Le 09/03/2020 à 09:58, Ravi Bangoria a écrit :
So far powerpc hw supported only one watchpoint. But Future Power
architecture is introducing 2nd DAWR. Convert thread_struct->hw_brk
into an array.

Looks like you are doing a lot more than that in this patch.

Should this patch be splitted in two parts ?

Christophe


Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com>
---
  arch/powerpc/include/asm/processor.h |  2 +-
  arch/powerpc/kernel/process.c        | 43 ++++++++++++++++++++--------
  arch/powerpc/kernel/ptrace.c         | 42 ++++++++++++++++++++-------
  arch/powerpc/kernel/ptrace32.c       |  4 +--
  arch/powerpc/kernel/signal.c         |  9 ++++--
  5 files changed, 72 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h 
b/arch/powerpc/include/asm/processor.h
index 666b2825278c..57a8fac2e72b 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -183,7 +183,7 @@ struct thread_struct {
         */
        struct perf_event *last_hit_ubp;
  #endif /* CONFIG_HAVE_HW_BREAKPOINT */
-       struct arch_hw_breakpoint hw_brk; /* info on the hardware breakpoint */
+       struct arch_hw_breakpoint hw_brk[HBP_NUM_MAX]; /* hardware breakpoint 
info */
        unsigned long   trap_nr;        /* last trap # on this thread */
        u8 load_slb;                    /* Ages out SLB preload cache entries */
        u8 load_fp;
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f6bb2586fa5d..42ff62ef749c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -704,21 +704,25 @@ void switch_booke_debug_regs(struct debug_reg *new_debug)
  EXPORT_SYMBOL_GPL(switch_booke_debug_regs);
  #else /* !CONFIG_PPC_ADV_DEBUG_REGS */
  #ifndef CONFIG_HAVE_HW_BREAKPOINT
-static void set_breakpoint(struct arch_hw_breakpoint *brk)
+static void set_breakpoint(struct arch_hw_breakpoint *brk, int i)
  {
        preempt_disable();
-       __set_breakpoint(brk, 0);
+       __set_breakpoint(brk, i);
        preempt_enable();
  }
static void set_debug_reg_defaults(struct thread_struct *thread)
  {
-       thread->hw_brk.address = 0;
-       thread->hw_brk.type = 0;
-       thread->hw_brk.len = 0;
-       thread->hw_brk.hw_len = 0;
-       if (ppc_breakpoint_available())
-               set_breakpoint(&thread->hw_brk);
+       int i;
+
+       for (i = 0; i < nr_wp_slots(); i++) {
+               thread->hw_brk[i].address = 0;
+               thread->hw_brk[i].type = 0;
+               thread->hw_brk[i].len = 0;
+               thread->hw_brk[i].hw_len = 0;
+               if (ppc_breakpoint_available())
+                       set_breakpoint(&thread->hw_brk[i], i);
+       }
  }
  #endif /* !CONFIG_HAVE_HW_BREAKPOINT */
  #endif        /* CONFIG_PPC_ADV_DEBUG_REGS */
@@ -1141,6 +1145,24 @@ static inline void restore_sprs(struct thread_struct 
*old_thread,
        thread_pkey_regs_restore(new_thread, old_thread);
  }
+#ifndef CONFIG_HAVE_HW_BREAKPOINT
+static void switch_hw_breakpoint(struct task_struct *new)
+{
+       int i;
+
+       for (i = 0; i < nr_wp_slots(); i++) {
+               if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk[i]),
+                                          &new->thread.hw_brk[i]))) {
+                       __set_breakpoint(&new->thread.hw_brk[i], i);
+               }
+       }
+}
+#else
+static void switch_hw_breakpoint(struct task_struct *new)
+{
+}
+#endif
+
  struct task_struct *__switch_to(struct task_struct *prev,
        struct task_struct *new)
  {
@@ -1172,10 +1194,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
   * For PPC_BOOK3S_64, we use the hw-breakpoint interfaces that would
   * schedule DABR
   */
-#ifndef CONFIG_HAVE_HW_BREAKPOINT
-       if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk[0]), 
&new->thread.hw_brk)))
-               __set_breakpoint(&new->thread.hw_brk, 0);
-#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+       switch_hw_breakpoint(new);
  #endif
/*
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index dd46e174dbe7..f6d7955fc61e 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2382,6 +2382,11 @@ void ptrace_triggered(struct perf_event *bp,
  }
  #endif /* CONFIG_HAVE_HW_BREAKPOINT */
+/*
+ * ptrace_set_debugreg() fakes DABR and DABR is only one. So even if
+ * internal hw supports more than one watchpoint, we support only one
+ * watchpoint with this interface.
+ */
  static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
                               unsigned long data)
  {
@@ -2451,7 +2456,7 @@ static int ptrace_set_debugreg(struct task_struct *task, 
unsigned long addr,
                        return ret;
                }
                thread->ptrace_bps[0] = bp;
-               thread->hw_brk = hw_brk;
+               thread->hw_brk[0] = hw_brk;
                return 0;
        }
@@ -2473,7 +2478,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
        if (set_bp && (!ppc_breakpoint_available()))
                return -ENODEV;
  #endif /* CONFIG_HAVE_HW_BREAKPOINT */
-       task->thread.hw_brk = hw_brk;
+       task->thread.hw_brk[0] = 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
@@ -2824,9 +2829,23 @@ static int set_dac_range(struct task_struct *child,
  }
  #endif /* CONFIG_PPC_ADV_DEBUG_DAC_RANGE */
+#ifndef CONFIG_PPC_ADV_DEBUG_REGS
+static int empty_hw_brk(struct thread_struct *thread)
+{
+       int i;
+
+       for (i = 0; i < nr_wp_slots(); i++) {
+               if (!thread->hw_brk[i].address)
+                       return i;
+       }
+       return -1;
+}
+#endif
+
  static long ppc_set_hwdebug(struct task_struct *child,
                     struct ppc_hw_breakpoint *bp_info)
  {
+       int i;
  #ifdef CONFIG_HAVE_HW_BREAKPOINT
        int len = 0;
        struct thread_struct *thread = &(child->thread);
@@ -2919,15 +2938,16 @@ static long ppc_set_hwdebug(struct task_struct *child,
        if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
                return -EINVAL;
- if (child->thread.hw_brk.address)
+       i = empty_hw_brk(&child->thread);
+       if (i < 0)
                return -ENOSPC;
if (!ppc_breakpoint_available())
                return -ENODEV;
- child->thread.hw_brk = brk;
+       child->thread.hw_brk[i] = brk;
- return 1;
+       return i + 1;
  #endif /* !CONFIG_PPC_ADV_DEBUG_DVCS */
  }
@@ -2955,7 +2975,7 @@ static long ppc_del_hwdebug(struct task_struct *child, long data)
        }
        return rc;
  #else
-       if (data != 1)
+       if (data < 1 || data > nr_wp_slots())
                return -EINVAL;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -2967,11 +2987,11 @@ static long ppc_del_hwdebug(struct task_struct *child, 
long data)
                ret = -ENOENT;
        return ret;
  #else /* CONFIG_HAVE_HW_BREAKPOINT */
-       if (child->thread.hw_brk.address == 0)
+       if (child->thread.hw_brk[data - 1].address == 0)
                return -ENOENT;
- child->thread.hw_brk.address = 0;
-       child->thread.hw_brk.type = 0;
+       child->thread.hw_brk[data - 1].address = 0;
+       child->thread.hw_brk[data - 1].type = 0;
  #endif /* CONFIG_HAVE_HW_BREAKPOINT */
return 0;
@@ -3124,8 +3144,8 @@ long arch_ptrace(struct task_struct *child, long request,
  #ifdef CONFIG_PPC_ADV_DEBUG_REGS
                ret = put_user(child->thread.debug.dac1, datalp);
  #else
-               dabr_fake = ((child->thread.hw_brk.address & 
(~HW_BRK_TYPE_DABR)) |
-                            (child->thread.hw_brk.type & HW_BRK_TYPE_DABR));
+               dabr_fake = ((child->thread.hw_brk[0].address & 
(~HW_BRK_TYPE_DABR)) |
+                            (child->thread.hw_brk[0].type & HW_BRK_TYPE_DABR));
                ret = put_user(dabr_fake, datalp);
  #endif
                break;
diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c
index f37eb53de1a1..e227cd320b46 100644
--- a/arch/powerpc/kernel/ptrace32.c
+++ b/arch/powerpc/kernel/ptrace32.c
@@ -270,8 +270,8 @@ long compat_arch_ptrace(struct task_struct *child, 
compat_long_t request,
                ret = put_user(child->thread.debug.dac1, (u32 __user *)data);
  #else
                dabr_fake = (
-                       (child->thread.hw_brk.address & (~HW_BRK_TYPE_DABR)) |
-                       (child->thread.hw_brk.type & HW_BRK_TYPE_DABR));
+                       (child->thread.hw_brk[0].address & (~HW_BRK_TYPE_DABR)) 
|
+                       (child->thread.hw_brk[0].type & HW_BRK_TYPE_DABR));
                ret = put_user(dabr_fake, (u32 __user *)data);
  #endif
                break;
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 8bc6cc55420a..3116896e89a6 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -107,6 +107,9 @@ static void do_signal(struct task_struct *tsk)
        struct ksignal ksig = { .sig = 0 };
        int ret;
        int is32 = is_32bit_task();
+#ifndef CONFIG_PPC_ADV_DEBUG_REGS
+       int i;
+#endif
BUG_ON(tsk != current); @@ -128,8 +131,10 @@ static void do_signal(struct task_struct *tsk)
         * user space. The DABR will have been cleared if it
         * triggered inside the kernel.
         */
-       if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
-               __set_breakpoint(&tsk->thread.hw_brk, 0);
+       for (i = 0; i < nr_wp_slots(); i++) {
+               if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
+                       __set_breakpoint(&tsk->thread.hw_brk[i], i);
+       }
  #endif
        /* Re-enable the breakpoints for the signal stack */
        thread_change_pc(tsk, tsk->thread.regs);

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