Disallow execution of RVC binaries on non-RVC pk

pk/elf.c

@@ -29,6 +29,10 @@ void load_elf(const char* fn, elf_info* info)
   assert(IS_ELF32(eh));
 #endif
 
+#ifndef __riscv_compressed
+  assert(!(eh.e_flags & EF_RISCV_RVC));
+#endif
+
   uintptr_t min_vaddr = -1;
   size_t phdr_size = eh.e_phnum * sizeof(Elf_Phdr);
   if (phdr_size > info->phdr_size)

pk/elf.h

@@ -23,6 +23,8 @@
 #define ET_EXEC 2
 #define ET_DYN 3
 
+#define EF_RISCV_RVC 1
+
 #define PT_LOAD 1
 
 #define AT_NULL   0