Merge tag 'for_linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb
Pull KGDB/KDB updates from Jason Wessel:
"Fixes:
- Fix KDB keyboard repeat scan codes and leaked keyboard events
- Fix kernel crash with kdb_printf() for users who compile new
kdb_printf()'s in early code
- Return all segment registers to gdb on x86_64
Features:
- KDB/KGDB hook the reboot notifier and end user can control if it
stops, detaches or does nothing (updated docs as well)
- Notify users who use CONFIG_DEBUG_RODATA to use hw breakpoints"
* tag 'for_linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
kdb: Add message about CONFIG_DEBUG_RODATA on failure to install breakpoint
kdb: Avoid using dbg_io_ops until it is initialized
kgdb,debug_core: add the ability to control the reboot notifier
KDB: Fix usability issues relating to the 'enter' key.
kgdb,debug-core,gdbstub: Hook the reboot notifier for debugger detach
kgdb: Respect that flush op is optional
kgdb: x86: Return all segment registers also in 64-bit mode
diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl
index d71b57f..4ee4ba3 100644
--- a/Documentation/DocBook/kgdb.tmpl
+++ b/Documentation/DocBook/kgdb.tmpl
@@ -362,6 +362,23 @@
</para>
</para>
</sect1>
+ <sect1 id="kgdbreboot">
+ <title>Run time parameter: kgdbreboot</title>
+ <para> The kgdbreboot feature allows you to change how the debugger
+ deals with the reboot notification. You have 3 choices for the
+ behavior. The default behavior is always set to 0.</para>
+ <orderedlist>
+ <listitem><para>echo -1 > /sys/module/debug_core/parameters/kgdbreboot</para>
+ <para>Ignore the reboot notification entirely.</para>
+ </listitem>
+ <listitem><para>echo 0 > /sys/module/debug_core/parameters/kgdbreboot</para>
+ <para>Send the detach message to any attached debugger client.</para>
+ </listitem>
+ <listitem><para>echo 1 > /sys/module/debug_core/parameters/kgdbreboot</para>
+ <para>Enter the debugger on reboot notify.</para>
+ </listitem>
+ </orderedlist>
+ </sect1>
</chapter>
<chapter id="usingKDB">
<title>Using kdb</title>
diff --git a/arch/x86/include/asm/kgdb.h b/arch/x86/include/asm/kgdb.h
index 77e95f5..332f98c 100644
--- a/arch/x86/include/asm/kgdb.h
+++ b/arch/x86/include/asm/kgdb.h
@@ -64,11 +64,15 @@
GDB_PS, /* 17 */
GDB_CS, /* 18 */
GDB_SS, /* 19 */
+ GDB_DS, /* 20 */
+ GDB_ES, /* 21 */
+ GDB_FS, /* 22 */
+ GDB_GS, /* 23 */
};
#define GDB_ORIG_AX 57
-#define DBG_MAX_REG_NUM 20
-/* 17 64 bit regs and 3 32 bit regs */
-#define NUMREGBYTES ((17 * 8) + (3 * 4))
+#define DBG_MAX_REG_NUM 24
+/* 17 64 bit regs and 5 32 bit regs */
+#define NUMREGBYTES ((17 * 8) + (5 * 4))
#endif /* ! CONFIG_X86_32 */
static inline void arch_kgdb_breakpoint(void)
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index faba577..fdc37b3 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -67,8 +67,6 @@
{ "ss", 4, offsetof(struct pt_regs, ss) },
{ "ds", 4, offsetof(struct pt_regs, ds) },
{ "es", 4, offsetof(struct pt_regs, es) },
- { "fs", 4, -1 },
- { "gs", 4, -1 },
#else
{ "ax", 8, offsetof(struct pt_regs, ax) },
{ "bx", 8, offsetof(struct pt_regs, bx) },
@@ -90,7 +88,11 @@
{ "flags", 4, offsetof(struct pt_regs, flags) },
{ "cs", 4, offsetof(struct pt_regs, cs) },
{ "ss", 4, offsetof(struct pt_regs, ss) },
+ { "ds", 4, -1 },
+ { "es", 4, -1 },
#endif
+ { "fs", 4, -1 },
+ { "gs", 4, -1 },
};
int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0d7c087..3f88a45 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -41,6 +41,7 @@
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/sysrq.h>
+#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/kgdb.h>
#include <linux/kdb.h>
@@ -75,6 +76,8 @@
struct kgdb_io *dbg_io_ops;
static DEFINE_SPINLOCK(kgdb_registration_lock);
+/* Action for the reboot notifiter, a global allow kdb to change it */
+static int kgdbreboot;
/* kgdb console driver is loaded */
static int kgdb_con_registered;
/* determine if kgdb console output should be used */
@@ -96,6 +99,7 @@
early_param("kgdbcon", opt_kgdb_con);
module_param(kgdb_use_con, int, 0644);
+module_param(kgdbreboot, int, 0644);
/*
* Holds information about breakpoints in a kernel. These breakpoints are
@@ -784,6 +788,33 @@
kdb_init(KDB_INIT_FULL);
}
+static int
+dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x)
+{
+ /*
+ * Take the following action on reboot notify depending on value:
+ * 1 == Enter debugger
+ * 0 == [the default] detatch debug client
+ * -1 == Do nothing... and use this until the board resets
+ */
+ switch (kgdbreboot) {
+ case 1:
+ kgdb_breakpoint();
+ case -1:
+ goto done;
+ }
+ if (!dbg_kdb_mode)
+ gdbstub_exit(code);
+done:
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block dbg_reboot_notifier = {
+ .notifier_call = dbg_notify_reboot,
+ .next = NULL,
+ .priority = INT_MAX,
+};
+
static void kgdb_register_callbacks(void)
{
if (!kgdb_io_module_registered) {
@@ -791,6 +822,7 @@
kgdb_arch_init();
if (!dbg_is_early)
kgdb_arch_late();
+ register_reboot_notifier(&dbg_reboot_notifier);
atomic_notifier_chain_register(&panic_notifier_list,
&kgdb_panic_event_nb);
#ifdef CONFIG_MAGIC_SYSRQ
@@ -812,6 +844,7 @@
*/
if (kgdb_io_module_registered) {
kgdb_io_module_registered = 0;
+ unregister_reboot_notifier(&dbg_reboot_notifier);
atomic_notifier_chain_unregister(&panic_notifier_list,
&kgdb_panic_event_nb);
kgdb_arch_exit();
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index c22d8c2..ce615e0 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -1111,6 +1111,13 @@
unsigned char checksum, ch, buffer[3];
int loop;
+ if (!kgdb_connected)
+ return;
+ kgdb_connected = 0;
+
+ if (!dbg_io_ops || dbg_kdb_mode)
+ return;
+
buffer[0] = 'W';
buffer[1] = hex_asc_hi(status);
buffer[2] = hex_asc_lo(status);
@@ -1129,5 +1136,6 @@
dbg_io_ops->write_char(hex_asc_lo(checksum));
/* make sure the output is flushed, lest the bootloader clobber it */
- dbg_io_ops->flush();
+ if (dbg_io_ops->flush)
+ dbg_io_ops->flush();
}
diff --git a/kernel/debug/kdb/kdb_bp.c b/kernel/debug/kdb/kdb_bp.c
index 20059ef..8418c2f 100644
--- a/kernel/debug/kdb/kdb_bp.c
+++ b/kernel/debug/kdb/kdb_bp.c
@@ -153,6 +153,13 @@
} else {
kdb_printf("%s: failed to set breakpoint at 0x%lx\n",
__func__, bp->bp_addr);
+#ifdef CONFIG_DEBUG_RODATA
+ if (!bp->bp_type) {
+ kdb_printf("Software breakpoints are unavailable.\n"
+ " Change the kernel CONFIG_DEBUG_RODATA=n\n"
+ " OR use hw breaks: help bph\n");
+ }
+#endif
return 1;
}
return 0;
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 4802eb5..9b5f17d 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -689,7 +689,7 @@
if (!dbg_kdb_mode && kgdb_connected) {
gdbstub_msg_write(kdb_buffer, retlen);
} else {
- if (!dbg_io_ops->is_console) {
+ if (dbg_io_ops && !dbg_io_ops->is_console) {
len = strlen(kdb_buffer);
cp = kdb_buffer;
while (len--) {
diff --git a/kernel/debug/kdb/kdb_keyboard.c b/kernel/debug/kdb/kdb_keyboard.c
index 4bca634..118527a 100644
--- a/kernel/debug/kdb/kdb_keyboard.c
+++ b/kernel/debug/kdb/kdb_keyboard.c
@@ -25,6 +25,7 @@
#define KBD_STAT_MOUSE_OBF 0x20 /* Mouse output buffer full */
static int kbd_exists;
+static int kbd_last_ret;
/*
* Check if the keyboard controller has a keypress for us.
@@ -90,8 +91,11 @@
return -1;
}
- if ((scancode & 0x80) != 0)
+ if ((scancode & 0x80) != 0) {
+ if (scancode == 0x9c)
+ kbd_last_ret = 0;
return -1;
+ }
scancode &= 0x7f;
@@ -178,35 +182,82 @@
return -1; /* ignore unprintables */
}
- if ((scancode & 0x7f) == 0x1c) {
- /*
- * enter key. All done. Absorb the release scancode.
- */
- while ((inb(KBD_STATUS_REG) & KBD_STAT_OBF) == 0)
- ;
-
- /*
- * Fetch the scancode
- */
- scancode = inb(KBD_DATA_REG);
- scanstatus = inb(KBD_STATUS_REG);
-
- while (scanstatus & KBD_STAT_MOUSE_OBF) {
- scancode = inb(KBD_DATA_REG);
- scanstatus = inb(KBD_STATUS_REG);
- }
-
- if (scancode != 0x9c) {
- /*
- * Wasn't an enter-release, why not?
- */
- kdb_printf("kdb: expected enter got 0x%x status 0x%x\n",
- scancode, scanstatus);
- }
-
+ if (scancode == 0x1c) {
+ kbd_last_ret = 1;
return 13;
}
return keychar & 0xff;
}
EXPORT_SYMBOL_GPL(kdb_get_kbd_char);
+
+/*
+ * Best effort cleanup of ENTER break codes on leaving KDB. Called on
+ * exiting KDB, when we know we processed an ENTER or KP ENTER scan
+ * code.
+ */
+void kdb_kbd_cleanup_state(void)
+{
+ int scancode, scanstatus;
+
+ /*
+ * Nothing to clean up, since either
+ * ENTER was never pressed, or has already
+ * gotten cleaned up.
+ */
+ if (!kbd_last_ret)
+ return;
+
+ kbd_last_ret = 0;
+ /*
+ * Enter key. Need to absorb the break code here, lest it gets
+ * leaked out if we exit KDB as the result of processing 'g'.
+ *
+ * This has several interesting implications:
+ * + Need to handle KP ENTER, which has break code 0xe0 0x9c.
+ * + Need to handle repeat ENTER and repeat KP ENTER. Repeats
+ * only get a break code at the end of the repeated
+ * sequence. This means we can't propagate the repeated key
+ * press, and must swallow it away.
+ * + Need to handle possible PS/2 mouse input.
+ * + Need to handle mashed keys.
+ */
+
+ while (1) {
+ while ((inb(KBD_STATUS_REG) & KBD_STAT_OBF) == 0)
+ cpu_relax();
+
+ /*
+ * Fetch the scancode.
+ */
+ scancode = inb(KBD_DATA_REG);
+ scanstatus = inb(KBD_STATUS_REG);
+
+ /*
+ * Skip mouse input.
+ */
+ if (scanstatus & KBD_STAT_MOUSE_OBF)
+ continue;
+
+ /*
+ * If we see 0xe0, this is either a break code for KP
+ * ENTER, or a repeat make for KP ENTER. Either way,
+ * since the second byte is equivalent to an ENTER,
+ * skip the 0xe0 and try again.
+ *
+ * If we see 0x1c, this must be a repeat ENTER or KP
+ * ENTER (and we swallowed 0xe0 before). Try again.
+ *
+ * We can also see make and break codes for other keys
+ * mashed before or after pressing ENTER. Thus, if we
+ * see anything other than 0x9c, we have to try again.
+ *
+ * Note, if you held some key as ENTER was depressed,
+ * that break code would get leaked out.
+ */
+ if (scancode != 0x9c)
+ continue;
+
+ return;
+ }
+}
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index e2ae734..67b847d 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1400,6 +1400,9 @@
if (KDB_STATE(DOING_SS))
KDB_STATE_CLEAR(SSBPT);
+ /* Clean up any keyboard devices before leaving */
+ kdb_kbd_cleanup_state();
+
return result;
}
diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index e381d10..47c4e56 100644
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -246,6 +246,13 @@
extern void kdb_set_current_task(struct task_struct *);
extern struct task_struct *kdb_current_task;
+
+#ifdef CONFIG_KDB_KEYBOARD
+extern void kdb_kbd_cleanup_state(void);
+#else /* ! CONFIG_KDB_KEYBOARD */
+#define kdb_kbd_cleanup_state()
+#endif /* ! CONFIG_KDB_KEYBOARD */
+
#ifdef CONFIG_MODULES
extern struct list_head *kdb_modules;
#endif /* CONFIG_MODULES */