1 /* Emulation of eBPF helpers.
2 Copyright (C) 2020-2021 Free Software Foundation, Inc.
4 This file is part of GDB, the GNU debugger.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 /* BPF programs rely on the existence of several helper functions,
20 which are provided by the kernel. This simulator provides an
21 implementation of the helpers, which can be customized by the
24 /* This must come before any other includes. */
27 #define WANT_CPU_BPFBF
28 #define WANT_CPU bpfbf
35 /* bpf_trace_printk is a printk-like facility for debugging.
37 In the kernel, it appends a line to the Linux's tracing debugging
40 In this simulator, it uses the simulator's tracing interface
43 The format tags recognized by this helper are:
44 %d, %i, %u, %x, %ld, %li, %lu, %lx, %lld, %lli, %llu, %llx,
47 A maximum of three tags are supported.
49 This helper returns the number of bytes written, or a negative
50 value in case of failure. */
53 bpf_trace_printk (SIM_CPU
*current_cpu
)
56 SIM_DESC sd
= CPU_STATE (current_cpu
);
59 uint32_t size
, tags_processed
;
60 size_t i
, bytes_written
= 0;
62 /* The first argument is the format string, which is passed as a
64 fmt_address
= GET_H_GPR (1);
66 /* The second argument is the length of the format string, as an
67 unsigned 32-bit number in %r2. */
70 /* Read the format string from the memory pointed by %r2, printing
71 out the stuff as we go. There is a maximum of three format tags
72 supported, which are read from %r3, %r4 and %r5 respectively. */
73 for (i
= 0, tags_processed
= 0; i
< size
;)
75 QI c
= GETMEMUQI (current_cpu
, CPU_PC_GET (current_cpu
),
81 /* Check we are not exceeding the limit of three format
83 if (tags_processed
> 2)
84 return -1; /* XXX look for kernel error code. */
86 /* Depending on the kind of tag, extract the value from the
89 return -1; /* XXX look for kernel error code. */
91 UDI value
= GET_H_GPR (3 + tags_processed
);
93 switch ((GETMEMUQI (current_cpu
, CPU_PC_GET (current_cpu
),
97 trace_printf (sd
, current_cpu
, "%d", value
);
100 trace_printf (sd
, current_cpu
, "%i", value
);
103 trace_printf (sd
, current_cpu
, "%u", value
);
106 trace_printf (sd
, current_cpu
, "%x", value
);
112 switch (GETMEMUQI (current_cpu
, CPU_PC_GET (current_cpu
),
116 trace_printf (sd
, current_cpu
, "%ld", value
);
119 trace_printf (sd
, current_cpu
, "%li", value
);
122 trace_printf (sd
, current_cpu
, "%lu", value
);
125 trace_printf (sd
, current_cpu
, "%lx", value
);
131 switch (GETMEMUQI (current_cpu
, CPU_PC_GET (current_cpu
),
134 trace_printf (sd
, current_cpu
, "%lld", value
);
137 trace_printf (sd
, current_cpu
, "%lli", value
);
140 trace_printf (sd
, current_cpu
, "%llu", value
);
143 trace_printf (sd
, current_cpu
, "%llx", value
);
170 trace_printf (sd
, current_cpu
, "%c", c
);
177 return bytes_written
;