1 files changed, 179 insertions, 62 deletions

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8d82a77a3f3b..b2258ca91003 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -42,7 +42,9 @@
 #include <linux/init.h>
 #include <linux/smp.h>
 #include <linux/nmi.h>
+#include <linux/hw_breakpoint.h>
 
+#include <asm/debugreg.h>
 #include <asm/apicdef.h>
 #include <asm/system.h>
 
@@ -85,10 +87,15 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
         gdb_regs[GDB_DS]        = regs->ds;
         gdb_regs[GDB_ES]        = regs->es;
         gdb_regs[GDB_CS]        = regs->cs;
-        gdb_regs[GDB_SS]        = __KERNEL_DS;
         gdb_regs[GDB_FS]        = 0xFFFF;
         gdb_regs[GDB_GS]        = 0xFFFF;
-        gdb_regs[GDB_SP]        = (int)&regs->sp;
+        if (user_mode_vm(regs)) {
+                gdb_regs[GDB_SS] = regs->ss;
+                gdb_regs[GDB_SP] = regs->sp;
+        } else {
+                gdb_regs[GDB_SS] = __KERNEL_DS;
+                gdb_regs[GDB_SP] = kernel_stack_pointer(regs);
+        }
 #else
         gdb_regs[GDB_R8]        = regs->r8;
         gdb_regs[GDB_R9]        = regs->r9;
@@ -101,7 +108,7 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
         gdb_regs32[GDB_PS]      = regs->flags;
         gdb_regs32[GDB_CS]      = regs->cs;
         gdb_regs32[GDB_SS]      = regs->ss;
-        gdb_regs[GDB_SP]        = regs->sp;
+        gdb_regs[GDB_SP]        = kernel_stack_pointer(regs);
 #endif
 }
 
@@ -198,41 +205,81 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 
 static struct hw_breakpoint {
         unsigned                enabled;
-        unsigned                type;
-        unsigned                len;
         unsigned long           addr;
+        int                     len;
+        int                     type;
+        struct perf_event       **pev;
 } breakinfo[4];
 
 static void kgdb_correct_hw_break(void)
 {
-        unsigned long dr7;
-        int correctit = 0;
-        int breakbit;
         int breakno;
 
-        get_debugreg(dr7, 7);
         for (breakno = 0; breakno < 4; breakno++) {
-                breakbit = 2 << (breakno << 1);
-                if (!(dr7 & breakbit) && breakinfo[breakno].enabled) {
-                        correctit = 1;
-                        dr7 |= breakbit;
-                        dr7 &= ~(0xf0000 << (breakno << 2));
-                        dr7 |= ((breakinfo[breakno].len << 2) |
-                                 breakinfo[breakno].type) <<
-                               ((breakno << 2) + 16);
-                        if (breakno >= 0 && breakno <= 3)
-                                set_debugreg(breakinfo[breakno].addr, breakno);
-
-                } else {
-                        if ((dr7 & breakbit) && !breakinfo[breakno].enabled) {
-                                correctit = 1;
-                                dr7 &= ~breakbit;
-                                dr7 &= ~(0xf0000 << (breakno << 2));
-                        }
-                }
+                struct perf_event *bp;
+                struct arch_hw_breakpoint *info;
+                int val;
+                int cpu = raw_smp_processor_id();
+                if (!breakinfo[breakno].enabled)
+                        continue;
+                bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
+                info = counter_arch_bp(bp);
+                if (bp->attr.disabled != 1)
+                        continue;
+                bp->attr.bp_addr = breakinfo[breakno].addr;
+                bp->attr.bp_len = breakinfo[breakno].len;
+                bp->attr.bp_type = breakinfo[breakno].type;
+                info->address = breakinfo[breakno].addr;
+                info->len = breakinfo[breakno].len;
+                info->type = breakinfo[breakno].type;
+                val = arch_install_hw_breakpoint(bp);
+                if (!val)
+                        bp->attr.disabled = 0;
         }
-        if (correctit)
-                set_debugreg(dr7, 7);
+        hw_breakpoint_restore();
+}
+
+static int hw_break_reserve_slot(int breakno)
+{
+        int cpu;
+        int cnt = 0;
+        struct perf_event **pevent;
+
+        for_each_online_cpu(cpu) {
+                cnt++;
+                pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+                if (dbg_reserve_bp_slot(*pevent))
+                        goto fail;
+        }
+
+        return 0;
+
+fail:
+        for_each_online_cpu(cpu) {
+                cnt--;
+                if (!cnt)
+                        break;
+                pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+                dbg_release_bp_slot(*pevent);
+        }
+        return -1;
+}
+
+static int hw_break_release_slot(int breakno)
+{
+        struct perf_event **pevent;
+        int cpu;
+
+        for_each_online_cpu(cpu) {
+                pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+                if (dbg_release_bp_slot(*pevent))
+                        /*
+                         * The debugger is responisble for handing the retry on
+                         * remove failure.
+                         */
+                        return -1;
+        }
+        return 0;
 }
 
 static int
@@ -246,6 +293,10 @@ kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
         if (i == 4)
                 return -1;
 
+        if (hw_break_release_slot(i)) {
+                printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
+                return -1;
+        }
         breakinfo[i].enabled = 0;
 
         return 0;
@@ -254,15 +305,23 @@ kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 static void kgdb_remove_all_hw_break(void)
 {
         int i;
+        int cpu = raw_smp_processor_id();
+        struct perf_event *bp;
 
-        for (i = 0; i < 4; i++)
-                memset(&breakinfo[i], 0, sizeof(struct hw_breakpoint));
+        for (i = 0; i < 4; i++) {
+                if (!breakinfo[i].enabled)
+                        continue;
+                bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
+                if (bp->attr.disabled == 1)
+                        continue;
+                arch_uninstall_hw_breakpoint(bp);
+                bp->attr.disabled = 1;
+        }
 }
 
 static int
 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 {
-        unsigned type;
         int i;
 
         for (i = 0; i < 4; i++)
@@ -273,27 +332,42 @@ kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 
         switch (bptype) {
         case BP_HARDWARE_BREAKPOINT:
-                type = 0;
-                len  = 1;
+                len = 1;
+                breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
                 break;
         case BP_WRITE_WATCHPOINT:
-                type = 1;
+                breakinfo[i].type = X86_BREAKPOINT_WRITE;
                 break;
         case BP_ACCESS_WATCHPOINT:
-                type = 3;
+                breakinfo[i].type = X86_BREAKPOINT_RW;
                 break;
         default:
                 return -1;
         }
-
-        if (len == 1 || len == 2 || len == 4)
-                breakinfo[i].len  = len - 1;
-        else
+        switch (len) {
+        case 1:
+                breakinfo[i].len = X86_BREAKPOINT_LEN_1;
+                break;
+        case 2:
+                breakinfo[i].len = X86_BREAKPOINT_LEN_2;
+                break;
+        case 4:
+                breakinfo[i].len = X86_BREAKPOINT_LEN_4;
+                break;
+#ifdef CONFIG_X86_64
+        case 8:
+                breakinfo[i].len = X86_BREAKPOINT_LEN_8;
+                break;
+#endif
+        default:
                 return -1;
-
-        breakinfo[i].enabled = 1;
+        }
         breakinfo[i].addr = addr;
-        breakinfo[i].type = type;
+        if (hw_break_reserve_slot(i)) {
+                breakinfo[i].addr = 0;
+                return -1;
+        }
+        breakinfo[i].enabled = 1;
 
         return 0;
 }
@@ -308,8 +382,21 @@ kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
  */
 void kgdb_disable_hw_debug(struct pt_regs *regs)
 {
+        int i;
+        int cpu = raw_smp_processor_id();
+        struct perf_event *bp;
+
         /* Disable hardware debugging while we are in kgdb: */
         set_debugreg(0UL, 7);
+        for (i = 0; i < 4; i++) {
+                if (!breakinfo[i].enabled)
+                        continue;
+                bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
+                if (bp->attr.disabled == 1)
+                        continue;
+                arch_uninstall_hw_breakpoint(bp);
+                bp->attr.disabled = 1;
+        }
 }
 
 /**
@@ -373,7 +460,6 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
                                struct pt_regs *linux_regs)
 {
         unsigned long addr;
-        unsigned long dr6;
         char *ptr;
         int newPC;
 
@@ -395,25 +481,10 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
                 /* set the trace bit if we're stepping */
                 if (remcomInBuffer[0] == 's') {
                         linux_regs->flags |= X86_EFLAGS_TF;
-                        kgdb_single_step = 1;
                         atomic_set(&kgdb_cpu_doing_single_step,
                                    raw_smp_processor_id());
                 }
 
-                get_debugreg(dr6, 6);
-                if (!(dr6 & 0x4000)) {
-                        int breakno;
-
-                        for (breakno = 0; breakno < 4; breakno++) {
-                                if (dr6 & (1 << breakno) &&
-                                    breakinfo[breakno].type == 0) {
-                                        /* Set restore flag: */
-                                        linux_regs->flags |= X86_EFLAGS_RF;
-                                        break;
-                                }
-                        }
-                }
-                set_debugreg(0UL, 6);
                 kgdb_correct_hw_break();
 
                 return 0;
@@ -434,6 +505,11 @@ single_step_cont(struct pt_regs *regs, struct die_args *args)
                         "resuming...\n");
         kgdb_arch_handle_exception(args->trapnr, args->signr,
                                    args->err, "c", "", regs);
+        /*
+         * Reset the BS bit in dr6 (pointed by args->err) to
+         * denote completion of processing
+         */
+        (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
 
         return NOTIFY_STOP;
 }
@@ -476,8 +552,7 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
                 break;
 
         case DIE_DEBUG:
-                if (atomic_read(&kgdb_cpu_doing_single_step) ==
-                    raw_smp_processor_id()) {
+                if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
                         if (user_mode(regs))
                                 return single_step_cont(regs, args);
                         break;
@@ -530,7 +605,42 @@ static struct notifier_block kgdb_notifier = {
  */
 int kgdb_arch_init(void)
 {
-        return register_die_notifier(&kgdb_notifier);
+        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
+         * complete.
+         */
+        hw_breakpoint_init(&attr);
+        attr.bp_addr = (unsigned long)kgdb_arch_init;
+        attr.bp_len = HW_BREAKPOINT_LEN_1;
+        attr.bp_type = HW_BREAKPOINT_W;
+        attr.disabled = 1;
+        for (i = 0; i < 4; i++) {
+                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");
+                        breakinfo[i].pev = NULL;
+                        kgdb_arch_exit();
+                        return -1;
+                }
+                for_each_online_cpu(cpu) {
+                        pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
+                        pevent[0]->hw.sample_period = 1;
+                        if (pevent[0]->destroy != NULL) {
+                                pevent[0]->destroy = NULL;
+                                release_bp_slot(*pevent);
+                        }
+                }
+        }
+        return ret;
 }
 
 /**
@@ -541,6 +651,13 @@ int kgdb_arch_init(void)
  */
 void kgdb_arch_exit(void)
 {
+        int i;
+        for (i = 0; i < 4; i++) {
+                if (breakinfo[i].pev) {
+                        unregister_wide_hw_breakpoint(breakinfo[i].pev);
+                        breakinfo[i].pev = NULL;
+                }
+        }
         unregister_die_notifier(&kgdb_notifier);
 }