[patch] updated alpha uac patch

alpha-sysctl-uac-updated.patch (text/plain), 4.83 KB, created by Mike Pagano on 2008-04-12 00:34:54 UTC

--- src/arch/alpha/Kconfig.orig	2008-04-11 19:24:19.000000000 -0400
+++ src/arch/alpha/Kconfig	2008-04-11 19:28:07.000000000 -0400
@@ -616,6 +616,32 @@ config VERBOSE_MCHECK_ON
 
 	  Take the default (1) unless you want more control or more info.
 
+config ALPHA_UAC_SYSCTL
+	bool "Configure UAC policy via sysctl"
+	depends on SYSCTL
+	default y
+	---help---
+	  Configuring the UAC (unaligned access control) policy on a Linux
+	  system usually involves setting a compile time define. If you say
+	  Y here, you will be able to modify the UAC policy at runtime using
+	  the /proc interface.
+
+	  The UAC policy defines the action Linux should take when an
+	  unaligned memory access occurs. The action can include printing a
+	  warning message (NOPRINT), sending a signal to the offending
+	  program to help developers debug their applications (SIGBUS), or
+	  disabling the transparent fixing (NOFIX).
+
+	  The sysctls will be initialized to the compile-time defined UAC
+	  policy. You can change these manually, or with the sysctl(8)
+	  userspace utility.
+
+	  To disable the warning messages at runtime, you would use
+
+	    echo 1 > /proc/sys/kernel/uac/noprint
+
+	  This is pretty harmless. Say Y if you're not sure.
+
 source "drivers/pci/Kconfig"
 source "drivers/eisa/Kconfig"
 
--- src/arch/alpha/kernel/traps.c.orig	2008-04-11 19:24:50.000000000 -0400
+++ src/arch/alpha/kernel/traps.c	2008-04-11 19:50:31.000000000 -0400
@@ -102,6 +102,47 @@ static char * ireg_name[] = {"v0", "t0",
 			   "t10", "t11", "ra", "pv", "at", "gp", "sp", "zero"};
 #endif
 
+#ifdef CONFIG_ALPHA_UAC_SYSCTL
+static struct ctl_table_header *uac_sysctl_header;
+
+/* /proc/sys/kernel/uac */
+enum
+{
+   /* UAC policy on Alpha */
+   KERN_UAC_NOPRINT=1, /* int: printk() on unaligned access */
+   KERN_UAC_SIGBUS=2,  /* int: send SIGBUS on unaligned access */
+   KERN_UAC_NOFIX=3,   /* int: don't fix the unaligned access */
+};
+
+static int enabled_noprint = 0;
+static int enabled_sigbus = 0;
+static int enabled_nofix = 0;
+
+ctl_table uac_table[] = {
+	{KERN_UAC_NOPRINT, "noprint", &enabled_noprint, sizeof (int), 0644, NULL, NULL, &proc_dointvec},
+	{KERN_UAC_SIGBUS, "sigbus", &enabled_sigbus, sizeof (int), 0644, NULL, NULL, &proc_dointvec},
+	{KERN_UAC_NOFIX, "nofix", &enabled_nofix, sizeof (int), 0644, NULL, NULL, &proc_dointvec},
+        {0}
+};
+
+static int __init init_uac_sysctl(void)
+{
+	/* Initialize sysctls with the #defined UAC policy */
+	enabled_noprint = (test_thread_flag (TIF_UAC_NOPRINT)) ? 1 : 0;
+	enabled_sigbus = (test_thread_flag (TIF_UAC_SIGBUS)) ? 1 : 0;
+	enabled_nofix = (test_thread_flag (TIF_UAC_NOFIX)) ? 1 : 0;
+
+	/* save this for later so we can clean up */
+	uac_sysctl_header = register_sysctl_table(uac_table);
+	return 0;
+}
+
+static void __exit exit_uac_sysctl(void)
+{
+	unregister_sysctl_table(uac_sysctl_header);
+}
+#endif
+
 static void
 dik_show_code(unsigned int *pc)
 {
@@ -780,7 +821,11 @@ do_entUnaUser(void __user * va, unsigned
 	/* Check the UAC bits to decide what the user wants us to do
 	   with the unaliged access.  */
 
+#ifndef CONFIG_ALPHA_UAC_SYSCTL
 	if (!test_thread_flag (TIF_UAC_NOPRINT)) {
+#else  /* CONFIG_ALPHA_UAC_SYSCTL */
+	if (!(enabled_noprint)) {
+#endif /* CONFIG_ALPHA_UAC_SYSCTL */
 		if (cnt >= 5 && jiffies - last_time > 5*HZ) {
 			cnt = 0;
 		}
@@ -791,10 +836,18 @@ do_entUnaUser(void __user * va, unsigned
 		}
 		last_time = jiffies;
 	}
+#ifndef CONFIG_ALPHA_UAC_SYSCTL
 	if (test_thread_flag (TIF_UAC_SIGBUS))
+#else  /* CONFIG_ALPHA_UAC_SYSCTL */
+	if (enabled_sigbus)
+#endif /* CONFIG_ALPHA_UAC_SYSCTL */
 		goto give_sigbus;
 	/* Not sure why you'd want to use this, but... */
+#ifndef CONFIG_ALPHA_UAC_SYSCTL
 	if (test_thread_flag (TIF_UAC_NOFIX))
+#else  /* CONFIG_ALPHA_UAC_SYSCTL */
+	if (enabled_nofix)
+#endif /* CONFIG_ALPHA_UAC_SYSCTL */
 		return;
 
 	/* Don't bother reading ds in the access check since we already
@@ -1089,3 +1142,7 @@ trap_init(void)
 	wrent(entSys, 5);
 	wrent(entDbg, 6);
 }
+
+#ifdef CONFIG_ALPHA_UAC_SYSCTL
+__initcall(init_uac_sysctl);
+#endif
--- src/kernel/sysctl.c.orig	2008-04-11 19:26:51.000000000 -0400
+++ src/kernel/sysctl.c	2008-04-11 19:38:44.000000000 -0400
@@ -155,6 +155,10 @@ static int proc_dointvec_taint(struct ct
 			       void __user *buffer, size_t *lenp, loff_t *ppos);
 #endif
 
+#ifdef CONFIG_ALPHA_UAC_SYSCTL
+extern ctl_table uac_table[];
+#endif
+
 static struct ctl_table root_table[];
 static struct ctl_table_header root_table_header =
 	{ root_table, LIST_HEAD_INIT(root_table_header.ctl_entry) };
@@ -221,6 +225,14 @@ static struct ctl_table root_table[] = {
  * NOTE: do not add new entries to this table unless you have read
  * Documentation/sysctl/ctl_unnumbered.txt
  */
+#ifdef CONFIG_ALPHA_UAC_SYSCTL
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "uac",
+		.mode		= 0555,
+		.child		= uac_table,
+	},
+#endif /* CONFIG_ALPHA_UAC_SYSCTL */
 	{ .ctl_name = 0 }
 };