From 56c1cfd4797af7367c5d830d5125baa75d4f0bdb Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Tue, 5 May 2015 21:25:58 +0200
Subject: [PATCH gnumach 10/10] fix error handling

---
 i386/i386/locore.S | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/i386/i386/locore.S b/i386/i386/locore.S
index 0d08be5..d8241a7 100644
--- a/i386/i386/locore.S
+++ b/i386/i386/locore.S
@@ -1305,11 +1305,12 @@ ENTRY(sysenter_entry)
 	xchgl	%ebx, %esp		/* switch to kernel stack */
 					/* %ebx points to user registers */
 	negl	%eax			/* get system call number */
-	/* xxx sysenter_mach_call_range */
-	jl	mach_call_range		/* out of range if it was positive */
-	cmpl	EXT(mach_trap_count),%eax	/* check system call table bounds */
-	/* xxx sysenter_mach_call_range */
-	jg	mach_call_range		/* error if out of range */
+	jl	sysenter_mach_call_range
+					/* out of range if it was positive */
+	cmpl	EXT(mach_trap_count),%eax
+					/* check system call table bounds */
+	jg	sysenter_mach_call_range
+					/* error if out of range */
 
 	shll	$4,%eax			/* manual indexing */
 	movl	EXT(mach_trap_table)(%eax),%ecx
@@ -1339,6 +1340,7 @@ se_args_5plus:
 
 	movl	$USER_DS,%edx		/* use user data segment for accesses */
 	mov	%dx,%fs
+	movl	%esp,%edx		/* save kernel ESP for error recovery */
 
 0:	subl	$4,%esi
 	RECOVER(sysenter_mach_call_addr_push)
@@ -1370,12 +1372,28 @@ return_from_sysenter:			/* return here */
 	sti				/* xxx: sti/cli where ? */
 	sysexit
 
+/*
+ * Address out of range.  Change to page fault.
+ * %esi holds failing address.
+ */
 sysenter_mach_call_addr_push:
-	movl	%ebx,%esp		/* clean parameters from stack */
-	/* xxx signal page-fault */
-	jmp sysenter_mach_call_addr_push
-#undef SE_STACK_POINTER
-#undef SE_RETURN_ADDRESS
+	movl	%edx,%esp		/* clean parameters from stack */
+	movl	%esi,R_CR2(%ebx)	/* set fault address */
+	movl	$(T_PAGE_FAULT),R_TRAPNO(%ebx)
+					/* set page-fault trap */
+	movl	$(T_PF_USER),R_ERR(%ebx)
+					/* set error code - read user space */
+	jmp	_take_trap		/* treat as a trap */
+
+/*
+ * System call out of range.  Treat as invalid-instruction trap.
+ * (? general protection?)
+ */
+sysenter_mach_call_range:
+	movl	$(T_INVALID_OPCODE),R_TRAPNO(%ebx)
+					/* set invalid-operation trap */
+	movl	$0,R_ERR(%ebx)		/* clear error code */
+	jmp	_take_trap		/* treat as a trap */
 
 	.data
 DATA(cpu_features)
-- 
2.1.4