[PATCH] aarch64: Add support for %dtprel(var) and R_AARCH64_TLS_DTPREL64
Shivam Gupta
shivam98.tkg@gmail.com
Fri Mar 13 20:41:53 GMT 2026
This patch allows R_AARCH64_TLS_DTPREL64 relocations in non-allocated
sections, which is required for DWARF debug information when using
Thread Local Storage. This matches the behavior in LLD.
Also a new syntax to parse dtprel operator use to describe tls
location in debug information. Please see the reference 3 below.
References:
- https://github.com/llvm/llvm-project/pull/146572
[AArch64] Support TLS variables in debug info
- https://github.com/llvm/llvm-project/pull/183962
[LLD][AArch64] Handle R_AARCH64_TLS_DTPREL64 in non-alloc sections
- https://github.com/ARM-software/abi-aa/pull/330
[AAELF64] Allow R_AARCH64_TLS_DTPREL to be used statically.
bfd/
* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Handle
BFD_RELOC_AARCH64_TLS_DTPREL.
gas/
* config/tc-aarch64.c (s_aarch64_cons): Parse %dtprel(var) syntax.
* testsuite/gas/aarch64/tls-debug.s: New test.
* testsuite/gas/aarch64/tls-debug.d: Run the test.
gold/
* aarch64-reloc-property.h (code_to_array_index): Handle
R_AARCH64_TLS_DTPREL64.
* aarch64.cc (Relocate::relocate): Handle R_AARCH64_TLS_DTPREL64.
ld/
* testsuite/ld-aarch64/tls-debug.s: New test.
* testsuite/ld-aarch64/tls-debug.d: Run the test.
Signed-off-by: Shivam Gupta <shivam98.tkg@gmail.com>
---
bfd/elfnn-aarch64.c | 12 +++++++
gas/config/tc-aarch64.c | 44 +++++++++++++++++++++++++
gas/testsuite/gas/aarch64/tls-debug.d | 10 ++++++
gas/testsuite/gas/aarch64/tls-debug.s | 9 +++++
gold/aarch64-reloc-property.h | 2 ++
gold/aarch64.cc | 8 ++++-
ld/testsuite/ld-aarch64/aarch64-elf.exp | 1 +
ld/testsuite/ld-aarch64/tls-debug.d | 9 +++++
ld/testsuite/ld-aarch64/tls-debug.s | 9 +++++
9 files changed, 103 insertions(+), 1 deletion(-)
create mode 100644 gas/testsuite/gas/aarch64/tls-debug.d
create mode 100644 gas/testsuite/gas/aarch64/tls-debug.s
create mode 100644 ld/testsuite/ld-aarch64/tls-debug.d
create mode 100644 ld/testsuite/ld-aarch64/tls-debug.s
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 66049c81..acf207dd 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -6496,6 +6496,18 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
*unresolved_reloc_p = false;
break;
+ case BFD_RELOC_AARCH64_TLS_DTPREL:
+ /* Handle R_AARCH64_TLS_DTPREL64 in non-alloc sections */
+ if (!(input_section->flags & SEC_ALLOC))
+ {
+ value -= dtpoff_base (info);
+ value += rel->r_addend;
+
+ bfd_put_64 (output_bfd, value, contents + rel->r_offset);
+ }
+ *unresolved_reloc_p = false;
+ break;
+
case BFD_RELOC_AARCH64_TLSDESC_OFF_G0_NC:
case BFD_RELOC_AARCH64_TLSDESC_OFF_G1:
if (globals->root.sgot == NULL)
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index cd761634..6cc7481a 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -2229,6 +2229,40 @@ s_aarch64_cons (int nbytes)
{
struct reloc_table_entry *reloc;
+ /* Check for %dtprel(var) syntax */
+ if (*input_line_pointer == '%')
+ {
+ char *p = ++input_line_pointer; /* skip '%' */
+
+ /* Look for "dtprel" */
+ if (strncmp (p, "dtprel", 6) == 0 && p[6] == '(')
+ {
+ input_line_pointer = p + 7; /* Skip "dtprel(" */
+
+ /* Parse the symbol inside the parentheses */
+ expression (&exp);
+
+ /* Ensure we have a closing parenthesis */
+ if (*input_line_pointer == ')')
+ input_line_pointer++;
+ else
+ as_bad (_("missing ')' after %%dtprel(...)"));
+
+ /* Create the fixup using your DTPREL ID */
+ addressT where = frag_now_fix ();
+ fix_new_exp (frag_now, where, nbytes, &exp, 0,
+ BFD_RELOC_AARCH64_TLS_DTPREL);
+
+ char *dest = frag_more (nbytes);
+ memset (dest, 0, nbytes);
+ continue;
+ }
+ else
+ {
+ as_bad (_("unknown relocation operator %%%s"), p);
+ }
+ }
+
expression (&exp);
if (exp.X_op != O_symbol)
@@ -3292,6 +3326,15 @@ static struct reloc_table_entry reloc_table[] =
0,
0},
+ /* TLS relative offset. */
+ {"dtprel", 0,
+ 0, /* adr_type */
+ 0,
+ 0,
+ 0,
+ 0,
+ BFD_RELOC_AARCH64_TLS_DTPREL},
+
/* Lower 16 bit offset into GOT entry for a symbol */
{"tlsdesc_off_g0_nc", 0,
0, /* adr_type */
@@ -10114,6 +10157,7 @@ md_apply_fix (fixS * fixP, valueT * valP, segT seg)
case BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1:
case BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1_NC:
case BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G2:
+ case BFD_RELOC_AARCH64_TLS_DTPREL:
S_SET_THREAD_LOCAL (fixP->fx_addsy);
/* Should always be exported to object file, see
aarch64_force_relocation(). */
diff --git a/gas/testsuite/gas/aarch64/tls-debug.d b/gas/testsuite/gas/aarch64/tls-debug.d
new file mode 100644
index 00000000..a64ff67f
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/tls-debug.d
@@ -0,0 +1,10 @@
+#as:
+#objdump: -r
+#target: aarch64*-*-*
+
+#...
+RELOCATION RECORDS FOR \[\.debug_info\]:
+OFFSET +TYPE +VALUE
+0+0 R_AARCH64_TLS_DTPREL64 +var
+0+8 R_AARCH64_TLS_DTPREL64 +var\+0x0+1
+#...
diff --git a/gas/testsuite/gas/aarch64/tls-debug.s b/gas/testsuite/gas/aarch64/tls-debug.s
new file mode 100644
index 00000000..9590ad40
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/tls-debug.s
@@ -0,0 +1,9 @@
+.section .tdata,"awT",@progbits
+.skip 8 // Force var to have an offset of 8
+.globl var
+var:
+ .word 0
+
+.section .debug_info,"",@progbits
+ .xword %dtprel(var)
+ .xword %dtprel(var+1)
diff --git a/gold/aarch64-reloc-property.h b/gold/aarch64-reloc-property.h
index 986adf9d..c1ce0033 100644
--- a/gold/aarch64-reloc-property.h
+++ b/gold/aarch64-reloc-property.h
@@ -220,6 +220,8 @@ class AArch64_reloc_property_table
code_to_array_index(unsigned int code) const
{
if (code == 0) return 0;
+ if (code == elfcpp::R_AARCH64_TLS_DTPREL64)
+ return 0;
if (!((code >= elfcpp::R_AARCH64_ABS64 &&
code <= elfcpp::R_AARCH64_LD64_GOTPAGE_LO15)
|| (code >= elfcpp::R_AARCH64_TLSGD_ADR_PREL21 &&
diff --git a/gold/aarch64.cc b/gold/aarch64.cc
index 9ef5df79..5575f78b 100644
--- a/gold/aarch64.cc
+++ b/gold/aarch64.cc
@@ -7330,13 +7330,19 @@ Target_aarch64<size, big_endian>::Relocate::relocate(
gsym, psymval, view, address);
break;
+ case elfcpp::R_AARCH64_TLS_DTPREL64:
+ {
+ uint64_t val = psymval->value (object, 0) + rela.get_r_addend ();
+ elfcpp::Swap<64, big_endian>::writeval (view, val);
+ break;
+ }
+
// These are dynamic relocations, which are unexpected when linking.
case elfcpp::R_AARCH64_COPY:
case elfcpp::R_AARCH64_GLOB_DAT:
case elfcpp::R_AARCH64_JUMP_SLOT:
case elfcpp::R_AARCH64_RELATIVE:
case elfcpp::R_AARCH64_IRELATIVE:
- case elfcpp::R_AARCH64_TLS_DTPREL64:
case elfcpp::R_AARCH64_TLS_DTPMOD64:
case elfcpp::R_AARCH64_TLS_TPREL64:
case elfcpp::R_AARCH64_TLSDESC:
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index a0a8867d..096f5f9f 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -252,6 +252,7 @@ run_dump_test "tls-relax-ld-le-small-ilp32"
run_dump_test "tls-relax-ld-le-tiny"
run_dump_test "tls-relax-ld-le-tiny-ilp32"
run_dump_test "tls-desc-ie"
+run_dump_test "tls-debug"
run_dump_test "tls-desc-ie-ilp32"
run_dump_test "tls-relax-gdesc-le-2"
run_dump_test "tls-relax-gdesc-le-2-ilp32"
diff --git a/ld/testsuite/ld-aarch64/tls-debug.d b/ld/testsuite/ld-aarch64/tls-debug.d
new file mode 100644
index 00000000..4344b02e
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/tls-debug.d
@@ -0,0 +1,9 @@
+#source: tls-debug.s
+#ld: -shared -T relocs.ld -e0
+#objdump: -s -j .debug_info
+
+#...
+Contents of section .debug_info:
+#...
+ [0-9a-f]+ 08000000 00000000 09000000 00000000 .*
+#...
diff --git a/ld/testsuite/ld-aarch64/tls-debug.s b/ld/testsuite/ld-aarch64/tls-debug.s
new file mode 100644
index 00000000..9590ad40
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/tls-debug.s
@@ -0,0 +1,9 @@
+.section .tdata,"awT",@progbits
+.skip 8 // Force var to have an offset of 8
+.globl var
+var:
+ .word 0
+
+.section .debug_info,"",@progbits
+ .xword %dtprel(var)
+ .xword %dtprel(var+1)
--
2.34.1
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