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link_reloc_desc.h (3882B)

      1 #ifndef KIT_LINK_RELOC_DESC_H
      2 #define KIT_LINK_RELOC_DESC_H
      3 
      4 #include "core/core.h"
      5 #include "obj/obj.h"
      6 #include "obj/reloc.h"
      7 
      8 /* Arch-aware resolution of a relocation kind's static descriptor.
      9  *
     10  * The per-arch slice (via link_arch_desc_for(c)->reloc_desc) takes
     11  * precedence; it falls back to the arch-neutral table.  Returns NULL when k
     12  * is not a relocation this target applies.  This is the single source of a
     13  * kind's width + classification — the wire encoding and the diagnostic name
     14  * live on the per-(arch,format) ops.  See doc/plan/RELOC.md (WS-B).
     15  *
     16  * The thin reloc_kind_* predicates below replace the former generic
     17  * switches (reloc_width / reloc_uses_got / reloc_is_tls_got) and the
     18  * per-arch LinkArchDesc.is_* hooks; each reads one descriptor flag. */
     19 const RelocDesc* reloc_desc(const Compiler* c, RelocKind k);
     20 
     21 /* Patched-field width in bytes, or 0 when k has no descriptor — the
     22  * "unsupported relocation kind" gate the linker enforces.  Nominal (gate)
     23  * value for RELOC_WIDTH_DYN kinds, whose true span is read at apply time. */
     24 static inline u8 reloc_kind_width(const Compiler* c, RelocKind k) {
     25   const RelocDesc* d = reloc_desc(c, k);
     26   return d ? d->width : 0u;
     27 }
     28 
     29 /* Needs a GOT slot (the ELF / static GOT pass's notion): a direct GOT load
     30  * OR a TLS-IE GOT slot holding a TP-relative offset. */
     31 static inline int reloc_kind_uses_got(const Compiler* c, RelocKind k) {
     32   const RelocDesc* d = reloc_desc(c, k);
     33   return d && (d->flags & (RELOC_USES_GOT | RELOC_IS_TLS_GOT)) ? 1 : 0;
     34 }
     35 
     36 /* GOT slot is filled with the symbol's TP-relative offset (TLS Initial-Exec)
     37  * rather than its address. */
     38 static inline int reloc_kind_is_tls_got(const Compiler* c, RelocKind k) {
     39   const RelocDesc* d = reloc_desc(c, k);
     40   return d && (d->flags & RELOC_IS_TLS_GOT) ? 1 : 0;
     41 }
     42 
     43 /* ELF Local-Exec TLS access (the per-arch tp-relative idiom). The in-process
     44  * JIT relaxes these to in-image addressing via LinkArchDesc.jit_tls_le_relax. */
     45 static inline int reloc_kind_is_tls_le(const Compiler* c, RelocKind k) {
     46   const RelocDesc* d = reloc_desc(c, k);
     47   return d && (d->flags & RELOC_IS_TLS_LE) ? 1 : 0;
     48 }
     49 
     50 /* A direct GOT-load instruction reloc (the Mach-O linker's notion): non-TLS
     51  * GOT load.  Distinct from reloc_kind_uses_got, which also counts TLS-IE. */
     52 static inline int reloc_kind_is_got_load(const Compiler* c, RelocKind k) {
     53   const RelocDesc* d = reloc_desc(c, k);
     54   return d && (d->flags & RELOC_USES_GOT) ? 1 : 0;
     55 }
     56 
     57 /* Range-limited call/jump that may need a JIT/range call stub or veneer. */
     58 static inline int reloc_kind_is_branch(const Compiler* c, RelocKind k) {
     59   const RelocDesc* d = reloc_desc(c, k);
     60   return d && (d->flags & RELOC_IS_BRANCH) ? 1 : 0;
     61 }
     62 
     63 /* Mach-O TLV descriptor page / pageoff reloc. */
     64 static inline int reloc_kind_is_tlvp(const Compiler* c, RelocKind k) {
     65   const RelocDesc* d = reloc_desc(c, k);
     66   return d && (d->flags & RELOC_IS_TLVP) ? 1 : 0;
     67 }
     68 
     69 /* Mach-O ADRP-direct (non-GOT) page / pageoff reloc. */
     70 static inline int reloc_kind_is_direct_page(const Compiler* c, RelocKind k) {
     71   const RelocDesc* d = reloc_desc(c, k);
     72   return d && (d->flags & RELOC_DIRECT_PAGE) ? 1 : 0;
     73 }
     74 
     75 /* PC-relative HI20 anchor (RISC-V AUIPC for PCREL_HI20 / GOT_HI20) that a
     76  * paired PCREL_LO12 resolves against. The in-process JIT scans for the anchor
     77  * to recompute the low-12 displacement under its layout. */
     78 static inline int reloc_kind_is_pcrel_anchor(const Compiler* c, RelocKind k) {
     79   const RelocDesc* d = reloc_desc(c, k);
     80   return d && (d->flags & RELOC_IS_PCREL_ANCHOR) ? 1 : 0;
     81 }
     82 
     83 /* COFF section-relative value (R_COFF_SECREL). A TLS Local-Exec access exactly
     84  * when its target is a TLS symbol; the in-process JIT relaxes those. */
     85 static inline int reloc_kind_is_secrel(const Compiler* c, RelocKind k) {
     86   const RelocDesc* d = reloc_desc(c, k);
     87   return d && (d->flags & RELOC_IS_SECREL) ? 1 : 0;
     88 }
     89 
     90 #endif