1 /* tc-bpf.c -- Assembler for the Linux eBPF.
2 Copyright (C) 2019-2020 Free Software Foundation, Inc.
3 Contributed by Oracle, Inc.
5 This file is part of GAS, the GNU Assembler.
7 GAS is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GAS is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GAS; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street - Fifth Floor,
20 Boston, MA 02110-1301, USA. */
25 #include "opcodes/bpf-desc.h"
26 #include "opcodes/bpf-opc.h"
28 #include "elf/common.h"
30 #include "dwarf2dbg.h"
32 const char comment_chars
[] = ";";
33 const char line_comment_chars
[] = "#";
34 const char line_separator_chars
[] = "`";
35 const char EXP_CHARS
[] = "eE";
36 const char FLT_CHARS
[] = "fFdD";
38 /* Like s_lcomm_internal in gas/read.c but the alignment string
39 is allowed to be optional. */
42 pe_lcomm_internal (int needs_align
, symbolS
*symbolP
, addressT size
)
49 && *input_line_pointer
== ',')
51 align
= parse_align (needs_align
- 1);
53 if (align
== (addressT
) -1)
68 bss_alloc (symbolP
, size
, align
);
73 pe_lcomm (int needs_align
)
75 s_comm_internal (needs_align
* 2, pe_lcomm_internal
);
78 /* The target specific pseudo-ops which we support. */
79 const pseudo_typeS md_pseudo_table
[] =
84 { "lcomm", pe_lcomm
, 1 },
91 static CGEN_BITSET
*bpf_isa
;
95 /* Command-line options processing. */
99 OPTION_LITTLE_ENDIAN
= OPTION_MD_BASE
,
103 struct option md_longopts
[] =
105 { "EL", no_argument
, NULL
, OPTION_LITTLE_ENDIAN
},
106 { "EB", no_argument
, NULL
, OPTION_BIG_ENDIAN
},
107 { NULL
, no_argument
, NULL
, 0 },
110 size_t md_longopts_size
= sizeof (md_longopts
);
112 const char * md_shortopts
= "";
114 extern int target_big_endian
;
116 /* Whether target_big_endian has been set while parsing command-line
118 static int set_target_endian
= 0;
121 md_parse_option (int c
, const char * arg ATTRIBUTE_UNUSED
)
125 case OPTION_BIG_ENDIAN
:
126 set_target_endian
= 1;
127 target_big_endian
= 1;
129 case OPTION_LITTLE_ENDIAN
:
130 set_target_endian
= 1;
131 target_big_endian
= 0;
141 md_show_usage (FILE * stream
)
143 fprintf (stream
, _("\nBPF options:\n"));
144 fprintf (stream
, _("\
145 --EL generate code for a little endian machine\n\
146 --EB generate code for a big endian machine\n"));
153 /* Initialize the `cgen' interface. */
155 /* If not specified in the command line, use the host
157 if (!set_target_endian
)
159 #ifdef WORDS_BIGENDIAN
160 target_big_endian
= 1;
162 target_big_endian
= 0;
166 /* Set the ISA, which depends on the target endianness. */
167 bpf_isa
= cgen_bitset_create (ISA_MAX
);
168 if (target_big_endian
)
169 cgen_bitset_set (bpf_isa
, ISA_EBPFBE
);
171 cgen_bitset_set (bpf_isa
, ISA_EBPFLE
);
173 /* Set the machine number and endian. */
174 gas_cgen_cpu_desc
= bpf_cgen_cpu_open (CGEN_CPU_OPEN_ENDIAN
,
176 CGEN_ENDIAN_BIG
: CGEN_ENDIAN_LITTLE
,
177 CGEN_CPU_OPEN_INSN_ENDIAN
,
182 bpf_cgen_init_asm (gas_cgen_cpu_desc
);
184 /* This is a callback from cgen to gas to parse operands. */
185 cgen_set_parse_operand_fn (gas_cgen_cpu_desc
, gas_cgen_parse_operand
);
187 /* Set the machine type. */
188 bfd_default_set_arch_mach (stdoutput
, bfd_arch_bpf
, bfd_mach_bpf
);
192 md_section_align (segT segment
, valueT size
)
194 int align
= bfd_section_alignment (segment
);
196 return ((size
+ (1 << align
) - 1) & -(1 << align
));
200 /* Functions concerning relocs. */
202 /* The location from which a PC relative jump should be calculated,
203 given a PC relative reloc. */
206 md_pcrel_from_section (fixS
*fixP
, segT sec
)
208 if (fixP
->fx_addsy
!= (symbolS
*) NULL
209 && (! S_IS_DEFINED (fixP
->fx_addsy
)
210 || (S_GET_SEGMENT (fixP
->fx_addsy
) != sec
)
211 || S_IS_EXTERNAL (fixP
->fx_addsy
)
212 || S_IS_WEAK (fixP
->fx_addsy
)))
214 /* The symbol is undefined (or is defined but not in this section).
215 Let the linker figure it out. */
219 return fixP
->fx_where
+ fixP
->fx_frag
->fr_address
;
222 /* Write a value out to the object file, using the appropriate endianness. */
225 md_number_to_chars (char * buf
, valueT val
, int n
)
227 if (target_big_endian
)
228 number_to_chars_bigendian (buf
, val
, n
);
230 number_to_chars_littleendian (buf
, val
, n
);
234 tc_gen_reloc (asection
*sec
, fixS
*fix
)
236 return gas_cgen_tc_gen_reloc (sec
, fix
);
239 /* Return the bfd reloc type for OPERAND of INSN at fixup FIXP. This
240 is called when the operand is an expression that couldn't be fully
241 resolved. Returns BFD_RELOC_NONE if no reloc type can be found.
242 *FIXP may be modified if desired. */
244 bfd_reloc_code_real_type
245 md_cgen_lookup_reloc (const CGEN_INSN
*insn ATTRIBUTE_UNUSED
,
246 const CGEN_OPERAND
*operand
,
249 switch (operand
->type
)
251 case BPF_OPERAND_OFFSET16
:
252 return BFD_RELOC_BPF_16
;
253 case BPF_OPERAND_IMM32
:
254 return BFD_RELOC_BPF_32
;
255 case BPF_OPERAND_IMM64
:
256 return BFD_RELOC_BPF_64
;
257 case BPF_OPERAND_DISP16
:
259 return BFD_RELOC_BPF_DISP16
;
260 case BPF_OPERAND_DISP32
:
262 return BFD_RELOC_BPF_DISP32
;
266 return BFD_RELOC_NONE
;
269 /* *FRAGP has been relaxed to its final size, and now needs to have
270 the bytes inside it modified to conform to the new size.
272 Called after relaxation is finished.
273 fragP->fr_type == rs_machine_dependent.
274 fragP->fr_subtype is the subtype of what the address relaxed to. */
277 md_convert_frag (bfd
*abfd ATTRIBUTE_UNUSED
,
278 segT sec ATTRIBUTE_UNUSED
,
279 fragS
*fragP ATTRIBUTE_UNUSED
)
281 as_fatal (_("convert_frag called"));
285 md_estimate_size_before_relax (fragS
*fragP ATTRIBUTE_UNUSED
,
286 segT segment ATTRIBUTE_UNUSED
)
288 as_fatal (_("estimate_size_before_relax called"));
294 md_apply_fix (fixS
*fixP
, valueT
*valP
, segT seg
)
296 /* Some fixups for instructions require special attention. This is
297 handled in the code block below. */
298 if ((int) fixP
->fx_r_type
>= (int) BFD_RELOC_UNUSED
)
300 int opindex
= (int) fixP
->fx_r_type
- (int) BFD_RELOC_UNUSED
;
301 const CGEN_OPERAND
*operand
= cgen_operand_lookup_by_num (gas_cgen_cpu_desc
,
305 switch (operand
->type
)
307 case BPF_OPERAND_DISP32
:
308 /* eBPF supports two kind of CALL instructions: the so
309 called pseudo calls ("bpf to bpf") and external calls
312 Both kind of calls use the same instruction (CALL).
313 However, external calls are constructed by passing a
314 constant argument to the instruction, whereas pseudo
315 calls result from expressions involving symbols. In
316 practice, instructions requiring a fixup are interpreted
317 as pseudo-calls. If we are executing this code, this is
320 The kernel expects for pseudo-calls to be annotated by
321 having BPF_PSEUDO_CALL in the SRC field of the
322 instruction. But beware the infamous nibble-swapping of
323 eBPF and take endianness into account here.
325 Note that the CALL instruction has only one operand, so
326 this code is executed only once per instruction. */
327 where
= fixP
->fx_frag
->fr_literal
+ fixP
->fx_where
+ 1;
328 where
[0] = target_big_endian
? 0x01 : 0x10;
330 case BPF_OPERAND_DISP16
:
331 /* The PC-relative displacement fields in jump instructions
332 shouldn't be in bytes. Instead, they hold the number of
333 64-bit words to the target, _minus one_. */
334 *valP
= (((long) (*valP
)) - 8) / 8;
341 /* And now invoke CGEN's handler, which will eventually install
342 *valP into the corresponding operand. */
343 gas_cgen_md_apply_fix (fixP
, valP
, seg
);
347 md_assemble (char *str
)
349 const CGEN_INSN
*insn
;
354 CGEN_INSN_INT buffer
[CGEN_MAX_INSN_SIZE
/ sizeof (CGEN_INT_INSN_P
)];
356 unsigned char buffer
[CGEN_MAX_INSN_SIZE
];
359 gas_cgen_init_parse ();
360 insn
= bpf_cgen_assemble_insn (gas_cgen_cpu_desc
, str
, &fields
,
365 as_bad ("%s", errmsg
);
369 gas_cgen_finish_insn (insn
, buffer
, CGEN_FIELDS_BITSIZE (&fields
),
370 0, /* zero to ban relaxable insns. */
371 NULL
); /* NULL so results not returned here. */
375 md_operand (expressionS
*expressionP
)
377 gas_cgen_md_operand (expressionP
);
382 md_undefined_symbol (char *name ATTRIBUTE_UNUSED
)
388 /* Turn a string in input_line_pointer into a floating point constant
389 of type TYPE, and store the appropriate bytes in *LITP. The number
390 of LITTLENUMS emitted is stored in *SIZEP. An error message is
391 returned, or NULL on OK. */
394 md_atof (int type
, char *litP
, int *sizeP
)
396 return ieee_md_atof (type
, litP
, sizeP
, FALSE
);