Author: imp
Date: Sat Aug 9 22:51:26 2014
New Revision: 269767
URL: http://svnweb.freebsd.org/changeset/base/269767
Log:
Per discussion on arm@, the compiler generates misaligned
relocations. Cope with memcpy when needed.
Submitted by: fabient@ (plus changes suggested by thread)
Modified:
head/sys/arm/arm/elf_machdep.c
Modified: head/sys/arm/arm/elf_machdep.c
==============================================================================
--- head/sys/arm/arm/elf_machdep.c Sat Aug 9 21:01:24 2014
(r269766)
+++ head/sys/arm/arm/elf_machdep.c Sat Aug 9 22:51:26 2014
(r269767)
@@ -120,6 +120,34 @@ elf32_dump_thread(struct thread *td __un
{
}
+/*
+ * It is possible for the compiler to emit relocations for unaligned data.
+ * We handle this situation with these inlines.
+ */
+#define RELOC_ALIGNED_P(x) \
+ (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
+
+static __inline Elf_Addr
+load_ptr(Elf_Addr *where)
+{
+ Elf_Addr res;
+
+ if (RELOC_ALIGNED_P(where))
+ return *where;
+ memcpy(&res, where, sizeof(res));
+ return (res);
+}
+
+static __inline void
+store_ptr(Elf_Addr *where, Elf_Addr val)
+{
+ if (RELOC_ALIGNED_P(where))
+ *where = val;
+ else
+ memcpy(where, &val, sizeof(val));
+}
+#undef RELOC_ALIGNED_P
+
/* Process one elf relocation with addend. */
static int
@@ -137,7 +165,7 @@ elf_reloc_internal(linker_file_t lf, Elf
case ELF_RELOC_REL:
rel = (const Elf_Rel *)data;
where = (Elf_Addr *) (relocbase + rel->r_offset);
- addend = *where;
+ addend = load_ptr(where);
rtype = ELF_R_TYPE(rel->r_info);
symidx = ELF_R_SYM(rel->r_info);
break;
@@ -155,8 +183,8 @@ elf_reloc_internal(linker_file_t lf, Elf
if (local) {
if (rtype == R_ARM_RELATIVE) { /* A + B */
addr = elf_relocaddr(lf, relocbase + addend);
- if (*where != addr)
- *where = addr;
+ if (load_ptr(where) != addr)
+ store_ptr(where, addr);
}
return (0);
}
@@ -170,7 +198,7 @@ elf_reloc_internal(linker_file_t lf, Elf
addr = lookup(lf, symidx, 1);
if (addr == 0)
return -1;
- *where += addr;
+ store_ptr(where, addr + load_ptr(where));
break;
case R_ARM_COPY: /* none */
@@ -185,7 +213,7 @@ elf_reloc_internal(linker_file_t lf, Elf
case R_ARM_JUMP_SLOT:
addr = lookup(lf, symidx, 1);
if (addr) {
- *where = addr;
+ store_ptr(where, addr);
return (0);
}
return (-1);
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