[PATCH 0/5] Powerpc/hw-breakpoint: Fixes plus Code refactor

do_dabr() was renamed with do_break() long ago. But I still see
some comments mentioning do_dabr(). Replace it.

Signed-off-by: Ravi Bangoria <redacted>
---
 arch/powerpc/kernel/hw_breakpoint.c | 2 +-
 arch/powerpc/kernel/ptrace.c        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c

b/arch/powerpc/kernel/hw_breakpoint.c
index a293a53b4365..1908e4fcc132 100644

--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c

@@ -232,7 +232,7 @@ int hw_breakpoint_handler(struct die_args *args)
 	 * Return early after invoking user-callback function without restoring
 	 * DABR if the breakpoint is from ptrace which always operates in
 	 * one-shot mode. The ptrace-ed process will receive the SIGTRAP signal
-	 * generated in do_dabr().
+	 * generated in do_break().
 	 */
 	if (bp->overflow_handler == ptrace_triggered) {
 		perf_bp_event(bp, regs);

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 684b0b315c32..44b823e5e8c8 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c

@@ -2373,7 +2373,7 @@ void ptrace_triggered(struct perf_event *bp,
 	/*
 	 * Disable the breakpoint request here since ptrace has defined a
 	 * one-shot behaviour for breakpoint exceptions in PPC64.
-	 * The SIGTRAP signal is generated automatically for us in do_dabr().
+	 * The SIGTRAP signal is generated automatically for us in do_break().
 	 * We don't have to do anything about that here
 	 */
 	attr = bp->attr;

Signed-off-by: Ravi Bangoria <redacted>
---
  arch/powerpc/kernel/hw_breakpoint.c | 2 +-
  arch/powerpc/kernel/ptrace.c        | 2 +-
  2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index a293a53b4365..1908e4fcc132 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c

@@ -232,7 +232,7 @@ int hw_breakpoint_handler(struct die_args *args)
  	 * Return early after invoking user-callback function without restoring
  	 * DABR if the breakpoint is from ptrace which always operates in
  	 * one-shot mode. The ptrace-ed process will receive the SIGTRAP signal
-	 * generated in do_dabr().
+	 * generated in do_break().
  	 */
  	if (bp->overflow_handler == ptrace_triggered) {
  		perf_bp_event(bp, regs);

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 684b0b315c32..44b823e5e8c8 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c

@@ -2373,7 +2373,7 @@ void ptrace_triggered(struct perf_event *bp,
  	/*
  	 * Disable the breakpoint request here since ptrace has defined a
  	 * one-shot behaviour for breakpoint exceptions in PPC64.
-	 * The SIGTRAP signal is generated automatically for us in do_dabr().
+	 * The SIGTRAP signal is generated automatically for us in do_break().
  	 * We don't have to do anything about that here
  	 */
  	attr = bp->attr;

Signed-off-by: Ravi Bangoria <redacted>
---
  arch/powerpc/kernel/hw_breakpoint.c | 34 +++++++++++++++--------------
  1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 1908e4fcc132..36bcf705df65 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c

@@ -133,10 +133,13 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
  			     const struct perf_event_attr *attr,
  			     struct arch_hw_breakpoint *hw)
  {
-	int ret = -EINVAL, length_max;
+	int length_max;
+
+	if (!ppc_breakpoint_available())
+		return -ENODEV;
  
  	if (!bp)
-		return ret;
+		return -EINVAL;
  
  	hw->type = HW_BRK_TYPE_TRANSLATE;
  	if (attr->bp_type & HW_BREAKPOINT_R)

@@ -145,34 +148,33 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
  		hw->type |= HW_BRK_TYPE_WRITE;
  	if (hw->type == HW_BRK_TYPE_TRANSLATE)
  		/* must set alteast read or write */
-		return ret;
+		return -EINVAL;
+
  	if (!attr->exclude_user)
  		hw->type |= HW_BRK_TYPE_USER;
  	if (!attr->exclude_kernel)
  		hw->type |= HW_BRK_TYPE_KERNEL;
  	if (!attr->exclude_hv)
  		hw->type |= HW_BRK_TYPE_HYP;
+
  	hw->address = attr->bp_addr;
  	hw->len = attr->bp_len;
  
-	/*
-	 * Since breakpoint length can be a maximum of HW_BREAKPOINT_LEN(8)
-	 * and breakpoint addresses are aligned to nearest double-word
-	 * HW_BREAKPOINT_ALIGN by rounding off to the lower address, the
-	 * 'symbolsize' should satisfy the check below.
-	 */
-	if (!ppc_breakpoint_available())
-		return -ENODEV;
  	length_max = 8; /* DABR */
  	if (dawr_enabled()) {
  		length_max = 512 ; /* 64 doublewords */
-		/* DAWR region can't cross 512 boundary */
-		if ((attr->bp_addr >> 9) !=
-		    ((attr->bp_addr + attr->bp_len - 1) >> 9))
+		/* DAWR region can't cross 512 bytes boundary */
+		if ((hw->address >> 9) != ((hw->address + hw->len - 1) >> 9))
  			return -EINVAL;
  	}
-	if (hw->len >
-	    (length_max - (hw->address & HW_BREAKPOINT_ALIGN)))
+
+	/*
+	 * Since breakpoint length can be a maximum of length_max and
+	 * breakpoint addresses are aligned to nearest double-word
+	 * HW_BREAKPOINT_ALIGN by rounding off to the lower address,
+	 * the 'symbolsize' should satisfy the check below.
+	 */
+	if (hw->len > (length_max - (hw->address & HW_BREAKPOINT_ALIGN)))
  		return -EINVAL;
  	return 0;
  }

Remove unnecessary comments. Code itself is self explanatory.
And, ISA already talks about MRD field. I Don't think we need
to re-describe it.

Signed-off-by: Ravi Bangoria <redacted>
---
 arch/powerpc/kernel/process.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f0fbbf6a6a1f..f002d2ffff86 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -799,18 +799,11 @@ int set_dawr(struct arch_hw_breakpoint *brk)
 
 	dawr = brk->address;
 
-	dawrx  = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) \
-		                   << (63 - 58); //* read/write bits */
-	dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) \
-		                   << (63 - 59); //* translate */
-	dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) \
-		                   >> 3; //* PRIM bits */
-	/* dawr length is stored in field MDR bits 48:53.  Matches range in
-	   doublewords (64 bits) baised by -1 eg. 0b000000=1DW and
-	   0b111111=64DW.
-	   brk->len is in bytes.
-	   This aligns up to double word size, shifts and does the bias.
-	*/
+	dawrx  = (brk->type & HW_BRK_TYPE_RDWR) << (63 - 58);
+	dawrx |= ((brk->type & HW_BRK_TYPE_TRANSLATE) >> 2) << (63 - 59);
+	dawrx |= (brk->type & HW_BRK_TYPE_PRIV_ALL) >> 3;
+
+	/* brk->len is in bytes. */
 	mrd = ((brk->len + 7) >> 3) - 1;
 	dawrx |= (mrd & 0x3f) << (63 - 53);
 

Signed-off-by: Ravi Bangoria <redacted>
---
  arch/powerpc/kernel/process.c | 17 +++++------------
  1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f0fbbf6a6a1f..f002d2ffff86 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -799,18 +799,11 @@ int set_dawr(struct arch_hw_breakpoint *brk)
  
  	dawr = brk->address;
  
-	dawrx  = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) \
-		                   << (63 - 58); //* read/write bits */
-	dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) \
-		                   << (63 - 59); //* translate */
-	dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) \
-		                   >> 3; //* PRIM bits */
-	/* dawr length is stored in field MDR bits 48:53.  Matches range in
-	   doublewords (64 bits) baised by -1 eg. 0b000000=1DW and
-	   0b111111=64DW.
-	   brk->len is in bytes.
-	   This aligns up to double word size, shifts and does the bias.
-	*/
+	dawrx  = (brk->type & HW_BRK_TYPE_RDWR) << (63 - 58);
+	dawrx |= ((brk->type & HW_BRK_TYPE_TRANSLATE) >> 2) << (63 - 59);
+	dawrx |= (brk->type & HW_BRK_TYPE_PRIV_ALL) >> 3;
+
+	/* brk->len is in bytes. */
  	mrd = ((brk->len + 7) >> 3) - 1;
  	dawrx |= (mrd & 0x3f) << (63 - 53);
  

Directly setting dawr and dawrx with 0 should be enough to
disable watchpoint. No need to reset individual bits in
variable and then set in hw.

Signed-off-by: Ravi Bangoria <redacted>
---
  arch/powerpc/include/asm/hw_breakpoint.h |  3 ++-
  arch/powerpc/kernel/process.c            | 12 ++++++++++++
  2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 78202d5fb13a..8acbbdd4a2d5 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h

@@ -19,6 +19,7 @@ struct arch_hw_breakpoint {
  /* Note: Don't change the the first 6 bits below as they are in the same order
   * as the dabr and dabrx.
   */
+#define HW_BRK_TYPE_DISABLE		0x00

  #define HW_BRK_TYPE_READ		0x01
  #define HW_BRK_TYPE_WRITE		0x02
  #define HW_BRK_TYPE_TRANSLATE		0x04

@@ -68,7 +69,7 @@ static inline void hw_breakpoint_disable(void)
  	struct arch_hw_breakpoint brk;
  
  	brk.address = 0;
-	brk.type = 0;
+	brk.type = HW_BRK_TYPE_DISABLE;
  	brk.len = 0;
  	if (ppc_breakpoint_available())
  		__set_breakpoint(&brk);

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f002d2ffff86..265fac9fb3a4 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -793,10 +793,22 @@ static inline int set_dabr(struct arch_hw_breakpoint *brk)
  	return __set_dabr(dabr, dabrx);
  }
  
+static int disable_dawr(void)
+{
+	if (ppc_md.set_dawr)
+		return ppc_md.set_dawr(0, 0);
+
+	mtspr(SPRN_DAWRX, 0);

Signed-off-by: Ravi Bangoria <redacted>
---
 arch/powerpc/include/asm/hw_breakpoint.h |  3 ++-
 arch/powerpc/kernel/process.c            | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h

b/arch/powerpc/include/asm/hw_breakpoint.h
index 78202d5fb13a..8acbbdd4a2d5 100644

--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h

@@ -19,6 +19,7 @@ struct arch_hw_breakpoint {
 /* Note: Don't change the the first 6 bits below as they are in the same

order
  * as the dabr and dabrx.
  */
+#define HW_BRK_TYPE_DISABLE		0x00
 #define HW_BRK_TYPE_READ		0x01
 #define HW_BRK_TYPE_WRITE		0x02
 #define HW_BRK_TYPE_TRANSLATE		0x04

@@ -68,7 +69,7 @@ static inline void hw_breakpoint_disable(void)
 	struct arch_hw_breakpoint brk;
 
 	brk.address = 0;
-	brk.type = 0;
+	brk.type = HW_BRK_TYPE_DISABLE;
 	brk.len = 0;
 	if (ppc_breakpoint_available())
 		__set_breakpoint(&brk);

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f002d2ffff86..265fac9fb3a4 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -793,10 +793,22 @@ static inline int set_dabr(struct arch_hw_breakpoint

*brk)
 	return __set_dabr(dabr, dabrx);
 }
 
+static int disable_dawr(void)
+{
+	if (ppc_md.set_dawr)
+		return ppc_md.set_dawr(0, 0);
+
+	mtspr(SPRN_DAWRX, 0);
+	return 0;
+}
+
 int set_dawr(struct arch_hw_breakpoint *brk)
 {
 	unsigned long dawr, dawrx, mrd;
 
+	if (brk->type == HW_BRK_TYPE_DISABLE)
+		return disable_dawr();
+
 	dawr = brk->address;
 
 	dawrx  = (brk->type & HW_BRK_TYPE_RDWR) << (63 - 58);

Watchpoint match range is always doubleword(8 bytes) aligned on
powerpc. If the given range is crossing doubleword boundary, we
need to increase the length such that next doubleword also get
covered. Ex,

           address   len = 6 bytes
                 |=========.
    |------------v--|------v--------|
    | | | | | | | | | | | | | | | | |
    |---------------|---------------|
     <---8 bytes--->

In such case, current code configures hw as:
   start_addr = address & ~HW_BREAKPOINT_ALIGN
   len = 8 bytes

And thus read/write in last 4 bytes of the given range is ignored.
Fix this by including next doubleword in the length. Watchpoint
exception handler already ignores extraneous exceptions, so no
changes required for that.

Signed-off-by: Ravi Bangoria <redacted>
---
  arch/powerpc/include/asm/hw_breakpoint.h |  7 ++--
  arch/powerpc/kernel/hw_breakpoint.c      | 44 +++++++++++++-----------
  arch/powerpc/kernel/process.c            | 34 ++++++++++++++++--
  3 files changed, 60 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 8acbbdd4a2d5..749a357164d5 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h

@@ -34,6 +34,8 @@ struct arch_hw_breakpoint {
  #define HW_BRK_TYPE_PRIV_ALL	(HW_BRK_TYPE_USER | HW_BRK_TYPE_KERNEL | \
  				 HW_BRK_TYPE_HYP)
  
+#define HW_BREAKPOINT_ALIGN 0x7
+
  #ifdef CONFIG_HAVE_HW_BREAKPOINT
  #include <linux/kdebug.h>
  #include <asm/reg.h>

@@ -45,8 +47,6 @@ struct pmu;
  struct perf_sample_data;
  struct task_struct;
  
-#define HW_BREAKPOINT_ALIGN 0x7
-
  extern int hw_breakpoint_slots(int type);
  extern int arch_bp_generic_fields(int type, int *gen_bp_type);
  extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);

@@ -76,7 +76,8 @@ static inline void hw_breakpoint_disable(void)
  }
  extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
  int hw_breakpoint_handler(struct die_args *args);
-
+extern u16 hw_breakpoint_get_final_len(struct arch_hw_breakpoint *brk,
+		unsigned long *start_addr, unsigned long *end_addr);
  extern int set_dawr(struct arch_hw_breakpoint *brk);
  extern bool dawr_force_enable;
  static inline bool dawr_enabled(void)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 36bcf705df65..c122fd55aa44 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c

@@ -126,6 +126,28 @@ int arch_bp_generic_fields(int type, int *gen_bp_type)
  	return 0;
  }
  
+/* Maximum len for DABR is 8 bytes and DAWR is 512 bytes */
+static int hw_breakpoint_validate_len(struct arch_hw_breakpoint *hw)
+{
+	u16 length_max = 8;
+	u16 final_len;

  /*
   * Validate the arch-specific HW Breakpoint register settings
   */

@@ -133,12 +155,10 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
  			     const struct perf_event_attr *attr,
  			     struct arch_hw_breakpoint *hw)
  {
-	int length_max;
-
  	if (!ppc_breakpoint_available())
  		return -ENODEV;
  
-	if (!bp)
+	if (!bp || !attr->bp_len)
  		return -EINVAL;
  
  	hw->type = HW_BRK_TYPE_TRANSLATE;

@@ -160,23 +180,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
  	hw->address = attr->bp_addr;
  	hw->len = attr->bp_len;
  
-	length_max = 8; /* DABR */
-	if (dawr_enabled()) {
-		length_max = 512 ; /* 64 doublewords */
-		/* DAWR region can't cross 512 bytes boundary */
-		if ((hw->address >> 9) != ((hw->address + hw->len - 1) >> 9))
-			return -EINVAL;
-	}
-
-	/*
-	 * Since breakpoint length can be a maximum of length_max and
-	 * breakpoint addresses are aligned to nearest double-word
-	 * HW_BREAKPOINT_ALIGN by rounding off to the lower address,
-	 * the 'symbolsize' should satisfy the check below.
-	 */
-	if (hw->len > (length_max - (hw->address & HW_BREAKPOINT_ALIGN)))
-		return -EINVAL;
-	return 0;
+	return hw_breakpoint_validate_len(hw);
  }
  
  /*

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 265fac9fb3a4..159aaa70de46 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -802,9 +802,39 @@ static int disable_dawr(void)
  	return 0;
  }
  
+/*
+ * Watchpoint match range is always doubleword(8 bytes) aligned on
+ * powerpc. If the given range is crossing doubleword boundary, we
+ * need to increase the length such that next doubleword also get
+ * covered. Ex,
+ *
+ *          address   len = 6 bytes
+ *                |=========.
+ *   |------------v--|------v--------|
+ *   | | | | | | | | | | | | | | | | |
+ *   |---------------|---------------|
+ *    <---8 bytes--->
+ *
+ * In this case, we should configure hw as:
+ *   start_addr = address & ~HW_BREAKPOINT_ALIGN
+ *   len = 16 bytes
+ *
+ * @start_addr and @end_addr are inclusive.
+ */
+u16 hw_breakpoint_get_final_len(struct arch_hw_breakpoint *brk,
+				unsigned long *start_addr,
+				unsigned long *end_addr)
+{
+	*start_addr = brk->address & ~HW_BREAKPOINT_ALIGN;
+	*end_addr = (brk->address + brk->len - 1) | HW_BREAKPOINT_ALIGN;
+	return *end_addr - *start_addr + 1;
+}

+
  int set_dawr(struct arch_hw_breakpoint *brk)
  {
  	unsigned long dawr, dawrx, mrd;
+	unsigned long start_addr, end_addr;
+	u16 final_len;
  
  	if (brk->type == HW_BRK_TYPE_DISABLE)
  		return disable_dawr();

@@ -815,8 +845,8 @@ int set_dawr(struct arch_hw_breakpoint *brk)
  	dawrx |= ((brk->type & HW_BRK_TYPE_TRANSLATE) >> 2) << (63 - 59);
  	dawrx |= (brk->type & HW_BRK_TYPE_PRIV_ALL) >> 3;
  
-	/* brk->len is in bytes. */
-	mrd = ((brk->len + 7) >> 3) - 1;
+	final_len = hw_breakpoint_get_final_len(brk, &start_addr, &end_addr);
+	mrd = ((final_len + 7) >> 3) - 1;
  	dawrx |= (mrd & 0x3f) << (63 - 53);
  
  	if (ppc_md.set_dawr)

Signed-off-by: Ravi Bangoria <redacted>
---
 arch/powerpc/include/asm/hw_breakpoint.h |  7 ++--
 arch/powerpc/kernel/hw_breakpoint.c      | 44 +++++++++++++-----------
 arch/powerpc/kernel/process.c            | 34 ++++++++++++++++--
 3 files changed, 60 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h

b/arch/powerpc/include/asm/hw_breakpoint.h
index 8acbbdd4a2d5..749a357164d5 100644

--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h

@@ -34,6 +34,8 @@ struct arch_hw_breakpoint {
 #define HW_BRK_TYPE_PRIV_ALL	(HW_BRK_TYPE_USER | HW_BRK_TYPE_KERNEL | \
 				 HW_BRK_TYPE_HYP)
 
+#define HW_BREAKPOINT_ALIGN 0x7
+
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 #include <linux/kdebug.h>
 #include <asm/reg.h>

@@ -45,8 +47,6 @@ struct pmu;
 struct perf_sample_data;
 struct task_struct;
 
-#define HW_BREAKPOINT_ALIGN 0x7
-
 extern int hw_breakpoint_slots(int type);
 extern int arch_bp_generic_fields(int type, int *gen_bp_type);
 extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);

@@ -76,7 +76,8 @@ static inline void hw_breakpoint_disable(void)
 }
 extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
 int hw_breakpoint_handler(struct die_args *args);
-
+extern u16 hw_breakpoint_get_final_len(struct arch_hw_breakpoint *brk,
+		unsigned long *start_addr, unsigned long *end_addr);
 extern int set_dawr(struct arch_hw_breakpoint *brk);
 extern bool dawr_force_enable;
 static inline bool dawr_enabled(void)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c

b/arch/powerpc/kernel/hw_breakpoint.c
index 36bcf705df65..c122fd55aa44 100644

--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c

@@ -126,6 +126,28 @@ int arch_bp_generic_fields(int type, int *gen_bp_type)
 	return 0;
 }
 
+/* Maximum len for DABR is 8 bytes and DAWR is 512 bytes */
+static int hw_breakpoint_validate_len(struct arch_hw_breakpoint *hw)
+{
+	u16 length_max = 8;
+	u16 final_len;
+	unsigned long start_addr, end_addr;
+
+	final_len = hw_breakpoint_get_final_len(hw, &start_addr, &end_addr);
+
+	if (dawr_enabled()) {
+		length_max = 512;
+		/* DAWR region can't cross 512 bytes boundary */
+		if ((start_addr >> 9) != (end_addr >> 9))
+			return -EINVAL;
+	}
+
+	if (final_len > length_max)
+		return -EINVAL;
+
+	return 0;
+}
+
 /*
  * Validate the arch-specific HW Breakpoint register settings
  */

@@ -133,12 +155,10 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 			     const struct perf_event_attr *attr,
 			     struct arch_hw_breakpoint *hw)
 {
-	int length_max;
-
 	if (!ppc_breakpoint_available())
 		return -ENODEV;
 
-	if (!bp)
+	if (!bp || !attr->bp_len)
 		return -EINVAL;
 
 	hw->type = HW_BRK_TYPE_TRANSLATE;

@@ -160,23 +180,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 	hw->address = attr->bp_addr;
 	hw->len = attr->bp_len;
 
-	length_max = 8; /* DABR */
-	if (dawr_enabled()) {
-		length_max = 512 ; /* 64 doublewords */
-		/* DAWR region can't cross 512 bytes boundary */
-		if ((hw->address >> 9) != ((hw->address + hw->len - 1) >> 9))
-			return -EINVAL;
-	}
-
-	/*
-	 * Since breakpoint length can be a maximum of length_max and
-	 * breakpoint addresses are aligned to nearest double-word
-	 * HW_BREAKPOINT_ALIGN by rounding off to the lower address,
-	 * the 'symbolsize' should satisfy the check below.
-	 */
-	if (hw->len > (length_max - (hw->address & HW_BREAKPOINT_ALIGN)))
-		return -EINVAL;
-	return 0;
+	return hw_breakpoint_validate_len(hw);
 }
 
 /*

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 265fac9fb3a4..159aaa70de46 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -802,9 +802,39 @@ static int disable_dawr(void)
 	return 0;
 }
 
+/*
+ * Watchpoint match range is always doubleword(8 bytes) aligned on
+ * powerpc. If the given range is crossing doubleword boundary, we
+ * need to increase the length such that next doubleword also get
+ * covered. Ex,
+ *
+ *          address   len = 6 bytes
+ *                |=========.
+ *   |------------v--|------v--------|
+ *   | | | | | | | | | | | | | | | | |
+ *   |---------------|---------------|
+ *    <---8 bytes--->
+ *
+ * In this case, we should configure hw as:
+ *   start_addr = address & ~HW_BREAKPOINT_ALIGN
+ *   len = 16 bytes
+ *
+ * @start_addr and @end_addr are inclusive.
+ */
+u16 hw_breakpoint_get_final_len(struct arch_hw_breakpoint *brk,
+				unsigned long *start_addr,
+				unsigned long *end_addr)

+{
+	*start_addr = brk->address & ~HW_BREAKPOINT_ALIGN;
+	*end_addr = (brk->address + brk->len - 1) | HW_BREAKPOINT_ALIGN;
+	return *end_addr - *start_addr + 1;
+}
+
 int set_dawr(struct arch_hw_breakpoint *brk)
 {
 	unsigned long dawr, dawrx, mrd;
+	unsigned long start_addr, end_addr;
+	u16 final_len;
 
 	if (brk->type == HW_BRK_TYPE_DISABLE)
 		return disable_dawr();

@@ -815,8 +845,8 @@ int set_dawr(struct arch_hw_breakpoint *brk)
 	dawrx |= ((brk->type & HW_BRK_TYPE_TRANSLATE) >> 2) << (63 - 59);
 	dawrx |= (brk->type & HW_BRK_TYPE_PRIV_ALL) >> 3;
 
-	/* brk->len is in bytes. */
-	mrd = ((brk->len + 7) >> 3) - 1;
+	final_len = hw_breakpoint_get_final_len(brk, &start_addr, &end_addr);