[PATCH v2 2/6] RISC-V: Fix relocations in big endian mode
Marcus Comstedt
marcus@mc.pp.se
Sun Dec 20 11:29:13 GMT 2020
bfd/
* elfnn-riscv.c: (riscv_get_insn, riscv_put_insn): Add them.
(riscv_is_insn_reloc): Add it.
(perform_relocation): Use either target endian or fixed little
endian memory access functions depending on whether the relocation
is against data or an instruction.
(riscv_zero_pcrel_hi_reloc, riscv_elf_relocate_section),
(riscv_elf_finish_dynamic_symbol, riscv_elf_finish_dynamic_sections),
(_bfd_riscv_relax_call, _bfd_riscv_relax_lui, _bfd_riscv_relax_align),
(_bfd_riscv_relax_pc): Use fixed little endian memory access
functions for accesing instructions.
---
bfd/elfnn-riscv.c | 93 +++++++++++++++++++++++++++++++----------------
1 file changed, 61 insertions(+), 32 deletions(-)
diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
index 618fe9319f..d241ff2f09 100644
--- a/bfd/elfnn-riscv.c
+++ b/bfd/elfnn-riscv.c
@@ -126,6 +126,18 @@ struct riscv_elf_link_hash_table
};
+/* Instruction access functions. */
+#define riscv_get_insn(bits, ptr) \
+ ((bits) == 16 ? bfd_getl16 (ptr) \
+ : (bits) == 32 ? bfd_getl32 (ptr) \
+ : (bits) == 64 ? bfd_getl64 (ptr) \
+ : (abort (), (bfd_vma) - 1))
+#define riscv_put_insn(bits, val, ptr) \
+ ((bits) == 16 ? bfd_putl16 (val, ptr) \
+ : (bits) == 32 ? bfd_putl32 (val, ptr) \
+ : (bits) == 64 ? bfd_putl64 (val, ptr) \
+ : (abort (), (void) 0))
+
/* Get the RISC-V ELF linker hash table from a link_info structure. */
#define riscv_elf_hash_table(p) \
((is_elf_hash_table ((p)->hash) \
@@ -152,6 +164,17 @@ riscv_elf_append_rela (bfd *abfd, asection *s, Elf_Internal_Rela *rel)
bed->s->swap_reloca_out (abfd, rel, loc);
}
+/* Return true if a relocation is modifying an instruction. */
+
+static bfd_boolean
+riscv_is_insn_reloc (const reloc_howto_type *howto)
+{
+ /* Heuristic: A multibyte destination with a nontrivial mask
+ is an instruction */
+ return howto->bitsize > 8 && howto->dst_mask != 0 &&
+ ~(howto->dst_mask | (((bfd_vma)0 - 1) << howto->bitsize)) != 0;
+}
+
/* PLT/GOT stuff. */
#define PLT_HEADER_INSNS 8
@@ -1636,10 +1659,10 @@ perform_relocation (const reloc_howto_type *howto,
/* Linker relaxation can convert an address equal to or greater than
0x800 to slightly below 0x800. C.LUI does not accept zero as a
valid immediate. We can fix this by converting it to a C.LI. */
- bfd_vma insn = bfd_get (howto->bitsize, input_bfd,
- contents + rel->r_offset);
+ bfd_vma insn = riscv_get_insn (howto->bitsize,
+ contents + rel->r_offset);
insn = (insn & ~MATCH_C_LUI) | MATCH_C_LI;
- bfd_put (howto->bitsize, input_bfd, insn, contents + rel->r_offset);
+ riscv_put_insn (howto->bitsize, insn, contents + rel->r_offset);
value = ENCODE_RVC_IMM (0);
}
else if (!VALID_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (value)))
@@ -1675,9 +1698,16 @@ perform_relocation (const reloc_howto_type *howto,
return bfd_reloc_notsupported;
}
- bfd_vma word = bfd_get (howto->bitsize, input_bfd, contents + rel->r_offset);
+ bfd_vma word;
+ if (riscv_is_insn_reloc (howto))
+ word = riscv_get_insn (howto->bitsize, contents + rel->r_offset);
+ else
+ word = bfd_get (howto->bitsize, input_bfd, contents + rel->r_offset);
word = (word & ~howto->dst_mask) | (value & howto->dst_mask);
- bfd_put (howto->bitsize, input_bfd, word, contents + rel->r_offset);
+ if (riscv_is_insn_reloc (howto))
+ riscv_put_insn (howto->bitsize, word, contents + rel->r_offset);
+ else
+ bfd_put (howto->bitsize, input_bfd, word, contents + rel->r_offset);
return bfd_reloc_ok;
}
@@ -1755,7 +1785,7 @@ riscv_zero_pcrel_hi_reloc (Elf_Internal_Rela *rel,
bfd_vma addr,
bfd_byte *contents,
const reloc_howto_type *howto,
- bfd *input_bfd)
+ bfd *input_bfd ATTRIBUTE_UNUSED)
{
/* We may need to reference low addreses in PC-relative modes even when the
* PC is far away from these addresses. For example, undefweak references
@@ -1781,9 +1811,9 @@ riscv_zero_pcrel_hi_reloc (Elf_Internal_Rela *rel,
rel->r_info = ELFNN_R_INFO(addr, R_RISCV_HI20);
- bfd_vma insn = bfd_get(howto->bitsize, input_bfd, contents + rel->r_offset);
+ bfd_vma insn = riscv_get_insn(howto->bitsize, contents + rel->r_offset);
insn = (insn & ~MASK_AUIPC) | MATCH_LUI;
- bfd_put(howto->bitsize, input_bfd, insn, contents + rel->r_offset);
+ riscv_put_insn(howto->bitsize, insn, contents + rel->r_offset);
return TRUE;
}
@@ -2371,10 +2401,9 @@ riscv_elf_relocate_section (bfd *output_bfd,
&& (!bfd_link_pic (info) || h->plt.offset == MINUS_ONE))
{
/* We can use x0 as the base register. */
- bfd_vma insn = bfd_get_32 (input_bfd,
- contents + rel->r_offset + 4);
+ bfd_vma insn = bfd_getl32 (contents + rel->r_offset + 4);
insn &= ~(OP_MASK_RS1 << OP_SH_RS1);
- bfd_put_32 (input_bfd, insn, contents + rel->r_offset + 4);
+ bfd_putl32 (insn, contents + rel->r_offset + 4);
/* Set the relocation value so that we get 0 after the pc
relative adjustment. */
relocation = sec_addr (input_section) + rel->r_offset;
@@ -2407,10 +2436,10 @@ riscv_elf_relocate_section (bfd *output_bfd,
if (VALID_ITYPE_IMM (relocation + rel->r_addend))
{
/* We can use tp as the base register. */
- bfd_vma insn = bfd_get_32 (input_bfd, contents + rel->r_offset);
+ bfd_vma insn = bfd_getl32 (contents + rel->r_offset);
insn &= ~(OP_MASK_RS1 << OP_SH_RS1);
insn |= X_TP << OP_SH_RS1;
- bfd_put_32 (input_bfd, insn, contents + rel->r_offset);
+ bfd_putl32 (insn, contents + rel->r_offset);
}
else
r = bfd_reloc_overflow;
@@ -2424,14 +2453,14 @@ riscv_elf_relocate_section (bfd *output_bfd,
if (x0_base || VALID_ITYPE_IMM (relocation + rel->r_addend - gp))
{
/* We can use x0 or gp as the base register. */
- bfd_vma insn = bfd_get_32 (input_bfd, contents + rel->r_offset);
+ bfd_vma insn = bfd_getl32 (contents + rel->r_offset);
insn &= ~(OP_MASK_RS1 << OP_SH_RS1);
if (!x0_base)
{
rel->r_addend -= gp;
insn |= X_GP << OP_SH_RS1;
}
- bfd_put_32 (input_bfd, insn, contents + rel->r_offset);
+ bfd_putl32 (insn, contents + rel->r_offset);
}
else
r = bfd_reloc_overflow;
@@ -2855,7 +2884,7 @@ riscv_elf_finish_dynamic_symbol (bfd *output_bfd,
return FALSE;
for (i = 0; i < PLT_ENTRY_INSNS; i++)
- bfd_put_32 (output_bfd, plt_entry[i], loc + 4*i);
+ bfd_putl32 (plt_entry[i], loc + 4*i);
/* Fill in the initial value of the .got.plt entry. */
loc = gotplt->contents + (got_address - sec_addr (gotplt));
@@ -3152,7 +3181,7 @@ riscv_elf_finish_dynamic_sections (bfd *output_bfd,
return ret;
for (i = 0; i < PLT_HEADER_INSNS; i++)
- bfd_put_32 (output_bfd, plt_header[i], splt->contents + 4*i);
+ bfd_putl32 (plt_header[i], splt->contents + 4*i);
elf_section_data (splt->output_section)->this_hdr.sh_entsize
= PLT_ENTRY_SIZE;
@@ -4142,8 +4171,8 @@ _bfd_riscv_relax_call (bfd *abfd, asection *sec, asection *sym_sec,
/* Shorten the function call. */
BFD_ASSERT (rel->r_offset + 8 <= sec->size);
- auipc = bfd_get_32 (abfd, contents + rel->r_offset);
- jalr = bfd_get_32 (abfd, contents + rel->r_offset + 4);
+ auipc = bfd_getl32 (contents + rel->r_offset);
+ jalr = bfd_getl32 (contents + rel->r_offset + 4);
rd = (jalr >> OP_SH_RD) & OP_MASK_RD;
rvc = rvc && VALID_RVC_J_IMM (foff);
@@ -4173,7 +4202,7 @@ _bfd_riscv_relax_call (bfd *abfd, asection *sec, asection *sym_sec,
/* Replace the R_RISCV_CALL reloc. */
rel->r_info = ELFNN_R_INFO (ELFNN_R_SYM (rel->r_info), r_type);
/* Replace the AUIPC. */
- bfd_put (8 * len, abfd, auipc, contents + rel->r_offset);
+ riscv_put_insn (8 * len, auipc, contents + rel->r_offset);
/* Delete unnecessary JALR. */
*again = TRUE;
@@ -4247,9 +4276,9 @@ _bfd_riscv_relax_lui (bfd *abfd,
if (undefined_weak)
{
/* Change the RS1 to zero. */
- bfd_vma insn = bfd_get_32 (abfd, contents + rel->r_offset);
+ bfd_vma insn = bfd_getl32 (contents + rel->r_offset);
insn &= ~(OP_MASK_RS1 << OP_SH_RS1);
- bfd_put_32 (abfd, insn, contents + rel->r_offset);
+ bfd_putl32 (insn, contents + rel->r_offset);
}
else
rel->r_info = ELFNN_R_INFO (sym, R_RISCV_GPREL_I);
@@ -4259,9 +4288,9 @@ _bfd_riscv_relax_lui (bfd *abfd,
if (undefined_weak)
{
/* Change the RS1 to zero. */
- bfd_vma insn = bfd_get_32 (abfd, contents + rel->r_offset);
+ bfd_vma insn = bfd_getl32 (contents + rel->r_offset);
insn &= ~(OP_MASK_RS1 << OP_SH_RS1);
- bfd_put_32 (abfd, insn, contents + rel->r_offset);
+ bfd_putl32 (insn, contents + rel->r_offset);
}
else
rel->r_info = ELFNN_R_INFO (sym, R_RISCV_GPREL_S);
@@ -4292,13 +4321,13 @@ _bfd_riscv_relax_lui (bfd *abfd,
: ELF_MAXPAGESIZE)))
{
/* Replace LUI with C.LUI if legal (i.e., rd != x0 and rd != x2/sp). */
- bfd_vma lui = bfd_get_32 (abfd, contents + rel->r_offset);
+ bfd_vma lui = bfd_getl32 (contents + rel->r_offset);
unsigned rd = ((unsigned)lui >> OP_SH_RD) & OP_MASK_RD;
if (rd == 0 || rd == X_SP)
return TRUE;
lui = (lui & (OP_MASK_RD << OP_SH_RD)) | MATCH_C_LUI;
- bfd_put_32 (abfd, lui, contents + rel->r_offset);
+ bfd_putl32 (lui, contents + rel->r_offset);
/* Replace the R_RISCV_HI20 reloc. */
rel->r_info = ELFNN_R_INFO (ELFNN_R_SYM (rel->r_info), R_RISCV_RVC_LUI);
@@ -4400,11 +4429,11 @@ _bfd_riscv_relax_align (bfd *abfd, asection *sec,
/* Write as many RISC-V NOPs as we need. */
for (pos = 0; pos < (nop_bytes & -4); pos += 4)
- bfd_put_32 (abfd, RISCV_NOP, contents + rel->r_offset + pos);
+ bfd_putl32 (RISCV_NOP, contents + rel->r_offset + pos);
/* Write a final RVC NOP if need be. */
if (nop_bytes % 4 != 0)
- bfd_put_16 (abfd, RVC_NOP, contents + rel->r_offset + pos);
+ bfd_putl16 (RVC_NOP, contents + rel->r_offset + pos);
/* Delete the excess bytes. */
return riscv_relax_delete_bytes (abfd, sec, rel->r_offset + nop_bytes,
@@ -4511,9 +4540,9 @@ _bfd_riscv_relax_pc (bfd *abfd ATTRIBUTE_UNUSED,
{
/* Change the RS1 to zero, and then modify the relocation
type to R_RISCV_LO12_I. */
- bfd_vma insn = bfd_get_32 (abfd, contents + rel->r_offset);
+ bfd_vma insn = bfd_getl32 (contents + rel->r_offset);
insn &= ~(OP_MASK_RS1 << OP_SH_RS1);
- bfd_put_32 (abfd, insn, contents + rel->r_offset);
+ bfd_putl32 (insn, contents + rel->r_offset);
rel->r_info = ELFNN_R_INFO (sym, R_RISCV_LO12_I);
rel->r_addend = hi_reloc.hi_addend;
}
@@ -4529,9 +4558,9 @@ _bfd_riscv_relax_pc (bfd *abfd ATTRIBUTE_UNUSED,
{
/* Change the RS1 to zero, and then modify the relocation
type to R_RISCV_LO12_S. */
- bfd_vma insn = bfd_get_32 (abfd, contents + rel->r_offset);
+ bfd_vma insn = bfd_getl32 (contents + rel->r_offset);
insn &= ~(OP_MASK_RS1 << OP_SH_RS1);
- bfd_put_32 (abfd, insn, contents + rel->r_offset);
+ bfd_putl32 (insn, contents + rel->r_offset);
rel->r_info = ELFNN_R_INFO (sym, R_RISCV_LO12_S);
rel->r_addend = hi_reloc.hi_addend;
}
--
2.26.2
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