ asm volatile("lea (%%rip), %0\n\t"
-+ "mov %%rsp, %1\n\t"
-+ "mov %%rbp, %2\n\t"
-+ : "=r" (state->ip), "=r" (state->sp),
-+ "=r" (state->bp));
-+
-+ } else {
-+ struct inactive_task_frame *frame = (void *)task->thread.sp;
-+
-+ state->sp = task->thread.sp;
-+ state->bp = READ_ONCE_NOCHECK(frame->bp);
-+ state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
-+ }
-+
-+ if (get_stack_info((unsigned long *)state->sp, state->task,
-+ &state->stack_info, &state->stack_mask))
-+ return;
-+
-+ /*
-+ * The caller can provide the address of the first frame directly
-+ * (first_frame) or indirectly (regs->sp) to indicate which stack frame
-+ * to start unwinding at. Skip ahead until we reach it.
-+ */
-+
-+ /* When starting from regs, skip the regs frame: */
-+ if (regs) {
-+ unwind_next_frame(state);
-+ return;
-+ }
-+
-+ /* Otherwise, skip ahead to the user-specified starting frame: */
-+ while (!unwind_done(state) &&
-+ (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
-+ state->sp <= (unsigned long)first_frame))
-+ unwind_next_frame(state);
-+
-+ return;
-+
-+done:
-+ state->stack_info.type = STACK_TYPE_UNKNOWN;
-+ return;
-+}
-+EXPORT_SYMBOL_GPL(__unwind_start);
-diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
-index 658fcf67862c..d6f45f6d1054 100644
---- a/arch/x86/Kconfig
-+++ b/arch/x86/Kconfig
-@@ -158,6 +158,7 @@ config X86
- select HAVE_MEMBLOCK
- select HAVE_MEMBLOCK_NODE_MAP
- select HAVE_MIXED_BREAKPOINTS_REGS
-+ select HAVE_MOD_ARCH_SPECIFIC
- select HAVE_NMI
- select HAVE_OPROFILE
- select HAVE_OPTPROBES
-diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
-index 1fc519f3c49e..d5bca2ec8a74 100644
---- a/arch/x86/Kconfig.debug
-+++ b/arch/x86/Kconfig.debug
-@@ -356,4 +356,29 @@ config PUNIT_ATOM_DEBUG
- The current power state can be read from
- /sys/kernel/debug/punit_atom/dev_power_state
-
-+config ORC_UNWINDER
-+ bool "ORC unwinder"
-+ depends on X86_64
-+ select STACK_VALIDATION
-+ ---help---
-+ This option enables the ORC (Oops Rewind Capability) unwinder for
-+ unwinding kernel stack traces. It uses a custom data format which is
-+ a simplified version of the DWARF Call Frame Information standard.
-+
-+ This unwinder is more accurate across interrupt entry frames than the
-+ frame pointer unwinder. It can also enable a 5-10% performance
-+ improvement across the entire kernel if CONFIG_FRAME_POINTER is
-+ disabled.
-+
-+ Enabling this option will increase the kernel's runtime memory usage
-+ by roughly 2-4MB, depending on your kernel config.
-+
-+config FRAME_POINTER_UNWINDER
-+ def_bool y
-+ depends on !ORC_UNWINDER && FRAME_POINTER
-+
-+config GUESS_UNWINDER
-+ def_bool y
-+ depends on !ORC_UNWINDER && !FRAME_POINTER
-+
- endmenu
-diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
-index c8a3b61be0aa..f05f00acac89 100644
---- a/arch/x86/kernel/vmlinux.lds.S
-+++ b/arch/x86/kernel/vmlinux.lds.S
-@@ -24,6 +24,7 @@
- #include <asm/asm-offsets.h>
- #include <asm/thread_info.h>
- #include <asm/page_types.h>
-+#include <asm/orc_lookup.h>
- #include <asm/cache.h>
- #include <asm/boot.h>
-
-@@ -148,6 +149,8 @@ SECTIONS
-
- BUG_TABLE
-
-+ ORC_UNWIND_TABLE
-+
- . = ALIGN(PAGE_SIZE);
- __vvar_page = .;
-
-diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
-index c617b9d1d6cb..0b4d1b3880b0 100644
---- a/lib/Kconfig.debug
-+++ b/lib/Kconfig.debug
-@@ -374,6 +374,9 @@ config STACK_VALIDATION
- pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
- that runtime stack traces are more reliable.
-
-+ This is also a prerequisite for generation of ORC unwind data, which
-+ is needed for CONFIG_ORC_UNWINDER.
-+
- For more information, see
- tools/objtool/Documentation/stack-validation.txt.
-
---
-2.14.2
-