Keyboard lights, TLB shootdowns, battery in sysfs, /proc/pid/maps

Caps, Num and Scroll Lock now light their LEDs on PS/2 and USB keyboards,
share one state between keyboards, and stop toggling on key repeat. X sets
them through evdev writes while it holds the keyboard.

Unmapping memory in a process with threads on other CPUs now flushes their
TLBs with an IPI. Without it a freed page stayed reachable through stale
translations, which corrupted Epiphany's heap on SMP.

ACPI batteries and AC adapters appear under /sys/class/power_supply.
/proc/<pid>/maps lists file mappings, and a process killed by a fault
names the file and offset it died in. r8169 gets a 256-entry RX ring.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

kernel/dev/kbd.c

@@ -1,6 +1,7 @@
 #include "core/types.h"
 #include "arch/x86.h"
 #include "core/defs.h"
+#include "core/spinlock.h"
 #include "dev/kbd.h"
 #include "uapi/posix.h"
 #include "dev/vt.h"   /* NVT -- how many terminals the chords reach */
@@ -99,6 +100,104 @@ queue_utf8(uint32 cp)
   return pend[pend_i++];
 }
 
+// --- the lock keys and their lights -------------------------------------------
+//
+// Caps, Num and Scroll Lock are one state for the machine, whichever keyboard
+// pressed them -- the laptop's own and a USB one agree -- and the lights on
+// every keyboard show it. They never did: caps lock worked and its light
+// stayed dark. Under X the server keeps its own lock state and sets the
+// lights through /dev/input (see inputwrite), so these are left to it while
+// it holds the keyboard.
+
+static uint kbd_locks;          // CAPSLOCK | NUMLOCK | SCROLLLOCK
+static uint lock_held;          // lock keys down now: a held key repeats
+static struct spinlock ledlock;
+static int ledlock_ready;
+
+// The PS/2 side is a two-byte command, 0xED and the lights, and each byte
+// must be acknowledged (0xFA) before the next is sent. That cannot be waited
+// for here -- this runs in the keyboard's interrupt, and the acknowledgement
+// *is* a keyboard interrupt -- so the second byte goes out when kbdgetc sees
+// the first one acknowledged.
+static int led_want = -1;       // PS/2 light byte still to send
+static int led_stage;           // 0 idle, 1 0xED sent, 2 the byte sent
+static uint led_since;
+
+static void
+ps2_led_kick(void)
+{
+  if (led_stage != 0 && ticks - led_since > HZ)
+    led_stage = 0;              // no keyboard answered: start over
+  if (led_stage == 0 && led_want >= 0 && !(inb(KBSTATP) & 0x02)) {
+    outb(KBDATAP, 0xED);
+    led_stage = 1;
+    led_since = ticks;
+  }
+}
+
+// Show `locks` on every keyboard.
+void
+kbd_set_leds(uint locks)
+{
+  if (!ledlock_ready) {
+    initlock(&ledlock, "kbdled");
+    ledlock_ready = 1;
+  }
+  acquire(&ledlock);
+  led_want = ((locks & SCROLLLOCK) ? 1 : 0) | ((locks & NUMLOCK) ? 2 : 0) |
+             ((locks & CAPSLOCK) ? 4 : 0);
+  ps2_led_kick();
+  release(&ledlock);
+  // USB numbers them the other way round: Num, Caps, Scroll.
+  hid_leds_want(((locks & NUMLOCK) ? 1 : 0) | ((locks & CAPSLOCK) ? 2 : 0) |
+                ((locks & SCROLLLOCK) ? 4 : 0));
+}
+
+// A lock key pressed, on any keyboard. `down` 0 is its release.
+void
+kbd_lock_key(uint lock, int down)
+{
+  if (!down) {
+    lock_held &= ~lock;
+    return;
+  }
+  if (lock_held & lock)
+    return;                     // the keyboard's repeat, not a new press
+  lock_held |= lock;
+  kbd_locks ^= lock;
+  if (!input_is_grabbed(INPUT_KBD))
+    kbd_set_leds(kbd_locks);
+}
+
+uint
+kbd_lock_state(void)
+{
+  return kbd_locks;
+}
+
+// 0xFA and 0xFE from the keyboard: answers to a light command, not keys.
+static int
+ps2_led_answer(uint data)
+{
+  if (led_stage == 0 || (data != 0xFA && data != 0xFE))
+    return 0;
+  if (!ledlock_ready)
+    return 0;
+  acquire(&ledlock);
+  if (data == 0xFE) {
+    led_stage = 0;              // "resend": try again with the next change
+  } else if (led_stage == 1 && led_want >= 0) {
+    outb(KBDATAP, (uchar)led_want);
+    led_want = -1;
+    led_stage = 2;
+  } else {
+    led_stage = 0;
+    ps2_led_kick();             // changed again meanwhile
+  }
+  release(&ledlock);
+  return 1;
+}
+
 int
 kbdgetc(void)
 {
@@ -119,6 +218,9 @@ kbdgetc(void)
 
   data = inb(KBDATAP);
 
+  if(ps2_led_answer(data))
+    return 0;
+
   if(data == 0xE0){
     shift |= E0ESC;
     return 0;
@@ -137,9 +239,10 @@ kbdgetc(void)
     if(data & 0x80){
       data = (shift & E0ESC ? data : data & 0x7F);
       shift &= ~(shiftcode[data] | E0ESC);
+      if(togglecode[data]) kbd_lock_key(togglecode[data], 0);
     } else {
       shift |= shiftcode[data];
-      shift ^= togglecode[data];
+      if(togglecode[data]) kbd_lock_key(togglecode[data], 1);
     }
     return 0;
   }
@@ -147,6 +250,7 @@ kbdgetc(void)
   if(data & 0x80){
     data = (shift & E0ESC ? data : data & 0x7F);
     shift &= ~(shiftcode[data] | E0ESC);
+    if(togglecode[data]) kbd_lock_key(togglecode[data], 0);
     return 0;
   } else if(shift & E0ESC){
     data |= 0x80;
@@ -154,7 +258,9 @@ kbdgetc(void)
   }
 
   shift |= shiftcode[data];
-  shift ^= togglecode[data];
+  if(togglecode[data]) kbd_lock_key(togglecode[data], 1);
+  // The locks are the machine's, not this keyboard's: see kbd_lock_key().
+  shift = (shift & ~(CAPSLOCK | NUMLOCK | SCROLLLOCK)) | kbd_locks;
 
   // The switch chord, before the character tables, because there is no
   // character to look up: it is a combination that means "show me a different