dlan17/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

bpf: Add bpf_trace_vprintk helper

Browse Source 
This helper is meant to be "bpf_trace_printk, but with proper vararg
support". Follow bpf_snprintf's example and take a u64 pseudo-vararg
array. Write to /sys/kernel/debug/tracing/trace_pipe using the same
mechanism as bpf_trace_printk. The functionality of this helper was
requested in the libbpf issue tracker [0].

[0] Closes: https://github.com/libbpf/libbpf/issues/315

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210917182911.2426606-4-davemarchevsky@fb.com
This commit is contained in:
Dave Marchevsky
2021-09-17 14:02:05 -07:00
committed by Alexei Starovoitov
parent 84b4c52960
commit 10aceb629e
6 changed files with 81 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/trace/bpf_trace.c
+51 -1
View File
@@ -398,7 +398,7 @@ static const struct bpf_func_proto bpf_trace_printk_proto = {
.arg2_type = ARG_CONST_SIZE,
};
const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
static void __set_printk_clr_event(void)
{
/*
* This program might be calling bpf_trace_printk,
@@ -410,10 +410,58 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
*/
if (trace_set_clr_event("bpf_trace", "bpf_trace_printk", 1))
pr_warn_ratelimited("could not enable bpf_trace_printk events");
}
const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
{
__set_printk_clr_event();
return &bpf_trace_printk_proto;
}
BPF_CALL_4(bpf_trace_vprintk, char *, fmt, u32, fmt_size, const void *, data,
u32, data_len)
{
static char buf[BPF_TRACE_PRINTK_SIZE];
unsigned long flags;
int ret, num_args;
u32 *bin_args;
if (data_len & 7 || data_len > MAX_BPRINTF_VARARGS * 8 ||
(data_len && !data))
return -EINVAL;
num_args = data_len / 8;
ret = bpf_bprintf_prepare(fmt, fmt_size, data, &bin_args, num_args);
if (ret < 0)
return ret;
raw_spin_lock_irqsave(&trace_printk_lock, flags);
ret = bstr_printf(buf, sizeof(buf), fmt, bin_args);
trace_bpf_trace_printk(buf);
raw_spin_unlock_irqrestore(&trace_printk_lock, flags);
bpf_bprintf_cleanup();
return ret;
}
static const struct bpf_func_proto bpf_trace_vprintk_proto = {
.func = bpf_trace_vprintk,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_MEM,
.arg2_type = ARG_CONST_SIZE,
.arg3_type = ARG_PTR_TO_MEM_OR_NULL,
.arg4_type = ARG_CONST_SIZE_OR_ZERO,
};
const struct bpf_func_proto *bpf_get_trace_vprintk_proto(void)
{
__set_printk_clr_event();
return &bpf_trace_vprintk_proto;
}
BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size,
const void *, data, u32, data_len)
{
@@ -1160,6 +1208,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_get_func_ip_proto_tracing;
case BPF_FUNC_get_branch_snapshot:
return &bpf_get_branch_snapshot_proto;
case BPF_FUNC_trace_vprintk:
return bpf_get_trace_vprintk_proto();
default:
return bpf_base_func_proto(func_id);
}