[binutils-gdb] aarch64: Add support for %dtprel(var) and R_AARCH64_TLS_DTPREL64
Alice Carlotti
acarlotti@sourceware.org
Thu Apr 9 14:36:26 GMT 2026
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ed71fa9a44511cb8d933073f892ea041c3ff9107
commit ed71fa9a44511cb8d933073f892ea041c3ff9107
Author: Shivam Gupta <shivam98.tkg@gmail.com>
Date: Wed Apr 8 15:45:38 2026 +0530
aarch64: Add support for %dtprel(var) and R_AARCH64_TLS_DTPREL64
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.
ld/
* testsuite/ld-aarch64/tls-debug.s: New test.
* testsuite/ld-aarch64/tls-debug.d: Run the test.
Bug: https://sourceware.org/PR28351
Signed-off-by: Shivam Gupta <shivam98.tkg@gmail.com>
Diff:
---
bfd/elfnn-aarch64.c | 11 ++++++++++
gas/config/tc-aarch64.c | 37 +++++++++++++++++++++++++++++++++
gas/testsuite/gas/aarch64/tls-debug.d | 10 +++++++++
gas/testsuite/gas/aarch64/tls-debug.s | 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 ++++++++
7 files changed, 85 insertions(+)
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 66049c81edf..117e149866c 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -6496,6 +6496,17 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
*unresolved_reloc_p = false;
break;
+ case BFD_RELOC_AARCH64_TLS_DTPREL:
+ if (input_section->flags & SEC_ALLOC)
+ return bfd_reloc_notsupported;
+ 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 cd76163488c..73b549a16c9 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -2229,6 +2229,42 @@ s_aarch64_cons (int nbytes)
{
struct reloc_table_entry *reloc;
+ /* Check for %dtprel(var) syntax */
+ if (*input_line_pointer == '%')
+ {
+ if (strncmp (input_line_pointer, "%dtprel(", 8) == 0)
+ {
+ input_line_pointer += 8;
+
+ expression (&exp);
+
+ /* Ensure we have a closing parenthesis */
+ if (*input_line_pointer == ')')
+ input_line_pointer++;
+ else
+ {
+ as_bad (_("missing ')' after %%dtprel"));
+ ignore_rest_of_line ();
+ return;
+ }
+
+ 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"));
+ ignore_rest_of_line ();
+ return;
+ }
+ }
+
expression (&exp);
if (exp.X_op != O_symbol)
@@ -10114,6 +10150,7 @@ 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 00000000000..1dd4df17542
--- /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 00000000000..c45507ed110
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/tls-debug.s
@@ -0,0 +1,8 @@
+.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), %dtprel(var+1)
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index 24c73d530dc..fa80210500e 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -261,6 +261,7 @@ run_dump_test "tls-relax-ld-le-small"
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-debug"
run_dump_test "tls-desc-ie"
run_dump_test "tls-desc-ie-ilp32"
run_dump_test "tls-relax-gdesc-le-2"
diff --git a/ld/testsuite/ld-aarch64/tls-debug.d b/ld/testsuite/ld-aarch64/tls-debug.d
new file mode 100644
index 00000000000..4344b02e794
--- /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 00000000000..9590ad409f9
--- /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)
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