From: Arne Welzel <arne.welzel@gmail.com>
Date: Thu, 22 Mar 2018 13:27:32 +0000 (+0100)
Subject: kernel/arm: send SIGSEGV to processes
X-Git-Url: http://zhaoyanbai.com/repos/man.delv.html?a=commitdiff_plain;h=0dd719f1bd28ca1fd3474cf2d18d9e041c5ec028;p=minix.git

kernel/arm: send SIGSEGV to processes

On second thought, handle unknown faults caused by processes by sending
SIGSEGV to them instead of bringing the whole system to a grind.

arm/archconst: use values defined in armreg.h

Change-Id: Ieed5bb06910ab0c8eef1e68b0b4eec680867acd3
---

diff --git a/minix/kernel/arch/earm/exception.c b/minix/kernel/arch/earm/exception.c
index 1930b24ac..3a358d79d 100644
--- a/minix/kernel/arch/earm/exception.c
+++ b/minix/kernel/arch/earm/exception.c
@@ -116,25 +116,27 @@ data_abort(int is_nested, struct proc *pr, reg_t *saved_lr,
 	/* Extract fault status bit [0:3, 10] from DFSR */
 	u32_t fs = dfsr & 0x0F;
 	fs |= ((dfsr >> 6) & 0x10);
-	if (is_alignment_fault(fs)) {
-		if (is_nested) {
-			printf("KERNEL: alignment fault dfar=0x%lx\n", dfar);
-			inkernel_disaster(pr, saved_lr, ep, is_nested);
-		}
-		/* Send SIGBUS to violating process. */
-		cause_sig(proc_nr(pr), SIGBUS);
-		return;
-	} else if (is_translation_fault(fs) || is_permission_fault(fs)) {
-		/* Ask VM to handle translation and permission faults as pagefaults */
+
+	 /* Translation and permission faults are handled as pagefaults. */
+	if (is_trans_fault(fs) || is_perm_fault(fs)) {
 		pagefault(pr, saved_lr, is_nested, dfar, dfsr);
-		return;
-	} else {
-		/* Die on unknown things... */
-		printf("KERNEL: unhandled data abort dfar=0x%lx dfsr=0x%lx "
-			"fs=0x%lx is_nested=%d\n", dfar, dfsr, fs, is_nested);
-		panic("unhandled data abort");
+	} else if (!is_nested) {
+		/* A user process caused some other kind of data abort. */
+		int signum = SIGSEGV;
+
+		if (is_align_fault(fs)) {
+			signum = SIGBUS;
+		} else {
+			printf("KERNEL: unknown data abort by proc %d sending "
+			       "SIGSEGV (dfar=0x%lx dfsr=0x%lx fs=0x%lx)\n",
+			       proc_nr(pr), dfar, dfsr, fs);
+		}
+		cause_sig(proc_nr(pr), signum);
+	} else { /* is_nested */
+		printf("KERNEL: inkernel data abort - disaster (dfar=0x%lx "
+		       "dfsr=0x%lx fs=0x%lx)\n", dfar, dfsr, fs);
+		inkernel_disaster(pr, saved_lr, ep, is_nested);
 	}
-	NOT_REACHABLE;
 }
 
 static void inkernel_disaster(struct proc *saved_proc,
diff --git a/minix/kernel/arch/earm/include/archconst.h b/minix/kernel/arch/earm/include/archconst.h
index b52fe6a59..d85dd81e0 100644
--- a/minix/kernel/arch/earm/include/archconst.h
+++ b/minix/kernel/arch/earm/include/archconst.h
@@ -21,24 +21,15 @@
 #define INTERRUPT_VECTOR              6
 #define FAST_INTERRUPT_VECTOR         7
 
+/* Data abort helper */
+#define is_align_fault(fault_status) \
+	((fault_status) == FAULT_ALIGN_0)
 
-/* Known fault status bits */
-#define DFSR_FS_ALIGNMENT_FAULT			0x01
-#define DFSR_FS_TRANSLATION_FAULT_PAGE		0x07
-#define DFSR_FS_TRANSLATION_FAULT_SECTION	0x05
-#define DFSR_FS_PERMISSION_FAULT_PAGE		0x0F
-#define DFSR_FS_PERMISSION_FAULT_SECTION	0x0D
+#define is_trans_fault(fault_status) \
+	(((fault_status) == FAULT_TRANS_S) || ((fault_status) == FAULT_TRANS_P))
 
-#define is_alignment_fault(fault_status) \
-	((fault_status) == DFSR_FS_ALIGNMENT_FAULT)
-
-#define is_translation_fault(fault_status) \
-	(((fault_status) == DFSR_FS_TRANSLATION_FAULT_PAGE) \
-		|| ((fault_status) == DFSR_FS_TRANSLATION_FAULT_SECTION))
-
-#define is_permission_fault(fault_status) \
-	(((fault_status) == DFSR_FS_PERMISSION_FAULT_PAGE) \
-		|| ((fault_status) == DFSR_FS_PERMISSION_FAULT_SECTION))
+#define is_perm_fault(fault_status) \
+	(((fault_status) == FAULT_PERM_S) || ((fault_status) == FAULT_PERM_P))
 
 /*
  * defines how many bytes are reserved at the top of the kernel stack for global