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c978b63c3acf3689b62dffc2a2401c06a412ccd5
rtems/cpukit/libdl/rtl-mdreloc-arm.c
Kinsey Moore c978b63c3a cpukit/libdl/arm: Support BLX relocations that require a trampoline 
BLX relocations in Thumb code expect the target to be ARM code. This
means that the trampoline must be generated in ARM mode.
2024-10-17 22:32:47 +00:00

681 lines
21 KiB
C
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/*
* Taken from NetBSD and stripped of the relocations not needed on RTEMS.
*/
/* $NetBSD: mdreloc.c,v 1.33 2010/01/14 12:12:07 skrll Exp $ */
#include <sys/cdefs.h>
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <rtems/rtl/rtl.h>
#include "rtl-elf.h"
#include "rtl-error.h"
#include <rtems/rtl/rtl-trace.h>
#include "rtl-unwind-arm.h"
/*
* Set to 1 to allow untested relocations. If you tested one and it
* works or you fixed the relocation please remove the guard.
*/
#define ALLOW_UNTESTED_RELOCS 1
/*
* It is possible for the compiler to emit relocations for unaligned data.
* We handle this situation with these inlines.
*/
#define RELOC_ALIGNED_P(x) \
(((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
#define SHT_ARM_EXIDX 0x70000001 /* Section holds ARM unwind info. */
static inline Elf_Addr
load_ptr(void *where)
{
Elf_Addr res;
memcpy(&res, where, sizeof(res));
return (res);
}
static inline void
store_ptr(void *where, Elf_Addr val)
{
memcpy(where, &val, sizeof(val));
}
/*
* The address of Thumb function symbols is it's real address plus one.
* This is done by compiler, thus do not consider symtype here.
*/
static inline int
isThumb(Elf_Word symvalue)
{
if ((symvalue & 0x1) == 0x1)
return true;
else return false;
}
static inline Elf_SOff
sign_extend31(Elf_Addr val)
{
if (0x40000000 & val)
val = ~((Elf_Addr)0x7fffffff) | (0x7fffffff & val);
return 0x7fffffff & val;
}
static void*
set_arm_veneer(void* trampoline, Elf_Addr target)
{
/*
* ARM mode:
* ldr pc, [pc, #-4]
*/
uint32_t* tramp = (uint32_t*) trampoline;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
*tramp++ = 0xe51ff004;
#else
*tramp++ = 0xe51ff004; /* not tested */
#endif
*tramp++ = (uint32_t) target;
return tramp;
}
static void*
set_veneer(void* trampoline, Elf_Addr target)
{
/*
* http://shell-storm.org/online/Online-Assembler-and-Disassembler/
*
* Thumb mode:
* ldr.w pc, [pc]
*
*/
#if defined(__thumb__)
uint32_t* tramp = (uint32_t*) trampoline;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
*tramp++ = 0xf000f8df;
#else
*tramp++ = 0xf8dff000; /* not tested */
#endif
*tramp++ = (uint32_t) target;
return tramp;
#else
return set_arm_veneer(trampoline, target);
#endif
}
static void*
set_thumb_bx_veneer(void* trampoline, Elf_Addr target)
{
/*
* http://shell-storm.org/online/Online-Assembler-and-Disassembler/
*
* Thumb mode:
* ldr.w r12, [pc, 4]
* bx r12
* .word target
*
*/
uint16_t* tramp = (uint16_t*) trampoline;
/* ldr.w r12, [pc, 4]*/
*tramp++ = 0xf8df;
*tramp++ = 0xc002;
/* bx r12 */
*tramp++ = 0x4760;
*tramp++ = (uint16_t) target & 0xffff;
*tramp++ = (uint16_t) ((target >> 16) & 0xffff);
return tramp;
}
static size_t
get_veneer_size(int type)
{
(void) type;
/* BX veneers need 10 bytes */
return 10;
}
uint32_t rtems_rtl_obj_tramp_alignment (const rtems_rtl_obj* obj)
{
(void) obj;
return sizeof(uint32_t);
}
size_t
rtems_rtl_elf_relocate_tramp_max_size (void)
{
return 8;
}
uint32_t
rtems_rtl_elf_section_flags (const rtems_rtl_obj* obj,
const Elf_Shdr* shdr)
{
uint32_t flags = 0;
if (shdr->sh_type == SHT_ARM_EXIDX)
flags = RTEMS_RTL_OBJ_SECT_EH | RTEMS_RTL_OBJ_SECT_LOAD;
return flags;
}
uint32_t
rtems_rtl_elf_arch_parse_section (const rtems_rtl_obj* obj,
int section,
const char* name,
const Elf_Shdr* shdr,
const uint32_t flags)
{
(void) obj;
(void) section;
(void) name;
(void) shdr;
return flags;
}
bool
rtems_rtl_elf_arch_section_alloc (const rtems_rtl_obj* obj,
rtems_rtl_obj_sect* sect)
{
(void) obj;
(void) sect;
return false;
}
bool
rtems_rtl_elf_arch_section_free (const rtems_rtl_obj* obj,
rtems_rtl_obj_sect* sect)
{
(void) obj;
(void) sect;
return false;
}
bool
rtems_rtl_elf_rel_resolve_sym (Elf_Word type)
{
return true;
}
rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rela_tramp (rtems_rtl_obj* obj,
const Elf_Rela* rela,
const rtems_rtl_obj_sect* sect,
const char* symname,
const Elf_Byte syminfo,
const Elf_Word symvalue)
{
(void) obj;
(void) rela;
(void) sect;
(void) symname;
(void) syminfo;
(void) symvalue;
rtems_rtl_set_error (EINVAL, "rela type record not supported");
return rtems_rtl_elf_rel_failure;
}
rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rela (rtems_rtl_obj* obj,
const Elf_Rela* rela,
const rtems_rtl_obj_sect* sect,
const char* symname,
const Elf_Byte syminfo,
const Elf_Word symvalue)
{
(void) obj;
(void) rela;
(void) sect;
(void) symname;
(void) syminfo;
(void) symvalue;
rtems_rtl_set_error (EINVAL, "rela type record not supported");
return rtems_rtl_elf_rel_failure;
}
static rtems_rtl_elf_rel_status
rtems_rtl_elf_reloc_rel (rtems_rtl_obj* obj,
const Elf_Rel* rel,
const rtems_rtl_obj_sect* sect,
const char* symname,
const Elf_Byte syminfo,
const Elf_Word symvalue,
const bool parsing)
{
Elf_Addr *where;
Elf_Addr tmp;
Elf_Word insn, addend;
Elf_Word sign, i1, i2;
uint16_t lower_insn, upper_insn;
where = (Elf_Addr *)(sect->base + rel->r_offset);
switch (ELF_R_TYPE(rel->r_info)) {
case R_TYPE(NONE):
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC)) {
printf ("rtl: NONE %p in %s\n", where, rtems_rtl_obj_oname (obj));
}
break;
case R_TYPE(CALL): /* BL/BLX */
case R_TYPE(JUMP24): /* B/BL<cond> */
if (parsing)
{
addend = 0;
}
else
{
insn = *where;
if (insn & 0x00800000)
addend = insn | 0xff000000;
else addend = insn & 0x00ffffff;
if (isThumb(symvalue)) {
if ((insn & 0xfe000000) == 0xfa000000); /* Already blx */
else {
if ((insn & 0xff000000) == 0xeb000000) { /* BL <label> */
*where = (insn & 0x00ffffff) | 0xfa000000; /* BL-->BLX */
} else {
printf("JUMP24 is not suppored from arm to thumb\n");
return rtems_rtl_elf_rel_failure;
}
}
}
}
if (parsing && sect->base == 0) {
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: JUMP24/PC24/CALL tramp cache\n");
return rtems_rtl_elf_rel_tramp_cache;
}
tmp = symvalue + (addend << 2) - (Elf_Addr)where;
tmp = (Elf_Sword)tmp >> 2;
if (((Elf_Sword)tmp > 0x7fffff) || ((Elf_Sword)tmp < -0x800000)) {
Elf_Word tramp_addr;
size_t tramp_size = get_veneer_size(ELF_R_TYPE(rel->r_info));
if (parsing) {
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: JUMP24/PC24/CALL tramp add\n");
return rtems_rtl_elf_rel_tramp_add;
}
if (!rtems_rtl_obj_has_tramp_space (obj, tramp_size)) {
rtems_rtl_set_error (EINVAL,
"%s: CALL/JUMP24: overflow: no tramp memory",
sect->name);
return rtems_rtl_elf_rel_failure;
}
tramp_addr = ((Elf_Addr) obj->tramp_brk) | (symvalue & 1);
obj->tramp_brk = set_veneer(obj->tramp_brk, symvalue);
tmp = tramp_addr + (addend << 2) - (Elf_Addr)where;
tmp = (Elf_Sword)tmp >> 2;
}
if (!parsing) {
*where = (*where & 0xff000000) | (tmp & 0xffffff);
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: JUMP24/PC24/CALL %p @ %p in %s\n",
(void *)*where, where, rtems_rtl_obj_oname (obj));
}
break;
case R_TYPE(V4BX):
/* Miscellaneous, ignore */
if (!parsing && rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC)) {
printf ("rtl: V4BX @ %p in %s\n",
where, rtems_rtl_obj_oname (obj));
}
break;
case R_TYPE(MOVT_ABS):
case R_TYPE(MOVW_ABS_NC):
if (!parsing) {
insn = *where;
addend = ((insn >> 4) & 0xf000) | (insn & 0x0fff);
if (addend & 0x8000)
addend |= 0xffff0000;
tmp = symvalue + addend;
if (ELF_R_TYPE(rel->r_info) == R_TYPE(MOVW_ABS_NC))
tmp &= 0xffff;
else {
tmp = (Elf_Sword)tmp >> 16;
if (((Elf_Sword)tmp > 0x7fff) || ((Elf_Sword)tmp < -0x8000)) {
printf("MOVT_ABS Overflow\n");
return rtems_rtl_elf_rel_failure;
}
}
*where = (insn & 0xfff0f000) | ((tmp & 0xf000) << 4) | (tmp & 0xfff);
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: MOVT_ABS/MOVW_ABS_NC %p @ %p in %s\n",
(void *)*where, where, rtems_rtl_obj_oname (obj));
}
break;
case R_TYPE(REL32): /* word32 (S + A) | T - P */
case R_TYPE(ABS32): /* word32 (S + A) | T */
case R_TYPE(GLOB_DAT): /* word32 (S + A) | T */
case R_TYPE(PREL31): /* word32 (S + A) | T - P */
case R_TYPE(TARGET1): /* Equivalent to ABS32 */
case R_TYPE(TARGET2): /* Equivalent to REL32 */
if (!parsing) {
if (__predict_true(RELOC_ALIGNED_P(where))) {
tmp = *where + symvalue;
if (isThumb(symvalue))
tmp |= 1;
if (ELF_R_TYPE(rel->r_info) == R_TYPE(REL32) ||
ELF_R_TYPE(rel->r_info) == R_TYPE(TARGET2))
tmp -= (Elf_Addr)where;
else if (ELF_R_TYPE(rel->r_info) == R_TYPE(PREL31))
tmp = sign_extend31(tmp - (Elf_Addr)where);
if (!parsing) {
*where = tmp;
}
} else {
tmp = load_ptr(where) + symvalue;
if (isThumb(symvalue))
tmp |= 1;
if (ELF_R_TYPE(rel->r_info) == R_TYPE(REL32) ||
ELF_R_TYPE(rel->r_info) == R_TYPE(TARGET2))
tmp -= (Elf_Addr)where;
else if (ELF_R_TYPE(rel->r_info) == R_TYPE(PREL31))
tmp = sign_extend31(tmp - (Elf_Addr)where);
store_ptr(where, tmp);
}
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: REL32/ABS32/GLOB_DAT/PREL31/TARGET2 %p @ %p in %s\n",
(void *)tmp, where, rtems_rtl_obj_oname (obj));
}
break;
case R_TYPE(THM_MOVT_ABS):
case R_TYPE(THM_MOVW_ABS_NC):
if (!parsing) {
upper_insn = *(uint16_t *)where;
lower_insn = *((uint16_t *)where + 1);
addend = ((upper_insn & 0x000f) << 12) | ((upper_insn & 0x0400) << 1) |
((lower_insn & 0x7000) >> 4) | (lower_insn & 0x00ff);
addend = (addend ^ 0x8000) - 0x8000;
tmp = addend + symvalue;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
tmp >>= 16;
*(uint16_t *)where = (uint16_t)((upper_insn & 0xfbf0) |
((tmp & 0xf000) >> 12) |
((tmp & 0x0800) >> 1));
*((uint16_t *)where + 1) = (uint16_t)((lower_insn & 0x8f00) |
((tmp & 0x0700) << 4) |
(tmp & 0x00ff));
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC)) {
printf ("rtl: THM_MOVT_ABS/THM_MOVW_ABS_NC %p @ %p in %s\n",
(void *)*where, where, rtems_rtl_obj_oname (obj));
}
}
break;
case R_TYPE(THM_JUMP24):
/* same as THM_PC22; insn b.w */
case R_TYPE(THM_PC22):
if (parsing)
{
addend = 0;
upper_insn = 0;
lower_insn = 0;
}
else
{
upper_insn = *(uint16_t *)where;
lower_insn = *((uint16_t *)where + 1);
sign = (upper_insn & (1 << 10)) >> 10;
i1 = ((lower_insn >> 13) & 1) ^ sign ? 0 : 1;
i2 = ((lower_insn >> 11) & 1) ^ sign ? 0 : 1;
tmp = (i1 << 23) | (i2 << 22) | ((upper_insn & 0x3ff) << 12) | ((lower_insn & 0x7ff) << 1);
addend = (tmp | ((sign ? 0 : 1) << 24)) - (1 << 24);
}
if (isThumb(symvalue) == false
&& ELF_R_TYPE(rel->r_info) != R_TYPE(THM_JUMP24)) {
/* THM_CALL bl-->blx */
lower_insn &= ~(1<<12);
}
if (parsing && sect->base == 0) {
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: THM_CALL/JUMP24 tramp cache\n");
return rtems_rtl_elf_rel_tramp_cache;
}
tmp = symvalue + addend;
if (isThumb(symvalue)) {
tmp = tmp - (Elf_Addr)where;
} else {
/*
* where[1:0] are set to 0 for ARM-targeted relocations because the jump
* offset[1:0] are also 0
*/
tmp = tmp - (Elf_Addr)((uintptr_t)where & 0xfffffffc);
}
if (isThumb(symvalue) == false && ELF_R_TYPE(rel->r_info) == R_TYPE(THM_JUMP24)) {
Elf_Word tramp_addr;
size_t tramp_size = get_veneer_size(ELF_R_TYPE(rel->r_info));
if (parsing) {
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: THM_JUMP24 tramp add: %08x - %p = %i\n",
symvalue + addend, where, (Elf_Sword) tmp);
return rtems_rtl_elf_rel_tramp_add;
}
if (!rtems_rtl_obj_has_tramp_space (obj, tramp_size)) {
rtems_rtl_set_error (EINVAL,
"%s: THM_JUMP24: overflow: no tramp memory",
sect->name);
return rtems_rtl_elf_rel_failure;
}
tramp_addr = (Elf_Addr) obj->tramp_brk;
obj->tramp_brk = set_thumb_bx_veneer(obj->tramp_brk, symvalue);
tmp = tramp_addr + addend;
/* This targets a thumb trampoline, so no need to adjust the PC */
tmp = tmp - (Elf_Addr)where;
} else if (((Elf_Sword)tmp > 0x7fffff) || ((Elf_Sword)tmp < -0x800000)) {
Elf_Word tramp_addr;
size_t tramp_size = get_veneer_size(ELF_R_TYPE(rel->r_info));
if (parsing) {
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: THM_CALL/JUMP24 tramp add: %08x - %p = %i\n",
symvalue + addend, where, (Elf_Sword) tmp);
return rtems_rtl_elf_rel_tramp_add;
}
if (!rtems_rtl_obj_has_tramp_space (obj, tramp_size)) {
rtems_rtl_set_error (EINVAL,
"%s: THM_CALL/JUMP24: overflow: no tramp memory",
sect->name);
return rtems_rtl_elf_rel_failure;
}
tramp_addr = ((Elf_Addr) obj->tramp_brk) | (symvalue & 1);
tmp = tramp_addr + addend;
if (isThumb(symvalue)) {
obj->tramp_brk = set_veneer(obj->tramp_brk, symvalue);
tmp = tmp - (Elf_Addr)where;
} else {
/*
* The B[L]X expects ARM code at the target. Align tramp_brk as
* necessary.
*/
obj->tramp_brk = (void *)RTEMS_ALIGN_UP((uintptr_t)obj->tramp_brk, 4);
tramp_addr = (Elf_Addr) obj->tramp_brk;
obj->tramp_brk = set_arm_veneer(obj->tramp_brk, symvalue);
/*
* where[1:0] are set to 0 for ARM-targeted relocations because the jump
* offset[1:0] are also 0
*/
tmp = tmp - (Elf_Addr)((uintptr_t)where & 0xfffffffc);
}
}
if (!parsing) {
uint16_t bl_tmp;
sign = (tmp >> 24) & 1;
*(uint16_t *)where = (uint16_t)((upper_insn & 0xf800) | (sign << 10) |
((tmp >> 12) & 0x3ff));
bl_tmp = (uint16_t)((lower_insn & 0xd000)|
((sign ^ (~(tmp >> 23) & 1)) << 13) |
((sign ^ (~(tmp >> 22) & 1)) << 11) |
((tmp >> 1) & 0x7ff));
/* Thumb jumps to ARM mode must have 0 in the LSB of the BLX */
if ((bl_tmp & 0xf000) == 0xe000) {
bl_tmp &= 0xfffe;
}
*((uint16_t *)where + 1) = bl_tmp;
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC)){
printf ("rtl: THM_CALL/JUMP24 %p @ %p in %s\n",
(void *)*where, where, rtems_rtl_obj_oname (obj));
}
}
break;
case R_TYPE(THM_JUMP19):
if (!isThumb(symvalue)) {
printf("THM_JUMP19 to arm not supported\n");
return rtems_rtl_elf_rel_failure;
}
upper_insn = *(uint16_t *)where;
lower_insn = *((uint16_t *)where + 1);
sign = (upper_insn >> 10) & 0x1;
if ((((upper_insn & 0x3f) >> 7) & 0x7) == 0x7) {
printf("THM_JUMP19 failed\n");
return false; /*if cond <3:1> == '111', see Related codings in armv7a manual */
}
i1 = (lower_insn >> 13) & 0x1;
i2 = (lower_insn >> 11) & 0x1;
tmp = ((i2 << 19) | (i1 << 18) | ((upper_insn & 0x3f) << 12) | ((lower_insn & 0x7ff) << 1));
addend = (tmp | ((sign ? 0 : 1) << 20)) - (1 << 20);
tmp = symvalue + addend;
tmp = tmp - (Elf_Addr)where;
if (((Elf_Sword)tmp > 0x7ffffe) || ((Elf_Sword)tmp < -0x800000)) {
rtems_rtl_set_error (EINVAL, "%s: Overflow %" PRIu32 " "
"THM_JUMP19 relocations",
sect->name, (uint32_t) ELF_R_TYPE(rel->r_info));
return rtems_rtl_elf_rel_failure;
}
sign = (tmp >> 20) & 0x1;
i2 = (tmp >> 19) & 0x1;
i1 = (tmp >> 18) & 0x1;
*(uint16_t*)where = (upper_insn & 0xfbc0) | (sign << 10) | ((tmp >> 12) & 0x3f);
*((uint16_t*)where + 1) = (lower_insn & 0xd000) | (i1 << 13) |
(i2 << 11) | ((tmp >> 1) & 0x7ff);
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: THM_JUMP19 %p @ %p in %s\n",
(void *)*where, where, rtems_rtl_obj_oname (obj));
break;
case R_TYPE(TLS_LE32):
if (!parsing) {
addend = *where;
*where = symvalue + addend;
if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
printf ("rtl: TLS_LE32 %p @ %p in %s\n",
(void *)*where, where, rtems_rtl_obj_oname (obj));
}
break;
case R_TYPE(TLS_GD32):
case R_TYPE(TLS_LDM32):
case R_TYPE(TLS_LDO32):
case R_TYPE(TLS_IE32):
case R_TYPE(TLS_LDO12):
case R_TYPE(TLS_LE12):
case R_TYPE(TLS_IE12GP):
printf("TSL relocations not supported\n");
default:
printf ("rtl: reloc unknown: sym = %" PRIu32 ", type = %" PRIu32 ", offset = %p",
ELF_R_SYM(rel->r_info), (uint32_t) ELF_R_TYPE(rel->r_info),
(void *)rel->r_offset);
if (!parsing)
printf("contents = %p", (void *)*where);
printf("\n");
rtems_rtl_set_error (EINVAL,
"%s: Unsupported relocation type %" PRIu32 " "
"in non-PLT relocations",
sect->name, (uint32_t) ELF_R_TYPE(rel->r_info));
return rtems_rtl_elf_rel_failure;
}
return rtems_rtl_elf_rel_no_error;
}
rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rel_tramp (rtems_rtl_obj* obj,
const Elf_Rel* rel,
const rtems_rtl_obj_sect* sect,
const char* symname,
const Elf_Byte syminfo,
const Elf_Word symvalue)
{
return rtems_rtl_elf_reloc_rel (obj,
rel,
sect,
symname,
syminfo,
symvalue,
true);
}
rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rel (rtems_rtl_obj* obj,
const Elf_Rel* rel,
const rtems_rtl_obj_sect* sect,
const char* symname,
const Elf_Byte syminfo,
const Elf_Word symvalue)
{
return rtems_rtl_elf_reloc_rel (obj,
rel,
sect,
symname,
syminfo,
symvalue,
false);
}
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