gen-hyprel.c File Reference

#include <elf.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <generated/autoconf.h>

Include dependency graph for gen-hyprel.c:

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Macros
#define	HYP_SECTION_PREFIX   ".hyp"
#define	HYP_RELOC_SECTION   ".hyp.reloc"
#define	HYP_SECTION_SYMBOL_PREFIX   "__hyp_section_"
#define	R_AARCH64_ABS64   257
#define	R_AARCH64_PREL64   260
#define	R_AARCH64_PREL32   261
#define	R_AARCH64_PREL16   262
#define	R_AARCH64_PLT32   314
#define	R_AARCH64_LD_PREL_LO19   273
#define	R_AARCH64_ADR_PREL_LO21   274
#define	R_AARCH64_ADR_PREL_PG_HI21   275
#define	R_AARCH64_ADR_PREL_PG_HI21_NC   276
#define	R_AARCH64_ADD_ABS_LO12_NC   277
#define	R_AARCH64_LDST8_ABS_LO12_NC   278
#define	R_AARCH64_TSTBR14   279
#define	R_AARCH64_CONDBR19   280
#define	R_AARCH64_JUMP26   282
#define	R_AARCH64_CALL26   283
#define	R_AARCH64_LDST16_ABS_LO12_NC   284
#define	R_AARCH64_LDST32_ABS_LO12_NC   285
#define	R_AARCH64_LDST64_ABS_LO12_NC   286
#define	R_AARCH64_MOVW_PREL_G0   287
#define	R_AARCH64_MOVW_PREL_G0_NC   288
#define	R_AARCH64_MOVW_PREL_G1   289
#define	R_AARCH64_MOVW_PREL_G1_NC   290
#define	R_AARCH64_MOVW_PREL_G2   291
#define	R_AARCH64_MOVW_PREL_G2_NC   292
#define	R_AARCH64_MOVW_PREL_G3   293
#define	R_AARCH64_LDST128_ABS_LO12_NC   299
#define	fatal_error(fmt, ...)
#define	fatal_perror(msg)
#define	assert_op(lhs, rhs, fmt, op)
#define	assert_eq(lhs, rhs, fmt)   assert_op(lhs, rhs, fmt, ==)
#define	assert_ne(lhs, rhs, fmt)   assert_op(lhs, rhs, fmt, !=)
#define	assert_lt(lhs, rhs, fmt)   assert_op(lhs, rhs, fmt, <)
#define	assert_ge(lhs, rhs, fmt)   assert_op(lhs, rhs, fmt, >=)
#define	elf_ptr(type, off)   ((type *)(elf.begin + (off)))
#define	for_each_section(var)    for (var = elf.sh_table; var < elf.sh_table + elf16toh(elf.ehdr->e_shnum); ++var)
#define	for_each_rela(shdr, var)

Functions
static bool	starts_with (const char *str, const char *prefix)
static const char *	section_name (Elf64_Shdr *shdr)
static const char *	section_begin (Elf64_Shdr *shdr)
static Elf64_Shdr *	section_by_off (Elf64_Off off)
static Elf64_Shdr *	section_by_idx (uint16_t idx)
static void	init_elf (const char *path)
static void	emit_prologue (void)
static void	emit_section_prologue (const char *sh_orig_name)
static void	emit_rela_abs64 (Elf64_Rela *rela, const char *sh_orig_name)
static void	emit_epilogue (void)
static void	emit_rela_section (Elf64_Shdr *sh_rela)
static void	emit_all_relocs (void)
int	main (int argc, const char **argv)

Variables
struct {
const char *   path
char *   begin
size_t   size
Elf64_Ehdr *   ehdr
Elf64_Shdr *   sh_table
const char *   sh_string
}	elf

Macro Definition Documentation

assert_eq

#define assert_eq	(		lhs,
			rhs,
			fmt
	)		assert_op(lhs, rhs, fmt, ==)

Definition at line 189 of file gen-hyprel.c.

assert_ge

#define assert_ge	(		lhs,
			rhs,
			fmt
	)		assert_op(lhs, rhs, fmt, >=)

Definition at line 192 of file gen-hyprel.c.

assert_lt

#define assert_lt	(		lhs,
			rhs,
			fmt
	)		assert_op(lhs, rhs, fmt, <)

Definition at line 191 of file gen-hyprel.c.

assert_ne

#define assert_ne	(		lhs,
			rhs,
			fmt
	)		assert_op(lhs, rhs, fmt, !=)

Definition at line 190 of file gen-hyprel.c.

assert_op

#define assert_op	(		lhs,
			rhs,
			fmt,
			op
	)

Value:

    ({                              \
        typeof(lhs) _lhs = (lhs);               \
        typeof(rhs) _rhs = (rhs);               \
                                    \
        if (!(_lhs op _rhs)) {                  \
            fatal_error("assertion " #lhs " " #op " " #rhs  \
                " failed (lhs=" fmt ", rhs=" fmt    \
                ", line=%d)", _lhs, _rhs, __LINE__);    \
        }                           \
    })

Definition at line 177 of file gen-hyprel.c.

elf_ptr

#define elf_ptr	(		type,
			off
	)		((type *)(elf.begin + (off)))

Definition at line 198 of file gen-hyprel.c.

fatal_error

#define fatal_error	(		fmt,
			...
	)

Value:

    ({                              \
        fprintf(stderr, "error: %s: " fmt "\n",         \
            elf.path, ## __VA_ARGS__);          \
        exit(EXIT_FAILURE);                 \
        __builtin_unreachable();                \
    })

Definition at line 161 of file gen-hyprel.c.

fatal_perror

#define fatal_perror

(

msg

)

Value:

    ({                              \
        fprintf(stderr, "error: %s: " msg ": %s\n",     \
            elf.path, strerror(errno));         \
        exit(EXIT_FAILURE);                 \
        __builtin_unreachable();                \
    })

Definition at line 169 of file gen-hyprel.c.

for_each_rela

#define for_each_rela	(		shdr,
			var
	)

Value:

    for (var = elf_ptr(Elf64_Rela, elf64toh(shdr->sh_offset));  \
         var < elf_ptr(Elf64_Rela, elf64toh(shdr->sh_offset) + elf64toh(shdr->sh_size)); var++)

Definition at line 205 of file gen-hyprel.c.

for_each_section

#define for_each_section

(

var

)

for (var = elf.sh_table; var < elf.sh_table + elf16toh(elf.ehdr->e_shnum); ++var)

Definition at line 201 of file gen-hyprel.c.

HYP_RELOC_SECTION

#define HYP_RELOC_SECTION   ".hyp.reloc"

Definition at line 43 of file gen-hyprel.c.

HYP_SECTION_PREFIX

#define HYP_SECTION_PREFIX   ".hyp"

Definition at line 42 of file gen-hyprel.c.

HYP_SECTION_SYMBOL_PREFIX

#define HYP_SECTION_SYMBOL_PREFIX   "__hyp_section_"

Definition at line 44 of file gen-hyprel.c.

R_AARCH64_ABS64

#define R_AARCH64_ABS64   257

Definition at line 51 of file gen-hyprel.c.

R_AARCH64_ADD_ABS_LO12_NC

#define R_AARCH64_ADD_ABS_LO12_NC   277

Definition at line 78 of file gen-hyprel.c.

R_AARCH64_ADR_PREL_LO21

#define R_AARCH64_ADR_PREL_LO21   274

Definition at line 69 of file gen-hyprel.c.

R_AARCH64_ADR_PREL_PG_HI21

#define R_AARCH64_ADR_PREL_PG_HI21   275

Definition at line 72 of file gen-hyprel.c.

R_AARCH64_ADR_PREL_PG_HI21_NC

#define R_AARCH64_ADR_PREL_PG_HI21_NC   276

Definition at line 75 of file gen-hyprel.c.

R_AARCH64_CALL26

#define R_AARCH64_CALL26   283

Definition at line 93 of file gen-hyprel.c.

R_AARCH64_CONDBR19

#define R_AARCH64_CONDBR19   280

Definition at line 87 of file gen-hyprel.c.

R_AARCH64_JUMP26

#define R_AARCH64_JUMP26   282

Definition at line 90 of file gen-hyprel.c.

R_AARCH64_LD_PREL_LO19

#define R_AARCH64_LD_PREL_LO19   273

Definition at line 66 of file gen-hyprel.c.

R_AARCH64_LDST128_ABS_LO12_NC

#define R_AARCH64_LDST128_ABS_LO12_NC   299

Definition at line 126 of file gen-hyprel.c.

R_AARCH64_LDST16_ABS_LO12_NC

#define R_AARCH64_LDST16_ABS_LO12_NC   284

Definition at line 96 of file gen-hyprel.c.

R_AARCH64_LDST32_ABS_LO12_NC

#define R_AARCH64_LDST32_ABS_LO12_NC   285

Definition at line 99 of file gen-hyprel.c.

R_AARCH64_LDST64_ABS_LO12_NC

#define R_AARCH64_LDST64_ABS_LO12_NC   286

Definition at line 102 of file gen-hyprel.c.

R_AARCH64_LDST8_ABS_LO12_NC

#define R_AARCH64_LDST8_ABS_LO12_NC   278

Definition at line 81 of file gen-hyprel.c.

R_AARCH64_MOVW_PREL_G0

#define R_AARCH64_MOVW_PREL_G0   287

Definition at line 105 of file gen-hyprel.c.

R_AARCH64_MOVW_PREL_G0_NC

#define R_AARCH64_MOVW_PREL_G0_NC   288

Definition at line 108 of file gen-hyprel.c.

R_AARCH64_MOVW_PREL_G1

#define R_AARCH64_MOVW_PREL_G1   289

Definition at line 111 of file gen-hyprel.c.

R_AARCH64_MOVW_PREL_G1_NC

#define R_AARCH64_MOVW_PREL_G1_NC   290

Definition at line 114 of file gen-hyprel.c.

R_AARCH64_MOVW_PREL_G2

#define R_AARCH64_MOVW_PREL_G2   291

Definition at line 117 of file gen-hyprel.c.

R_AARCH64_MOVW_PREL_G2_NC

#define R_AARCH64_MOVW_PREL_G2_NC   292

Definition at line 120 of file gen-hyprel.c.

R_AARCH64_MOVW_PREL_G3

#define R_AARCH64_MOVW_PREL_G3   293

Definition at line 123 of file gen-hyprel.c.

R_AARCH64_PLT32

#define R_AARCH64_PLT32   314

Definition at line 63 of file gen-hyprel.c.

R_AARCH64_PREL16

#define R_AARCH64_PREL16   262

Definition at line 60 of file gen-hyprel.c.

R_AARCH64_PREL32

#define R_AARCH64_PREL32   261

Definition at line 57 of file gen-hyprel.c.

R_AARCH64_PREL64

#define R_AARCH64_PREL64   260

Definition at line 54 of file gen-hyprel.c.

R_AARCH64_TSTBR14

#define R_AARCH64_TSTBR14   279

Definition at line 84 of file gen-hyprel.c.

Function Documentation

emit_all_relocs()

static void emit_all_relocs ( void  )

static

Definition at line 426 of file gen-hyprel.c.

{
    Elf64_Shdr *shdr;
 
    for_each_section(shdr) {
        switch (elf32toh(shdr->sh_type)) {
        case SHT_REL:
            fatal_error("Unexpected SHT_REL section \"%s\"",
                section_name(shdr));
        case SHT_RELA:
            emit_rela_section(shdr);
            break;
        }
    }
}

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emit_epilogue()

static void emit_epilogue ( void  )

static

Definition at line 348 of file gen-hyprel.c.

{
    printf(".popsection\n");
}

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emit_prologue()

static void emit_prologue ( void  )

static

Definition at line 297 of file gen-hyprel.c.

{
    printf(".data\n"
           ".pushsection " HYP_RELOC_SECTION ", \"a\"\n");
}

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emit_rela_abs64()

static void emit_rela_abs64 ( Elf64_Rela *  rela, const char *  sh_orig_name  )

static

Definition at line 326 of file gen-hyprel.c.

{
    /* Offset of this reloc from the beginning of HYP_RELOC_SECTION. */
    static size_t reloc_offset;
 
    /* Create storage for the 32-bit offset. */
    printf(".word 0\n");
 
    /*
     * Create a PREL32 relocation which instructs the linker of `vmlinux`
     * to insert offset to position <base> + <offset>, where <base> is
     * a symbol at the beginning of the relocated section, and <offset>
     * is `rela->r_offset`.
     */
    printf(".reloc %lu, R_AARCH64_PREL32, %s%s + 0x%lx\n",
           reloc_offset, HYP_SECTION_SYMBOL_PREFIX, sh_orig_name,
           elf64toh(rela->r_offset));
 
    reloc_offset += 4;
}

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emit_rela_section()

static void emit_rela_section ( Elf64_Shdr *  sh_rela )

static

Definition at line 360 of file gen-hyprel.c.

{
    Elf64_Shdr *sh_orig = &elf.sh_table[elf32toh(sh_rela->sh_info)];
    const char *sh_orig_name = section_name(sh_orig);
    Elf64_Rela *rela;
 
    /* Skip all non-hyp sections. */
    if (!starts_with(sh_orig_name, HYP_SECTION_PREFIX))
        return;
 
    emit_section_prologue(sh_orig_name);
 
    for_each_rela(sh_rela, rela) {
        uint32_t type = (uint32_t)elf64toh(rela->r_info);
 
        /* Check that rela points inside the relocated section. */
        assert_lt(elf64toh(rela->r_offset), elf64toh(sh_orig->sh_size), "0x%lx");
 
        switch (type) {
        /*
         * Data relocations to generate absolute addressing.
         * Emit a hyp relocation.
         */
        case R_AARCH64_ABS64:
            emit_rela_abs64(rela, sh_orig_name);
            break;
        /* Allow position-relative data relocations. */
        case R_AARCH64_PREL64:
        case R_AARCH64_PREL32:
        case R_AARCH64_PREL16:
        case R_AARCH64_PLT32:
            break;
        /* Allow relocations to generate PC-relative addressing. */
        case R_AARCH64_LD_PREL_LO19:
        case R_AARCH64_ADR_PREL_LO21:
        case R_AARCH64_ADR_PREL_PG_HI21:
        case R_AARCH64_ADR_PREL_PG_HI21_NC:
        case R_AARCH64_ADD_ABS_LO12_NC:
        case R_AARCH64_LDST8_ABS_LO12_NC:
        case R_AARCH64_LDST16_ABS_LO12_NC:
        case R_AARCH64_LDST32_ABS_LO12_NC:
        case R_AARCH64_LDST64_ABS_LO12_NC:
        case R_AARCH64_LDST128_ABS_LO12_NC:
            break;
        /* Allow relative relocations for control-flow instructions. */
        case R_AARCH64_TSTBR14:
        case R_AARCH64_CONDBR19:
        case R_AARCH64_JUMP26:
        case R_AARCH64_CALL26:
            break;
        /* Allow group relocations to create PC-relative offset inline. */
        case R_AARCH64_MOVW_PREL_G0:
        case R_AARCH64_MOVW_PREL_G0_NC:
        case R_AARCH64_MOVW_PREL_G1:
        case R_AARCH64_MOVW_PREL_G1_NC:
        case R_AARCH64_MOVW_PREL_G2:
        case R_AARCH64_MOVW_PREL_G2_NC:
        case R_AARCH64_MOVW_PREL_G3:
            break;
        default:
            fatal_error("Unexpected RELA type %u", type);
        }
    }
}

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emit_section_prologue()

static void emit_section_prologue ( const char *  sh_orig_name )

static

Definition at line 304 of file gen-hyprel.c.

{
    /* Declare the hyp section symbol. */
    printf(".global %s%s\n", HYP_SECTION_SYMBOL_PREFIX, sh_orig_name);
}

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init_elf()

static void init_elf ( const char *  path )

static

Definition at line 245 of file gen-hyprel.c.

{
    int fd, ret;
    struct stat stat;
 
    /* Store path in the global struct for error printing. */
    elf.path = path;
 
    /* Open the ELF file. */
    fd = open(path, O_RDONLY);
    if (fd < 0)
        fatal_perror("Could not open ELF file");
 
    /* Get status of ELF file to obtain its size. */
    ret = fstat(fd, &stat);
    if (ret < 0) {
        close(fd);
        fatal_perror("Could not get status of ELF file");
    }
 
    /* mmap() the entire ELF file read-only at an arbitrary address. */
    elf.begin = mmap(0, stat.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (elf.begin == MAP_FAILED) {
        close(fd);
        fatal_perror("Could not mmap ELF file");
    }
 
    /* mmap() was successful, close the FD. */
    close(fd);
 
    /* Get pointer to the ELF header. */
    assert_ge(stat.st_size, sizeof(*elf.ehdr), "%lu");
    elf.ehdr = elf_ptr(Elf64_Ehdr, 0);
 
    /* Check the ELF magic. */
    assert_eq(elf.ehdr->e_ident[EI_MAG0], ELFMAG0, "0x%x");
    assert_eq(elf.ehdr->e_ident[EI_MAG1], ELFMAG1, "0x%x");
    assert_eq(elf.ehdr->e_ident[EI_MAG2], ELFMAG2, "0x%x");
    assert_eq(elf.ehdr->e_ident[EI_MAG3], ELFMAG3, "0x%x");
 
    /* Sanity check that this is an ELF64 relocatable object for AArch64. */
    assert_eq(elf.ehdr->e_ident[EI_CLASS], ELFCLASS64, "%u");
    assert_eq(elf.ehdr->e_ident[EI_DATA], ELFENDIAN, "%u");
    assert_eq(elf16toh(elf.ehdr->e_type), ET_REL, "%u");
    assert_eq(elf16toh(elf.ehdr->e_machine), EM_AARCH64, "%u");
 
    /* Populate fields of the global struct. */
    elf.sh_table = section_by_off(elf64toh(elf.ehdr->e_shoff));
    elf.sh_string = section_begin(section_by_idx(elf16toh(elf.ehdr->e_shstrndx)));
}

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main()

int main	(	int	argc,
		const char **	argv
	)

Definition at line 442 of file gen-hyprel.c.

{
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <elf_input>\n", argv[0]);
        return EXIT_FAILURE;
    }
 
    init_elf(argv[1]);
 
    emit_prologue();
    emit_all_relocs();
    emit_epilogue();
 
    return EXIT_SUCCESS;
}

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section_begin()

static const char* section_begin ( Elf64_Shdr *  shdr )

inlinestatic

Definition at line 222 of file gen-hyprel.c.

{
    return elf_ptr(char, elf64toh(shdr->sh_offset));
}

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section_by_idx()

static Elf64_Shdr* section_by_idx ( uint16_t  idx )

inlinestatic

Definition at line 235 of file gen-hyprel.c.

{
    assert_ne(idx, SHN_UNDEF, "%u");
    return &elf.sh_table[idx];
}

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section_by_off()

static Elf64_Shdr* section_by_off ( Elf64_Off  off )

inlinestatic

Definition at line 228 of file gen-hyprel.c.

{
    assert_ne(off, 0UL, "%lu");
    return elf_ptr(Elf64_Shdr, off);
}

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section_name()

static const char* section_name ( Elf64_Shdr *  shdr )

inlinestatic

Definition at line 216 of file gen-hyprel.c.

{
    return elf.sh_string + elf32toh(shdr->sh_name);
}

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starts_with()

static bool starts_with ( const char *  str, const char *  prefix  )

inlinestatic

Definition at line 210 of file gen-hyprel.c.

{
    return memcmp(str, prefix, strlen(prefix)) == 0;
}

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Variable Documentation

begin

char* begin

Definition at line 132 of file gen-hyprel.c.

ehdr

Elf64_Ehdr* ehdr

Definition at line 134 of file gen-hyprel.c.

struct { ... } elf

path

const char* path

Definition at line 131 of file gen-hyprel.c.

sh_string

const char* sh_string

Definition at line 136 of file gen-hyprel.c.

sh_table

Elf64_Shdr* sh_table

Definition at line 135 of file gen-hyprel.c.

size

size_t size

Definition at line 133 of file gen-hyprel.c.