4 files changed, 35 insertions, 18 deletions

diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index aaffaecffcd1..ba8ccfede964 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -111,8 +111,6 @@ int kgdb_arch_handle_exception(int exception_vector, int signo,
         case 'D':
         case 'k':
         case 'c':
-                kgdb_contthread = NULL;
-
                 /*
                  * Try to read optional parameter, pc unchanged if no parm.
                  * If this was a compiled breakpoint, we need to move
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index 8f6d58ede33c..6e152c80cd4a 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -236,8 +236,7 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 
                 atomic_set(&kgdb_cpu_doing_single_step, -1);
                 if (remcom_in_buffer[0] == 's')
-                        if (kgdb_contthread)
-                                atomic_set(&kgdb_cpu_doing_single_step, cpu);
+                        atomic_set(&kgdb_cpu_doing_single_step, cpu);
 
                 return 0;
         }
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index b4fdf2f2743c..fe8f71dd0b3f 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -347,9 +347,8 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
                         linux_regs->msr |= MSR_SE;
 #endif
                         kgdb_single_step = 1;
-                        if (kgdb_contthread)
-                                atomic_set(&kgdb_cpu_doing_single_step,
-                                           raw_smp_processor_id());
+                        atomic_set(&kgdb_cpu_doing_single_step,
+                                   raw_smp_processor_id());
                 }
                 return 0;
         }
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index f47f0eb886b8..8282a2139681 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -69,6 +69,9 @@ static int gdb_x86vector = -1;
  */
 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 {
+#ifndef CONFIG_X86_32
+        u32 *gdb_regs32 = (u32 *)gdb_regs;
+#endif
         gdb_regs[GDB_AX]        = regs->ax;
         gdb_regs[GDB_BX]        = regs->bx;
         gdb_regs[GDB_CX]        = regs->cx;
@@ -76,9 +79,9 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
         gdb_regs[GDB_SI]        = regs->si;
         gdb_regs[GDB_DI]        = regs->di;
         gdb_regs[GDB_BP]        = regs->bp;
-        gdb_regs[GDB_PS]        = regs->flags;
         gdb_regs[GDB_PC]        = regs->ip;
 #ifdef CONFIG_X86_32
+        gdb_regs[GDB_PS]        = regs->flags;
         gdb_regs[GDB_DS]        = regs->ds;
         gdb_regs[GDB_ES]        = regs->es;
         gdb_regs[GDB_CS]        = regs->cs;
@@ -94,6 +97,9 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
         gdb_regs[GDB_R13]       = regs->r13;
         gdb_regs[GDB_R14]       = regs->r14;
         gdb_regs[GDB_R15]       = regs->r15;
+        gdb_regs32[GDB_PS]      = regs->flags;
+        gdb_regs32[GDB_CS]      = regs->cs;
+        gdb_regs32[GDB_SS]      = regs->ss;
 #endif
         gdb_regs[GDB_SP]        = regs->sp;
 }
@@ -112,6 +118,9 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
  */
 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 {
+#ifndef CONFIG_X86_32
+        u32 *gdb_regs32 = (u32 *)gdb_regs;
+#endif
         gdb_regs[GDB_AX]        = 0;
         gdb_regs[GDB_BX]        = 0;
         gdb_regs[GDB_CX]        = 0;
@@ -129,8 +138,10 @@ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
         gdb_regs[GDB_FS]        = 0xFFFF;
         gdb_regs[GDB_GS]        = 0xFFFF;
 #else
-        gdb_regs[GDB_PS]        = *(unsigned long *)(p->thread.sp + 8);
-        gdb_regs[GDB_PC]        = 0;
+        gdb_regs32[GDB_PS]      = *(unsigned long *)(p->thread.sp + 8);
+        gdb_regs32[GDB_CS]      = __KERNEL_CS;
+        gdb_regs32[GDB_SS]      = __KERNEL_DS;
+        gdb_regs[GDB_PC]        = p->thread.ip;
         gdb_regs[GDB_R8]        = 0;
         gdb_regs[GDB_R9]        = 0;
         gdb_regs[GDB_R10]       = 0;
@@ -153,6 +164,9 @@ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
  */
 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 {
+#ifndef CONFIG_X86_32
+        u32 *gdb_regs32 = (u32 *)gdb_regs;
+#endif
         regs->ax                = gdb_regs[GDB_AX];
         regs->bx                = gdb_regs[GDB_BX];
         regs->cx                = gdb_regs[GDB_CX];
@@ -160,9 +174,9 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
         regs->si                = gdb_regs[GDB_SI];
         regs->di                = gdb_regs[GDB_DI];
         regs->bp                = gdb_regs[GDB_BP];
-        regs->flags             = gdb_regs[GDB_PS];
         regs->ip                = gdb_regs[GDB_PC];
 #ifdef CONFIG_X86_32
+        regs->flags             = gdb_regs[GDB_PS];
         regs->ds                = gdb_regs[GDB_DS];
         regs->es                = gdb_regs[GDB_ES];
         regs->cs                = gdb_regs[GDB_CS];
@@ -175,6 +189,9 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
         regs->r13               = gdb_regs[GDB_R13];
         regs->r14               = gdb_regs[GDB_R14];
         regs->r15               = gdb_regs[GDB_R15];
+        regs->flags             = gdb_regs32[GDB_PS];
+        regs->cs                = gdb_regs32[GDB_CS];
+        regs->ss                = gdb_regs32[GDB_SS];
 #endif
 }
 
@@ -378,10 +395,8 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
                 if (remcomInBuffer[0] == 's') {
                         linux_regs->flags |= X86_EFLAGS_TF;
                         kgdb_single_step = 1;
-                        if (kgdb_contthread) {
-                                atomic_set(&kgdb_cpu_doing_single_step,
-                                           raw_smp_processor_id());
-                        }
+                        atomic_set(&kgdb_cpu_doing_single_step,
+                                   raw_smp_processor_id());
                 }
 
                 get_debugreg(dr6, 6);
@@ -466,9 +481,15 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 
         case DIE_DEBUG:
                 if (atomic_read(&kgdb_cpu_doing_single_step) ==
-                        raw_smp_processor_id() &&
-                        user_mode(regs))
-                        return single_step_cont(regs, args);
+                    raw_smp_processor_id()) {
+                        if (user_mode(regs))
+                                return single_step_cont(regs, args);
+                        break;
+                } else if (test_thread_flag(TIF_SINGLESTEP))
+                        /* This means a user thread is single stepping
+                         * a system call which should be ignored
+                         */
+                        return NOTIFY_DONE;
                 /* fall through */
         default:
                 if (user_mode(regs))