Implementing BPF version of preempt_count() requires accessing lowcore from BPF. Since lowcore can be relocated, open-coding (struct lowcore *)0 does not work, so add a kfunc. Signed-off-by: Ilya Leoshkevich --- arch/s390/kernel/Makefile | 2 ++ arch/s390/kernel/bpf.c | 12 ++++++++++++ kernel/bpf/helpers.c | 3 +++ tools/testing/selftests/bpf/bpf_experimental.h | 4 ++++ 4 files changed, 21 insertions(+) create mode 100644 arch/s390/kernel/bpf.c diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile index 42c83d60d6fae..b522c6649fccb 100644 --- a/arch/s390/kernel/Makefile +++ b/arch/s390/kernel/Makefile @@ -80,5 +80,7 @@ obj-$(CONFIG_PERF_EVENTS) += perf_pai.o obj-$(CONFIG_TRACEPOINTS) += trace.o +obj-$(CONFIG_BPF_SYSCALL) += bpf.o + # vdso obj-y += vdso/ diff --git a/arch/s390/kernel/bpf.c b/arch/s390/kernel/bpf.c new file mode 100644 index 0000000000000..713337fae6263 --- /dev/null +++ b/arch/s390/kernel/bpf.c @@ -0,0 +1,12 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +__bpf_kfunc_start_defs(); + +__bpf_kfunc struct lowcore *bpf_get_lowcore(void) +{ + return get_lowcore(); +} + +__bpf_kfunc_end_defs(); diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 7ac32798eb041..8c1023da3855d 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -4578,6 +4578,9 @@ BTF_ID_FLAGS(func, bpf_key_put, KF_RELEASE) BTF_ID_FLAGS(func, bpf_verify_pkcs7_signature, KF_SLEEPABLE) #endif #endif +#ifdef CONFIG_S390 +BTF_ID_FLAGS(func, bpf_get_lowcore) +#endif BTF_KFUNCS_END(generic_btf_ids) static const struct btf_kfunc_id_set generic_kfunc_set = { diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 9df77e59d4f5d..4453ad27b2ef7 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -627,6 +627,10 @@ struct task_struct___preempt_rt { int softirq_disable_cnt; } __attribute__((preserve_access_index)); +#ifdef bpf_target_s390 +extern struct lowcore *bpf_get_lowcore(void) __weak __ksym; +#endif + static inline int get_preempt_count(void) { #if defined(bpf_target_x86) -- 2.53.0