// R_ARM_PREL31
//
// Coming soon (pending patches):
-// - Relocation
// - Defining section symbols __exidx_start and __exidx_stop.
// - Support interworking.
// - Mergeing all .ARM.xxx.yyy sections into .ARM.xxx. Currently, they
// - Make PLTs more flexible for different architecture features like
// Thumb-2 and BE8.
+// Utilities for manipulating integers of up to 32-bits
+
+namespace utils
+{
+ // Sign extend an n-bit unsigned integer stored in an uint32_t into
+ // an int32_t. NO_BITS must be between 1 to 32.
+ template<int no_bits>
+ static inline int32_t
+ sign_extend(uint32_t bits)
+ {
+ gold_assert(no_bits < 1 || no_bits > 32);
+ if (no_bits == 32)
+ return static_cast<int32_t>(bits);
+ uint32_t mask = (~((uint32_t) 0)) >> (32 - no_bits);
+ bits &= mask;
+ uint32_t top_bit = 1U << (no_bits - 1);
+ int32_t as_signed = static_cast<int32_t>(bits);
+ return (bits & top_bit) ? as_signed + (-top_bit * 2) : as_signed;
+ }
+
+ // Detects overflow of an NO_BITS integer stored in a uint32_t.
+ template<int no_bits>
+ static inline bool
+ has_overflow(uint32_t bits)
+ {
+ gold_assert(no_bits < 1 || no_bits > 32);
+ if (no_bits == 32)
+ return false;
+ int32_t max = (1 << (no_bits - 1)) - 1;
+ int32_t min = -(1 << (no_bits - 1));
+ int32_t as_signed = static_cast<int32_t>(bits);
+ return as_signed > max || as_signed < min;
+ }
+
+ // Select bits from A and B using bits in MASK. For each n in [0..31],
+ // the n-th bit in the result is chosen from the n-th bits of A and B.
+ // A zero selects A and a one selects B.
+ static inline uint32_t
+ bit_select(uint32_t a, uint32_t b, uint32_t mask)
+ { return (a & ~mask) | (b & mask); }
+};
+
template<bool big_endian>
class Target_arm : public Sized_target<32, big_endian>
{
const Symbol_value<32>*,
unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
section_size_type);
+
+ // Return whether we want to pass flag NON_PIC_REF for this
+ // reloc.
+ static inline bool
+ reloc_is_non_pic (unsigned int r_type)
+ {
+ switch (r_type)
+ {
+ case elfcpp::R_ARM_REL32:
+ case elfcpp::R_ARM_THM_CALL:
+ case elfcpp::R_ARM_CALL:
+ case elfcpp::R_ARM_JUMP24:
+ case elfcpp::R_ARM_PREL31:
+ return true;
+ default:
+ return false;
+ }
+ }
};
// A class which returns the size required for a relocation type,
0x1000 // common_pagesize (overridable by -z common-page-size)
};
+// Arm relocate functions class
+//
+
+template<bool big_endian>
+class Arm_relocate_functions : public Relocate_functions<32, big_endian>
+{
+ public:
+ typedef enum
+ {
+ STATUS_OKAY, // No error during relocation.
+ STATUS_OVERFLOW, // Relocation oveflow.
+ STATUS_BAD_RELOC // Relocation cannot be applied.
+ } Status;
+
+ private:
+ typedef Relocate_functions<32, big_endian> Base;
+ typedef Arm_relocate_functions<big_endian> This;
+
+ // Get an symbol value of *PSYMVAL with an ADDEND. This is a wrapper
+ // to Symbol_value::value(). If HAS_THUMB_BIT is true, that LSB is used
+ // to distinguish ARM and THUMB functions and it is treated specially.
+ static inline Symbol_value<32>::Value
+ arm_symbol_value (const Sized_relobj<32, big_endian> *object,
+ const Symbol_value<32>* psymval,
+ Symbol_value<32>::Value addend,
+ bool has_thumb_bit)
+ {
+ typedef Symbol_value<32>::Value Valtype;
+
+ if (has_thumb_bit)
+ {
+ Valtype raw = psymval->value(object, 0);
+ Valtype thumb_bit = raw & 1;
+ return ((raw & ~((Valtype) 1)) + addend) | thumb_bit;
+ }
+ else
+ return psymval->value(object, addend);
+ }
+
+ // FIXME: This probably only works for Android on ARM v5te. We should
+ // following GNU ld for the general case.
+ template<unsigned r_type>
+ static inline typename This::Status
+ arm_branch_common(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Addr address,
+ bool has_thumb_bit)
+ {
+ typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
+ Valtype* wv = reinterpret_cast<Valtype*>(view);
+ Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
+
+ bool insn_is_b = (((val >> 28) & 0xf) <= 0xe)
+ && ((val & 0x0f000000UL) == 0x0a000000UL);
+ bool insn_is_uncond_bl = (val & 0xff000000UL) == 0xeb000000UL;
+ bool insn_is_cond_bl = (((val >> 28) & 0xf) < 0xe)
+ && ((val & 0x0f000000UL) == 0x0b000000UL);
+ bool insn_is_blx = (val & 0xfe000000UL) == 0xfa000000UL;
+ bool insn_is_any_branch = (val & 0x0e000000UL) == 0x0a000000UL;
+
+ if (r_type == elfcpp::R_ARM_CALL)
+ {
+ if (!insn_is_uncond_bl && !insn_is_blx)
+ return This::STATUS_BAD_RELOC;
+ }
+ else if (r_type == elfcpp::R_ARM_JUMP24)
+ {
+ if (!insn_is_b && !insn_is_cond_bl)
+ return This::STATUS_BAD_RELOC;
+ }
+ else if (r_type == elfcpp::R_ARM_PLT32)
+ {
+ if (!insn_is_any_branch)
+ return This::STATUS_BAD_RELOC;
+ }
+ else
+ gold_unreachable();
+
+ Valtype addend = utils::sign_extend<26>(val << 2);
+ Valtype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
+ - address);
+
+ // If target has thumb bit set, we need to either turn the BL
+ // into a BLX (for ARMv5 or above) or generate a stub.
+ if (x & 1)
+ {
+ // Turn BL to BLX.
+ if (insn_is_uncond_bl)
+ val = (val & 0xffffff) | 0xfa000000 | ((x & 2) << 23);
+ else
+ return This::STATUS_BAD_RELOC;
+ }
+ else
+ gold_assert(!insn_is_blx);
+
+ val = utils::bit_select(val, (x >> 2), 0xffffffUL);
+ elfcpp::Swap<32, big_endian>::writeval(wv, val);
+ return (utils::has_overflow<26>(x)
+ ? This::STATUS_OVERFLOW : This::STATUS_OKAY);
+ }
+
+ public:
+ // R_ARM_ABS32: (S + A) | T
+ static inline typename This::Status
+ abs32(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ bool has_thumb_bit)
+ {
+ typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
+ Valtype* wv = reinterpret_cast<Valtype*>(view);
+ Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv);
+ Valtype x = This::arm_symbol_value(object, psymval, addend, has_thumb_bit);
+ elfcpp::Swap<32, big_endian>::writeval(wv, x);
+ return This::STATUS_OKAY;
+ }
+
+ // R_ARM_REL32: (S + A) | T - P
+ static inline typename This::Status
+ rel32(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Addr address,
+ bool has_thumb_bit)
+ {
+ typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
+ Valtype* wv = reinterpret_cast<Valtype*>(view);
+ Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv);
+ Valtype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
+ - address);
+ elfcpp::Swap<32, big_endian>::writeval(wv, x);
+ return This::STATUS_OKAY;
+ }
+
+ // R_ARM_THM_CALL: (S + A) | T - P
+ static inline typename This::Status
+ thm_call(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Addr address,
+ bool has_thumb_bit)
+ {
+ // A thumb call consists of two instructions.
+ typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
+ typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
+ Valtype* wv = reinterpret_cast<Valtype*>(view);
+ Valtype hi = elfcpp::Swap<16, big_endian>::readval(wv);
+ Valtype lo = elfcpp::Swap<16, big_endian>::readval(wv + 1);
+ // Must be a BL instruction. lo == 11111xxxxxxxxxxx.
+ gold_assert((lo & 0xf800) == 0xf800);
+ Reltype addend = utils::sign_extend<23>(((hi & 0x7ff) << 12)
+ | ((lo & 0x7ff) << 1));
+ Reltype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
+ - address);
+
+ // If target has no thumb bit set, we need to either turn the BL
+ // into a BLX (for ARMv5 or above) or generate a stub.
+ if ((x & 1) == 0)
+ {
+ // This only works for ARMv5 and above with interworking enabled.
+ lo &= 0xefff;
+ }
+ hi = utils::bit_select(hi, (x >> 12), 0x7ffU);
+ lo = utils::bit_select(lo, (x >> 1), 0x7ffU);
+ elfcpp::Swap<16, big_endian>::writeval(wv, hi);
+ elfcpp::Swap<16, big_endian>::writeval(wv + 1, lo);
+ return (utils::has_overflow<23>(x)
+ ? This::STATUS_OVERFLOW
+ : This::STATUS_OKAY);
+ }
+
+ // R_ARM_BASE_PREL: B(S) + A - P
+ static inline typename This::Status
+ base_prel(unsigned char* view,
+ elfcpp::Elf_types<32>::Elf_Addr origin,
+ elfcpp::Elf_types<32>::Elf_Addr address)
+ {
+ Base::rel32(view, origin - address);
+ return STATUS_OKAY;
+ }
+
+ // R_ARM_GOT_BREL: GOT(S) + A - GOT_ORG
+ static inline typename This::Status
+ got_brel(unsigned char* view,
+ typename elfcpp::Swap<32, big_endian>::Valtype got_offset)
+ {
+ Base::rel32(view, got_offset);
+ return This::STATUS_OKAY;
+ }
+
+ // R_ARM_PLT32: (S + A) | T - P
+ static inline typename This::Status
+ plt32(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Addr address,
+ bool has_thumb_bit)
+ {
+ return arm_branch_common<elfcpp::R_ARM_PLT32>(view, object, psymval,
+ address, has_thumb_bit);
+ }
+
+ // R_ARM_CALL: (S + A) | T - P
+ static inline typename This::Status
+ call(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Addr address,
+ bool has_thumb_bit)
+ {
+ return arm_branch_common<elfcpp::R_ARM_CALL>(view, object, psymval,
+ address, has_thumb_bit);
+ }
+
+ // R_ARM_JUMP24: (S + A) | T - P
+ static inline typename This::Status
+ jump24(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Addr address,
+ bool has_thumb_bit)
+ {
+ return arm_branch_common<elfcpp::R_ARM_JUMP24>(view, object, psymval,
+ address, has_thumb_bit);
+ }
+
+ // R_ARM_PREL: (S + A) | T - P
+ static inline typename This::Status
+ prel31(unsigned char *view,
+ const Sized_relobj<32, big_endian>* object,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Addr address,
+ bool has_thumb_bit)
+ {
+ typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
+ Valtype* wv = reinterpret_cast<Valtype*>(view);
+ Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
+ Valtype addend = utils::sign_extend<31>(val);
+ Valtype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
+ - address);
+ val = utils::bit_select(val, x, 0x7fffffffU);
+ elfcpp::Swap<32, big_endian>::writeval(wv, val);
+ return (utils::has_overflow<31>(x) ?
+ This::STATUS_OVERFLOW : This::STATUS_OKAY);
+ }
+};
+
// Get the GOT section, creating it if necessary.
template<bool big_endian>
template<bool big_endian>
inline bool
Target_arm<big_endian>::Relocate::relocate(
- const Relocate_info<32, big_endian>* /* relinfo */,
- Target_arm* /* target */,
- Output_section* /* output_section */,
- size_t /* relnum */,
- const elfcpp::Rel<32, big_endian>& /* rel */,
+ const Relocate_info<32, big_endian>* relinfo,
+ Target_arm* target,
+ Output_section *output_section,
+ size_t relnum,
+ const elfcpp::Rel<32, big_endian>& rel,
unsigned int r_type,
- const Sized_symbol<32>* /* gsym */,
- const Symbol_value<32>* /* psymval */,
- unsigned char* /* view */,
- elfcpp::Elf_types<32>::Elf_Addr /* address */,
+ const Sized_symbol<32>* gsym,
+ const Symbol_value<32>* psymval,
+ unsigned char* view,
+ elfcpp::Elf_types<32>::Elf_Addr address,
section_size_type /* view_size */ )
{
+ typedef Arm_relocate_functions<big_endian> Arm_relocate_functions;
+
+ r_type = get_real_reloc_type(r_type);
+
+ // If this the symbol may be a Thumb function, set thumb bit to 1.
+ bool has_thumb_bit = ((gsym != NULL)
+ && (gsym->type() == elfcpp::STT_FUNC
+ || gsym->type() == elfcpp::STT_ARM_TFUNC));
+
+ // Pick the value to use for symbols defined in shared objects.
+ Symbol_value<32> symval;
+ if (gsym != NULL
+ && gsym->use_plt_offset(reloc_is_non_pic(r_type)))
+ {
+ symval.set_output_value(target->plt_section()->address()
+ + gsym->plt_offset());
+ psymval = &symval;
+ has_thumb_bit = 0;
+ }
+
+ const Sized_relobj<32, big_endian>* object = relinfo->object;
+
+ // Get the GOT offset if needed.
+ // The GOT pointer points to the end of the GOT section.
+ // We need to subtract the size of the GOT section to get
+ // the actual offset to use in the relocation.
+ bool have_got_offset = false;
+ unsigned int got_offset = 0;
+ switch (r_type)
+ {
+ case elfcpp::R_ARM_GOT_BREL:
+ if (gsym != NULL)
+ {
+ gold_assert(gsym->has_got_offset(GOT_TYPE_STANDARD));
+ got_offset = (gsym->got_offset(GOT_TYPE_STANDARD)
+ - target->got_size());
+ }
+ else
+ {
+ unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
+ gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_STANDARD));
+ got_offset = (object->local_got_offset(r_sym, GOT_TYPE_STANDARD)
+ - target->got_size());
+ }
+ have_got_offset = true;
+ break;
+
+ default:
+ break;
+ }
+
+ typename Arm_relocate_functions::Status reloc_status =
+ Arm_relocate_functions::STATUS_OKAY;
switch (r_type)
{
case elfcpp::R_ARM_NONE:
break;
+ case elfcpp::R_ARM_ABS32:
+ if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
+ output_section))
+ reloc_status = Arm_relocate_functions::abs32(view, object, psymval,
+ has_thumb_bit);
+ break;
+
+ case elfcpp::R_ARM_REL32:
+ reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
+ address, has_thumb_bit);
+ break;
+
+ case elfcpp::R_ARM_THM_CALL:
+ reloc_status = Arm_relocate_functions::thm_call(view, object, psymval,
+ address, has_thumb_bit);
+ break;
+
+ case elfcpp::R_ARM_GOTOFF32:
+ {
+ elfcpp::Elf_types<32>::Elf_Addr got_origin;
+ got_origin = target->got_plt_section()->address();
+ reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
+ got_origin, has_thumb_bit);
+ }
+ break;
+
+ case elfcpp::R_ARM_BASE_PREL:
+ {
+ uint32_t origin;
+ // Get the addressing origin of the output segment defining the
+ // symbol gsym (AAELF 4.6.1.2 Relocation types)
+ gold_assert(gsym != NULL);
+ if (gsym->source() == Symbol::IN_OUTPUT_SEGMENT)
+ origin = gsym->output_segment()->vaddr();
+ else if (gsym->source () == Symbol::IN_OUTPUT_DATA)
+ origin = gsym->output_data()->address();
+ else
+ {
+ gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
+ _("cannot find origin of R_ARM_BASE_PREL"));
+ return true;
+ }
+ reloc_status = Arm_relocate_functions::base_prel(view, origin, address);
+ }
+ break;
+
+ case elfcpp::R_ARM_GOT_BREL:
+ gold_assert(have_got_offset);
+ reloc_status = Arm_relocate_functions::got_brel(view, got_offset);
+ break;
+
+ case elfcpp::R_ARM_PLT32:
+ gold_assert(gsym == NULL
+ || gsym->has_plt_offset()
+ || gsym->final_value_is_known()
+ || (gsym->is_defined()
+ && !gsym->is_from_dynobj()
+ && !gsym->is_preemptible()));
+ reloc_status = Arm_relocate_functions::plt32(view, object, psymval,
+ address, has_thumb_bit);
+ break;
+
+ case elfcpp::R_ARM_CALL:
+ reloc_status = Arm_relocate_functions::call(view, object, psymval,
+ address, has_thumb_bit);
+ break;
+
+ case elfcpp::R_ARM_JUMP24:
+ reloc_status = Arm_relocate_functions::jump24(view, object, psymval,
+ address, has_thumb_bit);
+ break;
+
+ case elfcpp::R_ARM_PREL31:
+ reloc_status = Arm_relocate_functions::prel31(view, object, psymval,
+ address, has_thumb_bit);
+ break;
+
+ case elfcpp::R_ARM_TARGET1:
+ // This should have been mapped to another type already.
+ // Fall through.
+ case elfcpp::R_ARM_COPY:
+ case elfcpp::R_ARM_GLOB_DAT:
+ case elfcpp::R_ARM_JUMP_SLOT:
+ case elfcpp::R_ARM_RELATIVE:
+ // These are relocations which should only be seen by the
+ // dynamic linker, and should never be seen here.
+ gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
+ _("unexpected reloc %u in object file"),
+ r_type);
+ break;
+
+ default:
+ gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
+ _("unsupported reloc %u"),
+ r_type);
+ break;
+ }
+
+ // Report any errors.
+ switch (reloc_status)
+ {
+ case Arm_relocate_functions::STATUS_OKAY:
+ break;
+ case Arm_relocate_functions::STATUS_OVERFLOW:
+ gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
+ _("relocation overflow in relocation %u"),
+ r_type);
+ break;
+ case Arm_relocate_functions::STATUS_BAD_RELOC:
+ gold_error_at_location(
+ relinfo,
+ relnum,
+ rel.get_r_offset(),
+ _("unexpected opcode while processing relocation %u"),
+ r_type);
+ break;
default:
gold_unreachable();
}
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