389 lines
10 KiB
C
389 lines
10 KiB
C
|
/* Target-dependent code for BPF.
|
|||
|
|
|
|||
|
|
Copyright (C) 2020-2022 Free Software Foundation, Inc.
|
|||
|
|
|
|||
|
|
This file is part of GDB.
|
|||
|
|
|
|||
|
|
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 "defs.h"
|
|||
|
|
#include "arch-utils.h"
|
|||
|
|
#include "dis-asm.h"
|
|||
|
|
#include "frame.h"
|
|||
|
|
#include "frame-unwind.h"
|
|||
|
|
#include "trad-frame.h"
|
|||
|
|
#include "symtab.h"
|
|||
|
|
#include "value.h"
|
|||
|
|
#include "gdbcmd.h"
|
|||
|
|
#include "breakpoint.h"
|
|||
|
|
#include "inferior.h"
|
|||
|
|
#include "regcache.h"
|
|||
|
|
#include "target.h"
|
|||
|
|
#include "dwarf2/frame.h"
|
|||
|
|
#include "osabi.h"
|
|||
|
|
#include "target-descriptions.h"
|
|||
|
|
#include "remote.h"
|
|||
|
|
#include "gdbarch.h"
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* eBPF registers. */
|
|||
|
|
|
|||
|
|
enum bpf_regnum
|
|||
|
|
{
|
|||
|
|
BPF_R0_REGNUM, /* return value */
|
|||
|
|
BPF_R1_REGNUM,
|
|||
|
|
BPF_R2_REGNUM,
|
|||
|
|
BPF_R3_REGNUM,
|
|||
|
|
BPF_R4_REGNUM,
|
|||
|
|
BPF_R5_REGNUM,
|
|||
|
|
BPF_R6_REGNUM,
|
|||
|
|
BPF_R7_REGNUM,
|
|||
|
|
BPF_R8_REGNUM,
|
|||
|
|
BPF_R9_REGNUM,
|
|||
|
|
BPF_R10_REGNUM, /* sp */
|
|||
|
|
BPF_PC_REGNUM,
|
|||
|
|
};
|
|||
|
|
|
|||
|
|
#define BPF_NUM_REGS (BPF_PC_REGNUM + 1)
|
|||
|
|
|
|||
|
|
/* Target-dependent structure in gdbarch. */
|
|||
|
|
struct bpf_gdbarch_tdep : gdbarch_tdep
|
|||
|
|
{
|
|||
|
|
};
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* Internal debugging facilities. */
|
|||
|
|
|
|||
|
|
/* When this is set to non-zero debugging information will be
|
|||
|
|
printed. */
|
|||
|
|
|
|||
|
|
static unsigned int bpf_debug_flag = 0;
|
|||
|
|
|
|||
|
|
/* The show callback for 'show debug bpf'. */
|
|||
|
|
|
|||
|
|
static void
|
|||
|
|
show_bpf_debug (struct ui_file *file, int from_tty,
|
|||
|
|
struct cmd_list_element *c, const char *value)
|
|||
|
|
{
|
|||
|
|
gdb_printf (file, _("Debugging of BPF is %s.\n"), value);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* BPF registers. */
|
|||
|
|
|
|||
|
|
static const char *bpf_register_names[] =
|
|||
|
|
{
|
|||
|
|
"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
|
|||
|
|
"r8", "r9", "r10", "pc"
|
|||
|
|
};
|
|||
|
|
|
|||
|
|
/* Return the name of register REGNUM. */
|
|||
|
|
|
|||
|
|
static const char *
|
|||
|
|
bpf_register_name (struct gdbarch *gdbarch, int reg)
|
|||
|
|
{
|
|||
|
|
if (reg >= 0 && reg < BPF_NUM_REGS)
|
|||
|
|
return bpf_register_names[reg];
|
|||
|
|
return NULL;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Return the GDB type of register REGNUM. */
|
|||
|
|
|
|||
|
|
static struct type *
|
|||
|
|
bpf_register_type (struct gdbarch *gdbarch, int reg)
|
|||
|
|
{
|
|||
|
|
if (reg == BPF_R10_REGNUM)
|
|||
|
|
return builtin_type (gdbarch)->builtin_data_ptr;
|
|||
|
|
else if (reg == BPF_PC_REGNUM)
|
|||
|
|
return builtin_type (gdbarch)->builtin_func_ptr;
|
|||
|
|
return builtin_type (gdbarch)->builtin_int64;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Return the GDB register number corresponding to DWARF's REG. */
|
|||
|
|
|
|||
|
|
static int
|
|||
|
|
bpf_dwarf2_reg_to_regnum (struct gdbarch *gdbarch, int reg)
|
|||
|
|
{
|
|||
|
|
if (reg >= 0 && reg < BPF_NUM_REGS)
|
|||
|
|
return reg;
|
|||
|
|
return -1;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Implement the "print_insn" gdbarch method. */
|
|||
|
|
|
|||
|
|
static int
|
|||
|
|
bpf_gdb_print_insn (bfd_vma memaddr, disassemble_info *info)
|
|||
|
|
{
|
|||
|
|
info->symbols = NULL;
|
|||
|
|
return default_print_insn (memaddr, info);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* Return PC of first real instruction of the function starting at
|
|||
|
|
START_PC. */
|
|||
|
|
|
|||
|
|
static CORE_ADDR
|
|||
|
|
bpf_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
|
|||
|
|
{
|
|||
|
|
gdb_printf (gdb_stdlog,
|
|||
|
|
"Skipping prologue: start_pc=%s\n",
|
|||
|
|
paddress (gdbarch, start_pc));
|
|||
|
|
/* XXX: to be completed. */
|
|||
|
|
return start_pc + 0;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* Frame unwinder.
|
|||
|
|
|
|||
|
|
XXX it is not clear how to unwind in eBPF, since the stack is not
|
|||
|
|
guaranteed to be contiguous, and therefore no relative stack
|
|||
|
|
addressing can be done in the callee in order to access the
|
|||
|
|
caller's stack frame. To explore with xBPF, which will relax this
|
|||
|
|
restriction. */
|
|||
|
|
|
|||
|
|
/* Given THIS_FRAME, return its ID. */
|
|||
|
|
|
|||
|
|
static void
|
|||
|
|
bpf_frame_this_id (struct frame_info *this_frame,
|
|||
|
|
void **this_prologue_cache,
|
|||
|
|
struct frame_id *this_id)
|
|||
|
|
{
|
|||
|
|
/* Note that THIS_ID defaults to the outermost frame if we don't set
|
|||
|
|
anything here. See frame.c:compute_frame_id. */
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Return the reason why we can't unwind past THIS_FRAME. */
|
|||
|
|
|
|||
|
|
static enum unwind_stop_reason
|
|||
|
|
bpf_frame_unwind_stop_reason (struct frame_info *this_frame,
|
|||
|
|
void **this_cache)
|
|||
|
|
{
|
|||
|
|
return UNWIND_OUTERMOST;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Ask THIS_FRAME to unwind its register. */
|
|||
|
|
|
|||
|
|
static struct value *
|
|||
|
|
bpf_frame_prev_register (struct frame_info *this_frame,
|
|||
|
|
void **this_prologue_cache, int regnum)
|
|||
|
|
{
|
|||
|
|
return frame_unwind_got_register (this_frame, regnum, regnum);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Frame unwinder machinery for BPF. */
|
|||
|
|
|
|||
|
|
static const struct frame_unwind bpf_frame_unwind =
|
|||
|
|
{
|
|||
|
|
"bpf prologue",
|
|||
|
|
NORMAL_FRAME,
|
|||
|
|
bpf_frame_unwind_stop_reason,
|
|||
|
|
bpf_frame_this_id,
|
|||
|
|
bpf_frame_prev_register,
|
|||
|
|
NULL,
|
|||
|
|
default_frame_sniffer
|
|||
|
|
};
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* Breakpoints. */
|
|||
|
|
|
|||
|
|
/* Enum describing the different kinds of breakpoints. We currently
|
|||
|
|
just support one, implemented by the brkpt xbpf instruction. */
|
|||
|
|
|
|||
|
|
enum bpf_breakpoint_kinds
|
|||
|
|
{
|
|||
|
|
BPF_BP_KIND_BRKPT = 0,
|
|||
|
|
};
|
|||
|
|
|
|||
|
|
/* Implement the breakpoint_kind_from_pc gdbarch method. */
|
|||
|
|
|
|||
|
|
static int
|
|||
|
|
bpf_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *start_pc)
|
|||
|
|
{
|
|||
|
|
/* We support just one kind of breakpoint. */
|
|||
|
|
return BPF_BP_KIND_BRKPT;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Implement the sw_breakpoint_from_kind gdbarch method. */
|
|||
|
|
|
|||
|
|
static const gdb_byte *
|
|||
|
|
bpf_sw_breakpoint_from_kind (struct gdbarch *gdbarch, int kind, int *size)
|
|||
|
|
{
|
|||
|
|
static unsigned char brkpt_insn[]
|
|||
|
|
= {0x8c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
|
|||
|
|
|
|||
|
|
switch (kind)
|
|||
|
|
{
|
|||
|
|
case BPF_BP_KIND_BRKPT:
|
|||
|
|
*size = 8;
|
|||
|
|
return brkpt_insn;
|
|||
|
|
default:
|
|||
|
|
gdb_assert_not_reached ("unexpected BPF breakpoint kind");
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* Assuming THIS_FRAME is a dummy frame, return its frame ID. */
|
|||
|
|
|
|||
|
|
static struct frame_id
|
|||
|
|
bpf_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
|
|||
|
|
{
|
|||
|
|
CORE_ADDR sp = get_frame_register_unsigned (this_frame,
|
|||
|
|
gdbarch_sp_regnum (gdbarch));
|
|||
|
|
return frame_id_build (sp, get_frame_pc (this_frame));
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Implement the push dummy call gdbarch callback. */
|
|||
|
|
|
|||
|
|
static CORE_ADDR
|
|||
|
|
bpf_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
|
|||
|
|
struct regcache *regcache, CORE_ADDR bp_addr,
|
|||
|
|
int nargs, struct value **args, CORE_ADDR sp,
|
|||
|
|
function_call_return_method return_method,
|
|||
|
|
CORE_ADDR struct_addr)
|
|||
|
|
{
|
|||
|
|
gdb_printf (gdb_stdlog, "Pushing dummy call: sp=%s\n",
|
|||
|
|
paddress (gdbarch, sp));
|
|||
|
|
/* XXX writeme */
|
|||
|
|
return sp;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Extract a function return value of TYPE from REGCACHE,
|
|||
|
|
and copy it into VALBUF. */
|
|||
|
|
|
|||
|
|
static void
|
|||
|
|
bpf_extract_return_value (struct type *type, struct regcache *regcache,
|
|||
|
|
gdb_byte *valbuf)
|
|||
|
|
{
|
|||
|
|
int len = TYPE_LENGTH (type);
|
|||
|
|
gdb_byte vbuf[8];
|
|||
|
|
|
|||
|
|
gdb_assert (len <= 8);
|
|||
|
|
regcache->cooked_read (BPF_R0_REGNUM, vbuf);
|
|||
|
|
memcpy (valbuf, vbuf + 8 - len, len);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Store the function return value of type TYPE from VALBUF into REGNAME. */
|
|||
|
|
|
|||
|
|
static void
|
|||
|
|
bpf_store_return_value (struct type *type, struct regcache *regcache,
|
|||
|
|
const gdb_byte *valbuf)
|
|||
|
|
{
|
|||
|
|
int len = TYPE_LENGTH (type);
|
|||
|
|
gdb_byte vbuf[8];
|
|||
|
|
|
|||
|
|
gdb_assert (len <= 8);
|
|||
|
|
memset (vbuf, 0, sizeof (vbuf));
|
|||
|
|
memcpy (vbuf + 8 - len, valbuf, len);
|
|||
|
|
regcache->cooked_write (BPF_R0_REGNUM, vbuf);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Handle function's return value. */
|
|||
|
|
|
|||
|
|
static enum return_value_convention
|
|||
|
|
bpf_return_value (struct gdbarch *gdbarch, struct value *function,
|
|||
|
|
struct type *type, struct regcache *regcache,
|
|||
|
|
gdb_byte *readbuf, const gdb_byte *writebuf)
|
|||
|
|
{
|
|||
|
|
int len = TYPE_LENGTH (type);
|
|||
|
|
|
|||
|
|
if (len > 8)
|
|||
|
|
return RETURN_VALUE_STRUCT_CONVENTION;
|
|||
|
|
|
|||
|
|
if (readbuf != NULL)
|
|||
|
|
bpf_extract_return_value (type, regcache, readbuf);
|
|||
|
|
if (writebuf != NULL)
|
|||
|
|
bpf_store_return_value (type, regcache, writebuf);
|
|||
|
|
|
|||
|
|
return RETURN_VALUE_REGISTER_CONVENTION;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* Initialize the current architecture based on INFO. If possible, re-use an
|
|||
|
|
architecture from ARCHES, which is a list of architectures already created
|
|||
|
|
during this debugging session. */
|
|||
|
|
|
|||
|
|
static struct gdbarch *
|
|||
|
|
bpf_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
|
|||
|
|
{
|
|||
|
|
/* If there is already a candidate, use it. */
|
|||
|
|
arches = gdbarch_list_lookup_by_info (arches, &info);
|
|||
|
|
if (arches != NULL)
|
|||
|
|
return arches->gdbarch;
|
|||
|
|
|
|||
|
|
/* Allocate space for the new architecture. */
|
|||
|
|
bpf_gdbarch_tdep *tdep = new bpf_gdbarch_tdep;
|
|||
|
|
struct gdbarch *gdbarch = gdbarch_alloc (&info, tdep);
|
|||
|
|
|
|||
|
|
/* Information about registers, etc. */
|
|||
|
|
set_gdbarch_num_regs (gdbarch, BPF_NUM_REGS);
|
|||
|
|
set_gdbarch_register_name (gdbarch, bpf_register_name);
|
|||
|
|
set_gdbarch_register_type (gdbarch, bpf_register_type);
|
|||
|
|
|
|||
|
|
/* Register numbers of various important registers. */
|
|||
|
|
set_gdbarch_sp_regnum (gdbarch, BPF_R10_REGNUM);
|
|||
|
|
set_gdbarch_pc_regnum (gdbarch, BPF_PC_REGNUM);
|
|||
|
|
|
|||
|
|
/* Map DWARF2 registers to GDB registers. */
|
|||
|
|
set_gdbarch_dwarf2_reg_to_regnum (gdbarch, bpf_dwarf2_reg_to_regnum);
|
|||
|
|
|
|||
|
|
/* Call dummy code. */
|
|||
|
|
set_gdbarch_call_dummy_location (gdbarch, ON_STACK);
|
|||
|
|
set_gdbarch_dummy_id (gdbarch, bpf_dummy_id);
|
|||
|
|
set_gdbarch_push_dummy_call (gdbarch, bpf_push_dummy_call);
|
|||
|
|
|
|||
|
|
/* Returning results. */
|
|||
|
|
set_gdbarch_return_value (gdbarch, bpf_return_value);
|
|||
|
|
|
|||
|
|
/* Advance PC across function entry code. */
|
|||
|
|
set_gdbarch_skip_prologue (gdbarch, bpf_skip_prologue);
|
|||
|
|
|
|||
|
|
/* Stack grows downward. */
|
|||
|
|
set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
|
|||
|
|
|
|||
|
|
/* Breakpoint manipulation. */
|
|||
|
|
set_gdbarch_breakpoint_kind_from_pc (gdbarch, bpf_breakpoint_kind_from_pc);
|
|||
|
|
set_gdbarch_sw_breakpoint_from_kind (gdbarch, bpf_sw_breakpoint_from_kind);
|
|||
|
|
|
|||
|
|
/* Frame handling. */
|
|||
|
|
set_gdbarch_frame_args_skip (gdbarch, 8);
|
|||
|
|
|
|||
|
|
/* Disassembly. */
|
|||
|
|
set_gdbarch_print_insn (gdbarch, bpf_gdb_print_insn);
|
|||
|
|
|
|||
|
|
/* Hook in ABI-specific overrides, if they have been registered. */
|
|||
|
|
gdbarch_init_osabi (info, gdbarch);
|
|||
|
|
|
|||
|
|
/* Install unwinders. */
|
|||
|
|
frame_unwind_append_unwinder (gdbarch, &bpf_frame_unwind);
|
|||
|
|
|
|||
|
|
return gdbarch;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
void _initialize_bpf_tdep ();
|
|||
|
|
void
|
|||
|
|
_initialize_bpf_tdep ()
|
|||
|
|
{
|
|||
|
|
register_gdbarch_init (bfd_arch_bpf, bpf_gdbarch_init);
|
|||
|
|
|
|||
|
|
/* Add commands 'set/show debug bpf'. */
|
|||
|
|
add_setshow_zuinteger_cmd ("bpf", class_maintenance,
|
|||
|
|
&bpf_debug_flag,
|
|||
|
|
_("Set BPF debugging."),
|
|||
|
|
_("Show BPF debugging."),
|
|||
|
|
_("Enables BPF specific debugging output."),
|
|||
|
|
NULL,
|
|||
|
|
&show_bpf_debug,
|
|||
|
|
&setdebuglist, &showdebuglist);
|
|||
|
|
}
|