Input: sysrq - allow specifying alternate reset sequence
This patch adds keyreset functionality to the sysrq driver. It allows certain button/key combinations to be used in order to trigger emergency reboots. Redefining the '__weak platform_sysrq_reset_seq' variable is required to trigger the feature. Alternatively keys can be passed to the driver via a module parameter. This functionality comes from the keyreset driver submitted by Arve Hjønnevåg in the Android kernel. Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Mathieu Poirier
Dmitry Torokhov
parent
0799a924bc
commit
154b7a489a
1 changed files with 202 additions and 74 deletions
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@ -41,6 +41,7 @@
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#include <linux/slab.h>
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#include <linux/input.h>
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#include <linux/uaccess.h>
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#include <linux/moduleparam.h>
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#include <asm/ptrace.h>
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#include <asm/irq_regs.h>
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@ -576,8 +577,71 @@ struct sysrq_state {
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bool active;
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bool need_reinject;
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bool reinjecting;
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/* reset sequence handling */
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bool reset_canceled;
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unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
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int reset_seq_len;
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int reset_seq_cnt;
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int reset_seq_version;
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};
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#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
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static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
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static unsigned int sysrq_reset_seq_len;
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static unsigned int sysrq_reset_seq_version = 1;
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static void sysrq_parse_reset_sequence(struct sysrq_state *state)
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{
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int i;
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unsigned short key;
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state->reset_seq_cnt = 0;
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for (i = 0; i < sysrq_reset_seq_len; i++) {
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key = sysrq_reset_seq[i];
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if (key == KEY_RESERVED || key > KEY_MAX)
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break;
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__set_bit(key, state->reset_keybit);
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state->reset_seq_len++;
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if (test_bit(key, state->key_down))
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state->reset_seq_cnt++;
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}
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/* Disable reset until old keys are not released */
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state->reset_canceled = state->reset_seq_cnt != 0;
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state->reset_seq_version = sysrq_reset_seq_version;
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}
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static bool sysrq_detect_reset_sequence(struct sysrq_state *state,
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unsigned int code, int value)
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{
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if (!test_bit(code, state->reset_keybit)) {
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/*
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* Pressing any key _not_ in reset sequence cancels
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* the reset sequence.
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*/
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if (value && state->reset_seq_cnt)
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state->reset_canceled = true;
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} else if (value == 0) {
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/* key release */
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if (--state->reset_seq_cnt == 0)
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state->reset_canceled = false;
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} else if (value == 1) {
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/* key press, not autorepeat */
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if (++state->reset_seq_cnt == state->reset_seq_len &&
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!state->reset_canceled) {
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return true;
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}
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}
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return false;
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}
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static void sysrq_reinject_alt_sysrq(struct work_struct *work)
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{
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struct sysrq_state *sysrq =
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@ -604,11 +668,104 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work)
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}
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}
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static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
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unsigned int code, int value)
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{
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bool was_active = sysrq->active;
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bool suppress;
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switch (code) {
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case KEY_LEFTALT:
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case KEY_RIGHTALT:
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if (!value) {
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/* One of ALTs is being released */
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if (sysrq->active && code == sysrq->alt_use)
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sysrq->active = false;
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sysrq->alt = KEY_RESERVED;
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} else if (value != 2) {
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sysrq->alt = code;
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sysrq->need_reinject = false;
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}
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break;
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case KEY_SYSRQ:
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if (value == 1 && sysrq->alt != KEY_RESERVED) {
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sysrq->active = true;
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sysrq->alt_use = sysrq->alt;
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/*
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* If nothing else will be pressed we'll need
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* to re-inject Alt-SysRq keysroke.
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*/
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sysrq->need_reinject = true;
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}
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/*
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* Pretend that sysrq was never pressed at all. This
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* is needed to properly handle KGDB which will try
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* to release all keys after exiting debugger. If we
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* do not clear key bit it KGDB will end up sending
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* release events for Alt and SysRq, potentially
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* triggering print screen function.
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*/
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if (sysrq->active)
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clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
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break;
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default:
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if (sysrq->active && value && value != 2) {
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sysrq->need_reinject = false;
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__handle_sysrq(sysrq_xlate[code], true);
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}
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break;
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}
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suppress = sysrq->active;
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if (!sysrq->active) {
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/*
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* See if reset sequence has changed since the last time.
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*/
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if (sysrq->reset_seq_version != sysrq_reset_seq_version)
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sysrq_parse_reset_sequence(sysrq);
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/*
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* If we are not suppressing key presses keep track of
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* keyboard state so we can release keys that have been
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* pressed before entering SysRq mode.
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*/
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if (value)
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set_bit(code, sysrq->key_down);
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else
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clear_bit(code, sysrq->key_down);
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if (was_active)
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schedule_work(&sysrq->reinject_work);
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if (sysrq_detect_reset_sequence(sysrq, code, value)) {
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/* Force emergency reboot */
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__handle_sysrq(sysrq_xlate[KEY_B], false);
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}
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} else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
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/*
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* Pass on release events for keys that was pressed before
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* entering SysRq mode.
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*/
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suppress = false;
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}
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return suppress;
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}
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static bool sysrq_filter(struct input_handle *handle,
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unsigned int type, unsigned int code, int value)
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{
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struct sysrq_state *sysrq = handle->private;
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bool was_active = sysrq->active;
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bool suppress;
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/*
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@ -625,79 +782,7 @@ static bool sysrq_filter(struct input_handle *handle,
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break;
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case EV_KEY:
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switch (code) {
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case KEY_LEFTALT:
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case KEY_RIGHTALT:
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if (!value) {
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/* One of ALTs is being released */
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if (sysrq->active && code == sysrq->alt_use)
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sysrq->active = false;
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sysrq->alt = KEY_RESERVED;
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} else if (value != 2) {
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sysrq->alt = code;
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sysrq->need_reinject = false;
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}
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break;
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case KEY_SYSRQ:
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if (value == 1 && sysrq->alt != KEY_RESERVED) {
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sysrq->active = true;
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sysrq->alt_use = sysrq->alt;
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/*
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* If nothing else will be pressed we'll need
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* to re-inject Alt-SysRq keysroke.
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*/
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sysrq->need_reinject = true;
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}
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/*
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* Pretend that sysrq was never pressed at all. This
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* is needed to properly handle KGDB which will try
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* to release all keys after exiting debugger. If we
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* do not clear key bit it KGDB will end up sending
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* release events for Alt and SysRq, potentially
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* triggering print screen function.
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*/
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if (sysrq->active)
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clear_bit(KEY_SYSRQ, handle->dev->key);
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break;
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default:
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if (sysrq->active && value && value != 2) {
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sysrq->need_reinject = false;
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__handle_sysrq(sysrq_xlate[code], true);
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}
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break;
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}
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suppress = sysrq->active;
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if (!sysrq->active) {
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/*
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* If we are not suppressing key presses keep track of
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* keyboard state so we can release keys that have been
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* pressed before entering SysRq mode.
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*/
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if (value)
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set_bit(code, sysrq->key_down);
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else
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clear_bit(code, sysrq->key_down);
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if (was_active)
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schedule_work(&sysrq->reinject_work);
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} else if (value == 0 &&
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test_and_clear_bit(code, sysrq->key_down)) {
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/*
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* Pass on release events for keys that was pressed before
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* entering SysRq mode.
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*/
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suppress = false;
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}
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suppress = sysrq_handle_keypress(sysrq, code, value);
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break;
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default:
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@ -785,7 +870,20 @@ static bool sysrq_handler_registered;
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static inline void sysrq_register_handler(void)
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{
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extern unsigned short platform_sysrq_reset_seq[] __weak;
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unsigned short key;
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int error;
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int i;
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if (platform_sysrq_reset_seq) {
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for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
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key = platform_sysrq_reset_seq[i];
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if (key == KEY_RESERVED || key > KEY_MAX)
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break;
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sysrq_reset_seq[sysrq_reset_seq_len++] = key;
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}
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}
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error = input_register_handler(&sysrq_handler);
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if (error)
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@ -802,6 +900,36 @@ static inline void sysrq_unregister_handler(void)
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}
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}
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static int sysrq_reset_seq_param_set(const char *buffer,
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const struct kernel_param *kp)
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{
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unsigned long val;
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int error;
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error = strict_strtoul(buffer, 0, &val);
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if (error < 0)
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return error;
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if (val > KEY_MAX)
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return -EINVAL;
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*((unsigned short *)kp->arg) = val;
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sysrq_reset_seq_version++;
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return 0;
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}
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static struct kernel_param_ops param_ops_sysrq_reset_seq = {
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.get = param_get_ushort,
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.set = sysrq_reset_seq_param_set,
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};
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#define param_check_sysrq_reset_seq(name, p) \
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__param_check(name, p, unsigned short)
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module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
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&sysrq_reset_seq_len, 0644);
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#else
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static inline void sysrq_register_handler(void)
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