Merge branch 'dbg-early-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb

* 'dbg-early-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  echi-dbgp: Add kernel debugger support for the usb debug port
  earlyprintk,vga,kdb: Fix \b and \r for earlyprintk=vga with kdb
  kgdboc: Add ekgdboc for early use of the kernel debugger
  x86,early dr regs,kgdb: Allow kernel debugger early dr register access
  x86,kgdb: Implement early hardware breakpoint debugging
  x86, kgdb, init: Add early and late debug states
  x86, kgdb: early trap init for early debug

6 files changed, 76 insertions, 25 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 5a51379dcbe4..7e5c6a60b8ee 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -789,6 +789,8 @@ static inline void wbinvd_halt(void)
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);
 
+extern void early_trap_init(void);
+
 /* Defined in head.S */
 extern struct desc_ptr          early_gdt_descr;
 
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c1c00d0b1692..cc83a002786e 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1084,6 +1084,20 @@ static void clear_all_debug_regs(void)
         }
 }
 
+#ifdef CONFIG_KGDB
+/*
+ * Restore debug regs if using kgdbwait and you have a kernel debugger
+ * connection established.
+ */
+static void dbg_restore_debug_regs(void)
+{
+        if (unlikely(kgdb_connected && arch_kgdb_ops.correct_hw_break))
+                arch_kgdb_ops.correct_hw_break();
+}
+#else /* ! CONFIG_KGDB */
+#define dbg_restore_debug_regs()
+#endif /* ! CONFIG_KGDB */
+
 /*
  * cpu_init() initializes state that is per-CPU. Some data is already
  * initialized (naturally) in the bootstrap process, such as the GDT
@@ -1174,18 +1188,8 @@ void __cpuinit cpu_init(void)
         load_TR_desc();
         load_LDT(&init_mm.context);
 
-#ifdef CONFIG_KGDB
-        /*
-         * If the kgdb is connected no debug regs should be altered.  This
-         * is only applicable when KGDB and a KGDB I/O module are built
-         * into the kernel and you are using early debugging with
-         * kgdbwait. KGDB will control the kernel HW breakpoint registers.
-         */
-        if (kgdb_connected && arch_kgdb_ops.correct_hw_break)
-                arch_kgdb_ops.correct_hw_break();
-        else
-#endif
-                clear_all_debug_regs();
+        clear_all_debug_regs();
+        dbg_restore_debug_regs();
 
         fpu_init();
 
@@ -1239,6 +1243,7 @@ void __cpuinit cpu_init(void)
 #endif
 
         clear_all_debug_regs();
+        dbg_restore_debug_regs();
 
         /*
          * Force FPU initialization:
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index b9c830c12b4a..fa99bae75ace 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -41,6 +41,14 @@ static void early_vga_write(struct console *con, const char *str, unsigned n)
                                 writew(0x720, VGABASE + 2*(max_xpos*j + i));
                         current_ypos = max_ypos-1;
                 }
+#ifdef CONFIG_KGDB_KDB
+                if (c == '\b') {
+                        if (current_xpos > 0)
+                                current_xpos--;
+                } else if (c == '\r') {
+                        current_xpos = 0;
+                } else
+#endif
                 if (c == '\n') {
                         current_xpos = 0;
                         current_ypos++;
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 95b89d4cb8f1..4f4af75b9482 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -199,6 +199,8 @@ static struct hw_breakpoint {
         struct perf_event       **pev;
 } breakinfo[4];
 
+static unsigned long early_dr7;
+
 static void kgdb_correct_hw_break(void)
 {
         int breakno;
@@ -210,6 +212,14 @@ static void kgdb_correct_hw_break(void)
                 int cpu = raw_smp_processor_id();
                 if (!breakinfo[breakno].enabled)
                         continue;
+                if (dbg_is_early) {
+                        set_debugreg(breakinfo[breakno].addr, breakno);
+                        early_dr7 |= encode_dr7(breakno,
+                                                breakinfo[breakno].len,
+                                                breakinfo[breakno].type);
+                        set_debugreg(early_dr7, 7);
+                        continue;
+                }
                 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
                 info = counter_arch_bp(bp);
                 if (bp->attr.disabled != 1)
@@ -224,7 +234,8 @@ static void kgdb_correct_hw_break(void)
                 if (!val)
                         bp->attr.disabled = 0;
         }
-        hw_breakpoint_restore();
+        if (!dbg_is_early)
+                hw_breakpoint_restore();
 }
 
 static int hw_break_reserve_slot(int breakno)
@@ -233,6 +244,9 @@ static int hw_break_reserve_slot(int breakno)
         int cnt = 0;
         struct perf_event **pevent;
 
+        if (dbg_is_early)
+                return 0;
+
         for_each_online_cpu(cpu) {
                 cnt++;
                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
@@ -258,6 +272,9 @@ static int hw_break_release_slot(int breakno)
         struct perf_event **pevent;
         int cpu;
 
+        if (dbg_is_early)
+                return 0;
+
         for_each_online_cpu(cpu) {
                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
                 if (dbg_release_bp_slot(*pevent))
@@ -302,7 +319,11 @@ static void kgdb_remove_all_hw_break(void)
                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
                 if (bp->attr.disabled == 1)
                         continue;
-                arch_uninstall_hw_breakpoint(bp);
+                if (dbg_is_early)
+                        early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
+                                                 breakinfo[i].type);
+                else
+                        arch_uninstall_hw_breakpoint(bp);
                 bp->attr.disabled = 1;
         }
 }
@@ -379,6 +400,11 @@ void kgdb_disable_hw_debug(struct pt_regs *regs)
         for (i = 0; i < 4; i++) {
                 if (!breakinfo[i].enabled)
                         continue;
+                if (dbg_is_early) {
+                        early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
+                                                 breakinfo[i].type);
+                        continue;
+                }
                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
                 if (bp->attr.disabled == 1)
                         continue;
@@ -596,14 +622,15 @@ static struct notifier_block kgdb_notifier = {
  */
 int kgdb_arch_init(void)
 {
+        return register_die_notifier(&kgdb_notifier);
+}
+
+void kgdb_arch_late(void)
+{
         int i, cpu;
-        int ret;
         struct perf_event_attr attr;
         struct perf_event **pevent;
 
-        ret = register_die_notifier(&kgdb_notifier);
-        if (ret != 0)
-                return ret;
         /*
          * Pre-allocate the hw breakpoint structions in the non-atomic
          * portion of kgdb because this operation requires mutexs to
@@ -615,12 +642,15 @@ int kgdb_arch_init(void)
         attr.bp_type = HW_BREAKPOINT_W;
         attr.disabled = 1;
         for (i = 0; i < 4; i++) {
+                if (breakinfo[i].pev)
+                        continue;
                 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
                 if (IS_ERR(breakinfo[i].pev)) {
-                        printk(KERN_ERR "kgdb: Could not allocate hw breakpoints\n");
+                        printk(KERN_ERR "kgdb: Could not allocate hw"
+                               "breakpoints\nDisabling the kernel debugger\n");
                         breakinfo[i].pev = NULL;
                         kgdb_arch_exit();
-                        return -1;
+                        return;
                 }
                 for_each_online_cpu(cpu) {
                         pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
@@ -631,7 +661,6 @@ int kgdb_arch_init(void)
                         }
                 }
         }
-        return ret;
 }
 
 /**
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index c4851eff57b3..e8029896309a 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -725,6 +725,7 @@ void __init setup_arch(char **cmdline_p)
         /* VMI may relocate the fixmap; do this before touching ioremap area */
         vmi_init();
 
+        early_trap_init();
         early_cpu_init();
         early_ioremap_init();
 
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 7eaad4c5110a..142d70c74b02 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -808,6 +808,16 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 }
 #endif
 
+/* Set of traps needed for early debugging. */
+void __init early_trap_init(void)
+{
+        set_intr_gate_ist(1, &debug, DEBUG_STACK);
+        /* int3 can be called from all */
+        set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
+        set_intr_gate(14, &page_fault);
+        load_idt(&idt_descr);
+}
+
 void __init trap_init(void)
 {
         int i;
@@ -821,10 +831,7 @@ void __init trap_init(void)
 #endif
 
         set_intr_gate(0, &divide_error);
-        set_intr_gate_ist(1, &debug, DEBUG_STACK);
         set_intr_gate_ist(2, &nmi, NMI_STACK);
-        /* int3 can be called from all */
-        set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
         /* int4 can be called from all */
         set_system_intr_gate(4, &overflow);
         set_intr_gate(5, &bounds);
@@ -840,7 +847,6 @@ void __init trap_init(void)
         set_intr_gate(11, &segment_not_present);
         set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
         set_intr_gate(13, &general_protection);
-        set_intr_gate(14, &page_fault);
         set_intr_gate(15, &spurious_interrupt_bug);
         set_intr_gate(16, &coprocessor_error);
         set_intr_gate(17, &alignment_check);