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authorJes Sorensen <jes@sgi.com>2006-02-28 09:42:23 -0800
committerTony Luck <tony.luck@intel.com>2006-02-28 09:42:23 -0800
commitd2b176ed878d4d5fcc0bd35656dfd373f3702af9 (patch)
treef5febd7d77fc374ddef9cbe549732bcb3b125c8b
parentc8c1635faa7c97329111ce32b927d37306521822 (diff)
[IA64] sysctl option to silence unaligned trap warnings
Allow sysadmin to disable all warnings about userland apps making unaligned accesses by using: # echo 1 > /proc/sys/kernel/ignore-unaligned-usertrap Rather than having to use prctl on a process by process basis. Default behaivour leaves the warnings enabled. Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
-rw-r--r--arch/ia64/kernel/unaligned.c31
-rw-r--r--include/linux/sysctl.h1
-rw-r--r--kernel/sysctl.c14
3 files changed, 43 insertions, 3 deletions
diff --git a/arch/ia64/kernel/unaligned.c b/arch/ia64/kernel/unaligned.c
index 11291389684..1e357550c77 100644
--- a/arch/ia64/kernel/unaligned.c
+++ b/arch/ia64/kernel/unaligned.c
@@ -53,6 +53,15 @@ dump (const char *str, void *vp, size_t len)
#define SIGN_EXT9 0xffffffffffffff00ul
/*
+ * sysctl settable hook which tells the kernel whether to honor the
+ * IA64_THREAD_UAC_NOPRINT prctl. Because this is user settable, we want
+ * to allow the super user to enable/disable this for security reasons
+ * (i.e. don't allow attacker to fill up logs with unaligned accesses).
+ */
+int no_unaligned_warning;
+static int noprint_warning;
+
+/*
* For M-unit:
*
* opcode | m | x6 |
@@ -1324,8 +1333,9 @@ ia64_handle_unaligned (unsigned long ifa, struct pt_regs *regs)
if ((current->thread.flags & IA64_THREAD_UAC_SIGBUS) != 0)
goto force_sigbus;
- if (!(current->thread.flags & IA64_THREAD_UAC_NOPRINT)
- && within_logging_rate_limit())
+ if (!no_unaligned_warning &&
+ !(current->thread.flags & IA64_THREAD_UAC_NOPRINT) &&
+ within_logging_rate_limit())
{
char buf[200]; /* comm[] is at most 16 bytes... */
size_t len;
@@ -1340,7 +1350,22 @@ ia64_handle_unaligned (unsigned long ifa, struct pt_regs *regs)
if (user_mode(regs))
tty_write_message(current->signal->tty, buf);
buf[len-1] = '\0'; /* drop '\r' */
- printk(KERN_WARNING "%s", buf); /* watch for command names containing %s */
+ /* watch for command names containing %s */
+ printk(KERN_WARNING "%s", buf);
+ } else {
+ if (no_unaligned_warning && !noprint_warning) {
+ noprint_warning = 1;
+ printk(KERN_WARNING "%s(%d) encountered an "
+ "unaligned exception which required\n"
+ "kernel assistance, which degrades "
+ "the performance of the application.\n"
+ "Unaligned exception warnings have "
+ "been disabled by the system "
+ "administrator\n"
+ "echo 0 > /proc/sys/kernel/ignore-"
+ "unaligned-usertrap to re-enable\n",
+ current->comm, current->pid);
+ }
}
} else {
if (within_logging_rate_limit())
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 0e92bf7ec28..bac61db2645 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -147,6 +147,7 @@ enum
KERN_SETUID_DUMPABLE=69, /* int: behaviour of dumps for setuid core */
KERN_SPIN_RETRY=70, /* int: number of spinlock retries */
KERN_ACPI_VIDEO_FLAGS=71, /* int: flags for setting up video after ACPI sleep */
+ KERN_IA64_UNALIGNED=72, /* int: ia64 unaligned userland trap enable */
};
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c05a2b7125e..acf6c1550f2 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -124,6 +124,10 @@ extern int sysctl_hz_timer;
extern int acct_parm[];
#endif
+#ifdef CONFIG_IA64
+extern int no_unaligned_warning;
+#endif
+
static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
ctl_table *, void **);
static int proc_doutsstring(ctl_table *table, int write, struct file *filp,
@@ -666,6 +670,16 @@ static ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
#endif
+#ifdef CONFIG_IA64
+ {
+ .ctl_name = KERN_IA64_UNALIGNED,
+ .procname = "ignore-unaligned-usertrap",
+ .data = &no_unaligned_warning,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+#endif
{ .ctl_name = 0 }
};