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Message-ID: <ec96d30c-56c2-484f-b64d-05bab7071c89@linaro.org>
Date: Tue, 30 Dec 2025 10:10:29 +0000
From: James Clark <james.clark@...aro.org>
To: Shimin Guo <shimin.guo@...dio.com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-perf-users@...r.kernel.org, linux-csky@...r.kernel.org,
linux-riscv@...ts.infradead.org, John Garry <john.g.garry@...cle.com>,
Will Deacon <will@...nel.org>, Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...ux.dev>, Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>, Guo Ren <guoren@...nel.org>,
Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>
Subject: Re: [PATCH] perf unwind-libdw: fix a cross-arch unwinding bug
On 25/12/2025 5:02 am, Shimin Guo wrote:
> On Wed, Dec 24, 2025 at 5:40 AM James Clark <james.clark@...aro.org> wrote:
>>
>>
>>
>> On 24/12/2025 2:19 am, Shimin Guo via B4 Relay wrote:
>>> From: Shimin Guo <shimin.guo@...dio.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.
>>> 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.
>>>
>>> Signed-off-by: Shimin Guo <shimin.guo@...dio.com>
>>> ---
>>> checkpatch flagged three issues:
>>>> tools/perf/util/unwind-libdw-arch/Build:232: WARNING: added, moved
>>> or deleted file(s), does MAINTAINERS need updating?
>>>
>>> Not sure what to do about that.
>>>
>>
>> You don't need to do anything here because there's a blanket rule for
>> the Perf dir.
>
> PERFORMANCE EVENTS TOOLING ARM64 has a rule that matches tools/perf/arch/arm*/.
> The new files for arm and arm64 will no longer be matched by the rule.
>
Oh I see, I thought it was a generic question. In this case I still
think the blanket rule is ok for this folder.
>>
>>>> checkpatch.pl: tools/perf/util/unwind-libdw.c:228: WARNING:
>>> Non-declarative macros with multiple statements should be enclosed in
>>> a do - while loop
>>
>> I think you can ignore this one.
>>
>>>> checkpatch.pl: tools/perf/util/unwind-libdw.c:228: WARNING: macros
>>> should not use a trailing semicolon
>>>
>>> Are these two false positives? I'm defining static global variables
>>> with the macro.
>>
>> But I don't see a reason not to follow this one, just remove the semicolon.
>
> Maybe it doesn't matter, but after I removed the semicolon, I got a new error
> from checkpatch "Macros with complex values should be enclosed in parentheses"
> instead of the warning that suggests do - while.
>
It explains in that warning. It's because Dwfl_Thread_Callbacks is
typedef'd and doesn't need 'struct' so the heuristic doesn't work. That
one can be ignored but I think the one about removing the semicolon is
the right thing to do.
>>
>>> ---
>>> 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} | 4 +-
>>> .../unwind-libdw-arch/unwind-libdw-arm64.c} | 4 +-
>>> .../unwind-libdw-arch/unwind-libdw-csky.c} | 6 +--
>>> .../unwind-libdw-arch/unwind-libdw-loongarch.c} | 4 +-
>>> .../unwind-libdw-arch/unwind-libdw-powerpc.c} | 4 +-
>>> .../unwind-libdw-arch/unwind-libdw-riscv.c} | 4 +-
>>> .../unwind-libdw-arch/unwind-libdw-s390.c} | 6 +--
>>> .../unwind-libdw-arch/unwind-libdw-x86.c} | 2 +-
>>> tools/perf/util/unwind-libdw.c | 49 +++++++++++++++++++---
>>> tools/perf/util/unwind-libdw.h | 10 ++++-
>>> 19 files changed, 79 insertions(+), 32 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
>>> diff --git a/tools/perf/arch/arm/util/unwind-libdw.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-arm.c
>>> similarity index 88%
>>> rename from tools/perf/arch/arm/util/unwind-libdw.c
>>> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-arm.c
>>> index fbb643f224ec4b27ce9d67051fe0bc4ad555b05e..c2718d6b6cff131cd67883e24bb0d3d963c8095a 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 "../../../arch/arm/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_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 92%
>>> rename from tools/perf/arch/arm64/util/unwind-libdw.c
>>> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-arm64.c
>>> index b89b0a7e5ad919fed23643d219fbdc3d84deff1e..87602503e057badc6efd37169cc60c96cf3949ab 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 "../../../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 93%
>>> rename from tools/perf/arch/powerpc/util/unwind-libdw.c
>>> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-powerpc.c
>>> index 82d0c28ae3459ecdb0039cac1f534420d142739b..28635af3c4aa420faa4de7e53428d82917f78021 100644
>>> --- a/tools/perf/arch/powerpc/util/unwind-libdw.c
>>> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-powerpc.c
>>> @@ -1,7 +1,7 @@
>>> // SPDX-License-Identifier: GPL-2.0
>>> #include <elfutils/libdwfl.h>
>>> #include <linux/kernel.h>
>>> -#include "perf_regs.h"
>>> +#include "../../../arch/powerpc/include/uapi/asm/perf_regs.h"
>>> #include "../../../util/unwind-libdw.h"
>>> #include "../../../util/perf_regs.h"
>>> #include "../../../util/sample.h"
>>> @@ -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 94%
>>> rename from tools/perf/arch/x86/util/unwind-libdw.c
>>> rename to tools/perf/util/unwind-libdw-arch/unwind-libdw-x86.c
>>> index 798493e887d7308cb293e29e4ba11054d0fda722..822e799fe1543d82dab27a8efeada3f5cde08a44 100644
>>> --- a/tools/perf/arch/x86/util/unwind-libdw.c
>>> +++ b/tools/perf/util/unwind-libdw-arch/unwind-libdw-x86.c
>>
>> You missed converting the unwind-libdw-x86.c perf_regs.h paths to a
>> static arch so now Perf can only be built on x86. If you try to build
>> for another arch then you get the local header and then missing x86
>> definitions.
>
> Yeah you are right. I'm also going to change some of the relative include paths
> from "../../../" to "../../" since the new files are two levels under
> tools/perf instead of
> three. The build worked without the change mostly by accident.
>
>>
>> Unfortunately you also have to convert the one in
>> tools/perf/arch/x86/include/perf_regs.h which is a bit weird, but the
>> build seems to work.
>
> How does tools/perf/arch/x86/include/perf_regs.h come up? I seem to be able to
> build an arm64 version without changing this file.
>
You're right. I changed one too many other ones trying to get it to
compile which resulted in me needing to change that one too.
>>
>> Other than that, looks good.
>>
>>> @@ -5,7 +5,7 @@
>>> #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..4a0f13bc5af99de446d440c551c718ef0187e195 100644
>>> --- a/tools/perf/util/unwind-libdw.c
>>> +++ b/tools/perf/util/unwind-libdw.c
>>> @@ -225,12 +225,46 @@ 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: 20251223-cross-arch-unwind-d890d6a5ff0a
>>>
>>> Best regards,
>>
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