x86: x86-32 thread_struct.debugreg

This replaces the debugreg[7] member of thread_struct with individual
members debugreg0, etc.  This saves two words for the dummies 4 and 5,
and harmonizes the code between 32 and 64.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

4 files changed, 48 insertions, 20 deletions

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 53406461074f..3744cf63682c 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -445,7 +445,12 @@ void flush_thread(void)
 {
         struct task_struct *tsk = current;
 
-        memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
+        tsk->thread.debugreg0 = 0;
+        tsk->thread.debugreg1 = 0;
+        tsk->thread.debugreg2 = 0;
+        tsk->thread.debugreg3 = 0;
+        tsk->thread.debugreg6 = 0;
+        tsk->thread.debugreg7 = 0;
         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));        
         clear_tsk_thread_flag(tsk, TIF_DEBUG);
         /*
@@ -522,7 +527,6 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
  */
 void dump_thread(struct pt_regs * regs, struct user * dump)
 {
-        int i;
         u16 gs;
 
 /* changed the size calculations - should hopefully work better. lbt */
@@ -533,8 +537,14 @@ void dump_thread(struct pt_regs * regs, struct user * dump)
         dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
         dump->u_dsize -= dump->u_tsize;
         dump->u_ssize = 0;
-        for (i = 0; i < 8; i++)
-                dump->u_debugreg[i] = current->thread.debugreg[i];  
+        dump->u_debugreg[0] = current->thread.debugreg0;
+        dump->u_debugreg[1] = current->thread.debugreg1;
+        dump->u_debugreg[2] = current->thread.debugreg2;
+        dump->u_debugreg[3] = current->thread.debugreg3;
+        dump->u_debugreg[4] = 0;
+        dump->u_debugreg[5] = 0;
+        dump->u_debugreg[6] = current->thread.debugreg6;
+        dump->u_debugreg[7] = current->thread.debugreg7;
 
         if (dump->start_stack < TASK_SIZE)
                 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
@@ -612,13 +622,13 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
                 wrmsr(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr, 0);
 
         if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
-                set_debugreg(next->debugreg[0], 0);
-                set_debugreg(next->debugreg[1], 1);
-                set_debugreg(next->debugreg[2], 2);
-                set_debugreg(next->debugreg[3], 3);
+                set_debugreg(next->debugreg0, 0);
+                set_debugreg(next->debugreg1, 1);
+                set_debugreg(next->debugreg2, 2);
+                set_debugreg(next->debugreg3, 3);
                 /* no 4 and 5 */
-                set_debugreg(next->debugreg[6], 6);
-                set_debugreg(next->debugreg[7], 7);
+                set_debugreg(next->debugreg6, 6);
+                set_debugreg(next->debugreg7, 7);
         }
 
 #ifdef CONFIG_SECCOMP
@@ -869,4 +879,3 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
         unsigned long range_end = mm->brk + 0x02000000;
         return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
 }
-
diff --git a/arch/x86/kernel/ptrace_32.c b/arch/x86/kernel/ptrace_32.c
index 26071305de2c..fed83d066135 100644
--- a/arch/x86/kernel/ptrace_32.c
+++ b/arch/x86/kernel/ptrace_32.c
@@ -133,19 +133,39 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
  */
 static unsigned long ptrace_get_debugreg(struct task_struct *child, int n)
 {
-        return child->thread.debugreg[n];
+        switch (n) {
+        case 0:         return child->thread.debugreg0;
+        case 1:         return child->thread.debugreg1;
+        case 2:         return child->thread.debugreg2;
+        case 3:         return child->thread.debugreg3;
+        case 6:         return child->thread.debugreg6;
+        case 7:         return child->thread.debugreg7;
+        }
+        return 0;
 }
 
 static int ptrace_set_debugreg(struct task_struct *child,
                                int n, unsigned long data)
 {
+        int i;
+
         if (unlikely(n == 4 || n == 5))
                 return -EIO;
 
         if (n < 4 && unlikely(data >= TASK_SIZE - 3))
                 return -EIO;
 
-        if (n == 7) {
+        switch (n) {
+        case 0:         child->thread.debugreg0 = data; break;
+        case 1:         child->thread.debugreg1 = data; break;
+        case 2:         child->thread.debugreg2 = data; break;
+        case 3:         child->thread.debugreg3 = data; break;
+
+        case 6:
+                child->thread.debugreg6 = data;
+                break;
+
+        case 7:
                 /*
                  * Sanity-check data. Take one half-byte at once with
                  * check = (val >> (16 + 4*i)) & 0xf. It contains the
@@ -176,19 +196,18 @@ static int ptrace_set_debugreg(struct task_struct *child,
                  * 64-bit kernel), so the x86_64 mask value is 0x5454.
                  * See the AMD manual no. 24593 (AMD64 System Programming)
                  */
-                int i;
                 data &= ~DR_CONTROL_RESERVED;
                 for (i = 0; i < 4; i++)
                         if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
                                 return -EIO;
+                child->thread.debugreg7 = data;
                 if (data)
                         set_tsk_thread_flag(child, TIF_DEBUG);
                 else
                         clear_tsk_thread_flag(child, TIF_DEBUG);
+                break;
         }
 
-        child->thread.debugreg[n] = data;
-
         return 0;
 }
 
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index 64cb3c05de69..2bf5c9aed106 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -605,8 +605,8 @@ static void fastcall do_signal(struct pt_regs *regs)
                  * have been cleared if the watchpoint triggered
                  * inside the kernel.
                  */
-                if (unlikely(current->thread.debugreg[7]))
-                        set_debugreg(current->thread.debugreg[7], 7);
+                if (unlikely(current->thread.debugreg7))
+                        set_debugreg(current->thread.debugreg7, 7);
 
                 /* Whee!  Actually deliver the signal.  */
                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 931ef10960ee..27713553cc59 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -852,7 +852,7 @@ fastcall void __kprobes do_debug(struct pt_regs * regs, long error_code)
 
         /* Mask out spurious debug traps due to lazy DR7 setting */
         if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
-                if (!tsk->thread.debugreg[7])
+                if (!tsk->thread.debugreg7)
                         goto clear_dr7;
         }
 
@@ -860,7 +860,7 @@ fastcall void __kprobes do_debug(struct pt_regs * regs, long error_code)
                 goto debug_vm86;
 
         /* Save debug status register where ptrace can see it */
-        tsk->thread.debugreg[6] = condition;
+        tsk->thread.debugreg6 = condition;
 
         /*
          * Single-stepping through TF: make sure we ignore any events in