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[IA64] sysctl option to silence unaligned trap warnings

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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>
This commit is contained in:
Jes Sorensen 2006-02-28 09:42:23 -08:00 committed by Tony Luck
parent c8c1635faa
commit d2b176ed87
3 changed files with 43 additions and 3 deletions
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31
arch/ia64/kernel/unaligned.c
View File

@ -52,6 +52,15 @@ dump (const char *str, void *vp, size_t len)
#define IA64_FIRST_ROTATING_FR 32
#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:
*
@ -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())

1
include/linux/sysctl.h
View File

@ -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 */
};

14
kernel/sysctl.c
View File

@ -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,
@ -665,6 +669,16 @@ static ctl_table kern_table[] = {
.mode = 0644,
.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 }
};