From c0074d3aa9a90089a36bc539750736241cc3507d Mon Sep 17 00:00:00 2001
From: Ben Gras <ben@minix3.org>
Date: Tue, 20 Jul 2010 17:10:09 +0000
Subject: [PATCH] kernel: fix case of EAX getting clobbered after sigreturn.

---
 kernel/arch/i386/memory.c    | 4 +++-
 kernel/proc.h                | 1 +
 kernel/system/do_sigreturn.c | 2 ++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/arch/i386/memory.c b/kernel/arch/i386/memory.c
index 8305df8c0..88054dff9 100644
--- a/kernel/arch/i386/memory.c
+++ b/kernel/arch/i386/memory.c
@@ -612,7 +612,9 @@ PUBLIC void delivermsg(struct proc *rp)
 		r = OK;
 	}
 
-	rp->p_reg.retreg = r;
+	if(!(rp->p_misc_flags & MF_CONTEXT_SET)) {
+		rp->p_reg.retreg = r;
+	}
 }
 
 PRIVATE char *flagstr(u32_t e, const int dir)
diff --git a/kernel/proc.h b/kernel/proc.h
index 5ce97d379..dc70a806c 100644
--- a/kernel/proc.h
+++ b/kernel/proc.h
@@ -224,6 +224,7 @@ struct proc {
 #define MF_FPU_INITIALIZED	0x1000  /* process already used math, so fpu
 					 * regs are significant (initialized)*/
 #define MF_SENDING_FROM_KERNEL	0x2000 /* message of this process is from kernel */
+#define MF_CONTEXT_SET	0x4000 /* don't touch context */
 
 /* Magic process table addresses. */
 #define BEG_PROC_ADDR (&proc[0])
diff --git a/kernel/system/do_sigreturn.c b/kernel/system/do_sigreturn.c
index 6e8e1abe1..7f91a0a34 100644
--- a/kernel/system/do_sigreturn.c
+++ b/kernel/system/do_sigreturn.c
@@ -65,6 +65,8 @@ PUBLIC int do_sigreturn(struct proc * caller, message * m_ptr)
   }
 #endif
 
+  rp->p_misc_flags |= MF_CONTEXT_SET;
+
   return(OK);
 }
 #endif /* USE_SIGRETURN */