powerpc/watchpoint: Introduce function to get nr watchpoints dynamically

So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
But Power10 is introducing 2nd DAWR and thus kernel should be able to
dynamically find actual number of watchpoints supported by hw it's
running on. Introduce function for the same. Also convert HBP_NUM macro
to HBP_NUM_MAX, which will now represent maximum number of watchpoints
supported by Powerpc.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-4-ravi.bangoria@linux.ibm.com

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 40a4d3c..c67b94f 100644 (file)
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -614,7 +614,11 @@ enum {
 };
 #endif /* __powerpc64__ */
 
-#define HBP_NUM 1
+/*
+ * Maximum number of hw breakpoint supported on powerpc. Number of
+ * breakpoints supported by actual hw might be less than this.
+ */
+#define HBP_NUM_MAX    1
 
 #endif /* !__ASSEMBLY__ */
 

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index f2f8d8a..518b41e 100644 (file)
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -43,6 +43,11 @@ struct arch_hw_breakpoint {
 #define DABR_MAX_LEN   8
 #define DAWR_MAX_LEN   512
 
+static inline int nr_wp_slots(void)
+{
+       return HBP_NUM_MAX;
+}
+
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 #include <linux/kdebug.h>
 #include <asm/reg.h>

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 5ab2020..f209c57 100644 (file)
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -180,7 +180,7 @@ struct thread_struct {
        int             fpexc_mode;     /* floating-point exception mode */
        unsigned int    align_ctl;      /* alignment handling control */
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-       struct perf_event *ptrace_bps[HBP_NUM];
+       struct perf_event *ptrace_bps[HBP_NUM_MAX];
        /*
         * Helps identify source of single-step exception and subsequent
         * hw-breakpoint enablement

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 423603c..01f07d9 100644 (file)
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -39,7 +39,7 @@ static DEFINE_PER_CPU(struct perf_event *, bp_per_reg);
 int hw_breakpoint_slots(int type)
 {
        if (type == TYPE_DATA)
-               return HBP_NUM;
+               return nr_wp_slots();
        return 0;               /* no instruction breakpoints available */
 }