The patch adds runtime pseudo relocation handling for 12-bit and 21-bit
relocations. The 26-bit relocation is handled using a jump stub generated by
the linker.
---
winsup/cygwin/pseudo-reloc.cc | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/winsup/cygwin/pseudo-reloc.cc b/winsup/cygwin/pseudo-reloc.cc
index 5a0eab936..fdc2a5d1b 100644
--- a/winsup/cygwin/pseudo-reloc.cc
+++ b/winsup/cygwin/pseudo-reloc.cc
@@ -199,6 +199,9 @@ do_pseudo_reloc (void * start, void * end, void * base)
ptrdiff_t reloc_target = (ptrdiff_t) ((char *)end - (char*)start);
runtime_pseudo_reloc_v2 *v2_hdr = (runtime_pseudo_reloc_v2 *) start;
runtime_pseudo_reloc_item_v2 *r;
+#ifdef __aarch64__
+ uint32_t opcode;
+#endif
/* A valid relocation list will contain at least one entry, and
* one v1 data structure (the smallest one) requires two DWORDs.
@@ -307,6 +310,13 @@ do_pseudo_reloc (void * start, void * end, void * base)
if ((reldata & 0x8000) != 0)
reldata |= ~((ptrdiff_t) 0xffff);
break;
+#ifdef __aarch64__
+ case 12:
+ case 21:
+ opcode = (*((unsigned int *) reloc_target));
+ reldata = 0;
+ break;
+#endif
case 32:
reldata = (ptrdiff_t) (*((unsigned int *)reloc_target));
#if defined (__x86_64__) || defined (_WIN64)
@@ -339,6 +349,31 @@ do_pseudo_reloc (void * start, void * end, void * base)
case 16:
__write_memory ((void *) reloc_target, &reldata, 2);
break;
+#ifdef __aarch64__
+ case 12:
+ /* Replace add Xn, Xn, :lo12:label with ldr Xn, [Xn,
:lo12:__imp__func].
+ That loads the address of _func into Xn. */
+ opcode = 0xf9400000 | (opcode & 0x3ff); // ldr
+ reldata = ((ptrdiff_t) base + r->sym) & ((1 << 12) - 1);
+ reldata >>= 3;
+ opcode |= reldata << 10;
+ __write_memory ((void *) reloc_target, &opcode, 4);
+ break;
+ case 21:
+ /* Replace adrp Xn, label with adrp Xn, __imp__func. */
+ opcode &= 0x9f00001f;
+ reldata = (((ptrdiff_t) base + r->sym) >> 12)
+ - (((ptrdiff_t) base + r->target) >> 12);
+ reldata &= (1 << 21) - 1;
+ opcode |= (reldata & 3) << 29;
+ reldata >>= 2;
+ opcode |= reldata << 5;
+ __write_memory ((void *) reloc_target, &opcode, 4);
+ break;
+ /* A note regarding 26 bits relocation.
+ A single opcode is not sufficient for 26 bits relocation in
dynamic linking.
+ The linker generates a jump stub instead. */
+#endif
case 32:
#if defined (__CYGWIN__) && defined (__x86_64__)
if (reldata > (ptrdiff_t) __INT32_MAX__
--
2.39.5
