Re: [PATCH v2 8/8] LoongArch: Add ORC unwinder support

From: Huacai Chen
Date: Wed Oct 11 2023 - 00:42:42 EST

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Hi, Tiezhu,

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

On Mon, Oct 9, 2023 at 9:03 PM Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> 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@xxxxxxxxxxx>
> Signed-off-by: Jinyang He <hejinyang@xxxxxxxxxxx>
> Co-developed-by: Youling Tang <tangyouling@xxxxxxxxxxx>
> Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
> Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> ---
> 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 than the
> Guess unwinder).
>
> +config UNWINDER_ORC
> + bool "ORC unwinder"
> + select OBJTOOL
> + 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.
> +
> + 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 = elf32loongarch
> 64bit-emul = elf64loongarch
>
> +ifdef CONFIG_OBJTOOL
> +# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ecb802d02eeb
> +# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=816029e06768
> +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 += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
> +KBUILD_CFLAGS += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
> +KBUILD_CFLAGS += -fno-optimize-sibling-calls -fno-jump-tables -falign-functions=4
> +endif
> +
> +ifdef CONFIG_UNWINDER_ORC
> +orc_hash_h := arch/$(SRCARCH)/include/generated/asm/orc_hash.h
> +orc_hash_sh := $(srctree)/scripts/orc_hash.sh
> +targets += $(orc_hash_h)
> +quiet_cmd_orc_hash = GEN $@
> + cmd_orc_hash = mkdir -p $(dir $@); \
> + $(CONFIG_SHELL) $(orc_hash_sh) < $< > $@
> +$(orc_hash_h): $(srctree)/arch/loongarch/include/asm/orc_types.h $(orc_hash_sh) FORCE
> + $(call if_changed,orc_hash)
> +archprepare: $(orc_hash_h)
> +endif
> +
> ifdef CONFIG_DYNAMIC_FTRACE
> KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
> CC_FLAGS_FTRACE := -fpatchable-function-entry=2
> 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=y
> CONFIG_HIGH_RES_TIMERS=y
> CONFIG_BPF_SYSCALL=y
> CONFIG_BPF_JIT=y
> +CONFIG_BPF_JIT_ALWAYS_ON=y
> CONFIG_PREEMPT=y
> CONFIG_BSD_PROCESS_ACCT=y
> CONFIG_BSD_PROCESS_ACCT_V3=y
> diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/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 += orc_hash.h
> generic-y += dma-contiguous.h
> generic-y += mcs_spinlock.h
> generic-y += parport.h
> diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/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/include/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/include/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; see
> + * scripts/orc_hash.sh.
> + */
> +#define ORC_HEADER \
> + __used __section(".orc_header") __aligned(4) \
> + static const u8 orc_header[] = { ORC_HASH }
> +
> +#endif /* _ORC_HEADER_H */
> diff --git a/arch/loongarch/include/asm/orc_lookup.h b/arch/loongarch/include/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@xxxxxxxxxx>
> + */
> +#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/loongarch/include/asm/orc_types.h b/arch/loongarch/include/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 other
> + * 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 current
> + * function.
> + *
> + * ORC_REG_UNDEFINED means the corresponding register's value didn't change in
> + * the current frame.
> + *
> + * The most commonly used base registers are SP and BP -- which the previous SP
> + * is usually based on -- and PREV_SP and UNDEFINED -- which the previous BP is
> + * usually based on.
> + *
> + * The rest of the base registers are needed for special cases like entry 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 tells 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 corresponds
> + * 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/include/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=0 docfi=0
> @@ -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=0
> @@ -219,6 +221,7 @@
>
> .macro RESTORE_SP_AND_RET docfi=0
> 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 == STACK_TYPE_UNKNOWN;
> @@ -61,14 +73,17 @@ static __always_inline void __unwind_start(struct unwind_state *state,
> state->sp = regs->regs[3];
> state->pc = regs->csr_era;
> state->ra = regs->regs[1];
> + state->fp = regs->regs[22];
> } else if (task && task != current) {
> state->sp = thread_saved_fp(task);
> state->pc = thread_saved_ra(task);
> state->ra = 0;
> + state->fp = 0;
> } else {
> state->sp = (unsigned long)__builtin_frame_address(0);
> state->pc = (unsigned long)__builtin_return_address(0);
> state->ra = 0;
> + state->fp = 0;
> }
> state->task = task;
> get_stack_info(state->sp, state->task, &state->stack_info);
> @@ -77,6 +92,9 @@ static __always_inline void __unwind_start(struct unwind_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/include/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=UNWIND_HINT_TYPE_UNDEFINED
> +.endm
We don't need to set sp_reg=ORC_REG_UNDEFINED for UNWIND_HINT_UNDEFINED?

> +
> +.macro UNWIND_HINT_EMPTY
> + UNWIND_HINT sp_reg=ORC_REG_UNDEFINED type=UNWIND_HINT_TYPE_CALL
> +.endm
We don't need to define UNWIND_HINT_END_OF_STACK?

> +
> +.macro UNWIND_HINT_REGS
> + UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_REGS
> +.endm
> +
> +.macro UNWIND_HINT_FUNC
> + UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_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/Makefile
> 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 := y
> +
> extra-y := vmlinux.lds
>
> obj-y += head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
> @@ -62,6 +64,7 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
>
> obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
> +obj-$(CONFIG_UNWINDER_ORC) += unwind_orc.o
>
> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
> obj-$(CONFIG_HAVE_HW_BREAKPOINT) += 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 = struct task_struct *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 = struct task_struct *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 :=y"

>
> /* Config direct window and set PG */
> li.d t0, CSR_DMW0_INIT # UC, PLV0, 0x8000 xxxx xxxx xxxx
> diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.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 *rela_stack_top)
> {
> @@ -515,7 +516,7 @@ static void module_init_ftrace_plt(const Elf_Ehdr *hdr,
> 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 = NULL, *orc_ip = NULL;
> const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
>
> for (s = sechdrs, se = 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 = s;
> + if (!strcmp(".orc_unwind_ip", secstrs + s->sh_name))
> + orc_ip = 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/kernel/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/stacktrace.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_entry, void *cookie,
> regs->csr_era = thread_saved_ra(task);
> }
> regs->regs[1] = 0;
> + regs->regs[22] = 0;
> }
>
> for (unwind_start(&state, task, regs);
> diff --git a/arch/loongarch/kernel/unwind_orc.c b/arch/loongarch/kernel/unwind_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 = {
> + .type = UNWIND_HINT_TYPE_CALL,
> + .sp_reg = ORC_REG_BP,
> + .sp_offset = 16,
> + .bp_reg = ORC_REG_PREV_SP,
> + .bp_offset = -16,
> + .ra_reg = ORC_REG_PREV_SP,
> + .ra_offset = -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_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
> +
> +#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 = ftrace_ops_trampoline(ip);
> + if (!ops)
> + return NULL;
> +
> + /* Set tramp_addr to the start of the code copied by the trampoline */
> + if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
> + tramp_addr = (unsigned long)ftrace_regs_caller;
> + else
> + tramp_addr = (unsigned long)ftrace_caller;
> +
> + /* Now place tramp_addr to the location within the trampoline ip is at */
> + offset = ip - ops->trampoline;
> + tramp_addr += offset;
> +
> + /* Prevent unlikely recursion */
> + if (ip == 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==0, the last successfully executed instruction
> + * 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==0 allows us to unwind from a NULL function
> + * pointer into its parent and then continue normally from there.
> + */
> +static struct orc_entry null_orc_entry = {
> + .sp_offset = sizeof(long),
> + .sp_reg = ORC_REG_SP,
> + .bp_reg = ORC_REG_UNDEFINED,
> + .type = ORC_TYPE_CALL
> +};
> +
> +static struct orc_entry *orc_find(unsigned long ip)
> +{
> + static struct orc_entry *orc;
> +
> + if (ip == 0)
> + return &null_orc_entry;
> +
> + /* 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=%pB\n",
> + idx, lookup_num_blocks, (void *)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=%pB\n",
> + idx, lookup_num_blocks, start, stop, (void *)ip);
> + return NULL;
> + }
> +
> + return __orc_find(__start_orc_unwind_ip + start,
> + __start_orc_unwind + start, stop - start, ip);
> + }
> +
> + /* vmlinux .init slow lookup: */
> + if (is_kernel_inittext(ip))
> + return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
> + __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
> +
> + /* Module lookup: */
> + orc = 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 = __start_orc_unwind_ip;
> +static struct orc_entry *cur_orc_table = __start_orc_unwind;
> +
> +static void orc_sort_swap(void *_a, void *_b, int size)
> +{
> + struct orc_entry *orc_a, *orc_b;
> + 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);
> + swap(*orc_a, *orc_b);
> +}
> +
> +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 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 = cur_orc_table + (a - cur_orc_ip_table);
> + return orc_a->type == 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 = _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;
> + }
> +
> + /*
> + * 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 = 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;
> +}
> +
> +static inline bool on_stack(struct stack_info *info, unsigned long addr, size_t len)
> +{
> + unsigned long begin = info->begin;
> + unsigned long end = info->end;
> +
> + return (info->type != STACK_TYPE_UNKNOWN &&
> + addr >= begin && addr < end &&
> + addr + len > begin && addr + len <= end);
> +}
> +
> +static bool stack_access_ok(struct unwind_state *state, unsigned long addr,
> + size_t len)
> +{
> + struct stack_info *info = &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 >= (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 >= eentry && ra < eentry + EXCCODE_INT_END * VECSIZE) {
> + unsigned long type = (ra - eentry) / VECSIZE;
> + unsigned long offset = (ra - eentry) % VECSIZE;
> + unsigned long func;
> +
> + switch (type) {
> + case EXCCODE_TLBL:
> + case EXCCODE_TLBI:
> + func = (unsigned long)handle_tlb_load;
> + break;
> + case EXCCODE_TLBS:
> + func = (unsigned long)handle_tlb_store;
> + break;
> + case EXCCODE_TLBM:
> + func = (unsigned long)handle_tlb_modify;
> + break;
> + case EXCCODE_TLBNR:
> + case EXCCODE_TLBNX:
> + case EXCCODE_TLBPE:
> + func = (unsigned long)handle_tlb_protect;
> + break;
> + case EXCCODE_ADE:
> + func = (unsigned long)handle_ade;
> + break;
> + case EXCCODE_ALE:
> + func = (unsigned long)handle_ale;
> + break;
> + case EXCCODE_BCE:
> + func = (unsigned long)handle_bce;
> + break;
> + case EXCCODE_SYS:
> + func = (unsigned long)handle_sys;
> + break;
> + case EXCCODE_BP:
> + func = (unsigned long)handle_bp;
> + break;
> + case EXCCODE_INE:
> + case EXCCODE_IPE:
> + func = (unsigned long)handle_ri;
> + break;
> + case EXCCODE_FPDIS:
> + func = (unsigned long)handle_fpu;
> + break;
> + case EXCCODE_LSXDIS:
> + func = (unsigned long)handle_lsx;
> + break;
> + case EXCCODE_LASXDIS:
> + func = (unsigned long)handle_lasx;
> + break;
> + case EXCCODE_FPE:
> + func = (unsigned long)handle_fpe;
> + break;
> + case EXCCODE_WATCH:
> + func = (unsigned long)handle_watch;
> + break;
> + case EXCCODE_BTDIS:
> + func = (unsigned long)handle_lbt;
> + break;
> + case EXCCODE_INT_START ... EXCCODE_INT_END - 1:
> + func = (unsigned long)handle_vint;
> + break;
> + default:
> + func = (unsigned long)handle_reserved;
> + break;
> + }
> +
> + return func + offset;
> + }
> +
> + return ra;
> +}
> +
> +bool unwind_next_frame(struct unwind_state *state)
> +{
> + struct stack_info *info = &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 = orc_find(state->pc);
> + if (!orc) {
> + orc = &orc_fp_entry;
> + state->error = true;
> + }
> +
> + switch (orc->sp_reg) {
> + case ORC_REG_SP:
> + state->sp = state->sp + orc->sp_offset;
> + break;
> + case ORC_REG_BP:
> + state->sp = 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 = (unsigned long *)(state->sp + orc->bp_offset);
> + if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
> + goto err;
> +
> + state->fp = *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 == ORC_REG_PREV_SP) {
> + p = (unsigned long *)(state->sp + orc->ra_offset);
> + if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
> + goto err;
> +
> + pc = unwind_graph_addr(state, *p, state->sp);
> + pc -= LOONGARCH_INSN_SIZE;
> + } else if (orc->ra_reg == ORC_REG_UNDEFINED) {
> + if (!state->ra || state->ra == state->pc)
> + goto err;
> +
> + pc = unwind_graph_addr(state, state->ra, state->sp);
> + pc -= LOONGARCH_INSN_SIZE;
> + state->ra = 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 == STACK_TYPE_IRQ && state->sp == info->end)
> + regs = (struct pt_regs *)info->next_sp;
> + else
> + regs = (struct pt_regs *)state->sp;
> +
> + if (!stack_access_ok(state, (unsigned long)regs, sizeof(*regs)))
> + goto err;
> +
> + if ((info->end == (unsigned long)regs + sizeof(*regs)) &&
> + !regs->regs[3] && !regs->regs[1])
> + goto end;
> +
> + if (user_mode(regs))
> + goto end;
> +
> + pc = regs->csr_era;
> + if (!__kernel_text_address(pc))
> + goto err;
> +
> + state->sp = regs->regs[3];
> + state->ra = regs->regs[1];
> + state->fp = 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 = 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 = true;
> +
> +end:
> + preempt_enable();
> + state->stack_info.type = 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 = .;
> 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 := y
> +
> lib-y += 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/Makefile
> 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 := y
hibernate_asm.o has no problem?

Huacai
> +
> obj-y += platform.o
>
> obj-$(CONFIG_SUSPEND) += 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 := n
> KCOV_INSTRUMENT := n
> +OBJECT_FILES_NON_STANDARD := 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 := x86
> endif
> -HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/x86/include
> +ifeq ($(ARCH),loongarch)
> +ARCH := loongarch
> +endif
> +HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/$(ARCH)/include
> HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED
> endif
>
> --
> 2.1.0
>
>

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