423 lines
11 KiB
C
423 lines
11 KiB
C
/* tc-bpf.c -- Assembler for the Linux eBPF.
|
||
Copyright (C) 2019-2022 Free Software Foundation, Inc.
|
||
Contributed by Oracle, Inc.
|
||
|
||
This file is part of GAS, the GNU Assembler.
|
||
|
||
GAS 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, or (at your option)
|
||
any later version.
|
||
|
||
GAS 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 GAS; see the file COPYING. If not, write to
|
||
the Free Software Foundation, 51 Franklin Street - Fifth Floor,
|
||
Boston, MA 02110-1301, USA. */
|
||
|
||
#include "as.h"
|
||
#include "subsegs.h"
|
||
#include "symcat.h"
|
||
#include "opcodes/bpf-desc.h"
|
||
#include "opcodes/bpf-opc.h"
|
||
#include "cgen.h"
|
||
#include "elf/common.h"
|
||
#include "elf/bpf.h"
|
||
#include "dwarf2dbg.h"
|
||
|
||
const char comment_chars[] = ";";
|
||
const char line_comment_chars[] = "#";
|
||
const char line_separator_chars[] = "`";
|
||
const char EXP_CHARS[] = "eE";
|
||
const char FLT_CHARS[] = "fFdD";
|
||
|
||
/* Like s_lcomm_internal in gas/read.c but the alignment string
|
||
is allowed to be optional. */
|
||
|
||
static symbolS *
|
||
pe_lcomm_internal (int needs_align, symbolS *symbolP, addressT size)
|
||
{
|
||
addressT align = 0;
|
||
|
||
SKIP_WHITESPACE ();
|
||
|
||
if (needs_align
|
||
&& *input_line_pointer == ',')
|
||
{
|
||
align = parse_align (needs_align - 1);
|
||
|
||
if (align == (addressT) -1)
|
||
return NULL;
|
||
}
|
||
else
|
||
{
|
||
if (size >= 8)
|
||
align = 3;
|
||
else if (size >= 4)
|
||
align = 2;
|
||
else if (size >= 2)
|
||
align = 1;
|
||
else
|
||
align = 0;
|
||
}
|
||
|
||
bss_alloc (symbolP, size, align);
|
||
return symbolP;
|
||
}
|
||
|
||
static void
|
||
pe_lcomm (int needs_align)
|
||
{
|
||
s_comm_internal (needs_align * 2, pe_lcomm_internal);
|
||
}
|
||
|
||
/* The target specific pseudo-ops which we support. */
|
||
const pseudo_typeS md_pseudo_table[] =
|
||
{
|
||
{ "half", cons, 2 },
|
||
{ "word", cons, 4 },
|
||
{ "dword", cons, 8 },
|
||
{ "lcomm", pe_lcomm, 1 },
|
||
{ NULL, NULL, 0 }
|
||
};
|
||
|
||
|
||
|
||
/* ISA handling. */
|
||
static CGEN_BITSET *bpf_isa;
|
||
|
||
|
||
|
||
/* Command-line options processing. */
|
||
|
||
enum options
|
||
{
|
||
OPTION_LITTLE_ENDIAN = OPTION_MD_BASE,
|
||
OPTION_BIG_ENDIAN,
|
||
OPTION_XBPF
|
||
};
|
||
|
||
struct option md_longopts[] =
|
||
{
|
||
{ "EL", no_argument, NULL, OPTION_LITTLE_ENDIAN },
|
||
{ "EB", no_argument, NULL, OPTION_BIG_ENDIAN },
|
||
{ "mxbpf", no_argument, NULL, OPTION_XBPF },
|
||
{ NULL, no_argument, NULL, 0 },
|
||
};
|
||
|
||
size_t md_longopts_size = sizeof (md_longopts);
|
||
|
||
const char * md_shortopts = "";
|
||
|
||
extern int target_big_endian;
|
||
|
||
/* Whether target_big_endian has been set while parsing command-line
|
||
arguments. */
|
||
static int set_target_endian = 0;
|
||
|
||
static int target_xbpf = 0;
|
||
|
||
static int set_xbpf = 0;
|
||
|
||
int
|
||
md_parse_option (int c, const char * arg ATTRIBUTE_UNUSED)
|
||
{
|
||
switch (c)
|
||
{
|
||
case OPTION_BIG_ENDIAN:
|
||
set_target_endian = 1;
|
||
target_big_endian = 1;
|
||
break;
|
||
case OPTION_LITTLE_ENDIAN:
|
||
set_target_endian = 1;
|
||
target_big_endian = 0;
|
||
break;
|
||
case OPTION_XBPF:
|
||
set_xbpf = 1;
|
||
target_xbpf = 1;
|
||
break;
|
||
default:
|
||
return 0;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
void
|
||
md_show_usage (FILE * stream)
|
||
{
|
||
fprintf (stream, _("\nBPF options:\n"));
|
||
fprintf (stream, _("\
|
||
--EL generate code for a little endian machine\n\
|
||
--EB generate code for a big endian machine\n\
|
||
-mxbpf generate xBPF instructions\n"));
|
||
}
|
||
|
||
|
||
void
|
||
md_begin (void)
|
||
{
|
||
/* Initialize the `cgen' interface. */
|
||
|
||
/* If not specified in the command line, use the host
|
||
endianness. */
|
||
if (!set_target_endian)
|
||
{
|
||
#ifdef WORDS_BIGENDIAN
|
||
target_big_endian = 1;
|
||
#else
|
||
target_big_endian = 0;
|
||
#endif
|
||
}
|
||
|
||
/* If not specified in the command line, use eBPF rather
|
||
than xBPF. */
|
||
if (!set_xbpf)
|
||
target_xbpf = 0;
|
||
|
||
/* Set the ISA, which depends on the target endianness. */
|
||
bpf_isa = cgen_bitset_create (ISA_MAX);
|
||
if (target_big_endian)
|
||
{
|
||
if (target_xbpf)
|
||
cgen_bitset_set (bpf_isa, ISA_XBPFBE);
|
||
else
|
||
cgen_bitset_set (bpf_isa, ISA_EBPFBE);
|
||
}
|
||
else
|
||
{
|
||
if (target_xbpf)
|
||
cgen_bitset_set (bpf_isa, ISA_XBPFLE);
|
||
else
|
||
cgen_bitset_set (bpf_isa, ISA_EBPFLE);
|
||
}
|
||
|
||
/* Set the machine number and endian. */
|
||
gas_cgen_cpu_desc = bpf_cgen_cpu_open (CGEN_CPU_OPEN_ENDIAN,
|
||
target_big_endian ?
|
||
CGEN_ENDIAN_BIG : CGEN_ENDIAN_LITTLE,
|
||
CGEN_CPU_OPEN_INSN_ENDIAN,
|
||
CGEN_ENDIAN_LITTLE,
|
||
CGEN_CPU_OPEN_ISAS,
|
||
bpf_isa,
|
||
CGEN_CPU_OPEN_END);
|
||
bpf_cgen_init_asm (gas_cgen_cpu_desc);
|
||
|
||
/* This is a callback from cgen to gas to parse operands. */
|
||
cgen_set_parse_operand_fn (gas_cgen_cpu_desc, gas_cgen_parse_operand);
|
||
|
||
/* Set the machine type. */
|
||
bfd_default_set_arch_mach (stdoutput, bfd_arch_bpf, bfd_mach_bpf);
|
||
}
|
||
|
||
valueT
|
||
md_section_align (segT segment, valueT size)
|
||
{
|
||
int align = bfd_section_alignment (segment);
|
||
|
||
return ((size + (1 << align) - 1) & -(1 << align));
|
||
}
|
||
|
||
|
||
/* Functions concerning relocs. */
|
||
|
||
/* The location from which a PC relative jump should be calculated,
|
||
given a PC relative reloc. */
|
||
|
||
long
|
||
md_pcrel_from_section (fixS *fixP, segT sec)
|
||
{
|
||
if (fixP->fx_addsy != (symbolS *) NULL
|
||
&& (! S_IS_DEFINED (fixP->fx_addsy)
|
||
|| (S_GET_SEGMENT (fixP->fx_addsy) != sec)
|
||
|| S_IS_EXTERNAL (fixP->fx_addsy)
|
||
|| S_IS_WEAK (fixP->fx_addsy)))
|
||
{
|
||
/* The symbol is undefined (or is defined but not in this section).
|
||
Let the linker figure it out. */
|
||
return 0;
|
||
}
|
||
|
||
return fixP->fx_where + fixP->fx_frag->fr_address;
|
||
}
|
||
|
||
/* Write a value out to the object file, using the appropriate endianness. */
|
||
|
||
void
|
||
md_number_to_chars (char * buf, valueT val, int n)
|
||
{
|
||
if (target_big_endian)
|
||
number_to_chars_bigendian (buf, val, n);
|
||
else
|
||
number_to_chars_littleendian (buf, val, n);
|
||
}
|
||
|
||
arelent *
|
||
tc_gen_reloc (asection *sec, fixS *fix)
|
||
{
|
||
return gas_cgen_tc_gen_reloc (sec, fix);
|
||
}
|
||
|
||
/* Return the bfd reloc type for OPERAND of INSN at fixup FIXP. This
|
||
is called when the operand is an expression that couldn't be fully
|
||
resolved. Returns BFD_RELOC_NONE if no reloc type can be found.
|
||
*FIXP may be modified if desired. */
|
||
|
||
bfd_reloc_code_real_type
|
||
md_cgen_lookup_reloc (const CGEN_INSN *insn ATTRIBUTE_UNUSED,
|
||
const CGEN_OPERAND *operand,
|
||
fixS *fixP)
|
||
{
|
||
switch (operand->type)
|
||
{
|
||
case BPF_OPERAND_OFFSET16:
|
||
return BFD_RELOC_BPF_16;
|
||
case BPF_OPERAND_IMM32:
|
||
return BFD_RELOC_BPF_32;
|
||
case BPF_OPERAND_IMM64:
|
||
return BFD_RELOC_BPF_64;
|
||
case BPF_OPERAND_DISP16:
|
||
fixP->fx_pcrel = 1;
|
||
return BFD_RELOC_BPF_DISP16;
|
||
case BPF_OPERAND_DISP32:
|
||
fixP->fx_pcrel = 1;
|
||
return BFD_RELOC_BPF_DISP32;
|
||
default:
|
||
break;
|
||
}
|
||
return BFD_RELOC_NONE;
|
||
}
|
||
|
||
/* *FRAGP has been relaxed to its final size, and now needs to have
|
||
the bytes inside it modified to conform to the new size.
|
||
|
||
Called after relaxation is finished.
|
||
fragP->fr_type == rs_machine_dependent.
|
||
fragP->fr_subtype is the subtype of what the address relaxed to. */
|
||
|
||
void
|
||
md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED,
|
||
segT sec ATTRIBUTE_UNUSED,
|
||
fragS *fragP ATTRIBUTE_UNUSED)
|
||
{
|
||
as_fatal (_("convert_frag called"));
|
||
}
|
||
|
||
int
|
||
md_estimate_size_before_relax (fragS *fragP ATTRIBUTE_UNUSED,
|
||
segT segment ATTRIBUTE_UNUSED)
|
||
{
|
||
as_fatal (_("estimate_size_before_relax called"));
|
||
return 0;
|
||
}
|
||
|
||
|
||
void
|
||
md_apply_fix (fixS *fixP, valueT *valP, segT seg)
|
||
{
|
||
/* Some fixups for instructions require special attention. This is
|
||
handled in the code block below. */
|
||
if ((int) fixP->fx_r_type >= (int) BFD_RELOC_UNUSED)
|
||
{
|
||
int opindex = (int) fixP->fx_r_type - (int) BFD_RELOC_UNUSED;
|
||
const CGEN_OPERAND *operand = cgen_operand_lookup_by_num (gas_cgen_cpu_desc,
|
||
opindex);
|
||
char *where;
|
||
|
||
switch (operand->type)
|
||
{
|
||
case BPF_OPERAND_DISP32:
|
||
/* eBPF supports two kind of CALL instructions: the so
|
||
called pseudo calls ("bpf to bpf") and external calls
|
||
("bpf to kernel").
|
||
|
||
Both kind of calls use the same instruction (CALL).
|
||
However, external calls are constructed by passing a
|
||
constant argument to the instruction, whereas pseudo
|
||
calls result from expressions involving symbols. In
|
||
practice, instructions requiring a fixup are interpreted
|
||
as pseudo-calls. If we are executing this code, this is
|
||
a pseudo call.
|
||
|
||
The kernel expects for pseudo-calls to be annotated by
|
||
having BPF_PSEUDO_CALL in the SRC field of the
|
||
instruction. But beware the infamous nibble-swapping of
|
||
eBPF and take endianness into account here.
|
||
|
||
Note that the CALL instruction has only one operand, so
|
||
this code is executed only once per instruction. */
|
||
where = fixP->fx_frag->fr_literal + fixP->fx_where + 1;
|
||
where[0] = target_big_endian ? 0x01 : 0x10;
|
||
/* Fallthrough. */
|
||
case BPF_OPERAND_DISP16:
|
||
/* The PC-relative displacement fields in jump instructions
|
||
shouldn't be in bytes. Instead, they hold the number of
|
||
64-bit words to the target, _minus one_. */
|
||
*valP = (((long) (*valP)) - 8) / 8;
|
||
break;
|
||
default:
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* And now invoke CGEN's handler, which will eventually install
|
||
*valP into the corresponding operand. */
|
||
gas_cgen_md_apply_fix (fixP, valP, seg);
|
||
}
|
||
|
||
void
|
||
md_assemble (char *str)
|
||
{
|
||
const CGEN_INSN *insn;
|
||
char *errmsg;
|
||
CGEN_FIELDS fields;
|
||
|
||
#if CGEN_INT_INSN_P
|
||
CGEN_INSN_INT buffer[CGEN_MAX_INSN_SIZE / sizeof (CGEN_INT_INSN_P)];
|
||
#else
|
||
unsigned char buffer[CGEN_MAX_INSN_SIZE];
|
||
#endif
|
||
|
||
gas_cgen_init_parse ();
|
||
insn = bpf_cgen_assemble_insn (gas_cgen_cpu_desc, str, &fields,
|
||
buffer, &errmsg);
|
||
|
||
if (insn == NULL)
|
||
{
|
||
as_bad ("%s", errmsg);
|
||
return;
|
||
}
|
||
|
||
gas_cgen_finish_insn (insn, buffer, CGEN_FIELDS_BITSIZE (&fields),
|
||
0, /* zero to ban relaxable insns. */
|
||
NULL); /* NULL so results not returned here. */
|
||
}
|
||
|
||
void
|
||
md_operand (expressionS *expressionP)
|
||
{
|
||
gas_cgen_md_operand (expressionP);
|
||
}
|
||
|
||
|
||
symbolS *
|
||
md_undefined_symbol (char *name ATTRIBUTE_UNUSED)
|
||
{
|
||
return NULL;
|
||
}
|
||
|
||
|
||
/* Turn a string in input_line_pointer into a floating point constant
|
||
of type TYPE, and store the appropriate bytes in *LITP. The number
|
||
of LITTLENUMS emitted is stored in *SIZEP. An error message is
|
||
returned, or NULL on OK. */
|
||
|
||
const char *
|
||
md_atof (int type, char *litP, int *sizeP)
|
||
{
|
||
return ieee_md_atof (type, litP, sizeP, false);
|
||
}
|