ba8ea72388
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
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2020 Facebook */
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#include "vmlinux.h"
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#include <asm/unistd.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_core_read.h>
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#define MY_TV_NSEC 1337
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bool tp_called = false;
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bool raw_tp_called = false;
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bool tp_btf_called = false;
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bool kprobe_called = false;
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bool fentry_called = false;
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SEC("tp/syscalls/sys_enter_nanosleep")
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int handle__tp(struct syscall_trace_enter *args)
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{
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struct __kernel_timespec *ts;
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long tv_nsec;
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if (args->nr != __NR_nanosleep)
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return 0;
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ts = (void *)args->args[0];
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if (bpf_probe_read_user(&tv_nsec, sizeof(ts->tv_nsec), &ts->tv_nsec) ||
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tv_nsec != MY_TV_NSEC)
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return 0;
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tp_called = true;
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return 0;
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}
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SEC("raw_tp/sys_enter")
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int BPF_PROG(handle__raw_tp, struct pt_regs *regs, long id)
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{
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struct __kernel_timespec *ts;
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long tv_nsec;
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if (id != __NR_nanosleep)
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return 0;
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ts = (void *)PT_REGS_PARM1_CORE_SYSCALL(regs);
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if (bpf_probe_read_user(&tv_nsec, sizeof(ts->tv_nsec), &ts->tv_nsec) ||
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tv_nsec != MY_TV_NSEC)
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return 0;
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raw_tp_called = true;
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return 0;
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}
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SEC("tp_btf/sys_enter")
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int BPF_PROG(handle__tp_btf, struct pt_regs *regs, long id)
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{
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struct __kernel_timespec *ts;
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long tv_nsec;
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if (id != __NR_nanosleep)
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return 0;
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ts = (void *)PT_REGS_PARM1_CORE_SYSCALL(regs);
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if (bpf_probe_read_user(&tv_nsec, sizeof(ts->tv_nsec), &ts->tv_nsec) ||
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tv_nsec != MY_TV_NSEC)
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return 0;
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tp_btf_called = true;
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return 0;
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}
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SEC("kprobe/hrtimer_start_range_ns")
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int BPF_KPROBE(handle__kprobe, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
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const enum hrtimer_mode mode)
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{
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if (tim == MY_TV_NSEC)
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kprobe_called = true;
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return 0;
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}
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SEC("fentry/hrtimer_start_range_ns")
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int BPF_PROG(handle__fentry, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
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const enum hrtimer_mode mode)
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{
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if (tim == MY_TV_NSEC)
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fentry_called = true;
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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