Re: [PATCH v2] perf unwind-libdw: fix a cross-arch unwinding bug

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Mon, Jan 05, 2026 at 01:13:38PM -0800, Shimin Guo via B4 Relay wrote:
> From: Shimin Guo <shimin.guo@skydio.com>
> 
> The set_initial_registers field of Dwfl_Thread_Callbacks needs to be set
> according to the arch of the stack samples being analyzed, not the arch
> that perf itself is built for. Currently perf fails to unwind stack samples
> collected from archs different from that of the host perf is running on.

Thanks for the contribution!

> This patch moves the arch-specific implementations of set_initial_registers
> from tools/perf/arch to tools/perf/utli/unwind-libdw-arch, similar to the
> way the perf-regs-arch folder contains arch-specific functions related to
> registers, and chooses the implementation based on the arch of the data
> being processed.

I feel like some day we will just include all top-level arch directories
for multi-arch builds..

Btw, can you please show me an example how you tested this?

> 
> Signed-off-by: Shimin Guo <shimin.guo@skydio.com>
> ---
> Changes in v2:
> - Fixed the include path for perf_regs.h in unwind-libdw-x86.c
> - Removed one level of "../" from the include paths in the moved files
> now that they are two directory levels under tools/perf instead of three.
> - Link to v1: https://lore.kernel.org/r/20251223-cross-arch-unwind-v1-1-4d71ee7db512@skydio.com
> ---
>  tools/perf/arch/arm/util/Build                     |  1 -
>  tools/perf/arch/arm64/util/Build                   |  1 -
>  tools/perf/arch/csky/util/Build                    |  2 -
>  tools/perf/arch/powerpc/util/Build                 |  1 -
>  tools/perf/arch/riscv/util/Build                   |  1 -
>  tools/perf/arch/s390/util/Build                    |  2 -
>  tools/perf/arch/x86/util/Build                     |  1 -
>  tools/perf/util/Build                              |  1 +
>  tools/perf/util/unwind-libdw-arch/Build            |  8 ++++
>  .../unwind-libdw-arch/unwind-libdw-arm.c}          | 10 ++---
>  .../unwind-libdw-arch/unwind-libdw-arm64.c}        | 10 ++---
>  .../unwind-libdw-arch/unwind-libdw-csky.c}         |  6 +--
>  .../unwind-libdw-arch/unwind-libdw-loongarch.c}    |  4 +-
>  .../unwind-libdw-arch/unwind-libdw-powerpc.c}      | 10 ++---
>  .../unwind-libdw-arch/unwind-libdw-riscv.c}        |  4 +-
>  .../unwind-libdw-arch/unwind-libdw-s390.c}         |  6 +--
>  .../unwind-libdw-arch/unwind-libdw-x86.c}          |  8 ++--
>  tools/perf/util/unwind-libdw.c                     | 51 +++++++++++++++++++---
>  tools/perf/util/unwind-libdw.h                     | 10 ++++-
>  19 files changed, 92 insertions(+), 45 deletions(-)
> 
> diff --git a/tools/perf/arch/arm/util/Build b/tools/perf/arch/arm/util/Build
> index fd695e1fdaee2ccc300a206131b8b38a763b00ce..3291f893b943df0722dff583523fff4ae79919bc 100644
> --- a/tools/perf/arch/arm/util/Build
> +++ b/tools/perf/arch/arm/util/Build
> @@ -1,6 +1,5 @@
>  perf-util-y += perf_regs.o
>  
>  perf-util-$(CONFIG_LOCAL_LIBUNWIND)    += unwind-libunwind.o
> -perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
>  
>  perf-util-y += pmu.o auxtrace.o cs-etm.o
> diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build
> index d63881081d2eb1e9a83eabf82104d75308f7fc79..0177af19cc00038d6a6005592ddc530bf7eb1557 100644
> --- a/tools/perf/arch/arm64/util/Build
> +++ b/tools/perf/arch/arm64/util/Build
> @@ -1,4 +1,3 @@
> -perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
>  perf-util-$(CONFIG_LIBTRACEEVENT) += kvm-stat.o
>  perf-util-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.o
>  perf-util-y += ../../arm/util/auxtrace.o
> diff --git a/tools/perf/arch/csky/util/Build b/tools/perf/arch/csky/util/Build
> index 5e6ea82c42021d3d5651ca4c4a3a6e5138574e4e..6b2d0e021b11464e46d6b53974260d32ea969732 100644
> --- a/tools/perf/arch/csky/util/Build
> +++ b/tools/perf/arch/csky/util/Build
> @@ -1,3 +1 @@
>  perf-util-y += perf_regs.o
> -
> -perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
> diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build
> index 3d0d5427aef7f26a8c05c883cc7ad763f08cbb30..5fd28ec713a4db74ecd1d26866a65ddb20e94bd3 100644
> --- a/tools/perf/arch/powerpc/util/Build
> +++ b/tools/perf/arch/powerpc/util/Build
> @@ -9,5 +9,4 @@ perf-util-y += evsel.o
>  perf-util-$(CONFIG_LIBDW) += skip-callchain-idx.o
>  
>  perf-util-$(CONFIG_LIBUNWIND) += unwind-libunwind.o
> -perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
>  perf-util-y += auxtrace.o
> diff --git a/tools/perf/arch/riscv/util/Build b/tools/perf/arch/riscv/util/Build
> index 58a672246024dd0f72e767d11e9958bd9913ec3c..628b9ebd418bde8cdf1ab1332bf79f7c9d50760e 100644
> --- a/tools/perf/arch/riscv/util/Build
> +++ b/tools/perf/arch/riscv/util/Build
> @@ -2,4 +2,3 @@ perf-util-y += perf_regs.o
>  perf-util-y += header.o
>  
>  perf-util-$(CONFIG_LIBTRACEEVENT) += kvm-stat.o
> -perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
> diff --git a/tools/perf/arch/s390/util/Build b/tools/perf/arch/s390/util/Build
> index c64eb18dbdae93adafabf8542e4c9a763ecfe057..5391d26fedd46b7d30a1bef0bff2ec2d58ec30ed 100644
> --- a/tools/perf/arch/s390/util/Build
> +++ b/tools/perf/arch/s390/util/Build
> @@ -2,8 +2,6 @@ perf-util-y += header.o
>  perf-util-$(CONFIG_LIBTRACEEVENT) += kvm-stat.o
>  perf-util-y += perf_regs.o
>  
> -perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
> -
>  perf-util-y += machine.o
>  perf-util-y += pmu.o
>  
> diff --git a/tools/perf/arch/x86/util/Build b/tools/perf/arch/x86/util/Build
> index c0dc5965f3624a6f02525a04d287dff755356d20..fad256252bb95a8f8350b6bb1a54e8074eaebbec 100644
> --- a/tools/perf/arch/x86/util/Build
> +++ b/tools/perf/arch/x86/util/Build
> @@ -12,7 +12,6 @@ perf-util-y += evsel.o
>  perf-util-y += iostat.o
>  
>  perf-util-$(CONFIG_LOCAL_LIBUNWIND)    += unwind-libunwind.o
> -perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
>  
>  perf-util-y += auxtrace.o
>  perf-util-y += archinsn.o
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index 1c2a43e1dc68e7f751ec6082352b10de9ffeea62..15f8a4f4b24a46b6300e824f672dd9c0d5b7865f 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -226,6 +226,7 @@ perf-util-$(CONFIG_LIBDW) += debuginfo.o
>  perf-util-$(CONFIG_LIBDW) += annotate-data.o
>  
>  perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-arch/
>  perf-util-$(CONFIG_LOCAL_LIBUNWIND)    += unwind-libunwind-local.o
>  perf-util-$(CONFIG_LIBUNWIND)          += unwind-libunwind.o
>  perf-util-$(CONFIG_LIBUNWIND_X86)      += libunwind/x86_32.o
> diff --git a/tools/perf/util/unwind-libdw-arch/Build b/tools/perf/util/unwind-libdw-arch/Build
> new file mode 100644
> index 0000000000000000000000000000000000000000..e016d54ae2a40ecba47156c8f09cb72156105727
> --- /dev/null
> +++ b/tools/perf/util/unwind-libdw-arch/Build
> @@ -0,0 +1,8 @@
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-x86.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-arm.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-arm64.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-csky.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-loongarch.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-powerpc.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-riscv.o
> +perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw-s390.o
> \ No newline at end of file

Please fix.  And I think they can be simply perf-util-y at this point
since you added the directory with CONFIG_LIBDW_DWARF_UNWIND in the
Build file in the parent directory.


> diff --git a/tools/perf/arch/arm/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-arm.c
> similarity index 78%
> rename from tools/perf/arch/arm/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-arm.c
> index fbb643f224ec4b27ce9d67051fe0bc4ad555b05e..3c7f91a1af7416f57b0e4fa0dcd15a530cb44f8a 100644
> --- a/tools/perf/arch/arm/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-arm.c
> @@ -1,11 +1,11 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <elfutils/libdwfl.h>
> -#include "perf_regs.h"
> -#include "../../../util/unwind-libdw.h"
> -#include "../../../util/perf_regs.h"
> -#include "../../../util/sample.h"
> +#include "../../../arch/arm/include/uapi/asm/perf_regs.h"
> +#include "../../util/unwind-libdw.h"
> +#include "../../util/perf_regs.h"
> +#include "../../util/sample.h"

I think it'd be simpler if we assume the include path always starts from
tools/perf directory (which is set with -I already).  Then we don't need
to change the relative paths when we move files around.

Thanks,
Namhyung

>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_arm(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/arch/arm64/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-arm64.c
> similarity index 86%
> rename from tools/perf/arch/arm64/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-arm64.c
> index b89b0a7e5ad919fed23643d219fbdc3d84deff1e..a237af99d1f87a72b99d5ed2ff965d4ef2f75434 100644
> --- a/tools/perf/arch/arm64/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-arm64.c
> @@ -1,11 +1,11 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <elfutils/libdwfl.h>
> -#include "perf_regs.h"
> -#include "../../../util/unwind-libdw.h"
> -#include "../../../util/perf_regs.h"
> -#include "../../../util/sample.h"
> +#include "../../../arch/arm64/include/uapi/asm/perf_regs.h"
> +#include "../../util/unwind-libdw.h"
> +#include "../../util/perf_regs.h"
> +#include "../../util/sample.h"
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_arm64(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/arch/csky/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-csky.c
> similarity index 92%
> rename from tools/perf/arch/csky/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-csky.c
> index b20b1569783d7e982e91b1b40120d29ccf2f01d1..889d3b788931f3af55b03ef8b91d5def364972e5 100644
> --- a/tools/perf/arch/csky/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-csky.c
> @@ -2,12 +2,12 @@
>  // Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
>  
>  #include <elfutils/libdwfl.h>
> -#include "perf_regs.h"
> +#include "../../../arch/csky/include/uapi/asm/perf_regs.h"
>  #include "../../util/unwind-libdw.h"
>  #include "../../util/perf_regs.h"
> -#include "../../util/event.h"
> +#include "../../util/sample.h"
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_csky(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/arch/loongarch/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-loongarch.c
> similarity index 91%
> rename from tools/perf/arch/loongarch/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-loongarch.c
> index 60b1144bedd5f325e1512eeab05c29a1e8de2b03..1c5753ace6f63be771aa92365d3174ad8ed3a6fd 100644
> --- a/tools/perf/arch/loongarch/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-loongarch.c
> @@ -2,12 +2,12 @@
>  /* Copyright (C) 2020-2023 Loongson Technology Corporation Limited */
>  
>  #include <elfutils/libdwfl.h>
> -#include "perf_regs.h"
> +#include "../../../arch/loongarch/include/uapi/asm/perf_regs.h"
>  #include "../../util/unwind-libdw.h"
>  #include "../../util/perf_regs.h"
>  #include "../../util/sample.h"
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_loongarch(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/arch/powerpc/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-powerpc.c
> similarity index 88%
> rename from tools/perf/arch/powerpc/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-powerpc.c
> index 82d0c28ae3459ecdb0039cac1f534420d142739b..d5012f20a87e30809b8b44ee20572fab8668b7dd 100644
> --- a/tools/perf/arch/powerpc/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-powerpc.c
> @@ -1,10 +1,10 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <elfutils/libdwfl.h>
>  #include <linux/kernel.h>
> -#include "perf_regs.h"
> -#include "../../../util/unwind-libdw.h"
> -#include "../../../util/perf_regs.h"
> -#include "../../../util/sample.h"
> +#include "../../../arch/powerpc/include/uapi/asm/perf_regs.h"
> +#include "../../util/unwind-libdw.h"
> +#include "../../util/perf_regs.h"
> +#include "../../util/sample.h"
>  
>  /* See backends/ppc_initreg.c and backends/ppc_regs.c in elfutils.  */
>  static const int special_regs[3][2] = {
> @@ -13,7 +13,7 @@ static const int special_regs[3][2] = {
>  	{ 109, PERF_REG_POWERPC_CTR },
>  };
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_powerpc(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/arch/riscv/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-riscv.c
> similarity index 92%
> rename from tools/perf/arch/riscv/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-riscv.c
> index dc1476e16321736de897ad53a00fbc813bd706db..2a5442b3b5bdc27252378de0073deb8a620f8779 100644
> --- a/tools/perf/arch/riscv/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-riscv.c
> @@ -2,12 +2,12 @@
>  /* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
>  
>  #include <elfutils/libdwfl.h>
> -#include "perf_regs.h"
> +#include "../../../arch/riscv/include/uapi/asm/perf_regs.h"
>  #include "../../util/unwind-libdw.h"
>  #include "../../util/perf_regs.h"
>  #include "../../util/sample.h"
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_riscv(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/arch/s390/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-s390.c
> similarity index 89%
> rename from tools/perf/arch/s390/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-s390.c
> index c27c7a0d1076c890c35ba19543932c4ed5ac9c2a..18d44074a55bc1c7fa2d7150afc1f1a93d4eadf8 100644
> --- a/tools/perf/arch/s390/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-s390.c
> @@ -4,11 +4,11 @@
>  #include "../../util/perf_regs.h"
>  #include "../../util/event.h"
>  #include "../../util/sample.h"
> -#include "dwarf-regs-table.h"
> -#include "perf_regs.h"
> +#include "../../arch/s390/include/dwarf-regs-table.h"
> +#include "../../../arch/s390/include/uapi/asm/perf_regs.h"
>  
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_s390(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/arch/x86/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-x86.c
> similarity index 86%
> rename from tools/perf/arch/x86/util/unwind-libdw.c
> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-x86.c
> index 798493e887d7308cb293e29e4ba11054d0fda722..6619c60728ef6ad1e725cd86c7bcbf06b8aad28d 100644
> --- a/tools/perf/arch/x86/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-x86.c
> @@ -1,11 +1,11 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <elfutils/libdwfl.h>
> -#include "perf_regs.h"
> -#include "../../../util/unwind-libdw.h"
> -#include "../../../util/perf_regs.h"
> +#include "../../../arch/x86/include/uapi/asm/perf_regs.h"
> +#include "../../util/unwind-libdw.h"
> +#include "../../util/perf_regs.h"
>  #include "util/sample.h"
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
> +bool libdw_set_initial_registers_x86(Dwfl_Thread *thread, void *arg)
>  {
>  	struct unwind_info *ui = arg;
>  	struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
> diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
> index ae70fb56a05729b9f06a411d162eabebbf29ac52..f32694ff4ea52d4bf80a38405341864e7ff5e6c8 100644
> --- a/tools/perf/util/unwind-libdw.c
> +++ b/tools/perf/util/unwind-libdw.c
> @@ -225,11 +225,45 @@ static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *
>  	return true;
>  }
>  
> -static const Dwfl_Thread_Callbacks callbacks = {
> -	.next_thread		= next_thread,
> -	.memory_read		= memory_read,
> -	.set_initial_registers	= libdw__arch_set_initial_registers,
> -};
> +#define DEFINE_DWFL_THREAD_CALLBACKS(arch)                           \
> +static const Dwfl_Thread_Callbacks callbacks_##arch = {              \
> +	.next_thread           = next_thread,                        \
> +	.memory_read           = memory_read,                        \
> +	.set_initial_registers = libdw_set_initial_registers_##arch, \
> +}
> +
> +DEFINE_DWFL_THREAD_CALLBACKS(x86);
> +DEFINE_DWFL_THREAD_CALLBACKS(arm);
> +DEFINE_DWFL_THREAD_CALLBACKS(arm64);
> +DEFINE_DWFL_THREAD_CALLBACKS(csky);
> +DEFINE_DWFL_THREAD_CALLBACKS(loongarch);
> +DEFINE_DWFL_THREAD_CALLBACKS(powerpc);
> +DEFINE_DWFL_THREAD_CALLBACKS(riscv);
> +DEFINE_DWFL_THREAD_CALLBACKS(s390);
> +
> +static const Dwfl_Thread_Callbacks *get_thread_callbacks(const char *arch)
> +{
> +	if (!strcmp(arch, "arm"))
> +		return &callbacks_arm;
> +	else if (!strcmp(arch, "arm64"))
> +		return &callbacks_arm64;
> +	else if (!strcmp(arch, "csky"))
> +		return &callbacks_csky;
> +	else if (!strcmp(arch, "loongarch"))
> +		return &callbacks_loongarch;
> +	else if (!strcmp(arch, "powerpc"))
> +		return &callbacks_powerpc;
> +	else if (!strcmp(arch, "riscv"))
> +		return &callbacks_riscv;
> +	else if (!strcmp(arch, "s390"))
> +		return &callbacks_s390;
> +	else if (!strcmp(arch, "x86"))
> +		return &callbacks_x86;
> +
> +	pr_err("Fail to get thread callbacks for arch %s, returns NULL\n",
> +	       arch);
> +	return NULL;
> +}
>  
>  static int
>  frame_callback(Dwfl_Frame *state, void *arg)
> @@ -278,6 +312,7 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
>  	const char *arch = perf_env__arch(ui_buf.machine->env);
>  	Dwarf_Word ip;
>  	int err = -EINVAL, i;
> +	const Dwfl_Thread_Callbacks *callbacks;
>  
>  	if (!data->user_regs || !data->user_regs->regs)
>  		return -EINVAL;
> @@ -300,7 +335,11 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
>  	if (err)
>  		goto out;
>  
> -	err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), &callbacks, ui);
> +	callbacks = get_thread_callbacks(arch);
> +	if (!callbacks)
> +		goto out;
> +
> +	err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), callbacks, ui);
>  	if (err)
>  		goto out;
>  
> diff --git a/tools/perf/util/unwind-libdw.h b/tools/perf/util/unwind-libdw.h
> index 8c88bc4f2304b59561ffd482469ca63ce0f531f0..574b29848cce31e6bfd93021f752b518cebf73b7 100644
> --- a/tools/perf/util/unwind-libdw.h
> +++ b/tools/perf/util/unwind-libdw.h
> @@ -9,7 +9,15 @@ struct machine;
>  struct perf_sample;
>  struct thread;
>  
> -bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_x86(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_arm(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_arm64(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_csky(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_loongarch(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_mips(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_powerpc(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_riscv(Dwfl_Thread *thread, void *arg);
> +bool libdw_set_initial_registers_s390(Dwfl_Thread *thread, void *arg);
>  
>  struct unwind_info {
>  	Dwfl			*dwfl;
> 
> ---
> base-commit: cbd41c6d4c26c161a2b0e70ad411d3885ff13507
> change-id: 20260105-cross-arch-unwind-7238af40fb14
> 
> Best regards,
> -- 
> Shimin Guo <shimin.guo@skydio.com>
> 
>