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Diffstat (limited to 'kernel/bpf/helpers.c')
-rw-r--r--kernel/bpf/helpers.c35
1 files changed, 19 insertions, 16 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 544773970dbc..73443498d88f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -692,38 +692,41 @@ static int bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype,
return -EINVAL;
}
-/* Per-cpu temp buffers which can be used by printf-like helpers for %s or %p
+/* Per-cpu temp buffers used by printf-like helpers to store the bprintf binary
+ * arguments representation.
*/
-#define MAX_PRINTF_BUF_LEN 512
+#define MAX_BPRINTF_BUF_LEN 512
-struct bpf_printf_buf {
- char tmp_buf[MAX_PRINTF_BUF_LEN];
+/* Support executing three nested bprintf helper calls on a given CPU */
+#define MAX_BPRINTF_NEST_LEVEL 3
+struct bpf_bprintf_buffers {
+ char tmp_bufs[MAX_BPRINTF_NEST_LEVEL][MAX_BPRINTF_BUF_LEN];
};
-static DEFINE_PER_CPU(struct bpf_printf_buf, bpf_printf_buf);
-static DEFINE_PER_CPU(int, bpf_printf_buf_used);
+static DEFINE_PER_CPU(struct bpf_bprintf_buffers, bpf_bprintf_bufs);
+static DEFINE_PER_CPU(int, bpf_bprintf_nest_level);
static int try_get_fmt_tmp_buf(char **tmp_buf)
{
- struct bpf_printf_buf *bufs;
- int used;
+ struct bpf_bprintf_buffers *bufs;
+ int nest_level;
preempt_disable();
- used = this_cpu_inc_return(bpf_printf_buf_used);
- if (WARN_ON_ONCE(used > 1)) {
- this_cpu_dec(bpf_printf_buf_used);
+ nest_level = this_cpu_inc_return(bpf_bprintf_nest_level);
+ if (WARN_ON_ONCE(nest_level > MAX_BPRINTF_NEST_LEVEL)) {
+ this_cpu_dec(bpf_bprintf_nest_level);
preempt_enable();
return -EBUSY;
}
- bufs = this_cpu_ptr(&bpf_printf_buf);
- *tmp_buf = bufs->tmp_buf;
+ bufs = this_cpu_ptr(&bpf_bprintf_bufs);
+ *tmp_buf = bufs->tmp_bufs[nest_level - 1];
return 0;
}
void bpf_bprintf_cleanup(void)
{
- if (this_cpu_read(bpf_printf_buf_used)) {
- this_cpu_dec(bpf_printf_buf_used);
+ if (this_cpu_read(bpf_bprintf_nest_level)) {
+ this_cpu_dec(bpf_bprintf_nest_level);
preempt_enable();
}
}
@@ -760,7 +763,7 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
if (num_args && try_get_fmt_tmp_buf(&tmp_buf))
return -EBUSY;
- tmp_buf_end = tmp_buf + MAX_PRINTF_BUF_LEN;
+ tmp_buf_end = tmp_buf + MAX_BPRINTF_BUF_LEN;
*bin_args = (u32 *)tmp_buf;
}