c18n: Allow _rtld_unw_resume to resume purecap binaries.

CTSRD-CHERI · Mar 26, 2024 · a913fa0 · a913fa0
1 parent 3eb7e56
commit a913fa0
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diff --git a/libexec/rtld-elf/aarch64/rtld_c18n_asm.S b/libexec/rtld-elf/aarch64/rtld_c18n_asm.S
@@ -127,6 +127,13 @@ ENTRY(_rtld_dispatch_signal)
 	b	dispatch_signal_end
 END(_rtld_dispatch_signal)
 
+ENTRY(_rtld_unw_setcontext_epilogue)
+	mov	c16, c3
+	ldp	c3, c4, [c4, #-0x030]
+	mov	csp, c16
+	ret
+END(_rtld_unw_setcontext_epilogue)
+
 ENTRY(allocate_rstk)
 	/*
 	 * NON-STANDARD CALLING CONVENTION

diff --git a/libexec/rtld-elf/rtld_c18n.c b/libexec/rtld-elf/rtld_c18n.c
@@ -859,10 +859,17 @@ _rtld_longjmp(struct jmp_args ret, void *rcsp, void **buf)
 	    get_trusted_frame()));
 }
 
+struct jmp_args _rtld_unw_setcontext_epilogue(struct jmp_args ret, void *p,
+    void *rcsp, void **buf);
+
 struct jmp_args
 _rtld_unw_setcontext(struct jmp_args ret, void *p __unused, void *rcsp,
     void **buf)
 {
+	if (!C18N_ENABLED) {
+		__attribute__((musttail)) return (
+		    _rtld_unw_setcontext_epilogue(ret, p, rcsp, buf));
+	}
 	return (unwind_stack(ret, rcsp, cheri_unseal(*buf, sealer_unwbuf),
 	    get_trusted_frame()));
 }
@@ -871,6 +878,10 @@ struct jmp_args
 _rtld_unw_setcontext_unsealed(struct jmp_args ret, void *p __unused, void *rcsp,
     void **buf)
 {
+	if (!C18N_ENABLED) {
+		__attribute__((musttail)) return (
+		    _rtld_unw_setcontext_epilogue(ret, p, rcsp, buf));
+	}
 	return (unwind_stack(ret, rcsp, *buf, get_trusted_frame()));
 }