arm: add freestanding port

README.md

@@ -18,7 +18,7 @@ Adding support for new architectures is easy, but you need to know assembly lang
 | Architecture | Works on musl | Syscall | Supports FREESTANDING |
 |--------------|---------------|---------|-----------------------|
 |    aarch64   | ✓             |         |                       |
-|      arm     | ✓             |         |                       |
+|      arm     | ✓             |         | ✓                     |
 |     m68k     | ✓             |         | ✓                     |
 |     mips     | ✓             |         | ✓                     |
 |    mips64    | ✓             |         | ✓                     |

arch/arm/freestanding/bits.h

@@ -0,0 +1,28 @@
+#ifndef LIBUCONTEXT_BITS_H
+#define LIBUCONTEXT_BITS_H
+
+typedef int libucontext_greg_t, libucontext_gregset_t[18];
+
+typedef struct {
+	unsigned long trap_no, error_code, oldmask;
+	unsigned long arm_r0, arm_r1, arm_r2, arm_r3;
+	unsigned long arm_r4, arm_r5, arm_r6, arm_r7;
+	unsigned long arm_r8, arm_r9, arm_r10, arm_fp;
+	unsigned long arm_ip, arm_sp, arm_lr, arm_pc;
+	unsigned long arm_cpsr, fault_address;
+} libucontext_mcontext_t;
+
+typedef struct {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+} libucontext_stack_t;
+
+typedef struct libucontext_ucontext {
+	unsigned long uc_flags;
+	struct libucontext_ucontext *uc_link;
+	libucontext_stack_t uc_stack;
+	libucontext_mcontext_t uc_mcontext;
+} libucontext_ucontext_t;
+
+#endif

arch/arm/makecontext.c

@@ -25,7 +25,7 @@ extern void libucontext_trampoline(void);
 
 
 void
-libucontext_makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
+libucontext_makecontext(libucontext_ucontext_t *ucp, void (*func)(void), int argc, ...)
 {
 	unsigned long *sp;
 	unsigned long *regp;