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Message-ID: <20231013054219.172920-1-asavkov@redhat.com> Date: Fri, 13 Oct 2023 07:42:19 +0200 From: Artem Savkov <asavkov@...hat.com> To: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org, netdev@...r.kernel.org Cc: Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, linux-rt-users@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>, Artem Savkov <asavkov@...hat.com> Subject: [PATCH bpf-next] bpf: change syscall_nr type to int in struct syscall_tp_t linux-rt-devel tree contains a patch (b1773eac3f29c ("sched: Add support for lazy preemption")) that adds an extra member to struct trace_entry. This causes the offset of args field in struct trace_event_raw_sys_enter be different from the one in struct syscall_trace_enter: struct trace_event_raw_sys_enter { struct trace_entry ent; /* 0 12 */ /* XXX last struct has 3 bytes of padding */ /* XXX 4 bytes hole, try to pack */ long int id; /* 16 8 */ long unsigned int args[6]; /* 24 48 */ /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ char __data[]; /* 72 0 */ /* size: 72, cachelines: 2, members: 4 */ /* sum members: 68, holes: 1, sum holes: 4 */ /* paddings: 1, sum paddings: 3 */ /* last cacheline: 8 bytes */ }; struct syscall_trace_enter { struct trace_entry ent; /* 0 12 */ /* XXX last struct has 3 bytes of padding */ int nr; /* 12 4 */ long unsigned int args[]; /* 16 0 */ /* size: 16, cachelines: 1, members: 3 */ /* paddings: 1, sum paddings: 3 */ /* last cacheline: 16 bytes */ }; This, in turn, causes perf_event_set_bpf_prog() fail while running bpf test_profiler testcase because max_ctx_offset is calculated based on the former struct, while off on the latter: 10488 if (is_tracepoint || is_syscall_tp) { 10489 int off = trace_event_get_offsets(event->tp_event); 10490 10491 if (prog->aux->max_ctx_offset > off) 10492 return -EACCES; 10493 } What bpf program is actually getting is a pointer to struct syscall_tp_t, defined in kernel/trace/trace_syscalls.c. This patch fixes the problem by aligning struct syscall_tp_t with with struct syscall_trace_(enter|exit) and changing the tests to use these structs to dereference context. Signed-off-by: Artem Savkov <asavkov@...hat.com> Acked-by: Steven Rostedt (Google) <rostedt@...dmis.org> --- kernel/trace/trace_syscalls.c | 4 ++-- tools/testing/selftests/bpf/progs/profiler.inc.h | 2 +- tools/testing/selftests/bpf/progs/test_vmlinux.c | 4 ++-- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index de753403cdafb..9c581d6da843a 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -556,7 +556,7 @@ static int perf_call_bpf_enter(struct trace_event_call *call, struct pt_regs *re { struct syscall_tp_t { struct trace_entry ent; - unsigned long syscall_nr; + int syscall_nr; unsigned long args[SYSCALL_DEFINE_MAXARGS]; } __aligned(8) param; int i; @@ -661,7 +661,7 @@ static int perf_call_bpf_exit(struct trace_event_call *call, struct pt_regs *reg { struct syscall_tp_t { struct trace_entry ent; - unsigned long syscall_nr; + int syscall_nr; unsigned long ret; } __aligned(8) param; diff --git a/tools/testing/selftests/bpf/progs/profiler.inc.h b/tools/testing/selftests/bpf/progs/profiler.inc.h index f799d87e87002..897061930cb76 100644 --- a/tools/testing/selftests/bpf/progs/profiler.inc.h +++ b/tools/testing/selftests/bpf/progs/profiler.inc.h @@ -609,7 +609,7 @@ ssize_t BPF_KPROBE(kprobe__proc_sys_write, } SEC("tracepoint/syscalls/sys_enter_kill") -int tracepoint__syscalls__sys_enter_kill(struct trace_event_raw_sys_enter* ctx) +int tracepoint__syscalls__sys_enter_kill(struct syscall_trace_enter* ctx) { struct bpf_func_stats_ctx stats_ctx; diff --git a/tools/testing/selftests/bpf/progs/test_vmlinux.c b/tools/testing/selftests/bpf/progs/test_vmlinux.c index 4b8e37f7fd06c..78b23934d9f8f 100644 --- a/tools/testing/selftests/bpf/progs/test_vmlinux.c +++ b/tools/testing/selftests/bpf/progs/test_vmlinux.c @@ -16,12 +16,12 @@ bool kprobe_called = false; bool fentry_called = false; SEC("tp/syscalls/sys_enter_nanosleep") -int handle__tp(struct trace_event_raw_sys_enter *args) +int handle__tp(struct syscall_trace_enter *args) { struct __kernel_timespec *ts; long tv_nsec; - if (args->id != __NR_nanosleep) + if (args->nr != __NR_nanosleep) return 0; ts = (void *)args->args[0]; -- 2.41.0
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