[PATCH bpf-next v3 4/4] selftests/bpf: Update DENYLIST.riscv64

[Pu Lehui]

From: Pu Lehui <pulehui@xxxxxxxxxx>

Both probe_user and stacktrace_build_id fail on riscv64 due to riscv64's
trap-based kprobe handling.

For probe_user, kprobes on riscv64 are handled via traps where the entry
path invokes irqentry_nmi_enter(). Because bpf_probe_write_user()
rejects execution in NMI context, the test fails. Upstream discussions
regarding NMI semantics on riscv are ongoing [0] and will be tracked.

For stacktrace_build_id, under the kprobe trap context with interrupts
disabled, bpf_get_stackid() obtains a valid build_id, but the queued
irq_work is deferred. As a result, subsequent bpf_get_stack() fails to
acquire mmap_read_trylock() and falls back to BPF_STACK_BUILD_ID_IP,
causing an inconsistency between the two results.

Since stacktrace_build_id is already included in the generic DENYLIST,
only add probe_user to DENYLIST.riscv64.

Link: https://lore.kernel.org/linux-riscv/20230702025708.784106-1-guoren@xxxxxxxxxx [0]
Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/DENYLIST.riscv64 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/bpf/DENYLIST.riscv64 b/tools/testing/selftests/bpf/DENYLIST.riscv64
index ca1beae7fe8f..75a9690fb2f2 100644
--- a/tools/testing/selftests/bpf/DENYLIST.riscv64
+++ b/tools/testing/selftests/bpf/DENYLIST.riscv64
@@ -1,2 +1,3 @@
 # riscv64 deny list for BPF CI and local vmtest
 exceptions					# JIT does not support exceptions
+probe_user					# kprobe hit in trap
-- 
2.34.1