Commit 1f375aef authored Mar 11, 2025 by Kumar Kartikeya Dwivedi Committed by Alexei Starovoitov Mar 15, 2025

selftests/bpf: Fix arena_spin_lock compilation on PowerPC

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@linux.ibm.com



Fixes: 88d706ba ("selftests/bpf: Introduce arena spin lock")
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20250311154244.3775505-1-memxor@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 38c6104e

tools/testing/selftests/bpf/bpf_arena_spin_lock.h

+22 −1

Original line number	Diff line number	Diff line
		@@ -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; */

tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;