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In-Reply-To: <1696856590-30298-9-git-send-email-yangtiezhu@loongson.cn>
From:   Huacai Chen <chenhuacai@kernel.org>
Date:   Wed, 11 Oct 2023 12:37:56 +0800
Message-ID: <CAAhV-H4pVRLPZ9OrfvV-UbPm1kRRJ0gpTqRtVbDd-eA5WzUaXg@mail.gmail.com>
Subject: Re: [PATCH v2 8/8] LoongArch: Add ORC unwinder support
To:     Tiezhu Yang <yangtiezhu@loongson.cn>
Cc:     Josh Poimboeuf <jpoimboe@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        loongarch@lists.linux.dev, linux-kernel@vger.kernel.org,
        loongson-kernel@lists.loongnix.cn
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Hi, Tiezhu,

Maybe "LoongArch: Add ORC stack unwinder support" is better.

On Mon, Oct 9, 2023 at 9:03=E2=80=AFPM Tiezhu Yang <yangtiezhu@loongson.cn>=
 wrote:
>
> The kernel CONFIG_UNWINDER_ORC 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.
>
> Most of the logic are similar with x86, in order to get ra info before ra
> is saved into stack, add ra_reg and ra_offset into orc_entry. At the same
> time, modify some arch-specific code to silence the objtool warnings.
>
> Co-developed-by: Jinyang He <hejinyang@loongson.cn>
> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
> Co-developed-by: Youling Tang <tangyouling@loongson.cn>
> Signed-off-by: Youling Tang <tangyouling@loongson.cn>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  arch/loongarch/Kconfig                     |   2 +
>  arch/loongarch/Kconfig.debug               |  11 +
>  arch/loongarch/Makefile                    |  23 ++
>  arch/loongarch/configs/loongson3_defconfig |   1 +
>  arch/loongarch/include/asm/Kbuild          |   1 +
>  arch/loongarch/include/asm/bug.h           |   1 +
>  arch/loongarch/include/asm/linkage.h       |   2 +
>  arch/loongarch/include/asm/module.h        |   7 +
>  arch/loongarch/include/asm/orc_header.h    |  19 +
>  arch/loongarch/include/asm/orc_lookup.h    |  34 ++
>  arch/loongarch/include/asm/orc_types.h     |  58 +++
>  arch/loongarch/include/asm/stackframe.h    |   3 +
>  arch/loongarch/include/asm/unwind.h        |  22 +-
>  arch/loongarch/include/asm/unwind_hints.h  |  28 ++
>  arch/loongarch/kernel/Makefile             |   3 +
>  arch/loongarch/kernel/entry.S              |   9 +-
>  arch/loongarch/kernel/genex.S              |  20 +-
>  arch/loongarch/kernel/head.S               |   1 +
>  arch/loongarch/kernel/module.c             |  11 +-
>  arch/loongarch/kernel/relocate_kernel.S    |   2 +
>  arch/loongarch/kernel/setup.c              |   2 +
>  arch/loongarch/kernel/stacktrace.c         |   1 +
>  arch/loongarch/kernel/unwind_orc.c         | 571 +++++++++++++++++++++++=
++++++
>  arch/loongarch/kernel/vmlinux.lds.S        |   3 +
>  arch/loongarch/lib/Makefile                |   2 +
>  arch/loongarch/mm/tlbex.S                  |  45 ++-
>  arch/loongarch/power/Makefile              |   2 +
>  arch/loongarch/vdso/Makefile               |   1 +
>  include/linux/compiler.h                   |   9 +
>  scripts/Makefile                           |   5 +-
>  30 files changed, 867 insertions(+), 32 deletions(-)
>  create mode 100644 arch/loongarch/include/asm/orc_header.h
>  create mode 100644 arch/loongarch/include/asm/orc_lookup.h
>  create mode 100644 arch/loongarch/include/asm/orc_types.h
>  create mode 100644 arch/loongarch/include/asm/unwind_hints.h
>  create mode 100644 arch/loongarch/kernel/unwind_orc.c
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index e14396a..21ef3bb 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -131,6 +131,7 @@ config LOONGARCH
>         select HAVE_KRETPROBES
>         select HAVE_MOD_ARCH_SPECIFIC
>         select HAVE_NMI
> +       select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS
>         select HAVE_PCI
>         select HAVE_PERF_EVENTS
>         select HAVE_PERF_REGS
> @@ -141,6 +142,7 @@ config LOONGARCH
>         select HAVE_SAMPLE_FTRACE_DIRECT
>         select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>         select HAVE_SETUP_PER_CPU_AREA if NUMA
> +       select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
>         select HAVE_STACKPROTECTOR
>         select HAVE_SYSCALL_TRACEPOINTS
>         select HAVE_TIF_NOHZ
> diff --git a/arch/loongarch/Kconfig.debug b/arch/loongarch/Kconfig.debug
> index 8d36aab..98d6063 100644
> --- a/arch/loongarch/Kconfig.debug
> +++ b/arch/loongarch/Kconfig.debug
> @@ -26,4 +26,15 @@ config UNWINDER_PROLOGUE
>           Some of the addresses it reports may be incorrect (but better t=
han the
>           Guess unwinder).
>
> +config UNWINDER_ORC
> +       bool "ORC unwinder"
> +       select OBJTOOL
> +       help
> +         This option enables the ORC (Oops Rewind Capability) unwinder f=
or
> +         unwinding kernel stack traces.  It uses a custom data format wh=
ich is
> +         a simplified version of the DWARF Call Frame Information standa=
rd.
> +
> +         Enabling this option will increase the kernel's runtime memory =
usage
> +         by roughly 2-4MB, depending on your kernel config.
> +
>  endchoice
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index fb0fada..89a6e61 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -25,6 +25,29 @@ endif
>  32bit-emul             =3D elf32loongarch
>  64bit-emul             =3D elf64loongarch
>
> +ifdef CONFIG_OBJTOOL
> +# https://sourceware.org/git/?p=3Dbinutils-gdb.git;a=3Dcommit;h=3Decb802=
d02eeb
> +# https://sourceware.org/git/?p=3Dbinutils-gdb.git;a=3Dcommit;h=3D816029=
e06768
> +ifeq ($(shell as --help 2>&1 | grep -e '-mthin-add-sub'),)
> +  $(error Sorry, you need a newer gas version with -mthin-add-sub option=
)
I prefer no error out here, because without this option we can still
built a runnable kernel.

> +endif
> +KBUILD_AFLAGS  +=3D $(call cc-option,-mthin-add-sub) $(call cc-option,-W=
a$(comma)-mthin-add-sub)
> +KBUILD_CFLAGS  +=3D $(call cc-option,-mthin-add-sub) $(call cc-option,-W=
a$(comma)-mthin-add-sub)
> +KBUILD_CFLAGS  +=3D -fno-optimize-sibling-calls -fno-jump-tables -falign=
-functions=3D4
> +endif
> +
> +ifdef CONFIG_UNWINDER_ORC
> +orc_hash_h :=3D arch/$(SRCARCH)/include/generated/asm/orc_hash.h
> +orc_hash_sh :=3D $(srctree)/scripts/orc_hash.sh
> +targets +=3D $(orc_hash_h)
> +quiet_cmd_orc_hash =3D GEN     $@
> +      cmd_orc_hash =3D mkdir -p $(dir $@); \
> +                    $(CONFIG_SHELL) $(orc_hash_sh) < $< > $@
> +$(orc_hash_h): $(srctree)/arch/loongarch/include/asm/orc_types.h $(orc_h=
ash_sh) FORCE
> +       $(call if_changed,orc_hash)
> +archprepare: $(orc_hash_h)
> +endif
> +
>  ifdef CONFIG_DYNAMIC_FTRACE
>  KBUILD_CPPFLAGS +=3D -DCC_USING_PATCHABLE_FUNCTION_ENTRY
>  CC_FLAGS_FTRACE :=3D -fpatchable-function-entry=3D2
> diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/=
configs/loongson3_defconfig
> index a3b52aa..de911c3 100644
> --- a/arch/loongarch/configs/loongson3_defconfig
> +++ b/arch/loongarch/configs/loongson3_defconfig
> @@ -5,6 +5,7 @@ CONFIG_NO_HZ=3Dy
>  CONFIG_HIGH_RES_TIMERS=3Dy
>  CONFIG_BPF_SYSCALL=3Dy
>  CONFIG_BPF_JIT=3Dy
> +CONFIG_BPF_JIT_ALWAYS_ON=3Dy
>  CONFIG_PREEMPT=3Dy
>  CONFIG_BSD_PROCESS_ACCT=3Dy
>  CONFIG_BSD_PROCESS_ACCT_V3=3Dy
> diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/a=
sm/Kbuild
> index 93783fa..2bb285c 100644
> --- a/arch/loongarch/include/asm/Kbuild
> +++ b/arch/loongarch/include/asm/Kbuild
> @@ -1,4 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
> +generated-y +=3D orc_hash.h
>  generic-y +=3D dma-contiguous.h
>  generic-y +=3D mcs_spinlock.h
>  generic-y +=3D parport.h
> diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/as=
m/bug.h
> index d4ca3ba..0838887 100644
> --- a/arch/loongarch/include/asm/bug.h
> +++ b/arch/loongarch/include/asm/bug.h
> @@ -44,6 +44,7 @@
>  do {                                                           \
>         instrumentation_begin();                                \
>         __BUG_FLAGS(BUGFLAG_WARNING|(flags));                   \
> +       annotate_reachable();                                   \
>         instrumentation_end();                                  \
>  } while (0)
>
> diff --git a/arch/loongarch/include/asm/linkage.h b/arch/loongarch/includ=
e/asm/linkage.h
> index 81b0c4c..ae4e100 100644
> --- a/arch/loongarch/include/asm/linkage.h
> +++ b/arch/loongarch/include/asm/linkage.h
> @@ -2,6 +2,8 @@
>  #ifndef __ASM_LINKAGE_H
>  #define __ASM_LINKAGE_H
>
> +#include <asm/unwind_hints.h>
> +
>  #define __ALIGN                .align 2
>  #define __ALIGN_STR    __stringify(__ALIGN)
>
> diff --git a/arch/loongarch/include/asm/module.h b/arch/loongarch/include=
/asm/module.h
> index 2ecd82b..96af0ba 100644
> --- a/arch/loongarch/include/asm/module.h
> +++ b/arch/loongarch/include/asm/module.h
> @@ -6,6 +6,7 @@
>  #define _ASM_MODULE_H
>
>  #include <asm/inst.h>
> +#include <asm/orc_types.h>
>  #include <asm-generic/module.h>
>
>  #define RELA_STACK_DEPTH 16
> @@ -23,6 +24,12 @@ struct mod_arch_specific {
>
>         /* For CONFIG_DYNAMIC_FTRACE */
>         struct plt_entry *ftrace_trampolines;
> +
> +#ifdef CONFIG_UNWINDER_ORC
> +       unsigned int num_orcs;
> +       int *orc_unwind_ip;
> +       struct orc_entry *orc_unwind;
> +#endif
>  };
>
>  struct got_entry {
> diff --git a/arch/loongarch/include/asm/orc_header.h b/arch/loongarch/inc=
lude/asm/orc_header.h
> new file mode 100644
> index 0000000..07bacf3
> --- /dev/null
> +++ b/arch/loongarch/include/asm/orc_header.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/* Copyright (c) Meta Platforms, Inc. and affiliates. */
> +
> +#ifndef _ORC_HEADER_H
> +#define _ORC_HEADER_H
> +
> +#include <linux/types.h>
> +#include <linux/compiler.h>
> +#include <asm/orc_hash.h>
> +
> +/*
> + * The header is currently a 20-byte hash of the ORC entry definition; s=
ee
> + * scripts/orc_hash.sh.
> + */
> +#define ORC_HEADER                                     \
> +       __used __section(".orc_header") __aligned(4)    \
> +       static const u8 orc_header[] =3D { ORC_HASH }
> +
> +#endif /* _ORC_HEADER_H */
> diff --git a/arch/loongarch/include/asm/orc_lookup.h b/arch/loongarch/inc=
lude/asm/orc_lookup.h
> new file mode 100644
> index 0000000..2416312
> --- /dev/null
> +++ b/arch/loongarch/include/asm/orc_lookup.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
> + */
> +#ifndef _ORC_LOOKUP_H
> +#define _ORC_LOOKUP_H
> +
> +/*
> + * This is a lookup table for speeding up access to the .orc_unwind tabl=
e.
> + * 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' instruc=
tion.
> + *
> + * 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/loongarch/include/asm/orc_types.h b/arch/loongarch/incl=
ude/asm/orc_types.h
> new file mode 100644
> index 0000000..1d37e62
> --- /dev/null
> +++ b/arch/loongarch/include/asm/orc_types.h
> @@ -0,0 +1,58 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef _ORC_TYPES_H
> +#define _ORC_TYPES_H
> +
> +#include <linux/types.h>
> +
> +/*
> + * The ORC_REG_* registers are base registers which are used to find oth=
er
> + * registers on the stack.
> + *
> + * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the
> + * address of the previous frame: the caller's SP before it called the c=
urrent
> + * function.
> + *
> + * ORC_REG_UNDEFINED means the corresponding register's value didn't cha=
nge in
> + * the current frame.
> + *
> + * The most commonly used base registers are SP and BP -- which the prev=
ious SP
> + * is usually based on -- and PREV_SP and UNDEFINED -- which the previou=
s BP is
> + * usually based on.
> + *
> + * The rest of the base registers are needed for special cases like entr=
y code
> + * and GCC realigned stacks.
> + */
> +#define ORC_REG_UNDEFINED              0
> +#define ORC_REG_PREV_SP                        1
> +#define ORC_REG_SP                     2
> +#define ORC_REG_BP                     3
Use FP instead of BP in this patch, too.

> +#define ORC_REG_MAX                    4
> +
> +#define ORC_TYPE_UNDEFINED             0
> +#define ORC_TYPE_END_OF_STACK          1
> +#define ORC_TYPE_CALL                  2
> +#define ORC_TYPE_REGS                  3
> +#define ORC_TYPE_REGS_PARTIAL          4
> +
> +#ifndef __ASSEMBLY__
> +/*
> + * This struct is more or less a vastly simplified version of the DWARF =
Call
> + * Frame Information standard.  It contains only the necessary parts of =
DWARF
> + * CFI, simplified for ease of access by the in-kernel unwinder.  It tel=
ls the
> + * unwinder how to find the previous SP and BP (and sometimes entry regs=
) on
> + * the stack for a given code address.  Each instance of the struct corr=
esponds
> + * to one or more code locations.
> + */
> +struct orc_entry {
> +       s16             sp_offset;
> +       s16             bp_offset;
> +       s16             ra_offset;
> +       unsigned int    sp_reg:4;
> +       unsigned int    bp_reg:4;
> +       unsigned int    ra_reg:4;
> +       unsigned int    type:3;
> +       unsigned int    signal:1;
> +};
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* _ORC_TYPES_H */
> diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/inc=
lude/asm/stackframe.h
> index 4fb1e64..45b507a 100644
> --- a/arch/loongarch/include/asm/stackframe.h
> +++ b/arch/loongarch/include/asm/stackframe.h
> @@ -13,6 +13,7 @@
>  #include <asm/asm-offsets.h>
>  #include <asm/loongarch.h>
>  #include <asm/thread_info.h>
> +#include <asm/unwind_hints.h>
>
>  /* Make the addition of cfi info a little easier. */
>         .macro cfi_rel_offset reg offset=3D0 docfi=3D0
> @@ -162,6 +163,7 @@
>         li.w    t0, CSR_CRMD_WE
>         csrxchg t0, t0, LOONGARCH_CSR_CRMD
>  #endif
> +       UNWIND_HINT_REGS
>         .endm
>
>         .macro  SAVE_ALL docfi=3D0
> @@ -219,6 +221,7 @@
>
>         .macro  RESTORE_SP_AND_RET docfi=3D0
>         cfi_ld  sp, PT_R3, \docfi
> +       UNWIND_HINT_FUNC
>         ertn
>         .endm
>
> diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include=
/asm/unwind.h
> index b9dce87..d36e04e 100644
> --- a/arch/loongarch/include/asm/unwind.h
> +++ b/arch/loongarch/include/asm/unwind.h
> @@ -16,6 +16,7 @@
>  enum unwinder_type {
>         UNWINDER_GUESS,
>         UNWINDER_PROLOGUE,
> +       UNWINDER_ORC,
>  };
>
>  struct unwind_state {
> @@ -24,7 +25,7 @@ struct unwind_state {
>         struct task_struct *task;
>         bool first, error, reset;
>         int graph_idx;
> -       unsigned long sp, pc, ra;
> +       unsigned long sp, pc, ra, fp;
>  };
>
>  bool default_next_frame(struct unwind_state *state);
> @@ -34,6 +35,17 @@ void unwind_start(struct unwind_state *state,
>  bool unwind_next_frame(struct unwind_state *state);
>  unsigned long unwind_get_return_address(struct unwind_state *state);
>
> +#ifdef CONFIG_UNWINDER_ORC
> +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
> +
>  static inline bool unwind_done(struct unwind_state *state)
>  {
>         return state->stack_info.type =3D=3D STACK_TYPE_UNKNOWN;
> @@ -61,14 +73,17 @@ static __always_inline void __unwind_start(struct unw=
ind_state *state,
>                 state->sp =3D regs->regs[3];
>                 state->pc =3D regs->csr_era;
>                 state->ra =3D regs->regs[1];
> +               state->fp =3D regs->regs[22];
>         } else if (task && task !=3D current) {
>                 state->sp =3D thread_saved_fp(task);
>                 state->pc =3D thread_saved_ra(task);
>                 state->ra =3D 0;
> +               state->fp =3D 0;
>         } else {
>                 state->sp =3D (unsigned long)__builtin_frame_address(0);
>                 state->pc =3D (unsigned long)__builtin_return_address(0);
>                 state->ra =3D 0;
> +               state->fp =3D 0;
>         }
>         state->task =3D task;
>         get_stack_info(state->sp, state->task, &state->stack_info);
> @@ -77,6 +92,9 @@ static __always_inline void __unwind_start(struct unwin=
d_state *state,
>
>  static __always_inline unsigned long __unwind_get_return_address(struct =
unwind_state *state)
>  {
> -       return unwind_done(state) ? 0 : state->pc;
> +       if (unwind_done(state))
> +               return 0;
> +
> +       return __kernel_text_address(state->pc) ? state->pc : 0;
>  }
>  #endif /* _ASM_UNWIND_H */
> diff --git a/arch/loongarch/include/asm/unwind_hints.h b/arch/loongarch/i=
nclude/asm/unwind_hints.h
> new file mode 100644
> index 0000000..82443fe
> --- /dev/null
> +++ b/arch/loongarch/include/asm/unwind_hints.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_LOONGARCH_UNWIND_HINTS_H
> +#define _ASM_LOONGARCH_UNWIND_HINTS_H
> +
> +#include <linux/objtool.h>
> +#include <asm/orc_types.h>
> +
> +#ifdef __ASSEMBLY__
> +
> +.macro UNWIND_HINT_UNDEFINED

> +       UNWIND_HINT type=3DUNWIND_HINT_TYPE_UNDEFINED
> +.endm
We don't need to set sp_reg=3DORC_REG_UNDEFINED for UNWIND_HINT_UNDEFINED?

> +
> +.macro UNWIND_HINT_EMPTY
> +       UNWIND_HINT sp_reg=3DORC_REG_UNDEFINED type=3DUNWIND_HINT_TYPE_CA=
LL
> +.endm
We don't need to define UNWIND_HINT_END_OF_STACK?

> +
> +.macro UNWIND_HINT_REGS
> +       UNWIND_HINT sp_reg=3DORC_REG_SP type=3DUNWIND_HINT_TYPE_REGS
> +.endm
> +
> +.macro UNWIND_HINT_FUNC
> +       UNWIND_HINT sp_reg=3DORC_REG_SP type=3DUNWIND_HINT_TYPE_CALL
> +.endm
We don't need to set sp_offset for UNWIND_HINT_REGS and UNWIND_HINT_FUNC?

> +
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* _ASM_LOONGARCH_UNWIND_HINTS_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makef=
ile
> index 4fcc168..a89428c 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -3,6 +3,8 @@
>  # Makefile for the Linux/LoongArch kernel.
>  #
>
> +OBJECT_FILES_NON_STANDARD_head.o :=3D y
> +
>  extra-y                :=3D vmlinux.lds
>
>  obj-y          +=3D head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o=
 genex.o \
> @@ -62,6 +64,7 @@ obj-$(CONFIG_CRASH_DUMP)      +=3D crash_dump.o
>
>  obj-$(CONFIG_UNWINDER_GUESS)   +=3D unwind_guess.o
>  obj-$(CONFIG_UNWINDER_PROLOGUE) +=3D unwind_prologue.o
> +obj-$(CONFIG_UNWINDER_ORC)     +=3D unwind_orc.o
>
>  obj-$(CONFIG_PERF_EVENTS)      +=3D perf_event.o perf_regs.o
>  obj-$(CONFIG_HAVE_HW_BREAKPOINT)       +=3D hw_breakpoint.o
> diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.=
S
> index 65518bb..e43115f 100644
> --- a/arch/loongarch/kernel/entry.S
> +++ b/arch/loongarch/kernel/entry.S
> @@ -14,11 +14,13 @@
>  #include <asm/regdef.h>
>  #include <asm/stackframe.h>
>  #include <asm/thread_info.h>
> +#include <asm/unwind_hints.h>
>
>         .text
>         .cfi_sections   .debug_frame
>         .align  5
> -SYM_FUNC_START(handle_syscall)
> +SYM_CODE_START(handle_syscall)
Why?

> +       UNWIND_HINT_UNDEFINED
>         csrrd           t0, PERCPU_BASE_KS
>         la.pcrel        t1, kernelsp
>         add.d           t1, t1, t0
> @@ -56,6 +58,7 @@ SYM_FUNC_START(handle_syscall)
>         cfi_st          u0, PT_R21
>         cfi_st          fp, PT_R22
>
> +       UNWIND_HINT_REGS
>         SAVE_STATIC
>
>  #ifdef CONFIG_KGDB
> @@ -71,10 +74,11 @@ SYM_FUNC_START(handle_syscall)
>         bl              do_syscall
>
>         RESTORE_ALL_AND_RET
> -SYM_FUNC_END(handle_syscall)
> +SYM_CODE_END(handle_syscall)
>  _ASM_NOKPROBE(handle_syscall)
>
>  SYM_CODE_START(ret_from_fork)
> +       UNWIND_HINT_REGS
>         bl              schedule_tail           # a0 =3D struct task_stru=
ct *prev
>         move            a0, sp
>         bl              syscall_exit_to_user_mode
> @@ -84,6 +88,7 @@ SYM_CODE_START(ret_from_fork)
>  SYM_CODE_END(ret_from_fork)
>
>  SYM_CODE_START(ret_from_kernel_thread)
> +       UNWIND_HINT_REGS
>         bl              schedule_tail           # a0 =3D struct task_stru=
ct *prev
>         move            a0, s1
>         jirl            ra, s0, 0
> diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.=
S
> index 78f0663..3f18e3b 100644
> --- a/arch/loongarch/kernel/genex.S
> +++ b/arch/loongarch/kernel/genex.S
> @@ -31,7 +31,8 @@ SYM_FUNC_START(__arch_cpu_idle)
>  1:     jr      ra
>  SYM_FUNC_END(__arch_cpu_idle)
>
> -SYM_FUNC_START(handle_vint)
> +SYM_CODE_START(handle_vint)
> +       UNWIND_HINT_UNDEFINED
>         BACKUP_T0T1
>         SAVE_ALL
>         la_abs  t1, __arch_cpu_idle
> @@ -46,11 +47,12 @@ SYM_FUNC_START(handle_vint)
>         la_abs  t0, do_vint
>         jirl    ra, t0, 0
>         RESTORE_ALL_AND_RET
> -SYM_FUNC_END(handle_vint)
> +SYM_CODE_END(handle_vint)
>
> -SYM_FUNC_START(except_vec_cex)
> +SYM_CODE_START(except_vec_cex)
> +       UNWIND_HINT_UNDEFINED
>         b       cache_parity_error
> -SYM_FUNC_END(except_vec_cex)
> +SYM_CODE_END(except_vec_cex)
>
>         .macro  build_prep_badv
>         csrrd   t0, LOONGARCH_CSR_BADV
> @@ -66,7 +68,8 @@ SYM_FUNC_END(except_vec_cex)
>
>         .macro  BUILD_HANDLER exception handler prep
>         .align  5
> -       SYM_FUNC_START(handle_\exception)
> +       SYM_CODE_START(handle_\exception)
> +       UNWIND_HINT_UNDEFINED
>         666:
>         BACKUP_T0T1
>         SAVE_ALL
> @@ -76,7 +79,7 @@ SYM_FUNC_END(except_vec_cex)
>         jirl    ra, t0, 0
>         668:
>         RESTORE_ALL_AND_RET
> -       SYM_FUNC_END(handle_\exception)
> +       SYM_CODE_END(handle_\exception)
>         SYM_DATA(unwind_hint_\exception, .word 668b - 666b)
>         .endm
>
> @@ -93,7 +96,8 @@ SYM_FUNC_END(except_vec_cex)
>         BUILD_HANDLER watch watch none
>         BUILD_HANDLER reserved reserved none    /* others */
>
> -SYM_FUNC_START(handle_sys)
> +SYM_CODE_START(handle_sys)
> +       UNWIND_HINT_UNDEFINED
>         la_abs  t0, handle_syscall
>         jr      t0
> -SYM_FUNC_END(handle_sys)
> +SYM_CODE_END(handle_sys)
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index 53b883d..5664390 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -43,6 +43,7 @@ SYM_DATA(kernel_offset, .long _kernel_offset);
>         .align 12
>
>  SYM_CODE_START(kernel_entry)                   # kernel entry point
> +       UNWIND_HINT_EMPTY
I'm not sure but I think this isn't needed, because
"OBJECT_FILES_NON_STANDARD_head.o               :=3Dy"

>
>         /* Config direct window and set PG */
>         li.d            t0, CSR_DMW0_INIT       # UC, PLV0, 0x8000 xxxx x=
xxx xxxx
> diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/modul=
e.c
> index b13b285..83db7e5 100644
> --- a/arch/loongarch/kernel/module.c
> +++ b/arch/loongarch/kernel/module.c
> @@ -20,6 +20,7 @@
>  #include <linux/kernel.h>
>  #include <asm/alternative.h>
>  #include <asm/inst.h>
> +#include <asm/unwind.h>
>
>  static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rel=
a_stack_top)
>  {
> @@ -515,7 +516,7 @@ static void module_init_ftrace_plt(const Elf_Ehdr *hd=
r,
>  int module_finalize(const Elf_Ehdr *hdr,
>                     const Elf_Shdr *sechdrs, struct module *mod)
>  {
> -       const Elf_Shdr *s, *se;
> +       const Elf_Shdr *s, *se, *orc =3D NULL, *orc_ip =3D NULL;
>         const char *secstrs =3D (void *)hdr + sechdrs[hdr->e_shstrndx].sh=
_offset;
>
>         for (s =3D sechdrs, se =3D sechdrs + hdr->e_shnum; s < se; s++) {
> @@ -523,7 +524,15 @@ int module_finalize(const Elf_Ehdr *hdr,
>                         apply_alternatives((void *)s->sh_addr, (void *)s-=
>sh_addr + s->sh_size);
>                 if (!strcmp(".ftrace_trampoline", secstrs + s->sh_name))
>                         module_init_ftrace_plt(hdr, s, mod);
> +               if (!strcmp(".orc_unwind", secstrs + s->sh_name))
> +                       orc =3D s;
> +               if (!strcmp(".orc_unwind_ip", secstrs + s->sh_name))
> +                       orc_ip =3D s;
>         }
>
> +       if (orc && orc_ip)
> +               unwind_module_init(mod, (void *)orc_ip->sh_addr, orc_ip->=
sh_size,
> +                                      (void *)orc->sh_addr, orc->sh_size=
);
> +
>         return 0;
>  }
> diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/ker=
nel/relocate_kernel.S
> index f49f6b0..bcc191d 100644
> --- a/arch/loongarch/kernel/relocate_kernel.S
> +++ b/arch/loongarch/kernel/relocate_kernel.S
> @@ -15,6 +15,7 @@
>  #include <asm/addrspace.h>
>
>  SYM_CODE_START(relocate_new_kernel)
> +       UNWIND_HINT_UNDEFINED
>         /*
>          * a0: EFI boot flag for the new kernel
>          * a1: Command line pointer for the new kernel
> @@ -90,6 +91,7 @@ SYM_CODE_END(relocate_new_kernel)
>   * then start at the entry point from LOONGARCH_IOCSR_MBUF0.
>   */
>  SYM_CODE_START(kexec_smp_wait)
> +       UNWIND_HINT_UNDEFINED
>  1:     li.w            t0, 0x100                       /* wait for init =
loop */
>  2:     addi.w          t0, t0, -1                      /* limit mailbox =
access */
>         bnez            t0, 2b
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.=
c
> index 7783f0a..a173b02 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -48,6 +48,7 @@
>  #include <asm/sections.h>
>  #include <asm/setup.h>
>  #include <asm/time.h>
> +#include <asm/unwind.h>
>
>  #define SMBIOS_BIOSSIZE_OFFSET         0x09
>  #define SMBIOS_BIOSEXTERN_OFFSET       0x13
> @@ -605,6 +606,7 @@ static void __init prefill_possible_map(void)
>
>  void __init setup_arch(char **cmdline_p)
>  {
> +       unwind_init();
I think this line should be after cpu_probe().

>         cpu_probe();
>
>         init_environ();
> diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/s=
tacktrace.c
> index 92270f1..9848d42 100644
> --- a/arch/loongarch/kernel/stacktrace.c
> +++ b/arch/loongarch/kernel/stacktrace.c
> @@ -29,6 +29,7 @@ void arch_stack_walk(stack_trace_consume_fn consume_ent=
ry, void *cookie,
>                         regs->csr_era =3D thread_saved_ra(task);
>                 }
>                 regs->regs[1] =3D 0;
> +               regs->regs[22] =3D 0;
>         }
>
>         for (unwind_start(&state, task, regs);
> diff --git a/arch/loongarch/kernel/unwind_orc.c b/arch/loongarch/kernel/u=
nwind_orc.c
> new file mode 100644
> index 0000000..08f80ca0
> --- /dev/null
> +++ b/arch/loongarch/kernel/unwind_orc.c
> @@ -0,0 +1,571 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/objtool.h>
> +#include <linux/module.h>
> +#include <linux/sort.h>
> +#include <asm/exception.h>
> +#include <asm/orc_types.h>
> +#include <asm/orc_lookup.h>
> +#include <asm/orc_header.h>
> +#include <asm/ptrace.h>
> +#include <asm/setup.h>
> +#include <asm/stacktrace.h>
> +#include <asm/tlb.h>
> +#include <asm/unwind.h>
> +
> +ORC_HEADER;
> +
> +#define orc_warn(fmt, ...) \
> +       printk_deferred_once(KERN_WARNING "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 bool orc_init __ro_after_init;
> +static unsigned int lookup_num_blocks __ro_after_init;
> +
> +/* Fake frame pointer entry -- used as a fallback for generated code */
> +static struct orc_entry orc_fp_entry =3D {
> +       .type           =3D UNWIND_HINT_TYPE_CALL,
> +       .sp_reg         =3D ORC_REG_BP,
> +       .sp_offset      =3D 16,
> +       .bp_reg         =3D ORC_REG_PREV_SP,
> +       .bp_offset      =3D -16,
> +       .ra_reg         =3D ORC_REG_PREV_SP,
> +       .ra_offset      =3D -8,
> +};
> +
> +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_t=
able,
> +                                   unsigned int num_entries, unsigned lo=
ng ip)
> +{
> +       int *first =3D ip_table;
> +       int *last =3D ip_table + num_entries - 1;
> +       int *mid =3D first, *found =3D 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 <=3D last) {
> +               mid =3D first + ((last - first) / 2);
> +
> +               if (orc_ip(mid) <=3D ip) {
> +                       found =3D mid;
> +                       first =3D mid + 1;
> +               } else
> +                       last =3D 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 =3D __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
> +
> +#ifdef CONFIG_DYNAMIC_FTRACE
> +static struct orc_entry *orc_find(unsigned long ip);
> +
> +/*
> + * Ftrace dynamic trampolines do not have orc entries of their own.
> + * But they are copies of the ftrace entries that are static and
> + * defined in ftrace_*.S, which do have orc entries.
> + *
> + * If the unwinder comes across a ftrace trampoline, then find the
> + * ftrace function that was used to create it, and use that ftrace
> + * function's orc entry, as the placement of the return code in
> + * the stack will be identical.
> + */
> +static struct orc_entry *orc_ftrace_find(unsigned long ip)
> +{
> +       struct ftrace_ops *ops;
> +       unsigned long tramp_addr, offset;
> +
> +       ops =3D ftrace_ops_trampoline(ip);
> +       if (!ops)
> +               return NULL;
> +
> +       /* Set tramp_addr to the start of the code copied by the trampoli=
ne */
> +       if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
> +               tramp_addr =3D (unsigned long)ftrace_regs_caller;
> +       else
> +               tramp_addr =3D (unsigned long)ftrace_caller;
> +
> +       /* Now place tramp_addr to the location within the trampoline ip =
is at */
> +       offset =3D ip - ops->trampoline;
> +       tramp_addr +=3D offset;
> +
> +       /* Prevent unlikely recursion */
> +       if (ip =3D=3D tramp_addr)
> +               return NULL;
> +
> +       return orc_find(tramp_addr);
> +}
> +#else
> +static struct orc_entry *orc_ftrace_find(unsigned long ip)
> +{
> +       return NULL;
> +}
> +#endif
> +
> +/*
> + * If we crash with IP=3D=3D0, the last successfully executed instructio=
n
> + * was probably an indirect function call with a NULL function pointer,
> + * and we don't have unwind information for NULL.
> + * This hardcoded ORC entry for IP=3D=3D0 allows us to unwind from a NUL=
L function
> + * pointer into its parent and then continue normally from there.
> + */
> +static struct orc_entry null_orc_entry =3D {
> +       .sp_offset =3D sizeof(long),
> +       .sp_reg =3D ORC_REG_SP,
> +       .bp_reg =3D ORC_REG_UNDEFINED,
> +       .type =3D ORC_TYPE_CALL
> +};
> +
> +static struct orc_entry *orc_find(unsigned long ip)
> +{
> +       static struct orc_entry *orc;
> +
> +       if (ip =3D=3D 0)
> +               return &null_orc_entry;
> +
> +       /* For non-init vmlinux addresses, use the fast lookup table: */
> +       if (ip >=3D LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
> +               unsigned int idx, start, stop;
> +
> +               idx =3D (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
> +
> +               if (unlikely((idx >=3D lookup_num_blocks-1))) {
> +                       orc_warn("WARNING: bad lookup idx: idx=3D%u num=
=3D%u ip=3D%pB\n",
> +                                idx, lookup_num_blocks, (void *)ip);
> +                       return NULL;
> +               }
> +
> +               start =3D orc_lookup[idx];
> +               stop =3D orc_lookup[idx + 1] + 1;
> +
> +               if (unlikely((__start_orc_unwind + start >=3D __stop_orc_=
unwind) ||
> +                            (__start_orc_unwind + stop > __stop_orc_unwi=
nd))) {
> +                       orc_warn("WARNING: bad lookup value: idx=3D%u num=
=3D%u start=3D%u stop=3D%u ip=3D%pB\n",
> +                                idx, lookup_num_blocks, start, stop, (vo=
id *)ip);
> +                       return NULL;
> +               }
> +
> +               return __orc_find(__start_orc_unwind_ip + start,
> +                                 __start_orc_unwind + start, stop - star=
t, ip);
> +       }
> +
> +       /* vmlinux .init slow lookup: */
> +       if (is_kernel_inittext(ip))
> +               return __orc_find(__start_orc_unwind_ip, __start_orc_unwi=
nd,
> +                                 __stop_orc_unwind_ip - __start_orc_unwi=
nd_ip, ip);
> +
> +       /* Module lookup: */
> +       orc =3D orc_module_find(ip);
> +       if (orc)
> +               return orc;
> +
> +       return orc_ftrace_find(ip);
> +}
> +
> +#ifdef CONFIG_MODULES
> +
> +static DEFINE_MUTEX(sort_mutex);
> +static int *cur_orc_ip_table =3D __start_orc_unwind_ip;
> +static struct orc_entry *cur_orc_table =3D __start_orc_unwind;
> +
> +static void orc_sort_swap(void *_a, void *_b, int size)
> +{
> +       struct orc_entry *orc_a, *orc_b;
> +       int *a =3D _a, *b =3D _b, tmp;
> +       int delta =3D _b - _a;
> +
> +       /* Swap the .orc_unwind_ip entries: */
> +       tmp =3D *a;
> +       *a =3D *b + delta;
> +       *b =3D tmp - delta;
> +
> +       /* Swap the corresponding .orc_unwind entries: */
> +       orc_a =3D cur_orc_table + (a - cur_orc_ip_table);
> +       orc_b =3D cur_orc_table + (b - cur_orc_ip_table);
> +       swap(*orc_a, *orc_b);
> +}
> +
> +static int orc_sort_cmp(const void *_a, const void *_b)
> +{
> +       struct orc_entry *orc_a;
> +       const int *a =3D _a, *b =3D _b;
> +       unsigned long a_val =3D orc_ip(a);
> +       unsigned long b_val =3D 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 first
> +        * 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 =3D cur_orc_table + (a - cur_orc_ip_table);
> +       return orc_a->type =3D=3D ORC_TYPE_UNDEFINED ? -1 : 1;
> +}
> +
> +void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip=
_size,
> +                       void *_orc, size_t orc_size)
> +{
> +       int *orc_ip =3D _orc_ip;
> +       struct orc_entry *orc =3D _orc;
> +       unsigned int num_entries =3D orc_ip_size / sizeof(int);
> +
> +       WARN_ON_ONCE(orc_ip_size % sizeof(int) !=3D 0 ||
> +                    orc_size % sizeof(*orc) !=3D 0 ||
> +                    num_entries !=3D 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 =3D orc_ip;
> +       cur_orc_table =3D orc;
> +       sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swa=
p);
> +       mutex_unlock(&sort_mutex);
> +
> +       mod->arch.orc_unwind_ip =3D orc_ip;
> +       mod->arch.orc_unwind =3D orc;
> +       mod->arch.num_orcs =3D num_entries;
> +}
> +#endif
> +
> +void __init unwind_init(void)
> +{
> +       size_t orc_ip_size =3D (void *)__stop_orc_unwind_ip - (void *)__s=
tart_orc_unwind_ip;
> +       size_t orc_size =3D (void *)__stop_orc_unwind - (void *)__start_o=
rc_unwind;
> +       size_t num_entries =3D orc_ip_size / sizeof(int);
> +       struct orc_entry *orc;
> +       int i;
> +
> +       if (!num_entries || orc_ip_size % sizeof(int) !=3D 0 ||
> +           orc_size % sizeof(struct orc_entry) !=3D 0 ||
> +           num_entries !=3D orc_size / sizeof(struct orc_entry)) {
> +               orc_warn("WARNING: Bad or missing .orc_unwind table.  Dis=
abling unwinder.\n");
> +               return;
> +       }
> +
> +       /*
> +        * Note, the orc_unwind and orc_unwind_ip tables were already
> +        * sorted at build time via the 'sorttable' tool.
> +        * It's ready for binary search straight away, no need to sort it=
.
> +        */
> +
> +       /* Initialize the fast lookup table: */
> +       lookup_num_blocks =3D orc_lookup_end - orc_lookup;
> +       for (i =3D 0; i < lookup_num_blocks-1; i++) {
> +               orc =3D __orc_find(__start_orc_unwind_ip, __start_orc_unw=
ind,
> +                                num_entries,
> +                                LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i=
));
> +               if (!orc) {
> +                       orc_warn("WARNING: Corrupt .orc_unwind table.  Di=
sabling unwinder.\n");
> +                       return;
> +               }
> +
> +               orc_lookup[i] =3D orc - __start_orc_unwind;
> +       }
> +
> +       /* Initialize the ending block: */
> +       orc =3D __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] =3D orc - __start_orc_unwind;
> +
> +       orc_init =3D true;
> +}
> +
> +static inline bool on_stack(struct stack_info *info, unsigned long addr,=
 size_t len)
> +{
> +       unsigned long begin =3D info->begin;
> +       unsigned long end   =3D info->end;
> +
> +       return (info->type !=3D STACK_TYPE_UNKNOWN &&
> +               addr >=3D begin && addr < end &&
> +               addr + len > begin && addr + len <=3D end);
> +}
> +
> +static bool stack_access_ok(struct unwind_state *state, unsigned long ad=
dr,
> +                           size_t len)
> +{
> +       struct stack_info *info =3D &state->stack_info;
> +
> +       if (on_stack(info, addr, len))
> +               return true;
> +
> +       return !get_stack_info(addr, state->task, info) &&
> +               on_stack(info, addr, len);
> +}
> +
> +unsigned long unwind_get_return_address(struct unwind_state *state)
> +{
> +       return __unwind_get_return_address(state);
> +}
> +EXPORT_SYMBOL_GPL(unwind_get_return_address);
> +
> +void unwind_start(struct unwind_state *state, struct task_struct *task,
> +                   struct pt_regs *regs)
> +{
> +       __unwind_start(state, task, regs);
> +       if (!unwind_done(state) && !__kernel_text_address(state->pc))
> +               unwind_next_frame(state);
> +}
> +EXPORT_SYMBOL_GPL(unwind_start);
> +
> +static bool is_entry_func(unsigned long addr)
> +{
> +       extern u32 kernel_entry;
> +       extern u32 kernel_entry_end;
> +
> +       return addr >=3D (unsigned long)&kernel_entry &&
> +               addr < (unsigned long)&kernel_entry_end;
> +}
> +
> +static inline unsigned long bt_address(unsigned long ra)
> +{
> +       extern unsigned long eentry;
> +
> +       if (__kernel_text_address(ra))
> +               return ra;
> +
> +       /* We are in preempt_disable() here */
> +       if (__module_text_address(ra))
> +               return ra;
> +
> +       if (ra >=3D eentry && ra < eentry +  EXCCODE_INT_END * VECSIZE) {
> +               unsigned long type =3D (ra - eentry) / VECSIZE;
> +               unsigned long offset =3D (ra - eentry) % VECSIZE;
> +               unsigned long func;
> +
> +               switch (type) {
> +               case EXCCODE_TLBL:
> +               case EXCCODE_TLBI:
> +                       func =3D (unsigned long)handle_tlb_load;
> +                       break;
> +               case EXCCODE_TLBS:
> +                       func =3D (unsigned long)handle_tlb_store;
> +                       break;
> +               case EXCCODE_TLBM:
> +                       func =3D (unsigned long)handle_tlb_modify;
> +                       break;
> +               case EXCCODE_TLBNR:
> +               case EXCCODE_TLBNX:
> +               case EXCCODE_TLBPE:
> +                       func =3D (unsigned long)handle_tlb_protect;
> +                       break;
> +               case EXCCODE_ADE:
> +                       func =3D (unsigned long)handle_ade;
> +                       break;
> +               case EXCCODE_ALE:
> +                       func =3D (unsigned long)handle_ale;
> +                       break;
> +               case EXCCODE_BCE:
> +                       func =3D (unsigned long)handle_bce;
> +                       break;
> +               case EXCCODE_SYS:
> +                       func =3D (unsigned long)handle_sys;
> +                       break;
> +               case EXCCODE_BP:
> +                       func =3D (unsigned long)handle_bp;
> +                       break;
> +               case EXCCODE_INE:
> +               case EXCCODE_IPE:
> +                       func =3D (unsigned long)handle_ri;
> +                       break;
> +               case EXCCODE_FPDIS:
> +                       func =3D (unsigned long)handle_fpu;
> +                       break;
> +               case EXCCODE_LSXDIS:
> +                       func =3D (unsigned long)handle_lsx;
> +                       break;
> +               case EXCCODE_LASXDIS:
> +                       func =3D (unsigned long)handle_lasx;
> +                       break;
> +               case EXCCODE_FPE:
> +                       func =3D (unsigned long)handle_fpe;
> +                       break;
> +               case EXCCODE_WATCH:
> +                       func =3D (unsigned long)handle_watch;
> +                       break;
> +               case EXCCODE_BTDIS:
> +                       func =3D (unsigned long)handle_lbt;
> +                       break;
> +               case EXCCODE_INT_START ... EXCCODE_INT_END - 1:
> +                       func =3D (unsigned long)handle_vint;
> +                       break;
> +               default:
> +                       func =3D (unsigned long)handle_reserved;
> +                       break;
> +               }
> +
> +               return func + offset;
> +       }
> +
> +       return ra;
> +}
> +
> +bool unwind_next_frame(struct unwind_state *state)
> +{
> +       struct stack_info *info =3D &state->stack_info;
> +       struct orc_entry *orc;
> +       struct pt_regs *regs;
> +       unsigned long *p, pc;
> +
> +       if (unwind_done(state))
> +               return false;
> +
> +       /* Don't let modules unload while we're reading their ORC data. *=
/
> +       preempt_disable();
> +
> +       if (is_entry_func(state->pc))
> +               goto end;
> +
> +       orc =3D orc_find(state->pc);
> +       if (!orc) {
> +               orc =3D &orc_fp_entry;
> +               state->error =3D true;
> +       }
> +
> +       switch (orc->sp_reg) {
> +       case ORC_REG_SP:
> +               state->sp =3D state->sp + orc->sp_offset;
> +               break;
> +       case ORC_REG_BP:
> +               state->sp =3D state->fp;
> +               break;
> +       default:
> +               orc_warn("unknown SP base reg %d at %pB\n",
> +                       orc->sp_reg, (void *)state->pc);
> +               goto err;
> +       }
> +
> +       switch (orc->bp_reg) {
> +       case ORC_REG_PREV_SP:
> +               p =3D (unsigned long *)(state->sp + orc->bp_offset);
> +               if (!stack_access_ok(state, (unsigned long)p, sizeof(unsi=
gned long)))
> +                       goto err;
> +
> +               state->fp =3D *p;
> +               break;
> +       case ORC_REG_UNDEFINED:
> +               /* Nothing. */
> +               break;
> +       default:
> +               orc_warn("unknown FP base reg %d at %pB\n",
> +                       orc->bp_reg, (void *)state->pc);
> +               goto err;
> +       }
> +
> +       switch (orc->type) {
> +       case UNWIND_HINT_TYPE_CALL:
> +               if (orc->ra_reg =3D=3D ORC_REG_PREV_SP) {
> +                       p =3D (unsigned long *)(state->sp + orc->ra_offse=
t);
> +                       if (!stack_access_ok(state, (unsigned long)p, siz=
eof(unsigned long)))
> +                               goto err;
> +
> +                       pc =3D unwind_graph_addr(state, *p, state->sp);
> +                       pc -=3D LOONGARCH_INSN_SIZE;
> +               } else if (orc->ra_reg =3D=3D ORC_REG_UNDEFINED) {
> +                       if (!state->ra || state->ra =3D=3D state->pc)
> +                               goto err;
> +
> +                       pc =3D unwind_graph_addr(state, state->ra, state-=
>sp);
> +                       pc -=3D  LOONGARCH_INSN_SIZE;
> +                       state->ra =3D 0;
> +               } else {
> +                       orc_warn("unknown ra base reg %d at %pB\n",
> +                               orc->ra_reg, (void *)state->pc);
> +                       goto err;
> +               }
> +               break;
> +       case UNWIND_HINT_TYPE_REGS:
> +               if (state->stack_info.type =3D=3D STACK_TYPE_IRQ && state=
->sp =3D=3D info->end)
> +                       regs =3D (struct pt_regs *)info->next_sp;
> +               else
> +                       regs =3D (struct pt_regs *)state->sp;
> +
> +               if (!stack_access_ok(state, (unsigned long)regs, sizeof(*=
regs)))
> +                       goto err;
> +
> +               if ((info->end =3D=3D (unsigned long)regs + sizeof(*regs)=
) &&
> +                   !regs->regs[3] && !regs->regs[1])
> +                       goto end;
> +
> +               if (user_mode(regs))
> +                       goto end;
> +
> +               pc =3D regs->csr_era;
> +               if (!__kernel_text_address(pc))
> +                       goto err;
> +
> +               state->sp =3D regs->regs[3];
> +               state->ra =3D regs->regs[1];
> +               state->fp =3D regs->regs[22];
> +               get_stack_info(state->sp, state->task, info);
> +
> +               break;
> +       default:
> +               orc_warn("unknown .orc_unwind entry type %d at %pB\n",
> +                        orc->type, (void *)state->pc);
> +               goto err;
> +       }
> +
> +       state->pc =3D bt_address(pc);
> +       if (!state->pc) {
> +               pr_err("cannot find unwind pc at %pK\n", (void *)pc);
> +               goto err;
> +       }
> +
> +       if (!__kernel_text_address(state->pc))
> +               goto err;
> +
> +       preempt_enable();
> +       return true;
> +
> +err:
> +       state->error =3D true;
> +
> +end:
> +       preempt_enable();
> +       state->stack_info.type =3D STACK_TYPE_UNKNOWN;
> +       return false;
> +}
> +EXPORT_SYMBOL_GPL(unwind_next_frame);
> diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/=
vmlinux.lds.S
> index bb2ec86..09fd4eb 100644
> --- a/arch/loongarch/kernel/vmlinux.lds.S
> +++ b/arch/loongarch/kernel/vmlinux.lds.S
> @@ -2,6 +2,7 @@
>  #include <linux/sizes.h>
>  #include <asm/asm-offsets.h>
>  #include <asm/thread_info.h>
> +#include <asm/orc_lookup.h>
>
>  #define PAGE_SIZE _PAGE_SIZE
>  #define RO_EXCEPTION_TABLE_ALIGN       4
> @@ -99,6 +100,8 @@ SECTIONS
>         _sdata =3D .;
>         RO_DATA(4096)
>
> +       ORC_UNWIND_TABLE
> +
>         .got : ALIGN(16) { *(.got) }
>         .plt : ALIGN(16) { *(.plt) }
>         .got.plt : ALIGN(16) { *(.got.plt) }
> diff --git a/arch/loongarch/lib/Makefile b/arch/loongarch/lib/Makefile
> index a77bf160..e3023d9 100644
> --- a/arch/loongarch/lib/Makefile
> +++ b/arch/loongarch/lib/Makefile
> @@ -3,6 +3,8 @@
>  # Makefile for LoongArch-specific library files.
>  #
>
> +OBJECT_FILES_NON_STANDARD :=3D y
> +
>  lib-y  +=3D delay.o memset.o memcpy.o memmove.o \
>            clear_user.o copy_user.o csum.o dump_tlb.o unaligned.o
>
> diff --git a/arch/loongarch/mm/tlbex.S b/arch/loongarch/mm/tlbex.S
> index ca17dd3..a44387b 100644
> --- a/arch/loongarch/mm/tlbex.S
> +++ b/arch/loongarch/mm/tlbex.S
> @@ -17,7 +17,8 @@
>  #define PTRS_PER_PTE_BITS      (PAGE_SHIFT - 3)
>
>         .macro tlb_do_page_fault, write
> -       SYM_FUNC_START(tlb_do_page_fault_\write)
> +       SYM_CODE_START(tlb_do_page_fault_\write)
> +       UNWIND_HINT_UNDEFINED
>         SAVE_ALL
>         csrrd           a2, LOONGARCH_CSR_BADV
>         move            a0, sp
> @@ -25,13 +26,14 @@
>         li.w            a1, \write
>         bl              do_page_fault
>         RESTORE_ALL_AND_RET
> -       SYM_FUNC_END(tlb_do_page_fault_\write)
> +       SYM_CODE_END(tlb_do_page_fault_\write)
>         .endm
>
>         tlb_do_page_fault 0
>         tlb_do_page_fault 1
>
> -SYM_FUNC_START(handle_tlb_protect)
> +SYM_CODE_START(handle_tlb_protect)
> +       UNWIND_HINT_UNDEFINED
>         BACKUP_T0T1
>         SAVE_ALL
>         move            a0, sp
> @@ -41,9 +43,10 @@ SYM_FUNC_START(handle_tlb_protect)
>         la_abs          t0, do_page_fault
>         jirl            ra, t0, 0
>         RESTORE_ALL_AND_RET
> -SYM_FUNC_END(handle_tlb_protect)
> +SYM_CODE_END(handle_tlb_protect)
>
> -SYM_FUNC_START(handle_tlb_load)
> +SYM_CODE_START(handle_tlb_load)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, EXCEPTION_KS0
>         csrwr           t1, EXCEPTION_KS1
>         csrwr           ra, EXCEPTION_KS2
> @@ -187,16 +190,18 @@ nopage_tlb_load:
>         csrrd           ra, EXCEPTION_KS2
>         la_abs          t0, tlb_do_page_fault_0
>         jr              t0
> -SYM_FUNC_END(handle_tlb_load)
> +SYM_CODE_END(handle_tlb_load)
>
> -SYM_FUNC_START(handle_tlb_load_ptw)
> +SYM_CODE_START(handle_tlb_load_ptw)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_KS0
>         csrwr           t1, LOONGARCH_CSR_KS1
>         la_abs          t0, tlb_do_page_fault_0
>         jr              t0
> -SYM_FUNC_END(handle_tlb_load_ptw)
> +SYM_CODE_END(handle_tlb_load_ptw)
>
> -SYM_FUNC_START(handle_tlb_store)
> +SYM_CODE_START(handle_tlb_store)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, EXCEPTION_KS0
>         csrwr           t1, EXCEPTION_KS1
>         csrwr           ra, EXCEPTION_KS2
> @@ -343,16 +348,18 @@ nopage_tlb_store:
>         csrrd           ra, EXCEPTION_KS2
>         la_abs          t0, tlb_do_page_fault_1
>         jr              t0
> -SYM_FUNC_END(handle_tlb_store)
> +SYM_CODE_END(handle_tlb_store)
>
> -SYM_FUNC_START(handle_tlb_store_ptw)
> +SYM_CODE_START(handle_tlb_store_ptw)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_KS0
>         csrwr           t1, LOONGARCH_CSR_KS1
>         la_abs          t0, tlb_do_page_fault_1
>         jr              t0
> -SYM_FUNC_END(handle_tlb_store_ptw)
> +SYM_CODE_END(handle_tlb_store_ptw)
>
> -SYM_FUNC_START(handle_tlb_modify)
> +SYM_CODE_START(handle_tlb_modify)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, EXCEPTION_KS0
>         csrwr           t1, EXCEPTION_KS1
>         csrwr           ra, EXCEPTION_KS2
> @@ -497,16 +504,18 @@ nopage_tlb_modify:
>         csrrd           ra, EXCEPTION_KS2
>         la_abs          t0, tlb_do_page_fault_1
>         jr              t0
> -SYM_FUNC_END(handle_tlb_modify)
> +SYM_CODE_END(handle_tlb_modify)
>
> -SYM_FUNC_START(handle_tlb_modify_ptw)
> +SYM_CODE_START(handle_tlb_modify_ptw)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_KS0
>         csrwr           t1, LOONGARCH_CSR_KS1
>         la_abs          t0, tlb_do_page_fault_1
>         jr              t0
> -SYM_FUNC_END(handle_tlb_modify_ptw)
> +SYM_CODE_END(handle_tlb_modify_ptw)
>
> -SYM_FUNC_START(handle_tlb_refill)
> +SYM_CODE_START(handle_tlb_refill)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_TLBRSAVE
>         csrrd           t0, LOONGARCH_CSR_PGD
>         lddir           t0, t0, 3
> @@ -521,4 +530,4 @@ SYM_FUNC_START(handle_tlb_refill)
>         tlbfill
>         csrrd           t0, LOONGARCH_CSR_TLBRSAVE
>         ertn
> -SYM_FUNC_END(handle_tlb_refill)
> +SYM_CODE_END(handle_tlb_refill)
> diff --git a/arch/loongarch/power/Makefile b/arch/loongarch/power/Makefil=
e
> index 58151d0..bbd1d47 100644
> --- a/arch/loongarch/power/Makefile
> +++ b/arch/loongarch/power/Makefile
> @@ -1,3 +1,5 @@
> +OBJECT_FILES_NON_STANDARD_suspend_asm.o :=3D y
hibernate_asm.o has no problem?

Huacai
> +
>  obj-y  +=3D platform.o
>
>  obj-$(CONFIG_SUSPEND)          +=3D suspend.o suspend_asm.o
> diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
> index 5c97d1463..997f41c 100644
> --- a/arch/loongarch/vdso/Makefile
> +++ b/arch/loongarch/vdso/Makefile
> @@ -3,6 +3,7 @@
>
>  KASAN_SANITIZE :=3D n
>  KCOV_INSTRUMENT :=3D n
> +OBJECT_FILES_NON_STANDARD :=3D y
>
>  # Include the generic Makefile to check the built vdso.
>  include $(srctree)/lib/vdso/Makefile
> diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> index d7779a1..df29ddb 100644
> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -116,6 +116,14 @@ void ftrace_likely_update(struct ftrace_likely_data =
*f, int val,
>   */
>  #define __stringify_label(n) #n
>
> +#define __annotate_reachable(c) ({                                     \
> +       asm volatile(__stringify_label(c) ":\n\t"                       \
> +                       ".pushsection .discard.reachable\n\t"           \
> +                       ".long " __stringify_label(c) "b - .\n\t"       \
> +                       ".popsection\n\t");                             \
> +})
> +#define annotate_reachable() __annotate_reachable(__COUNTER__)
> +
>  #define __annotate_unreachable(c) ({                                   \
>         asm volatile(__stringify_label(c) ":\n\t"                       \
>                      ".pushsection .discard.unreachable\n\t"            \
> @@ -128,6 +136,7 @@ void ftrace_likely_update(struct ftrace_likely_data *=
f, int val,
>  #define __annotate_jump_table __section(".rodata..c_jump_table")
>
>  #else /* !CONFIG_OBJTOOL */
> +#define annotate_reachable()
>  #define annotate_unreachable()
>  #define __annotate_jump_table
>  #endif /* CONFIG_OBJTOOL */
> diff --git a/scripts/Makefile b/scripts/Makefile
> index 576cf64..baaed78 100644
> --- a/scripts/Makefile
> +++ b/scripts/Makefile
> @@ -33,7 +33,10 @@ ifdef CONFIG_UNWINDER_ORC
>  ifeq ($(ARCH),x86_64)
>  ARCH :=3D x86
>  endif
> -HOSTCFLAGS_sorttable.o +=3D -I$(srctree)/tools/arch/x86/include
> +ifeq ($(ARCH),loongarch)
> +ARCH :=3D loongarch
> +endif
> +HOSTCFLAGS_sorttable.o +=3D -I$(srctree)/tools/arch/$(ARCH)/include
>  HOSTCFLAGS_sorttable.o +=3D -DUNWINDER_ORC_ENABLED
>  endif
>
> --
> 2.1.0
>
>