[v1] LoongArch: Do not relax pcalau12i+ld.d when overflow occurs after relaxation
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Commit Message
Currently, there is no overflow check for the relaxation of
pcalau12i+ld.d => pcalau12i+addi.d. For instruction sequences that can
be relaxed, they are directly relaxed to pcalau12i+addi.d. However, when
the relative distance between the symbol and the pc exceeds the 32-bit
range, the symbol value cannot be obtained correctly.
This modification adds an overflow check for the relaxation of
pcalau12i+ld.d. If it is found that the relaxation will overflow, it
will not be relaxed.
---
bfd/elfnn-loongarch.c | 32 ++++++++++++++++---
.../ld-loongarch-elf/check_got_relax.d | 30 +++++++++++++++++
.../ld-loongarch-elf/check_got_relax.s | 16 ++++++++++
.../ld-loongarch-elf/ld-loongarch-elf.exp | 1 +
ld/testsuite/ld-loongarch-elf/relax.ld | 21 ++++++++++++
5 files changed, 95 insertions(+), 5 deletions(-)
create mode 100644 ld/testsuite/ld-loongarch-elf/check_got_relax.d
create mode 100644 ld/testsuite/ld-loongarch-elf/check_got_relax.s
create mode 100644 ld/testsuite/ld-loongarch-elf/relax.ld
@@ -5099,12 +5099,12 @@ loongarch_relax_call36 (bfd *abfd, asection *sec, asection *sym_sec,
/* Relax pcalau12i,ld.d => pcalau12i,addi.d. */
static bool
loongarch_relax_pcala_ld (bfd *abfd, asection *sec,
- asection *sym_sec ATTRIBUTE_UNUSED,
+ asection *sym_sec,
Elf_Internal_Rela *rel_hi,
- bfd_vma symval ATTRIBUTE_UNUSED,
- struct bfd_link_info *info ATTRIBUTE_UNUSED,
+ bfd_vma symval,
+ struct bfd_link_info *info,
bool *again ATTRIBUTE_UNUSED,
- bfd_vma max_alignment ATTRIBUTE_UNUSED)
+ bfd_vma max_alignment)
{
bfd_byte *contents = elf_section_data (sec)->this_hdr.contents;
Elf_Internal_Rela *rel_lo = rel_hi + 2;
@@ -5113,10 +5113,32 @@ loongarch_relax_pcala_ld (bfd *abfd, asection *sec,
uint32_t rd = LARCH_GET_RD (pca);
uint32_t addi_d = LARCH_OP_ADDI_D;
+ /* This section's output_offset need to subtract the bytes of instructions
+ relaxed by the previous sections, so it needs to be updated beforehand.
+ size_input_section already took care of updating it after relaxation,
+ so we additionally update once here. */
+ sec->output_offset = sec->output_section->size;
+ bfd_vma pc = sec_addr (sec) + rel_hi->r_offset;
+
+ /* If pc and symbol not in the same segment, add/sub segment alignment. */
+ if (!loongarch_two_sections_in_same_segment (info->output_bfd,
+ sec->output_section,
+ sym_sec->output_section))
+ max_alignment = info->maxpagesize > max_alignment ? info->maxpagesize
+ : max_alignment;
+
+ if (symval > pc)
+ pc -= (max_alignment > 4 ? max_alignment : 0);
+ else if (symval < pc)
+ pc += (max_alignment > 4 ? max_alignment : 0);
+
if ((ELFNN_R_TYPE (rel_lo->r_info) != R_LARCH_GOT_PC_LO12)
|| (LARCH_GET_RD (ld) != rd)
|| (LARCH_GET_RJ (ld) != rd)
- || !LARCH_INSN_LD_D (ld))
+ || !LARCH_INSN_LD_D (ld)
+ /* Within +-2G addressing range. */
+ || (bfd_signed_vma)(symval - pc) < (bfd_signed_vma)(int32_t)0x80000000
+ || (bfd_signed_vma)(symval - pc) > (bfd_signed_vma)(int32_t)0x7fffffff)
return false;
addi_d = addi_d | (rd << 5) | rd;
new file mode 100644
@@ -0,0 +1,30 @@
+#ld: -T relax.ld
+#objdump: -D -j.text -j.got -j.other
+
+.*: file format .*
+
+
+Disassembly of section \.text:
+
+0+10000 <_start>:
+ 10000: 1a000204 pcalau12i \$a0, 16
+ 10004: 28c02084 ld.d \$a0, \$a0, 8
+ 10008: 1a000204 pcalau12i \$a0, 16
+ 1000c: 28c04084 ld.d \$a0, \$a0, 16
+
+Disassembly of section \.got:
+
+0+20000 <_GLOBAL_OFFSET_TABLE_>:
+ ...
+ 20008: 0000000f .word 0x0000000f
+ 2000c: 00000001 .word 0x00000001
+ 20010: 00000013 .word 0x00000013
+ 20014: 00000001 .word 0x00000001
+
+Disassembly of section \.other:
+
+0+10000000f <sym_hidden>:
+ 10000000f: 03400000 nop
+
+0+100000013 <sym_protected>:
+ 100000013: 03400000 nop
new file mode 100644
@@ -0,0 +1,16 @@
+ .text
+ .global _start
+_start:
+ la.got $a0,sym_hidden
+ la.got $a0,sym_protected
+
+ .section .other
+ .global sym_hidden
+ .hidden sym_hidden
+sym_hidden:
+ nop
+
+ .global sym_protected
+ .protected sym_protected
+sym_protected:
+ nop
@@ -47,6 +47,7 @@ if [istarget "loongarch64-*-*"] {
run_dump_test "tls-le-relax"
run_dump_test "relax-medium-call"
run_dump_test "relax-medium-call-1"
+ run_dump_test "check_got_relax"
}
if [istarget "loongarch32-*-*"] {
new file mode 100644
@@ -0,0 +1,21 @@
+OUTPUT_ARCH(loongarch)
+ENTRY(_start)
+SECTIONS
+{
+ PROVIDE (__executable_start = 0x8000); . = 0x10000;
+ .text :
+ {
+ *(.text)
+ } =0
+ . = 0x20000;
+ .got :
+ {
+ *(.got)
+ *(.got.plt)
+ }
+ . = 0x10000000f;
+ .other :
+ {
+ *(.other)
+ }
+}