[ARM] Add IFunc support for static links#1251
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Shankar Easwaran (@quic-seaswara) can this PR be merged? |
This commit adds GNU IFunc support for ARM32 static executables, bringing ARM to parity with AArch64 and RISCV. Relocations are classified into four categories (control-flow, absolute data, PC-relative address-forming, and GOT-based). Relocations outside any valid category is warned as invalid; those in a valid category that eld cannot/does-not properly support is reported as unsupported. The MOVW_PREL / THM_MOVW_PREL apply functions are fixed to redirect S to PLT[fn] whenever PLT slot is available, matching the existing behaviour of their ABS counterparts. The R_ARM_TARGET1 -> R_ARM_ABS32 rewrite is centralised into scanRelocation rather than repeated across scanLocalReloc, scanGlobalReloc, and handleScanForNonPreemptibleIFunc. The __rel_iplt_start / __rel_iplt_end symbols are fixed to match RISCV: NOTYPE LOCAL DEFAULT with a section index pointing to .rel.plt, rather than OBJECT GLOBAL ABS. IFunc behaviour across all relevant ARM relocation categories is documented in IFunc.md. Signed-off-by: Parth Arora <partaror@qti.qualcomm.com>
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This commit adds GNU IFunc support for ARM32 static executables,
bringing ARM to parity with AArch64 and RISCV.
Relocations are classified into four categories (control-flow, absolute data,
PC-relative address-forming, and GOT-based). Relocations outside any
valid category is warned as invalid; those in a valid category that eld
cannot/does-not properly support is reported as unsupported.
The MOVW_PREL / THM_MOVW_PREL apply functions are fixed to redirect S to
PLT[fn] whenever PLT slot is available, matching the existing behaviour of
their ABS counterparts.
The R_ARM_TARGET1 -> R_ARM_ABS32 rewrite is centralised into
scanRelocation rather than repeated across scanLocalReloc, scanGlobalReloc,
and handleScanForNonPreemptibleIFunc.
The __rel_iplt_start / __rel_iplt_end symbols are fixed to match RISCV:
NOTYPE LOCAL DEFAULT with a section index pointing to .rel.plt, rather
than OBJECT GLOBAL ABS.
IFunc behaviour across all relevant ARM relocation categories is documented in
IFunc.md.