Cannot unwind past syscall boundary on aarch64

[bobrik]

Testing with:

stress-ng --syscall 1

When on x86_64:

2026/01/09 03:26:02 received trace event for pid=3000908, comm=stress-ng-sysca, executable=/usr/bin/stress-ng, container=
2026/01/09 03:26:02  non-native frame: xfs_buf_get_map [kernel]
2026/01/09 03:26:02  non-native frame: xfs_buf_read_map [kernel]
2026/01/09 03:26:02  non-native frame: xfs_trans_read_buf_map [kernel]
2026/01/09 03:26:02  non-native frame: xfs_read_agi [kernel]
2026/01/09 03:26:02  non-native frame: xfs_ialloc_read_agi [kernel]
2026/01/09 03:26:02  non-native frame: xfs_dialloc [kernel]
2026/01/09 03:26:02  non-native frame: xfs_create [kernel]
2026/01/09 03:26:02  non-native frame: xfs_generic_create [kernel]
2026/01/09 03:26:02  non-native frame: path_openat [kernel]
2026/01/09 03:26:02  non-native frame: do_filp_open [kernel]
2026/01/09 03:26:02  non-native frame: do_sys_openat2 [kernel]
2026/01/09 03:26:02  non-native frame: __x64_sys_openat [kernel]
2026/01/09 03:26:02  non-native frame: do_syscall_64 [kernel]
2026/01/09 03:26:02  non-native frame: entry_SYSCALL_64_after_hwframe [kernel]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/lib/x86_64-linux-gnu/libc.so.6]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/lib/x86_64-linux-gnu/libc.so.6]
2026/01/09 03:26:02  0x00103770+0x004c __open64 @ ??:0:0 [/usr/lib/x86_64-linux-gnu/libc.so.6]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/lib/x86_64-linux-gnu/libc.so.6]
2026/01/09 03:26:02  0x00029ce0+0x0084 __libc_start_main @ ??:0:0 [/usr/lib/x86_64-linux-gnu/libc.so.6]
2026/01/09 03:26:02  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]

When on aarch64:

2026/01/09 03:26:44 received trace event for pid=12907, comm=stress-ng-sysca, executable=/usr/bin/stress-ng, container=
2026/01/09 03:26:44  non-native frame: kmem_cache_free [kernel]
2026/01/09 03:26:44  non-native frame: xfs_btree_del_cursor [kernel]
2026/01/09 03:26:44  non-native frame: xfs_dialloc_ag_finobt_near [kernel]
2026/01/09 03:26:44  non-native frame: xfs_dialloc [kernel]
2026/01/09 03:26:44  non-native frame: xfs_create [kernel]
2026/01/09 03:26:44  non-native frame: xfs_generic_create [kernel]
2026/01/09 03:26:44  non-native frame: xfs_vn_create [kernel]
2026/01/09 03:26:44  non-native frame: path_openat [kernel]
2026/01/09 03:26:44  non-native frame: do_filp_open [kernel]
2026/01/09 03:26:44  non-native frame: do_sys_openat2 [kernel]
2026/01/09 03:26:44  non-native frame: __arm64_sys_openat [kernel]
2026/01/09 03:26:44  non-native frame: invoke_syscall.constprop.0 [kernel]
2026/01/09 03:26:44  non-native frame: do_el0_svc [kernel]
2026/01/09 03:26:44  non-native frame: el0_svc [kernel]
2026/01/09 03:26:44  non-native frame: el0t_64_sync_handler [kernel]
2026/01/09 03:26:44  non-native frame: el0t_64_sync [kernel]
2026/01/09 03:26:44  non-native frame:  [abort-marker]

It can unwind user-space separately:

2026/01/09 03:27:23 received trace event for pid=12907, comm=stress-ng-sysca, executable=/usr/bin/stress-ng, container=
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [linux-vdso.1.so]
2026/01/09 03:27:23  0x00000820+0x0107 __kernel_getrandom @ ??:0:0 [linux-vdso.1.so]
2026/01/09 03:27:23  0x0003a4c0+0x0097 getrandom_vdso @ getrandom.c:211:18 [/usr/lib/aarch64-linux-gnu/libc.so.6]
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]
2026/01/09 03:27:23  0x00022220+0x007b __libc_start_call_main @ libc_start_call_main.h:58:16 [/usr/lib/aarch64-linux-gnu/libc.so.6]
2026/01/09 03:27:23  0x000222e0+0x009b __libc_start_main_impl @ libc-start.c:360:3 [/usr/lib/aarch64-linux-gnu/libc.so.6]
2026/01/09 03:27:23  0x00000000+0x0000 [unknown] @ ??:0:0 [/usr/bin/stress-ng]

Both are running Linux v6.19-rc1, but I can also replicate on v6.12. I'm using opentelemetry-ebpf-profiler v0.0.202601, running it manually:

	tracer, err := tracer.NewTracer(context.Background(), &tracer.Config{
		ExecutableReporter: mapper,
		TraceReporter:      reporter,
		Intervals:          times.New(time.Second, time.Minute, time.Minute),
		IncludeTracers:     types.AllTracers(),
		SamplesPerSecond:   19,
		FilterIdleFrames:   true,
	})
	if err != nil {
		panic(err)
	}

I'm seeing this on both Ampere CPUs (bare metal) and on my Apple M1 laptop (in a VM).