[PowerPC] Implement Secure-PLT jump table processing for ppc32.

Due to clang and LLD's tendency to use a PLT for builtins, and as they
don't have full support for EABI, we sometimes have to deal with a PLT in
.ko files in a clang-built kernel.

As such, augment the in-kernel linker to support jump table processing.

As there is no particular reason to support lazy binding in kernel modules,
only implement Secure-PLT immediate binding.

As part of these changes, add elf_cpu_parse_dynamic() to the MD API of the
in-kernel linker (except on platforms that use raw object files.)

The new function will allow MD code to act on MD tags in _DYNAMIC.

Use this new function in the PowerPC MD code to ensure BSS-PLT modules using
PLT will be rejected during insertion, and to poison the runtime resolver to
ensure we get a clear panic reason if a call is made to the resolver.

Reviewed by:	jhibbits
Differential Revision:	https://reviews.freebsd.org/D22608

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/sys/linker.h b/sys/sys/linker.h
index 143d7473cf10..e48f4fd1c03b 100644
--- a/sys/sys/linker.h
+++ b/sys/sys/linker.h
@@ -305,6 +305,10 @@ int	linker_ctf_get(linker_file_t, linker_ctf_t *);
 
 int elf_cpu_load_file(linker_file_t);
 int elf_cpu_unload_file(linker_file_t);
+/* amd64 and mips use objects instead of shared libraries */
+#if !defined(__amd64__) && !defined(__mips__)
+int elf_cpu_parse_dynamic(linker_file_t, Elf_Dyn *);
+#endif
 
 /* values for type */
 #define ELF_RELOC_REL	1