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| author | Artem Savkov <asavkov@redhat.com> | 2023-10-13 07:42:19 +0200 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2023-10-13 12:39:36 -0700 |
| commit | ba8ea72388a192c10f1ee5f5a4a32332e7cced76 (patch) | |
| tree | f6b556d3e5fb7351d63c793c75e30def44909994 /kernel/trace | |
| parent | 9c1292eca243821249fa99f40175b0660d9329e3 (diff) | |
| download | linux-ba8ea72388a192c10f1ee5f5a4a32332e7cced76.tar.gz | |
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 struct
syscall_trace_(enter|exit) and changing the tests to use these structs
to dereference context.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/bpf/20231013054219.172920-1-asavkov@redhat.com
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace_syscalls.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index de753403cdafbd..9c581d6da843a3 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; |