From: Fenghua Yu <fenghua.yu@intel.com>
To: "Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@elte.hu>,
"H. Peter Anvin" <hpa@linux.intel.com>
Cc: "Ashok Raj" <ashok.raj@intel.com>,
"Dave Hansen" <dave.hansen@intel.com>,
"Rafael Wysocki" <rafael.j.wysocki@intel.com>,
"Tony Luck" <tony.luck@intel.com>,
"Alan Cox" <alan@linux.intel.com>,
"Ravi V Shankar" <ravi.v.shankar@intel.com>,
"Arjan van de Ven" <arjan@infradead.org>,
"linux-kernel" <linux-kernel@vger.kernel.org>,
"x86" <x86@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>
Subject: [RFC PATCH 12/16] x86/split_lock: Add a debugfs interface to allow user to change how to handle split lock in kernel mode during run time
Date: Sun, 27 May 2018 08:46:01 -0700 [thread overview]
Message-ID: <1527435965-202085-13-git-send-email-fenghua.yu@intel.com> (raw)
In-Reply-To: <1527435965-202085-1-git-send-email-fenghua.yu@intel.com>
CONFIG_SPLIT_LOCK_AC_PANIC_ON_KERNEL defines how to handle split lock in
kernel mode by default. But sometimes user wants to change the default
behavior.
The interface /sys/kernel/debug/x86/split_lock/kernel_mode is added
to allow user to do so.
For example, the interface shows "[re-execute] panic" which
means two behaviors: re-execute kernel faulting instruction
after #AC (default) and panic in #AC.
User can change the default behavior by writing "re-execute" or "panic"
to the interface.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
arch/x86/kernel/cpu/test_ctl.c | 89 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 89 insertions(+)
diff --git a/arch/x86/kernel/cpu/test_ctl.c b/arch/x86/kernel/cpu/test_ctl.c
index 6784f68af26a..0212a7979a14 100644
--- a/arch/x86/kernel/cpu/test_ctl.c
+++ b/arch/x86/kernel/cpu/test_ctl.c
@@ -18,6 +18,7 @@
#include <linux/reboot.h>
#include <linux/syscore_ops.h>
#include <linux/debugfs.h>
+#include <linux/uaccess.h>
#include <asm/msr.h>
#define DISABLE_SPLIT_LOCK_AC 0
@@ -49,6 +50,11 @@ enum {
KERNEL_MODE_LAST
};
+static const char * const kernel_modes[KERNEL_MODE_LAST] = {
+ [KERNEL_MODE_RE_EXECUTE] = "re-execute",
+ [KERNEL_MODE_PANIC] = "panic",
+};
+
static int kernel_mode_reaction = KERNEL_MODE_RE_EXECUTE;
/* Detete feature of #AC for split lock by probing bit 29 in MSR_TEST_CTL. */
@@ -361,10 +367,93 @@ static int enable_store(void *data, u64 val)
DEFINE_DEBUGFS_ATTRIBUTE(enable_ops, enable_show, enable_store, "%llx\n");
+static ssize_t
+mode_show(char __user *user_buf, const char * const *modes, int start_reaction,
+ int last_reaction, int mode_reaction, size_t count, loff_t *ppos)
+{
+ char buf[32], *s = buf;
+ int reaction, len;
+
+ mutex_lock(&split_lock_mutex);
+ for (reaction = start_reaction; reaction < last_reaction; reaction++) {
+ if (reaction == mode_reaction)
+ s += sprintf(s, "[%s] ", modes[reaction]);
+ else
+ s += sprintf(s, "%s ", modes[reaction]);
+ }
+
+ if (s != buf)
+ /* convert the last space to a newline */
+ *(s - 1) = '\n';
+ mutex_unlock(&split_lock_mutex);
+
+ len = strlen(buf);
+
+ return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+static ssize_t
+mode_store(const char __user *user_buf, size_t count, const char * const *modes,
+ int start_reaction, int last_reaction, int *mode_reaction)
+{
+ int reaction, len, ret = -EINVAL;
+ const char * const *s, *p;
+ char buf[32];
+
+ len = min(count, sizeof(buf) - 1);
+ if (copy_from_user(buf, user_buf, len))
+ return -EFAULT;
+
+ buf[len] = '\0';
+
+ mutex_lock(&split_lock_mutex);
+ p = memchr(buf, '\n', count);
+ len = p ? p - buf : count;
+
+ reaction = start_reaction;
+ for (s = &modes[reaction]; reaction < last_reaction; s++, reaction++) {
+ if (*s && len == strlen(*s) && !strncmp(buf, *s, len)) {
+ *mode_reaction = reaction;
+ ret = 0;
+ break;
+ }
+ }
+ mutex_unlock(&split_lock_mutex);
+
+ return ret;
+}
+
+static ssize_t kernel_mode_show(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ return mode_show(user_buf, kernel_modes, KERNEL_MODE_RE_EXECUTE,
+ KERNEL_MODE_LAST, kernel_mode_reaction, count, ppos);
+}
+
+static ssize_t kernel_mode_store(struct file *file, const char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+
+ ret = mode_store(user_buf, count, kernel_modes, KERNEL_MODE_RE_EXECUTE,
+ KERNEL_MODE_LAST, &kernel_mode_reaction);
+ if (ret)
+ return ret;
+
+ return count;
+}
+
+static const struct file_operations kernel_mode_ops = {
+ .read = kernel_mode_show,
+ .write = kernel_mode_store,
+ .llseek = default_llseek,
+};
+
static int __init debugfs_setup_split_lock(void)
{
struct debugfs_file debugfs_files[] = {
{"enable", 0600, &enable_ops},
+ {"kernel_mode", 0600, &kernel_mode_ops },
};
struct dentry *split_lock_dir, *fd;
int i;
--
2.5.0
next prev parent reply other threads:[~2018-05-27 15:46 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-27 15:45 [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 01/16] x86/split_lock: Add CONFIG and enumerate #AC exception for split locked access feature Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 02/16] x86/split_lock: Handle #AC exception for split lock in kernel mode Fenghua Yu
2018-06-21 19:46 ` Peter Zijlstra
2018-06-22 10:49 ` Thomas Gleixner
2018-06-22 11:59 ` Thomas Gleixner
2018-06-22 22:41 ` Fenghua Yu
2018-06-22 22:57 ` Thomas Gleixner
2018-06-22 23:03 ` Thomas Gleixner
2018-06-22 23:18 ` Fenghua Yu
2018-06-23 9:08 ` Thomas Gleixner
2018-06-23 4:20 ` Fenghua Yu
2018-06-23 9:17 ` Thomas Gleixner
2018-06-23 15:05 ` Fenghua Yu
2018-06-24 0:55 ` Thomas Gleixner
2018-06-24 1:17 ` Fenghua Yu
2018-06-24 6:43 ` Thomas Gleixner
2018-05-27 15:45 ` [RFC PATCH 03/16] x86/split_lock: Set up #AC exception for split locked accesses on all CPUs Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 04/16] x86/split_lock: Use non locked bit set instruction in set_cpu_cap Fenghua Yu
2018-06-21 19:55 ` Peter Zijlstra
2018-06-21 20:37 ` Thomas Gleixner
2018-06-27 23:35 ` Fenghua Yu
2018-06-28 7:53 ` Thomas Gleixner
2018-06-28 14:23 ` Fenghua Yu
2018-06-28 14:54 ` Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 05/16] x86/split_lock: Use non atomic set and clear bit instructions in clear_cpufeature() Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 06/16] x86/split_lock: Save #AC setting for split lock in firmware in boot time and restore the setting in reboot Fenghua Yu
2018-06-21 19:58 ` Peter Zijlstra
2018-06-22 15:11 ` Alan Cox
2018-06-26 9:05 ` Peter Zijlstra
2018-06-26 9:40 ` Thomas Gleixner
2018-06-26 11:02 ` Alan Cox
2018-06-26 11:31 ` Peter Zijlstra
2018-05-27 15:45 ` [RFC PATCH 07/16] x86/split_lock: Handle suspend/hibernate and resume Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 08/16] x86/split_lock: Set split lock during EFI runtime service Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 09/16] x86/split_lock: Add CONFIG to control #AC for split lock at boot time Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 10/16] x86/split_lock: Add a debugfs interface to allow user to enable or disable #AC for split lock during run time Fenghua Yu
2018-05-29 18:43 ` Greg KH
2018-05-27 15:46 ` [RFC PATCH 11/16] x86/split_lock: Add CONFIG to control #AC for split lock from kernel at boot time Fenghua Yu
2018-05-27 15:46 ` Fenghua Yu [this message]
2018-05-27 15:46 ` [RFC PATCH 13/16] x86/split_lock: Add debugfs interface to control user mode behavior Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 14/16] x86/split_lock: Add debugfs interface to show and control firmware setting for split lock Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 15/16] x86/split_lock: Add CONFIG and debugfs interface for testing #AC for split lock in kernel mode Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 16/16] x86/split_lock: Add user space split lock test in selftest Fenghua Yu
2018-05-29 16:39 ` [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses Dave Hansen
2018-05-29 17:25 ` Fenghua Yu
2018-05-29 17:28 ` Dave Hansen
2018-05-29 17:40 ` Fenghua Yu
2018-05-29 16:40 ` Dave Hansen
2018-05-29 17:38 ` Fenghua Yu
2018-06-21 20:06 ` Peter Zijlstra
2018-06-21 19:37 ` Peter Zijlstra
2018-06-21 20:18 ` Fenghua Yu
2018-06-21 20:32 ` Thomas Gleixner
2018-06-21 22:00 ` Fenghua Yu
2018-06-21 22:07 ` Peter Zijlstra
2018-06-21 22:08 ` Peter Zijlstra
2018-06-21 22:18 ` Dave Hansen
2018-06-21 22:42 ` Fenghua Yu
2018-06-22 8:11 ` Peter Zijlstra
2018-06-22 9:30 ` Thomas Gleixner
2018-06-21 22:10 ` Peter Zijlstra
2018-06-21 23:05 ` Fenghua Yu
2018-06-22 8:19 ` Peter Zijlstra
2018-06-21 22:11 ` Peter Zijlstra
2018-06-21 22:43 ` Fenghua Yu
2018-06-21 22:13 ` Peter Zijlstra
2018-06-23 18:47 ` Fenghua Yu
2018-06-22 9:18 ` Thomas Gleixner
2018-06-22 9:22 ` Thomas Gleixner
2018-06-22 9:25 ` Thomas Gleixner
2018-06-22 9:28 ` Thomas Gleixner
2018-06-21 20:36 ` Peter Zijlstra
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