1 files changed, 34 insertions, 0 deletions
diff --git a/compel/arch/arm/plugins/std/syscalls/syscall-common.S b/compel/arch/arm/plugins/std/syscalls/syscall-common.S
new file mode 100644
index 000000000..9ac53bdd2
--- /dev/null
+++ b/compel/arch/arm/plugins/std/syscalls/syscall-common.S
@@ -0,0 +1,34 @@
+#include "common/asm/linkage.h"
+
+@ We use the register R8 unlike libc that uses R12.
+@ This avoids corruption of the register by the stub
+@ for the syscall sys_munmap() when syscalls are hooked
+@ by ptrace(). However we have to make sure that
+@ the compiler doesn't use the register on the route
+@ between parasite_service() and sys_munmap().
+
+syscall_common:
+	ldr	r7, [r7]
+	add	r8, sp, #24
+	ldm	r8, {r4, r5, r6}
+	svc	0x00000000
+	pop	{r4, r5, r6, r7, r8, pc}
+
+
+.macro syscall name, nr
+	.nr_\name :
+		.long \nr
+
+	ENTRY(\name)
+		push	{r4, r5, r6, r7, r8, lr}
+		adr		r7, .nr_\name
+		b		syscall_common
+	END(\name)
+.endm
+
+
+ENTRY(__cr_restore_rt)
+	adr	r7, .nr_sys_rt_sigreturn
+	ldr	r7, [r7]
+	svc	#0
+END(__cr_restore_rt)