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[AAELF64] TLS GOT generating relocations must have 0 addend. (#313)
Bring TLS GOT generating relocations in line with non GOT generating relocations in #272. The ABI rule is that static linkers should generate a GOT entry for each unique tuple of (S,A). However static linkers such as GNU ld and lld only generate a unique entry per unique S, and handle A inconsistently. With GNU ld ignoring A and lld adding it after. The only consistent behaviour between implementations is when A is 0.
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‎aaelf64/aaelf64.rst‎

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@@ -288,6 +288,8 @@ changes to the content of the document for that release.
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| 2025Q1 | 7\ :sup:`th` | - In `Section Attribute Flags`_, added |
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| | April 2025 | `SHF_AARCH64_PURECODE` processor |
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| | | specific section attribute flag. |
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| | | - Clarify use of addends in GOT |
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| | | generating static TLS relocations. |
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+---------------+--------------------+-----------------------------------------+
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| 2025Q4 | 23\ :sup:`rd` | - In `Call and Jump relocations`_ added |
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| | January 2026 | static linker requirements on veneers |
@@ -1516,6 +1518,7 @@ In addition to the terms defined in `Relocation types`_, the tables listing the
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- ``TLSDESC(S+A)`` resolves to a contiguous pair of pointer-sized values, as created by ``GTLSDESC(S+A)``.
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Relocations using the operations ``GTLSDESC(S)``, ``GTPREL(S)`` and ``GTLSIDX(S)`` relocations must have a zero addend. Previous versions of this document included the addend ``A`` in ``Operation(S + A)`` where Operation is one of ``GTLSDESC,``, ``GTPREL`` and ``GTLSIDX``. This results in a GOT entry, or pair of entries for ``S + A``. With a zero addend ``Operation(S + 0)`` is equivalent to ``Operation(S)`` and ``Operation(S) + 0``.
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General Dynamic thread-local storage model
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -1527,15 +1530,15 @@ General Dynamic thread-local storage model
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+------------+------------+---------------------------------+---------------------------------+------------------------------------------------------------------------------------------+
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| ELF64 Code | ELF32 Code | Name | Operation | Comment |
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+============+============+=================================+=================================+==========================================================================================+
1530-
| 512 | 80 | R\_<CLS>\_TLSGD\_ADR\_PREL21 | G(GTLSIDX(S,A)) - P | Set an ADR immediate field to bits [20:0] of X; check –2\ :sup:`20` <= X < 2\ :sup:`20` |
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| 512 | 80 | R\_<CLS>\_TLSGD\_ADR\_PREL21 | G(GTLSIDX(S)) - P | Set an ADR immediate field to bits [20:0] of X; check –2\ :sup:`20` <= X < 2\ :sup:`20` |
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+------------+------------+---------------------------------+---------------------------------+------------------------------------------------------------------------------------------+
1532-
| 513 | 81 | R\_<CLS>\_TLSGD\_ADR\_PAGE21 | Page(G(GTLSIDX(S,A)) - Page(P) | Set an ADRP immediate field to bits [32:12] of X; check –2\ :sup:`32` <= X < 2\ :sup:`32`|
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| 513 | 81 | R\_<CLS>\_TLSGD\_ADR\_PAGE21 | Page(G(GTLSIDX(S)) - Page(P) | Set an ADRP immediate field to bits [32:12] of X; check –2\ :sup:`32` <= X < 2\ :sup:`32`|
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+------------+------------+---------------------------------+---------------------------------+------------------------------------------------------------------------------------------+
1534-
| 514 | 82 | R\_<CLS>\_TLSGD\_ADD\_LO12\_NC | G(GTLSIDX(S,A)) | Set an ADD immediate field to bits [11:0] of X. No overflow check |
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| 514 | 82 | R\_<CLS>\_TLSGD\_ADD\_LO12\_NC | G(GTLSIDX(S)) | Set an ADD immediate field to bits [11:0] of X. No overflow check |
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+------------+------------+---------------------------------+---------------------------------+------------------------------------------------------------------------------------------+
1536-
| 515 | \- | R\_<CLS>\_TLSGD\_MOVW\_G1 | G(GTLSIDX(S,A)) - GOT | Set a MOV[NZ] immediate field to bits [31:16] of X (see notes below) |
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| 515 | \- | R\_<CLS>\_TLSGD\_MOVW\_G1 | G(GTLSIDX(S)) - GOT | Set a MOV[NZ] immediate field to bits [31:16] of X (see notes below) |
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+------------+------------+---------------------------------+---------------------------------+------------------------------------------------------------------------------------------+
1538-
| 516 | \- | R\_<CLS>\_TLSGD\_MOVW\_G0\_NC | G(GTLSIDX(S,A)) - GOT | Set a MOVK immediate field to bits [15:0] of X. No overflow check |
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| 516 | \- | R\_<CLS>\_TLSGD\_MOVW\_G0\_NC | G(GTLSIDX(S)) - GOT | Set a MOVK immediate field to bits [15:0] of X. No overflow check |
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+------------+------------+---------------------------------+---------------------------------+------------------------------------------------------------------------------------------+
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.. note::
@@ -1627,17 +1630,17 @@ Initial Exec thread-local storage model
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+------------+------------+--------------------------------------------+--------------------------------+------------------------------------------------------------------------------------------+
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| ELF64 Code | ELF32 Code | Name | Operation | Comment |
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+============+============+============================================+================================+==========================================================================================+
1630-
| 539 | \- | R\_<CLS>\_TLSIE\_MOVW\_GOTTPREL\_G1 | G(GTPREL(S+A)) - GOT | Set a MOV[NZ] immediate field to bits [31:16] of X (see notes below) |
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| 539 | \- | R\_<CLS>\_TLSIE\_MOVW\_GOTTPREL\_G1 | G(GTPREL(S)) - GOT | Set a MOV[NZ] immediate field to bits [31:16] of X (see notes below) |
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+------------+------------+--------------------------------------------+--------------------------------+------------------------------------------------------------------------------------------+
1632-
| 540 | \- | R\_<CLS>\_TLSIE\_MOVW\_GOTTPREL\_G0\_NC | G(GTPREL(S+A)) - GOT | Set MOVK immediate to bits [15:0] of X. No overflow check |
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| 540 | \- | R\_<CLS>\_TLSIE\_MOVW\_GOTTPREL\_G0\_NC | G(GTPREL(S)) - GOT | Set MOVK immediate to bits [15:0] of X. No overflow check |
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+------------+------------+--------------------------------------------+--------------------------------+------------------------------------------------------------------------------------------+
1634-
| 541 | 103 | R\_<CLS>\_TLSIE\_ADR\_GOTTPREL\_PAGE21 | Page(G(GTPREL(S+A))) - Page(P) | Set an ADRP immediate field to bits [32:12] of X; check –2\ :sup:`32` <= X < 2\ :sup:`32`|
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| 541 | 103 | R\_<CLS>\_TLSIE\_ADR\_GOTTPREL\_PAGE21 | Page(G(GTPREL(S))) - Page(P) | Set an ADRP immediate field to bits [32:12] of X; check –2\ :sup:`32` <= X < 2\ :sup:`32`|
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+------------+------------+--------------------------------------------+--------------------------------+------------------------------------------------------------------------------------------+
1636-
| 542 | \- | R\_<CLS>\_TLSIE\_LD64\_GOTTPREL\_LO12\_NC | G(GTPREL(S+A)) | Set an LD offset field to bits [11:3] of X. No overflow check; check that X&7=0 |
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| 542 | \- | R\_<CLS>\_TLSIE\_LD64\_GOTTPREL\_LO12\_NC | G(GTPREL(S)) | Set an LD offset field to bits [11:3] of X. No overflow check; check that X&7=0 |
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+------------+------------+--------------------------------------------+--------------------------------+------------------------------------------------------------------------------------------+
1638-
| \- | 104 | R\_<CLS>\_TLSIE\_LD32\_GOTTPREL\_LO12\_NC | G(GTPREL(S+A)) | Set an LD offset field to bits [11:2] of X. No overflow check; check that X&3=0 |
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| \- | 104 | R\_<CLS>\_TLSIE\_LD32\_GOTTPREL\_LO12\_NC | G(GTPREL(S)) | Set an LD offset field to bits [11:2] of X. No overflow check; check that X&3=0 |
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+------------+------------+--------------------------------------------+--------------------------------+------------------------------------------------------------------------------------------+
1640-
| 543 | 105 | R\_<CLS>\_TLSIE\_LD\_GOTTPREL\_PREL19 | G(GTPREL(S+A)) – P | Set a load-literal immediate to bits [20:2] of X; check –2\ :sup:`20` <= X < 2\ :sup:`20`|
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| 543 | 105 | R\_<CLS>\_TLSIE\_LD\_GOTTPREL\_PREL19 | G(GTPREL(S)) – P | Set a load-literal immediate to bits [20:2] of X; check –2\ :sup:`20` <= X < 2\ :sup:`20`|
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+------------+------------+--------------------------------------------+--------------------------------+------------------------------------------------------------------------------------------+
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.. note::
@@ -1708,23 +1711,23 @@ Thread-local storage descriptors
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
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| ELF64 Code | ELF32 Code | Name | Operation | Comment |
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+============+============+=================================+==================================+==============================================================================================+
1711-
| 560 | 122 | R\_<CLS>\_TLSDESC\_LD\_PREL19 | G(GTLSDESC(S+A)) - P | Set a load-literal immediate to bits [20:2]; check -2\ :sup:`20` <= X < 2\ :sup:`20`; check |
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| 560 | 122 | R\_<CLS>\_TLSDESC\_LD\_PREL19 | G(GTLSDESC(S)) - P | Set a load-literal immediate to bits [20:2]; check -2\ :sup:`20` <= X < 2\ :sup:`20`; check |
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| | | | | X & 3 = 0. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
1714-
| 561 | 123 | R\_<CLS>\_TLSDESC\_ADR\_PREL21 | G(GTLSDESC(S+A)) - P | Set an ADR immediate field to bits [20:0]; check -2\ :sup:`20` <= X < 2\ :sup:`20`. |
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| 561 | 123 | R\_<CLS>\_TLSDESC\_ADR\_PREL21 | G(GTLSDESC(S)) - P | Set an ADR immediate field to bits [20:0]; check -2\ :sup:`20` <= X < 2\ :sup:`20`. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
1716-
| 562 | 124 | R\_<CLS>\_TLSDESC\_ADR\_PAGE21 | Page(G(GTLSDESC(S+A))) - Page(P) | Set an ADRP immediate field to bits [32:12] of X; check -2\ :sup:`32` <= X < 2\ :sup:`32`. |
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| 562 | 124 | R\_<CLS>\_TLSDESC\_ADR\_PAGE21 | Page(G(GTLSDESC(S))) - Page(P) | Set an ADRP immediate field to bits [32:12] of X; check -2\ :sup:`32` <= X < 2\ :sup:`32`. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
1718-
| 563 | \- | R\_<CLS>\_TLSDESC\_LD64\_LO12 | G(GTLSDESC(S+A)) | Set an LD offset field to bits [11:3] of X. No overflow check; check X & 7 = 0. |
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| 563 | \- | R\_<CLS>\_TLSDESC\_LD64\_LO12 | G(GTLSDESC(S)) | Set an LD offset field to bits [11:3] of X. No overflow check; check X & 7 = 0. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
1720-
| \- | 125 | R\_<CLS>\_TLSDESC\_LD32\_LO12 | G(GTLSDESC(S+A)) | Set an LD offset field to bits [11:2] of X. No overflow check; check X & 3 = 0. |
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| \- | 125 | R\_<CLS>\_TLSDESC\_LD32\_LO12 | G(GTLSDESC(S)) | Set an LD offset field to bits [11:2] of X. No overflow check; check X & 3 = 0. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
1722-
| 564 | 126 | R\_<CLS>\_TLSDESC\_ADD\_LO12 | G(GTLSDESC(S+A)) | Set an ADD immediate field to bits [11:0] of X. No overflow check. |
1725+
| 564 | 126 | R\_<CLS>\_TLSDESC\_ADD\_LO12 | G(GTLSDESC(S)) | Set an ADD immediate field to bits [11:0] of X. No overflow check. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
1724-
| 565 | \- | R\_<CLS>\_TLSDESC\_OFF\_G1 | G(GTLSDESC(S+A)) - GOT | Set a MOV[NZ] immediate field to bits [31:16] of X; check -2\ :sup:`32` <= X < 2\ :sup:`32`. |
1727+
| 565 | \- | R\_<CLS>\_TLSDESC\_OFF\_G1 | G(GTLSDESC(S)) - GOT | Set a MOV[NZ] immediate field to bits [31:16] of X; check -2\ :sup:`32` <= X < 2\ :sup:`32`. |
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| | | | | See notes below. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
1727-
| 566 | \- | R\_<CLS>\_TLSDESC\_OFF\_G0\_NC | G(GTLSDESC(S+A)) - GOT | Set a MOVK immediate field to bits [15:0] of X. No overflow check. |
1730+
| 566 | \- | R\_<CLS>\_TLSDESC\_OFF\_G0\_NC | G(GTLSDESC(S)) - GOT | Set a MOVK immediate field to bits [15:0] of X. No overflow check. |
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+------------+------------+---------------------------------+----------------------------------+----------------------------------------------------------------------------------------------+
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| 567 | \- | R\_<CLS>\_TLSDESC\_LDR | None | For relaxation only. Must be used to identify an LDR instruction which loads the TLS |
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| | | | | descriptor function pointer for S + A if it has no other relocation. |

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