Venkat reported a compilation error for BPF selftests on PowerPC [0].
The crux of the error is the following message:
In file included from progs/arena_spin_lock.c:7:
/root/bpf-next/tools/testing/selftests/bpf/bpf_arena_spin_lock.h:122:8:
error: member reference base type '__attribute__((address_space(1)))
u32' (aka '__attribute__((address_space(1))) unsigned int') is not a
structure or union
122 | old = atomic_read(&lock->val);
This is because PowerPC overrides the qspinlock type changing the
lock->val member's type from atomic_t to u32.
To remedy this, import the asm-generic version in the arena spin lock
header, name it __qspinlock (since it's aliased to arena_spinlock_t, the
actual name hardly matters), and adjust the selftest to not depend on
the type in vmlinux.h.
[0]: https://lore.kernel.org/bpf/7bc80a3b-d708-4735-aa3b-6a8c21720f9d@xxxxxxxxxxxxx
Fixes: 0201027a026c ("selftests/bpf: Introduce arena spin lock")
Reported-by: Venkat Rao Bagalkote <venkat88@xxxxxxxxxxxxx>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
---
.../selftests/bpf/bpf_arena_spin_lock.h | 23 ++++++++++++++++++-
.../bpf/prog_tests/arena_spin_lock.c | 4 ++--
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_arena_spin_lock.h b/tools/testing/selftests/bpf/bpf_arena_spin_lock.h
index 3aca389ce424..fb8dc0768999 100644
--- a/tools/testing/selftests/bpf/bpf_arena_spin_lock.h
+++ b/tools/testing/selftests/bpf/bpf_arena_spin_lock.h
@@ -22,7 +22,28 @@
extern unsigned long CONFIG_NR_CPUS __kconfig;
-#define arena_spinlock_t struct qspinlock
+/*
+ * Typically, we'd just rely on the definition in vmlinux.h for qspinlock, but
+ * PowerPC overrides the definition to define lock->val as u32 instead of
+ * atomic_t, leading to compilation errors. Import a local definition below so
+ * that we don't depend on the vmlinux.h version.
+ */
+
+struct __qspinlock {
+ union {
+ atomic_t val;
+ struct {
+ u8 locked;
+ u8 pending;
+ };
+ struct {
+ u16 locked_pending;
+ u16 tail;
+ };
+ };
+};
+
+#define arena_spinlock_t struct __qspinlock
/* FIXME: Using typedef causes CO-RE relocation error */
/* typedef struct qspinlock arena_spinlock_t; */
diff --git a/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
index bc3616ba891c..7565fc7690c2 100644
--- a/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
+++ b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
@@ -4,8 +4,8 @@
#include <network_helpers.h>
#include <sys/sysinfo.h>
-struct qspinlock { int val; };
-typedef struct qspinlock arena_spinlock_t;
+struct __qspinlock { int val; };
+typedef struct __qspinlock arena_spinlock_t;
struct arena_qnode {
unsigned long next;
--
2.47.1
