Morello: Stop using caprelocs for static binaries

lib/csu/aarch64/Makefile

@@ -6,6 +6,8 @@ CFLAGS+=	-I${.CURDIR}
 
 .if ${MACHINE_CPU:Mcheri}
 CFLAGS+=	-I${.CURDIR:H}/common-cheri
+
+NO_WCAST_ALIGN=
 .endif
 
 CRT1SRC=	crt1_s.S

lib/csu/aarch64/caprel.h

@@ -0,0 +1,93 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 SRI International
+ *
+ * This software was developed by SRI International, the University of
+ * Cambridge Computer Laboratory (Department of Computer Science and
+ * Technology), and Capabilities Limited under Defense Advanced Research
+ * Projects Agency (DARPA) Contract No. FA8750-24-C-B047 ("DEC").
+ */
+
+#ifndef __CAPREL_H__
+#define	__CAPREL_H__
+
+#include <sys/types.h>
+#include <machine/elf.h>
+
+#include <cheri/cheric.h>
+
+#define	FUNC_PTR_REMOVE_PERMS						\
+	(CHERI_PERM_SEAL | CHERI_PERM_STORE | CHERI_PERM_STORE_CAP |	\
+	CHERI_PERM_STORE_LOCAL_CAP)
+
+#define	DATA_PTR_REMOVE_PERMS						\
+	(CHERI_PERM_SEAL | CHERI_PERM_EXECUTE)
+
+#define	CAP_RELOC_REMOVE_PERMS						\
+	(CHERI_PERM_SW_VMEM)
+
+/*
+ * Fragments consist of a 64-bit address followed by a 56-bit length and an
+ * 8-bit permission field.
+ */
+static __always_inline uintcap_t
+init_cap_from_fragment(const Elf_Addr *fragment, void * __capability data_cap,
+    const void * __capability text_rodata_cap, Elf_Addr base_addr,
+    Elf_Size addend)
+{
+	uintcap_t cap;
+	Elf_Addr address, len;
+	uint8_t perms;
+
+	address = fragment[0];
+	len = fragment[1] & ((1UL << (8 * sizeof(*fragment) - 8)) - 1);
+	perms = fragment[1] >> (8 * sizeof(*fragment) - 8);
+
+	cap = perms == MORELLO_FRAG_EXECUTABLE ?
+	    (uintcap_t)text_rodata_cap : (uintcap_t)data_cap;
+	cap = cheri_setaddress(cap, base_addr + address);
+	cap = cheri_clearperm(cap, CAP_RELOC_REMOVE_PERMS);
+
+	if (perms == MORELLO_FRAG_EXECUTABLE || perms == MORELLO_FRAG_RODATA) {
+		cap = cheri_clearperm(cap, FUNC_PTR_REMOVE_PERMS);
+	}
+	if (perms == MORELLO_FRAG_RWDATA || perms == MORELLO_FRAG_RODATA) {
+		cap = cheri_clearperm(cap, DATA_PTR_REMOVE_PERMS);
+		cap = cheri_setbounds(cap, len);
+	}
+
+	cap += addend;
+
+	if (perms == MORELLO_FRAG_EXECUTABLE) {
+		/*
+		 * TODO tight bounds: lower bound and len should be set
+		 * with LSB == 0 for C64 code.
+		 */
+		cap = cheri_sealentry(cap);
+	}
+
+	return (cap);
+}
+
+static __always_inline void
+elf_reloc(const Elf_Rela *rela, void * __capability data_cap,
+    const void * __capability code_cap, Elf_Addr relocbase)
+{
+	Elf_Addr addr;
+	Elf_Addr *where;
+
+	if (ELF_R_TYPE(rela->r_info) != R_MORELLO_RELATIVE)
+		__builtin_trap();
+
+	addr = relocbase + rela->r_offset;
+#ifdef __CHERI_PURE_CAPABILITY__
+	where = cheri_setaddress(data_cap, addr);
+#else
+	where = (Elf_Addr *)addr;
+#endif
+	*(uintcap_t *)(void *)where = init_cap_from_fragment(where, data_cap,
+	    code_cap, relocbase, rela->r_addend);
+}
+
+#endif /* __CAPREL_H__ */

lib/csu/aarch64/crt1_c.c

@@ -38,9 +38,15 @@
  * need to include the code here.
  */
 #if __has_feature(capabilities) && !defined(PIC)
+#define CHERI_INIT_RELA
+
 extern int _DYNAMIC;
 #pragma weak _DYNAMIC
 
+#define	RODATA_PTR(x)	&x
+
+#include "caprel.h"
+
 #include "crt_init_globals.c"
 
 void	__process_cap_relocs(char *env[]);

lib/csu/aarch64c/Makefile

@@ -2,6 +2,8 @@
 
 .PATH:	${.CURDIR}/../common-cheri ${.CURDIR}/../common
 
-CFLAGS+=	-I${.CURDIR}
+CFLAGS+=	-I${.CURDIR} -I${.CURDIR}/../aarch64
+
+NO_WCAST_ALIGN=
 
 .include <bsd.lib.mk>

lib/csu/aarch64c/crt1_c.c

@@ -44,6 +44,19 @@
  * to include the code here.
  */
 #ifndef PIC
+#define	CHERI_INIT_RELA
+
+#define	RODATA_PTR(x) ({						\
+	__typeof__(x) *_p;						\
+									\
+	__asm__ (							\
+	    "adrp %0, " __STRING(x) "\n\t"				\
+	    "add %0, %0, :lo12:" __STRING(x) "\n\t"			\
+	    : "=C" (_p));						\
+	_p; })
+
+#include "caprel.h"
+
 #include "crt_init_globals.c"
 #endif
 

lib/csu/common-cheri/crt_init_globals.c

@@ -39,6 +39,34 @@
 #error "PIEs never need to initialise their own globals"
 #endif
 
+#ifdef CHERI_INIT_RELA
+extern const Elf_Rela __weak_symbol __rela_dyn_start __hidden;
+extern const Elf_Rela __weak_symbol __rela_dyn_end __hidden;
+
+static __always_inline void
+crt_init_rela(const Elf_Phdr *phdr __unused)
+{
+	const Elf_Rela *rela, *relalim;
+	void * __capability data_cap;
+	const void * __capability code_cap;
+
+#ifdef __CHERI_PURE_CAPABILITY__
+	data_cap = __DECONST(void *, phdr);
+#else
+	data_cap = cheri_getdefault();
+#endif
+	data_cap = cheri_clearperm(data_cap,
+	    CHERI_PERM_EXECUTE | CHERI_PERM_SW_VMEM);
+
+	code_cap = cheri_getpcc();
+
+	rela = RODATA_PTR(__rela_dyn_start);
+	relalim = RODATA_PTR(__rela_dyn_end);
+	for (; rela < relalim; rela++)
+		elf_reloc(rela, data_cap, code_cap, 0);
+}
+#endif
+
 #define CHERI_INIT_GLOBALS_GDC_ONLY
 #include <cheri_init_globals.h>
 #if !defined(CHERI_INIT_GLOBALS_VERSION) || CHERI_INIT_GLOBALS_VERSION < 4
@@ -66,6 +94,10 @@
 	const void * __capability code_cap;
 	const void * __capability rodata_cap;
 
+#ifdef CHERI_INIT_RELA
+	crt_init_rela(phdr);
+#endif
+
 	/* Attempt to bound the data capability to only the writable segment */
 	for (const Elf_Phdr *ph = phdr; ph < phlimit; ph++) {
 		if (ph->p_type != PT_LOAD && ph->p_type != PT_GNU_RELRO) {

libexec/rtld-elf/rtld.c

@@ -1485,6 +1485,11 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
 	    break;
 
 	case DT_JMPREL:
+#ifdef __aarch64__
+	    /* Ignore empty PLT entries for Morello. */
+	    if (dynp->d_un.d_ptr == 0)
+		break;
+#endif
 	    obj->pltrel = (const Elf_Rel *)
 	      (obj->relocbase + dynp->d_un.d_ptr);
 	    break;
@@ -1643,6 +1648,11 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
 	    break;
 
 	case DT_PLTGOT:
+#ifdef __aarch64__
+	    /* Ignore empty PLT entries for Morello. */
+	    if (dynp->d_un.d_ptr == 0)
+		break;
+#endif
 	    obj->pltgot = (uintptr_t *)(obj->relocbase + dynp->d_un.d_ptr);
 	    break;
 

share/mk/bsd.lib.mk

@@ -112,6 +112,10 @@ LDFLAGS+= -Wl,-zbti-report=error
 .endif
 .endif
 
+.if ${MACHINE_CPUARCH} == "aarch64" && ${MACHINE_CPU:Mcheri}
+LDFLAGS+= -Wl,--local-caprelocs=elf
+.endif
+
 # Initialize stack variables on function entry
 .if ${OPT_INIT_ALL} != "none"
 .if ${COMPILER_FEATURES:Minit-all}

share/mk/bsd.prog.mk

@@ -84,9 +84,13 @@
 .endif
 .endif
 
+.if ${MACHINE_CPUARCH} == "aarch64" && ${MACHINE_CPU:Mcheri}
+LDFLAGS+= -Wl,--local-caprelocs=elf
+.endif
+
 # Initialize stack variables on function entry
 .if ${OPT_INIT_ALL} != "none"
 .if ${COMPILER_FEATURES:Minit-all}
 CFLAGS+= -ftrivial-auto-var-init=${OPT_INIT_ALL}
 CXXFLAGS+= -ftrivial-auto-var-init=${OPT_INIT_ALL}
 .if ${OPT_INIT_ALL} == "zero" && ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000