powerpc: Hardware breakpoints rewrite to handle non DABR breakpoint registers

This is a rewrite so that we don't assume we are using the DABR throughout the
code.  We now use the arch_hw_breakpoint to store the breakpoint in a generic
manner in the thread_struct, rather than storing the raw DABR value.

The ptrace GET/SET_DEBUGREG interface currently passes the raw DABR in from
userspace.  We keep this functionality, so that future changes (like the POWER8
DAWR), will still fake the DABR to userspace.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 32 insertions, 28 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index c4970004d44d..d4afcccf1238 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -905,6 +905,9 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
         struct perf_event *bp;
         struct perf_event_attr attr;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
+#ifndef CONFIG_PPC_ADV_DEBUG_REGS
+        struct arch_hw_breakpoint hw_brk;
+#endif
 
         /* For ppc64 we support one DABR and no IABR's at the moment (ppc64).
          *  For embedded processors we support one DAC and no IAC's at the
@@ -931,14 +934,17 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
          */
 
         /* Ensure breakpoint translation bit is set */
-        if (data && !(data & DABR_TRANSLATION))
+        if (data && !(data & HW_BRK_TYPE_TRANSLATE))
                 return -EIO;
+        hw_brk.address = data & (~HW_BRK_TYPE_DABR);
+        hw_brk.type = (data & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
+        hw_brk.len = 8;
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
         if (ptrace_get_breakpoints(task) < 0)
                 return -ESRCH;
 
         bp = thread->ptrace_bps[0];
-        if ((!data) || !(data & (DABR_DATA_WRITE | DABR_DATA_READ))) {
+        if ((!data) || !(hw_brk.type & HW_BRK_TYPE_RDWR)) {
                 if (bp) {
                         unregister_hw_breakpoint(bp);
                         thread->ptrace_bps[0] = NULL;
@@ -948,10 +954,8 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
         }
         if (bp) {
                 attr = bp->attr;
-                attr.bp_addr = data & ~HW_BREAKPOINT_ALIGN;
-                arch_bp_generic_fields(data &
-                                        (DABR_DATA_WRITE | DABR_DATA_READ),
-                                                        &attr.bp_type);
+                attr.bp_addr = hw_brk.address;
+                arch_bp_generic_fields(hw_brk.type, &attr.bp_type);
 
                 /* Enable breakpoint */
                 attr.disabled = false;
@@ -963,16 +967,15 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
                 }
                 thread->ptrace_bps[0] = bp;
                 ptrace_put_breakpoints(task);
-                thread->dabr = data;
-                thread->dabrx = DABRX_ALL;
+                thread->hw_brk = hw_brk;
                 return 0;
         }
 
         /* Create a new breakpoint request if one doesn't exist already */
         hw_breakpoint_init(&attr);
-        attr.bp_addr = data & ~HW_BREAKPOINT_ALIGN;
-        arch_bp_generic_fields(data & (DABR_DATA_WRITE | DABR_DATA_READ),
-                                                                &attr.bp_type);
+        attr.bp_addr = hw_brk.address;
+        arch_bp_generic_fields(hw_brk.type,
+                               &attr.bp_type);
 
         thread->ptrace_bps[0] = bp = register_user_hw_breakpoint(&attr,
                                                ptrace_triggered, NULL, task);
@@ -985,10 +988,7 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
         ptrace_put_breakpoints(task);
 
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
-
-        /* Move contents to the DABR register */
-        task->thread.dabr = data;
-        task->thread.dabrx = DABRX_ALL;
+        task->thread.hw_brk = hw_brk;
 #else /* CONFIG_PPC_ADV_DEBUG_REGS */
         /* As described above, it was assumed 3 bits were passed with the data
          *  address, but we will assume only the mode bits will be passed
@@ -1349,7 +1349,7 @@ static long ppc_set_hwdebug(struct task_struct *child,
         struct perf_event_attr attr;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 #ifndef CONFIG_PPC_ADV_DEBUG_REGS
-        unsigned long dabr;
+        struct arch_hw_breakpoint brk;
 #endif
 
         if (bp_info->version != 1)
@@ -1397,12 +1397,12 @@ static long ppc_set_hwdebug(struct task_struct *child,
         if ((unsigned long)bp_info->addr >= TASK_SIZE)
                 return -EIO;
 
-        dabr = (unsigned long)bp_info->addr & ~7UL;
-        dabr |= DABR_TRANSLATION;
+        brk.address = bp_info->addr & ~7UL;
+        brk.type = HW_BRK_TYPE_TRANSLATE;
         if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
-                dabr |= DABR_DATA_READ;
+                brk.type |= HW_BRK_TYPE_READ;
         if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
-                dabr |= DABR_DATA_WRITE;
+                brk.type |= HW_BRK_TYPE_WRITE;
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
         if (ptrace_get_breakpoints(child) < 0)
                 return -ESRCH;
@@ -1427,8 +1427,7 @@ static long ppc_set_hwdebug(struct task_struct *child,
         hw_breakpoint_init(&attr);
         attr.bp_addr = (unsigned long)bp_info->addr & ~HW_BREAKPOINT_ALIGN;
         attr.bp_len = len;
-        arch_bp_generic_fields(dabr & (DABR_DATA_WRITE | DABR_DATA_READ),
-                                                                &attr.bp_type);
+        arch_bp_generic_fields(brk.type, &attr.bp_type);
 
         thread->ptrace_bps[0] = bp = register_user_hw_breakpoint(&attr,
                                                ptrace_triggered, NULL, child);
@@ -1445,11 +1444,10 @@ static long ppc_set_hwdebug(struct task_struct *child,
         if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
                 return -EINVAL;
 
-        if (child->thread.dabr)
+        if (child->thread.hw_brk.address)
                 return -ENOSPC;
 
-        child->thread.dabr = dabr;
-        child->thread.dabrx = DABRX_ALL;
+        child->thread.hw_brk = brk;
 
         return 1;
 #endif /* !CONFIG_PPC_ADV_DEBUG_DVCS */
@@ -1495,10 +1493,11 @@ static long ppc_del_hwdebug(struct task_struct *child, long data)
         ptrace_put_breakpoints(child);
         return ret;
 #else /* CONFIG_HAVE_HW_BREAKPOINT */
-        if (child->thread.dabr == 0)
+        if (child->thread.hw_brk.address == 0)
                 return -ENOENT;
 
-        child->thread.dabr = 0;
+        child->thread.hw_brk.address = 0;
+        child->thread.hw_brk.type = 0;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 
         return 0;
@@ -1642,6 +1641,9 @@ long arch_ptrace(struct task_struct *child, long request,
         }
 
         case PTRACE_GET_DEBUGREG: {
+#ifndef CONFIG_PPC_ADV_DEBUG_REGS
+                unsigned long dabr_fake;
+#endif
                 ret = -EINVAL;
                 /* We only support one DABR and no IABRS at the moment */
                 if (addr > 0)
@@ -1649,7 +1651,9 @@ long arch_ptrace(struct task_struct *child, long request,
 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
                 ret = put_user(child->thread.dac1, datalp);
 #else
-                ret = put_user(child->thread.dabr, datalp);
+                dabr_fake = ((child->thread.hw_brk.address & (~HW_BRK_TYPE_DABR)) |
+                             (child->thread.hw_brk.type & HW_BRK_TYPE_DABR));
+                ret = put_user(dabr_fake, datalp);
 #endif
                 break;
         }