From e3e5cf6d34284a84489ea4f81301af1c81cd163f Mon Sep 17 00:00:00 2001
From: Ben Gras <ben@minix3.org>
Date: Wed, 30 Jan 2013 03:13:24 +0100
Subject: [PATCH] arm: make signal handlers work

A few kernel and calling convention adjustments to make sigsend and
sigreturn work for arm.

	. provide a arch_proc_setcontext for earm in kernel
	. set LR in context of signal handler to provide a proper
	  return address (to __sigreturn)
	. change __sigreturn to retrieve the sigcontext pointer
	  from the sigframe struct and pass it to _sigreturn() in r0

Change-Id: Icd135a70595382c79d11d8dd9876f6a6f1df41f8
---
 kernel/arch/earm/arch_system.c            | 13 +++++++++++++
 kernel/system/do_sigsend.c                |  7 +++++++
 lib/libc/arch/arm/sys-minix/__sigreturn.S |  5 +++--
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/kernel/arch/earm/arch_system.c b/kernel/arch/earm/arch_system.c
index 4db5fdbe3..7d8357361 100644
--- a/kernel/arch/earm/arch_system.c
+++ b/kernel/arch/earm/arch_system.c
@@ -52,6 +52,19 @@ void arch_proc_reset(struct proc *pr)
 void arch_proc_setcontext(struct proc *p, struct stackframe_s *state,
 	int isuser, int trapstyle)
 {
+        assert(sizeof(p->p_reg) == sizeof(*state));
+        memcpy(&p->p_reg, state, sizeof(*state));
+
+        /* further code is instructed to not touch the context
+         * any more
+         */
+        p->p_misc_flags |= MF_CONTEXT_SET;
+
+        if(!(p->p_rts_flags)) {
+                printf("WARNINIG: setting full context of runnable process\n");
+                print_proc(p);
+                util_stacktrace();
+        }
 }
 
 void arch_set_secondary_ipc_return(struct proc *p, u32_t val)
diff --git a/kernel/system/do_sigsend.c b/kernel/system/do_sigsend.c
index bbf21149d..ddb8db93c 100644
--- a/kernel/system/do_sigsend.c
+++ b/kernel/system/do_sigsend.c
@@ -81,6 +81,13 @@ int do_sigsend(struct proc * caller, message * m_ptr)
   fr.sf_signo = smsg.sm_signo;
   fr.sf_retadr = (void (*)()) smsg.sm_sigreturn;
 
+#if defined(__arm__)
+  /* use the ARM link register to set the return address from the signal
+   * handler
+   */
+  rp->p_reg.lr = (reg_t) fr.sf_retadr;
+#endif
+
   /* Copy the sigframe structure to the user's stack. */
   if((r=data_copy_vmcheck(caller, KERNEL, (vir_bytes) &fr,
 	m_ptr->SIG_ENDPT, (vir_bytes) frp, 
diff --git a/lib/libc/arch/arm/sys-minix/__sigreturn.S b/lib/libc/arch/arm/sys-minix/__sigreturn.S
index 9d3f26170..9eee41635 100644
--- a/lib/libc/arch/arm/sys-minix/__sigreturn.S
+++ b/lib/libc/arch/arm/sys-minix/__sigreturn.S
@@ -5,5 +5,6 @@
 
 IMPORT(_sigreturn)
 ENTRY(__sigreturn)
-	add	sp, sp, #16
-	b	_C_LABEL(_sigreturn)
+	add	sp, sp, #24	/* make sp point to sigframe.sf_scpcopy */
+	pop	{r0}		/* load it into r0 as parameter */
+	b	_C_LABEL(_sigreturn)	/* _sigreturn(struct sigcontext *sf_scpcopy) */
-- 
2.11.4.GIT