ARC: Linux ABI

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

sysdeps/unix/sysv/linux/arc/setcontext.S

@@ -0,0 +1,93 @@
+/* Set current context for ARC.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include "ucontext-macros.h"
+
+/* int setcontext (const ucontext_t *ucp)
+     - Restores the machine context in @ucp and resumes execution
+       (doesn't return to caller).  */
+
+ENTRY (__setcontext)
+
+	mov  r9, r0	/* Stash @ucp across syscall.  */
+
+	/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, NULL, _NSIG8).  */
+	mov  r3, _NSIG8
+	mov  r2, 0
+	add  r1, r0, UCONTEXT_SIGMASK
+	mov  r0, SIG_SETMASK
+	mov  r8, __NR_rt_sigprocmask
+	ARC_TRAP_INSN
+	brhi r0, -1024, L (call_syscall_err)
+
+	/* Restore scratch/arg regs for makecontext case.  */
+	add r9, r9, UCONTEXT_MCONTEXT
+	LDR (r0,    r9, 22)
+	LDR (r1,    r9, 21)
+	LDR (r2,    r9, 20)
+	LDR (r3,    r9, 19)
+	LDR (r4,    r9, 18)
+	LDR (r5,    r9, 17)
+	LDR (r6,    r9, 16)
+	LDR (r7,    r9, 15)
+
+	/* Restore callee saved registers.  */
+	LDR (r13,   r9, 37)
+	LDR (r14,   r9, 36)
+	LDR (r15,   r9, 35)
+	LDR (r16,   r9, 34)
+	LDR (r17,   r9, 33)
+	LDR (r18,   r9, 32)
+	LDR (r19,   r9, 31)
+	LDR (r20,   r9, 30)
+	LDR (r21,   r9, 29)
+	LDR (r22,   r9, 28)
+	LDR (r23,   r9, 27)
+	LDR (r24,   r9, 26)
+
+	LDR (blink, r9,  7)
+	LDR (fp,    r9,  8)
+	LDR (gp,    r9,  9)
+	LDR (sp,    r9, 23)
+
+	j    [blink]
+
+PSEUDO_END (__setcontext)
+weak_alias (__setcontext, setcontext)
+
+
+/* Helper for activating makecontext created context
+     - r14 has @func, r15 has uc_link.  */
+
+ENTRY (__startcontext)
+
+	.cfi_label .Ldummy
+	cfi_undefined (blink)
+
+	/* Call user @func, loaded in r14 by setcontext.  */
+	jl   [r14]
+
+	/* If uc_link (r15) call setcontext with that.  */
+	mov  r0, r15
+	breq r0, 0, 1f
+
+	bl   __setcontext
+1:
+	/* Exit with status 0.  */
+	b    HIDDEN_JUMPTARGET(exit)
+END (__startcontext)