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/* Main simulator entry points specific to the eBPF.
Copyright (C) 2020-2021 Free Software Foundation, Inc.
This file is part of GDB, the GNU debugger.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <stdlib.h>
#include "sim-main.h"
#include "sim-options.h"
#include "libiberty.h"
#include "bfd.h"
/* Globals. */
/* String with the name of the section containing the BPF program to
run. */
static char *bpf_program_section = NULL;
extern uint64_t skb_data_offset;
/* Handle BPF-specific options. */
static SIM_RC bpf_option_handler (SIM_DESC, sim_cpu *, int, char *, int);
typedef enum
{
OPTION_BPF_SET_PROGRAM = OPTION_START,
OPTION_BPF_LIST_PROGRAMS,
OPTION_BPF_VERIFY_PROGRAM,
OPTION_BPF_SKB_DATA_OFFSET,
} BPF_OPTION;
static const OPTION bpf_options[] =
{
{ {"bpf-set-program", required_argument, NULL, OPTION_BPF_SET_PROGRAM},
'\0', "SECTION_NAME", "Set the entry point",
bpf_option_handler },
{ {"bpf-list-programs", no_argument, NULL, OPTION_BPF_LIST_PROGRAMS},
'\0', "", "List loaded bpf programs",
bpf_option_handler },
{ {"bpf-verify-program", required_argument, NULL, OPTION_BPF_VERIFY_PROGRAM},
'\0', "PROGRAM", "Run the verifier on the given BPF program",
bpf_option_handler },
{ {"skb-data-offset", required_argument, NULL, OPTION_BPF_SKB_DATA_OFFSET},
'\0', "OFFSET", "Configure offsetof(struct sk_buff, data)",
bpf_option_handler },
{ {NULL, no_argument, NULL, 0}, '\0', NULL, NULL, NULL, NULL }
};
static SIM_RC
bpf_option_handler (SIM_DESC sd, sim_cpu *cpu ATTRIBUTE_UNUSED, int opt,
char *arg, int is_command ATTRIBUTE_UNUSED)
{
switch ((BPF_OPTION) opt)
{
case OPTION_BPF_VERIFY_PROGRAM:
/* XXX call the verifier. */
sim_io_printf (sd, "Verifying BPF program %s...\n", arg);
break;
case OPTION_BPF_LIST_PROGRAMS:
/* XXX list programs. */
sim_io_printf (sd, "BPF programs available:\n");
break;
case OPTION_BPF_SET_PROGRAM:
/* XXX: check that the section exists and tell the user about a
new start_address. */
bpf_program_section = xstrdup (arg);
break;
case OPTION_BPF_SKB_DATA_OFFSET:
skb_data_offset = strtoul (arg, NULL, 0);
break;
default:
sim_io_eprintf (sd, "Unknown option `%s'\n", arg);
return SIM_RC_FAIL;
}
return SIM_RC_OK;
}
/* Like sim_state_free, but free the cpu buffers as well. */
static void
bpf_free_state (SIM_DESC sd)
{
if (STATE_MODULES (sd) != NULL)
sim_module_uninstall (sd);
sim_cpu_free_all (sd);
sim_state_free (sd);
}
/* Create an instance of the simulator. */
SIM_DESC
sim_open (SIM_OPEN_KIND kind,
host_callback *callback,
struct bfd *abfd,
char * const *argv)
{
/* XXX Analyze the program, and collect per-function information
like the kernel verifier does. The implementation of the CALL
instruction will need that information, to update %fp. */
SIM_DESC sd = sim_state_alloc (kind, callback);
if (sim_cpu_alloc_all (sd, 1, cgen_cpu_max_extra_bytes ())
!= SIM_RC_OK)
goto error;
if (sim_pre_argv_init (sd, argv[0]) != SIM_RC_OK)
goto error;
/* Add the BPF-specific option list to the simulator. */
if (sim_add_option_table (sd, NULL, bpf_options) != SIM_RC_OK)
{
bpf_free_state (sd);
return 0;
}
if (sim_parse_args (sd, argv) != SIM_RC_OK)
goto error;
if (sim_analyze_program (sd,
(STATE_PROG_ARGV (sd) != NULL
? *STATE_PROG_ARGV (sd)
: NULL), abfd) != SIM_RC_OK)
goto error;
if (sim_config (sd) != SIM_RC_OK)
goto error;
if (sim_post_argv_init (sd) != SIM_RC_OK)
goto error;
/* ... */
/* Initialize the CPU descriptors and the disassemble in the cpu
descriptor table entries. */
{
int i;
CGEN_CPU_DESC cd = bpf_cgen_cpu_open_1 (STATE_ARCHITECTURE (sd)->printable_name,
CGEN_ENDIAN_LITTLE);
/* We have one cpu per installed program! MAX_NR_PROCESSORS is an
arbitrary upper limit. XXX where is it defined? */
for (i = 0; i < MAX_NR_PROCESSORS; ++i)
{
SIM_CPU *cpu = STATE_CPU (sd, i);
CPU_CPU_DESC (cpu) = cd;
CPU_DISASSEMBLER (cpu) = sim_cgen_disassemble_insn;
}
bpf_cgen_init_dis (cd);
}
/* Initialize various cgen things not done by common framework.
Must be done after bpf_cgen_cpu_open. */
cgen_init (sd);
/* XXX do eBPF sim specific initializations. */
return sd;
error:
bpf_free_state (sd);
return NULL;
}
SIM_RC
sim_create_inferior (SIM_DESC sd, struct bfd *abfd,
char *const *argv, char *const *envp)
{
SIM_CPU *current_cpu = STATE_CPU (sd, 0);
SIM_ADDR addr;
/* Determine the start address.
XXX acknowledge bpf_program_section. If it is NULL, emit a
warning explaining that we are using the ELF file start address,
which often is not what is actually wanted. */
if (abfd != NULL)
addr = bfd_get_start_address (abfd);
else
addr = 0;
sim_pc_set (current_cpu, addr);
if (STATE_PROG_ARGV (sd) != argv)
{
freeargv (STATE_PROG_ARGV (sd));
STATE_PROG_ARGV (sd) = dupargv (argv);
}
return SIM_RC_OK;
}
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