[PATCH v2 00/16] powerpc/watchpoint: Preparation for more than one watchpoint

[PATCH v2 00/16] powerpc/watchpoint: Preparation for more than one watchpoint

[Ravi Bangoria]

So far, powerpc Book3S code has been written with an assumption of only
one watchpoint. But future power architecture is introducing second
watchpoint register (DAWR). Even though this patchset does not enable
2nd DAWR, it make the infrastructure ready so that enabling 2nd DAWR
should just be a matter of changing count.

Existing functionality works fine with the patchset. I've tested it with
perf, ptrace(gdb), xmon. All hw-breakpoint selftests are passing as well.
And I've build tested for 8xx and 'AMCC 44x, 46x or 47x'.

Note: kvm or PowerVM guest is not enabled yet.

v1:
  https://lore.kernel.org/linuxppc-dev/20200309085806.155823-1-ravi.bangoria@linux.ibm.com

v1->v2:
 - No major functionality changes. Changed few minor things as suggested
   by Christophe
 - Fixed build failure reported by 'kbuild test robot <lkp@intel.com>'
   for patch #9.
 - Rebased to powerpc/next plus Christophe's ptrace series[1][2]

[1]: https://lore.kernel.org/linuxppc-dev/cover.1582848567.git.christophe.leroy@c-s.fr 
[2]: https://lore.kernel.org/linuxppc-dev/5558d8c22ff0ed03cb5392798564dd203bd68501.1584787012.git.christophe.leroy@c-s.fr

Ravi Bangoria (16):
  powerpc/watchpoint: Rename current DAWR macros
  powerpc/watchpoint: Add SPRN macros for second DAWR
  powerpc/watchpoint: Introduce function to get nr watchpoints
    dynamically
  powerpc/watchpoint/ptrace: Return actual num of available watchpoints
  powerpc/watchpoint: Provide DAWR number to set_dawr
  powerpc/watchpoint: Provide DAWR number to __set_breakpoint
  powerpc/watchpoint: Get watchpoint count dynamically while disabling
    them
  powerpc/watchpoint: Disable all available watchpoints when
    !dawr_force_enable
  powerpc/watchpoint: Convert thread_struct->hw_brk to an array
  powerpc/watchpoint: Use loop for thread_struct->ptrace_bps
  powerpc/watchpoint: Introduce is_ptrace_bp() function
  powerpc/watchpoint: Use builtin ALIGN*() macros
  powerpc/watchpoint: Prepare handler to handle more than one
    watcnhpoint
  powerpc/watchpoint: Don't allow concurrent perf and ptrace events
  powerpc/watchpoint/xmon: Don't allow breakpoint overwriting
  powerpc/watchpoint/xmon: Support 2nd dawr

 arch/powerpc/include/asm/cputable.h       |   6 +-
 arch/powerpc/include/asm/debug.h          |   2 +-
 arch/powerpc/include/asm/hw_breakpoint.h  |  31 +-
 arch/powerpc/include/asm/processor.h      |   6 +-
 arch/powerpc/include/asm/reg.h            |   6 +-
 arch/powerpc/include/asm/sstep.h          |   2 +
 arch/powerpc/kernel/dawr.c                |  23 +-
 arch/powerpc/kernel/hw_breakpoint.c       | 636 ++++++++++++++++++----
 arch/powerpc/kernel/process.c             |  82 +--
 arch/powerpc/kernel/ptrace/ptrace-noadv.c |  72 ++-
 arch/powerpc/kernel/ptrace/ptrace32.c     |   4 +-
 arch/powerpc/kernel/signal.c              |   9 +-
 arch/powerpc/kvm/book3s_hv.c              |  12 +-
 arch/powerpc/kvm/book3s_hv_rmhandlers.S   |  18 +-
 arch/powerpc/xmon/xmon.c                  |  99 +++-
 kernel/events/hw_breakpoint.c             |  16 +
 16 files changed, 806 insertions(+), 218 deletions(-)

-- 
2.21.1

[PATCH v2 01/16] powerpc/watchpoint: Rename current DAWR macros

[Ravi Bangoria]

Future Power architecture is introducing second DAWR. Use real
register names from ISA for current macros:
  s/SPRN_DAWR/SPRN_DAWR0/
  s/SPRN_DAWRX/SPRN_DAWRX0/

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/reg.h          |  4 ++--
 arch/powerpc/kernel/dawr.c              |  4 ++--
 arch/powerpc/kvm/book3s_hv.c            | 12 ++++++------
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 18 +++++++++---------
 arch/powerpc/xmon/xmon.c                |  2 +-
 5 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index da5cab038e25..156ee89fa9be 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -283,14 +283,14 @@
 #define   CTRL_CT1	0x40000000	/* thread 1 */
 #define   CTRL_TE	0x00c00000	/* thread enable */
 #define   CTRL_RUNLATCH	0x1
-#define SPRN_DAWR	0xB4
+#define SPRN_DAWR0	0xB4
 #define SPRN_RPR	0xBA	/* Relative Priority Register */
 #define SPRN_CIABR	0xBB
 #define   CIABR_PRIV		0x3
 #define   CIABR_PRIV_USER	1
 #define   CIABR_PRIV_SUPER	2
 #define   CIABR_PRIV_HYPER	3
-#define SPRN_DAWRX	0xBC
+#define SPRN_DAWRX0	0xBC
 #define   DAWRX_USER	__MASK(0)
 #define   DAWRX_KERNEL	__MASK(1)
 #define   DAWRX_HYP	__MASK(2)
diff --git a/arch/powerpc/kernel/dawr.c b/arch/powerpc/kernel/dawr.c
index cc14aa6c4a1b..e91b613bf137 100644
--- a/arch/powerpc/kernel/dawr.c
+++ b/arch/powerpc/kernel/dawr.c
@@ -39,8 +39,8 @@ int set_dawr(struct arch_hw_breakpoint *brk)
 	if (ppc_md.set_dawr)
 		return ppc_md.set_dawr(dawr, dawrx);
 
-	mtspr(SPRN_DAWR, dawr);
-	mtspr(SPRN_DAWRX, dawrx);
+	mtspr(SPRN_DAWR0, dawr);
+	mtspr(SPRN_DAWRX0, dawrx);
 
 	return 0;
 }
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 33be4d93248a..498c57e1f5c9 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3383,8 +3383,8 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit,
 	int trap;
 	unsigned long host_hfscr = mfspr(SPRN_HFSCR);
 	unsigned long host_ciabr = mfspr(SPRN_CIABR);
-	unsigned long host_dawr = mfspr(SPRN_DAWR);
-	unsigned long host_dawrx = mfspr(SPRN_DAWRX);
+	unsigned long host_dawr = mfspr(SPRN_DAWR0);
+	unsigned long host_dawrx = mfspr(SPRN_DAWRX0);
 	unsigned long host_psscr = mfspr(SPRN_PSSCR);
 	unsigned long host_pidr = mfspr(SPRN_PID);
 
@@ -3413,8 +3413,8 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit,
 	mtspr(SPRN_SPURR, vcpu->arch.spurr);
 
 	if (dawr_enabled()) {
-		mtspr(SPRN_DAWR, vcpu->arch.dawr);
-		mtspr(SPRN_DAWRX, vcpu->arch.dawrx);
+		mtspr(SPRN_DAWR0, vcpu->arch.dawr);
+		mtspr(SPRN_DAWRX0, vcpu->arch.dawrx);
 	}
 	mtspr(SPRN_CIABR, vcpu->arch.ciabr);
 	mtspr(SPRN_IC, vcpu->arch.ic);
@@ -3466,8 +3466,8 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit,
 	      (local_paca->kvm_hstate.fake_suspend << PSSCR_FAKE_SUSPEND_LG));
 	mtspr(SPRN_HFSCR, host_hfscr);
 	mtspr(SPRN_CIABR, host_ciabr);
-	mtspr(SPRN_DAWR, host_dawr);
-	mtspr(SPRN_DAWRX, host_dawrx);
+	mtspr(SPRN_DAWR0, host_dawr);
+	mtspr(SPRN_DAWRX0, host_dawrx);
 	mtspr(SPRN_PID, host_pidr);
 
 	/*
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index dbc2fecc37f0..f4b412b7cad8 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -707,8 +707,8 @@ BEGIN_FTR_SECTION
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
 BEGIN_FTR_SECTION
 	mfspr	r5, SPRN_CIABR
-	mfspr	r6, SPRN_DAWR
-	mfspr	r7, SPRN_DAWRX
+	mfspr	r6, SPRN_DAWR0
+	mfspr	r7, SPRN_DAWRX0
 	mfspr	r8, SPRN_IAMR
 	std	r5, STACK_SLOT_CIABR(r1)
 	std	r6, STACK_SLOT_DAWR(r1)
@@ -803,8 +803,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
 	beq	1f
 	ld	r5, VCPU_DAWR(r4)
 	ld	r6, VCPU_DAWRX(r4)
-	mtspr	SPRN_DAWR, r5
-	mtspr	SPRN_DAWRX, r6
+	mtspr	SPRN_DAWR0, r5
+	mtspr	SPRN_DAWRX0, r6
 1:
 	ld	r7, VCPU_CIABR(r4)
 	ld	r8, VCPU_TAR(r4)
@@ -1772,8 +1772,8 @@ BEGIN_FTR_SECTION
 	 * If the DAWR doesn't work, it's ok to write these here as
 	 * this value should always be zero
 	*/
-	mtspr	SPRN_DAWR, r6
-	mtspr	SPRN_DAWRX, r7
+	mtspr	SPRN_DAWR0, r6
+	mtspr	SPRN_DAWRX0, r7
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 BEGIN_FTR_SECTION
 	ld	r5, STACK_SLOT_TID(r1)
@@ -2583,8 +2583,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 	mfmsr	r6
 	andi.	r6, r6, MSR_DR		/* in real mode? */
 	bne	4f
-	mtspr	SPRN_DAWR, r4
-	mtspr	SPRN_DAWRX, r5
+	mtspr	SPRN_DAWR0, r4
+	mtspr	SPRN_DAWRX0, r5
 4:	li	r3, 0
 	blr
 
@@ -3340,7 +3340,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
 	mtspr	SPRN_AMR, r0
 	mtspr	SPRN_IAMR, r0
 	mtspr	SPRN_CIABR, r0
-	mtspr	SPRN_DAWRX, r0
+	mtspr	SPRN_DAWRX0, r0
 
 BEGIN_MMU_FTR_SECTION
 	b	4f
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index ea303b7e4e29..75ca41c04dd1 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -1939,7 +1939,7 @@ static void dump_207_sprs(void)
 	printf("hfscr  = %.16lx  dhdes = %.16lx rpr    = %.16lx\n",
 		mfspr(SPRN_HFSCR), mfspr(SPRN_DHDES), mfspr(SPRN_RPR));
 	printf("dawr   = %.16lx  dawrx = %.16lx ciabr  = %.16lx\n",
-		mfspr(SPRN_DAWR), mfspr(SPRN_DAWRX), mfspr(SPRN_CIABR));
+		mfspr(SPRN_DAWR0), mfspr(SPRN_DAWRX0), mfspr(SPRN_CIABR));
 #endif
 }
 
-- 
2.21.1

[PATCH v2 02/16] powerpc/watchpoint: Add SPRN macros for second DAWR

[Ravi Bangoria]

Future Power architecture is introducing second DAWR. Add SPRN_ macros
for the same.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/reg.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 156ee89fa9be..062e74cf41fd 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -284,6 +284,7 @@
 #define   CTRL_TE	0x00c00000	/* thread enable */
 #define   CTRL_RUNLATCH	0x1
 #define SPRN_DAWR0	0xB4
+#define SPRN_DAWR1	0xB5
 #define SPRN_RPR	0xBA	/* Relative Priority Register */
 #define SPRN_CIABR	0xBB
 #define   CIABR_PRIV		0x3
@@ -291,6 +292,7 @@
 #define   CIABR_PRIV_SUPER	2
 #define   CIABR_PRIV_HYPER	3
 #define SPRN_DAWRX0	0xBC
+#define SPRN_DAWRX1	0xBD
 #define   DAWRX_USER	__MASK(0)
 #define   DAWRX_KERNEL	__MASK(1)
 #define   DAWRX_HYP	__MASK(2)
-- 
2.21.1

[PATCH v2 03/16] powerpc/watchpoint: Introduce function to get nr watchpoints dynamically

[Ravi Bangoria]

So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
But future Power architecture 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>
---
 arch/powerpc/include/asm/cputable.h      | 6 +++++-
 arch/powerpc/include/asm/hw_breakpoint.h | 5 +++++
 arch/powerpc/include/asm/processor.h     | 2 +-
 arch/powerpc/kernel/hw_breakpoint.c      | 2 +-
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 40a4d3c6fd99..c67b94f3334c 100644
--- 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 f2f8d8aa8e3b..518b41eef924 100644
--- 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 eedcbfb9a6ff..90f6dbc7ff00 100644
--- 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 72f461bd70fb..4120349e2abe 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -38,7 +38,7 @@ 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 */
 }
 
-- 
2.21.1

[PATCH v2 04/16] powerpc/watchpoint/ptrace: Return actual num of available watchpoints

[Ravi Bangoria]

User can ask for num of available watchpoints(dbginfo.num_data_bps)
using ptrace(PPC_PTRACE_GETHWDBGINFO). Return actual number of
available watchpoints on the machine rather than hardcoded 1.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/kernel/ptrace/ptrace-noadv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
index f87e7c5c3bf3..12962302d6a4 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
@@ -44,7 +44,7 @@ void ppc_gethwdinfo(struct ppc_debug_info *dbginfo)
 	dbginfo->version = 1;
 	dbginfo->num_instruction_bps = 0;
 	if (ppc_breakpoint_available())
-		dbginfo->num_data_bps = 1;
+		dbginfo->num_data_bps = nr_wp_slots();
 	else
 		dbginfo->num_data_bps = 0;
 	dbginfo->num_condition_regs = 0;
-- 
2.21.1

[PATCH v2 05/16] powerpc/watchpoint: Provide DAWR number to set_dawr

[Ravi Bangoria]

Introduce new parameter 'nr' to set_dawr() which indicates which DAWR
should be programed.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/hw_breakpoint.h |  4 ++--
 arch/powerpc/kernel/dawr.c               | 15 ++++++++++-----
 arch/powerpc/kernel/process.c            |  2 +-
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 518b41eef924..62549007c87a 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -104,10 +104,10 @@ static inline bool dawr_enabled(void)
 {
 	return dawr_force_enable;
 }
-int set_dawr(struct arch_hw_breakpoint *brk);
+int set_dawr(struct arch_hw_breakpoint *brk, int nr);
 #else
 static inline bool dawr_enabled(void) { return false; }
-static inline int set_dawr(struct arch_hw_breakpoint *brk) { return -1; }
+static inline int set_dawr(struct arch_hw_breakpoint *brk, int nr) { return -1; }
 #endif
 
 #endif	/* __KERNEL__ */
diff --git a/arch/powerpc/kernel/dawr.c b/arch/powerpc/kernel/dawr.c
index e91b613bf137..311e51ee09f4 100644
--- a/arch/powerpc/kernel/dawr.c
+++ b/arch/powerpc/kernel/dawr.c
@@ -16,7 +16,7 @@
 bool dawr_force_enable;
 EXPORT_SYMBOL_GPL(dawr_force_enable);
 
-int set_dawr(struct arch_hw_breakpoint *brk)
+int set_dawr(struct arch_hw_breakpoint *brk, int nr)
 {
 	unsigned long dawr, dawrx, mrd;
 
@@ -39,15 +39,20 @@ int set_dawr(struct arch_hw_breakpoint *brk)
 	if (ppc_md.set_dawr)
 		return ppc_md.set_dawr(dawr, dawrx);
 
-	mtspr(SPRN_DAWR0, dawr);
-	mtspr(SPRN_DAWRX0, dawrx);
+	if (nr == 0) {
+		mtspr(SPRN_DAWR0, dawr);
+		mtspr(SPRN_DAWRX0, dawrx);
+	} else {
+		mtspr(SPRN_DAWR1, dawr);
+		mtspr(SPRN_DAWRX1, dawrx);
+	}
 
 	return 0;
 }
 
 static void set_dawr_cb(void *info)
 {
-	set_dawr(info);
+	set_dawr(info, 0);
 }
 
 static ssize_t dawr_write_file_bool(struct file *file,
@@ -60,7 +65,7 @@ static ssize_t dawr_write_file_bool(struct file *file,
 	/* Send error to user if they hypervisor won't allow us to write DAWR */
 	if (!dawr_force_enable &&
 	    firmware_has_feature(FW_FEATURE_LPAR) &&
-	    set_dawr(&null_brk) != H_SUCCESS)
+	    set_dawr(&null_brk, 0) != H_SUCCESS)
 		return -ENODEV;
 
 	rc = debugfs_write_file_bool(file, user_buf, count, ppos);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 110db94cdf3c..b548a584e465 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -799,7 +799,7 @@ void __set_breakpoint(struct arch_hw_breakpoint *brk)
 
 	if (dawr_enabled())
 		// Power8 or later
-		set_dawr(brk);
+		set_dawr(brk, 0);
 	else if (IS_ENABLED(CONFIG_PPC_8xx))
 		set_breakpoint_8xx(brk);
 	else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
-- 
2.21.1

[PATCH v2 06/16] powerpc/watchpoint: Provide DAWR number to __set_breakpoint

[Ravi Bangoria]

Introduce new parameter 'nr' to __set_breakpoint() which indicates
which DAWR should be programed. Also convert current_brk variable
to an array.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/debug.h         |  2 +-
 arch/powerpc/include/asm/hw_breakpoint.h |  2 +-
 arch/powerpc/kernel/hw_breakpoint.c      |  8 ++++----
 arch/powerpc/kernel/process.c            | 14 +++++++-------
 arch/powerpc/kernel/signal.c             |  2 +-
 arch/powerpc/xmon/xmon.c                 |  2 +-
 6 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/include/asm/debug.h b/arch/powerpc/include/asm/debug.h
index 7756026b95ca..6228935a8b64 100644
--- a/arch/powerpc/include/asm/debug.h
+++ b/arch/powerpc/include/asm/debug.h
@@ -45,7 +45,7 @@ static inline int debugger_break_match(struct pt_regs *regs) { return 0; }
 static inline int debugger_fault_handler(struct pt_regs *regs) { return 0; }
 #endif
 
-void __set_breakpoint(struct arch_hw_breakpoint *brk);
+void __set_breakpoint(struct arch_hw_breakpoint *brk, int nr);
 bool ppc_breakpoint_available(void);
 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 extern void do_send_trap(struct pt_regs *regs, unsigned long address,
diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 62549007c87a..4e4976c3248b 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -85,7 +85,7 @@ static inline void hw_breakpoint_disable(void)
 	brk.len = 0;
 	brk.hw_len = 0;
 	if (ppc_breakpoint_available())
-		__set_breakpoint(&brk);
+		__set_breakpoint(&brk, 0);
 }
 extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
 int hw_breakpoint_handler(struct die_args *args);
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 4120349e2abe..7562f9ceb77e 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -63,7 +63,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
 	 * If so, DABR will be populated in single_step_dabr_instruction().
 	 */
 	if (current->thread.last_hit_ubp != bp)
-		__set_breakpoint(info);
+		__set_breakpoint(info, 0);
 
 	return 0;
 }
@@ -221,7 +221,7 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
 
 	info = counter_arch_bp(tsk->thread.last_hit_ubp);
 	regs->msr &= ~MSR_SE;
-	__set_breakpoint(info);
+	__set_breakpoint(info, 0);
 	tsk->thread.last_hit_ubp = NULL;
 }
 
@@ -346,7 +346,7 @@ int hw_breakpoint_handler(struct die_args *args)
 	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
 		perf_bp_event(bp, regs);
 
-	__set_breakpoint(info);
+	__set_breakpoint(info, 0);
 out:
 	rcu_read_unlock();
 	return rc;
@@ -379,7 +379,7 @@ static int single_step_dabr_instruction(struct die_args *args)
 	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
 		perf_bp_event(bp, regs);
 
-	__set_breakpoint(info);
+	__set_breakpoint(info, 0);
 	current->thread.last_hit_ubp = NULL;
 
 	/*
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index b548a584e465..e0275fcd0c55 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -630,7 +630,7 @@ void do_break (struct pt_regs *regs, unsigned long address,
 }
 #endif	/* CONFIG_PPC_ADV_DEBUG_REGS */
 
-static DEFINE_PER_CPU(struct arch_hw_breakpoint, current_brk);
+static DEFINE_PER_CPU(struct arch_hw_breakpoint, current_brk[HBP_NUM_MAX]);
 
 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 /*
@@ -707,7 +707,7 @@ EXPORT_SYMBOL_GPL(switch_booke_debug_regs);
 static void set_breakpoint(struct arch_hw_breakpoint *brk)
 {
 	preempt_disable();
-	__set_breakpoint(brk);
+	__set_breakpoint(brk, 0);
 	preempt_enable();
 }
 
@@ -793,13 +793,13 @@ static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)
 	return 0;
 }
 
-void __set_breakpoint(struct arch_hw_breakpoint *brk)
+void __set_breakpoint(struct arch_hw_breakpoint *brk, int nr)
 {
-	memcpy(this_cpu_ptr(&current_brk), brk, sizeof(*brk));
+	memcpy(this_cpu_ptr(&current_brk[nr]), brk, sizeof(*brk));
 
 	if (dawr_enabled())
 		// Power8 or later
-		set_dawr(brk, 0);
+		set_dawr(brk, nr);
 	else if (IS_ENABLED(CONFIG_PPC_8xx))
 		set_breakpoint_8xx(brk);
 	else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
@@ -1167,8 +1167,8 @@ struct task_struct *__switch_to(struct task_struct *prev,
  * schedule DABR
  */
 #ifndef CONFIG_HAVE_HW_BREAKPOINT
-	if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk), &new->thread.hw_brk)))
-		__set_breakpoint(&new->thread.hw_brk);
+	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 */
 #endif
 
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index d215f9554553..bbf237f072d4 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -129,7 +129,7 @@ static void do_signal(struct task_struct *tsk)
 	 * triggered inside the kernel.
 	 */
 	if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
-		__set_breakpoint(&tsk->thread.hw_brk);
+		__set_breakpoint(&tsk->thread.hw_brk, 0);
 #endif
 	/* Re-enable the breakpoints for the signal stack */
 	thread_change_pc(tsk, tsk->thread.regs);
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 75ca41c04dd1..508d353e7f06 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -935,7 +935,7 @@ static void insert_cpu_bpts(void)
 		brk.address = dabr.address;
 		brk.type = (dabr.enabled & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
 		brk.len = DABR_MAX_LEN;
-		__set_breakpoint(&brk);
+		__set_breakpoint(&brk, 0);
 	}
 
 	if (iabr)
-- 
2.21.1

[PATCH v2 07/16] powerpc/watchpoint: Get watchpoint count dynamically while disabling them

[Ravi Bangoria]

Instead of disabling only one watchpoint, get num of available
watchpoints dynamically and disable all of them.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/hw_breakpoint.h | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 4e4976c3248b..fae33c729ba9 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -78,14 +78,13 @@ extern void ptrace_triggered(struct perf_event *bp,
 			struct perf_sample_data *data, struct pt_regs *regs);
 static inline void hw_breakpoint_disable(void)
 {
-	struct arch_hw_breakpoint brk;
-
-	brk.address = 0;
-	brk.type = 0;
-	brk.len = 0;
-	brk.hw_len = 0;
-	if (ppc_breakpoint_available())
-		__set_breakpoint(&brk, 0);
+	int i;
+	struct arch_hw_breakpoint null_brk = {0};
+
+	if (ppc_breakpoint_available()) {
+		for (i = 0; i < nr_wp_slots(); i++)
+			__set_breakpoint(&null_brk, i);
+	}
 }
 extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
 int hw_breakpoint_handler(struct die_args *args);
-- 
2.21.1

[PATCH v2 08/16] powerpc/watchpoint: Disable all available watchpoints when !dawr_force_enable

[Ravi Bangoria]

Instead of disabling only first watchpoint, disable all available
watchpoints while clearing dawr_force_enable.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/kernel/dawr.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/dawr.c b/arch/powerpc/kernel/dawr.c
index 311e51ee09f4..5c882f07ac7d 100644
--- a/arch/powerpc/kernel/dawr.c
+++ b/arch/powerpc/kernel/dawr.c
@@ -50,9 +50,13 @@ int set_dawr(struct arch_hw_breakpoint *brk, int nr)
 	return 0;
 }
 
-static void set_dawr_cb(void *info)
+static void disable_dawrs(void *info)
 {
-	set_dawr(info, 0);
+	struct arch_hw_breakpoint null_brk = {0};
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++)
+		set_dawr(&null_brk, i);
 }
 
 static ssize_t dawr_write_file_bool(struct file *file,
@@ -74,7 +78,7 @@ static ssize_t dawr_write_file_bool(struct file *file,
 
 	/* If we are clearing, make sure all CPUs have the DAWR cleared */
 	if (!dawr_force_enable)
-		smp_call_function(set_dawr_cb, &null_brk, 0);
+		smp_call_function(disable_dawrs, NULL, 0);
 
 	return rc;
 }
-- 
2.21.1

[PATCH v2 09/16] powerpc/watchpoint: Convert thread_struct->hw_brk to an array

[Ravi Bangoria]

So far powerpc hw supported only one watchpoint. But Future Power
architecture is introducing 2nd DAWR. Convert thread_struct->hw_brk
into an array.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/processor.h      |  2 +-
 arch/powerpc/kernel/process.c             | 61 ++++++++++++++---------
 arch/powerpc/kernel/ptrace/ptrace-noadv.c | 40 +++++++++++----
 arch/powerpc/kernel/ptrace/ptrace32.c     |  4 +-
 arch/powerpc/kernel/signal.c              |  9 +++-
 5 files changed, 77 insertions(+), 39 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 90f6dbc7ff00..65b03162cd67 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -187,7 +187,7 @@ 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 e0275fcd0c55..f5b4f21e822b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -704,21 +704,50 @@ 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);
+	}
+}
+
+static inline bool hw_brk_match(struct arch_hw_breakpoint *a,
+				struct arch_hw_breakpoint *b)
+{
+	if (a->address != b->address)
+		return false;
+	if (a->type != b->type)
+		return false;
+	if (a->len != b->len)
+		return false;
+	/* no need to check hw_len. it's calculated from address and len */
+	return true;
+}
+
+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);
+		}
+	}
 }
 #endif /* !CONFIG_HAVE_HW_BREAKPOINT */
 #endif	/* CONFIG_PPC_ADV_DEBUG_REGS */
@@ -822,19 +851,6 @@ bool ppc_breakpoint_available(void)
 }
 EXPORT_SYMBOL_GPL(ppc_breakpoint_available);
 
-static inline bool hw_brk_match(struct arch_hw_breakpoint *a,
-			      struct arch_hw_breakpoint *b)
-{
-	if (a->address != b->address)
-		return false;
-	if (a->type != b->type)
-		return false;
-	if (a->len != b->len)
-		return false;
-	/* no need to check hw_len. it's calculated from address and len */
-	return true;
-}
-
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 
 static inline bool tm_enabled(struct task_struct *tsk)
@@ -1167,8 +1183,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
  * 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);
+	switch_hw_breakpoint(new);
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 #endif
 
diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
index 12962302d6a4..0dbb35392dd2 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
@@ -67,11 +67,16 @@ int ptrace_get_debugreg(struct task_struct *child, unsigned long addr,
 	/* We only support one DABR and no IABRS at the moment */
 	if (addr > 0)
 		return -EINVAL;
-	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));
 	return put_user(dabr_fake, datalp);
 }
 
+/*
+ * 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.
+ */
 int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned long data)
 {
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -137,7 +142,7 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
 			return ret;
 
 		thread->ptrace_bps[0] = bp;
-		thread->hw_brk = hw_brk;
+		thread->hw_brk[0] = hw_brk;
 		return 0;
 	}
 
@@ -159,12 +164,24 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
 	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;
 	return 0;
 }
 
+static int find_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;
+}
+
 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;
@@ -223,15 +240,16 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
 	if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
 		return -EINVAL;
 
-	if (child->thread.hw_brk.address)
+	i = find_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;
 }
 
 long ppc_del_hwdebug(struct task_struct *child, long data)
@@ -241,7 +259,7 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
 	struct thread_struct *thread = &child->thread;
 	struct perf_event *bp;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
-	if (data != 1)
+	if (data < 1 || data > nr_wp_slots())
 		return -EINVAL;
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -254,11 +272,11 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
 	}
 	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;
diff --git a/arch/powerpc/kernel/ptrace/ptrace32.c b/arch/powerpc/kernel/ptrace/ptrace32.c
index 7976ddf29c0e..7589a9665ffb 100644
--- a/arch/powerpc/kernel/ptrace/ptrace32.c
+++ b/arch/powerpc/kernel/ptrace/ptrace32.c
@@ -259,8 +259,8 @@ 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 bbf237f072d4..b559b114d03d 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);
-- 
2.21.1

[PATCH v2 10/16] powerpc/watchpoint: Use loop for thread_struct->ptrace_bps

[Ravi Bangoria]

ptrace_bps is already an array of size HBP_NUM_MAX. But we use
hardcoded index 0 while fetching/updating it. Convert such code
to loop over array.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/kernel/hw_breakpoint.c       |  7 ++++--
 arch/powerpc/kernel/process.c             |  6 ++++-
 arch/powerpc/kernel/ptrace/ptrace-noadv.c | 28 +++++++++++++++++------
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 7562f9ceb77e..6daa95b8bb88 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -419,10 +419,13 @@ NOKPROBE_SYMBOL(hw_breakpoint_exceptions_notify);
  */
 void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
 {
+	int i;
 	struct thread_struct *t = &tsk->thread;
 
-	unregister_hw_breakpoint(t->ptrace_bps[0]);
-	t->ptrace_bps[0] = NULL;
+	for (i = 0; i < nr_wp_slots(); i++) {
+		unregister_hw_breakpoint(t->ptrace_bps[i]);
+		t->ptrace_bps[i] = NULL;
+	}
 }
 
 void hw_breakpoint_pmu_read(struct perf_event *bp)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f5b4f21e822b..73c0800f0bcf 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1618,6 +1618,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
 	void (*f)(void);
 	unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 	struct thread_info *ti = task_thread_info(p);
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+	int i;
+#endif
 
 	klp_init_thread_info(p);
 
@@ -1677,7 +1680,8 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
 	p->thread.ksp_limit = (unsigned long)end_of_stack(p);
 #endif
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-	p->thread.ptrace_bps[0] = NULL;
+	for (i = 0; i < nr_wp_slots(); i++)
+		p->thread.ptrace_bps[i] = NULL;
 #endif
 
 	p->thread.fp_save_area = NULL;
diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
index 0dbb35392dd2..08cb8c1b504c 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
@@ -168,6 +168,19 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
 	return 0;
 }
 
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+static int find_empty_ptrace_bp(struct thread_struct *thread)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!thread->ptrace_bps[i])
+			return i;
+	}
+	return -1;
+}
+#endif
+
 static int find_empty_hw_brk(struct thread_struct *thread)
 {
 	int i;
@@ -217,8 +230,9 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
 		len = 1;
 	else
 		return -EINVAL;
-	bp = thread->ptrace_bps[0];
-	if (bp)
+
+	i = find_empty_ptrace_bp(thread);
+	if (i < 0)
 		return -ENOSPC;
 
 	/* Create a new breakpoint request if one doesn't exist already */
@@ -228,13 +242,13 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
 	arch_bp_generic_fields(brk.type, &attr.bp_type);
 
 	bp = register_user_hw_breakpoint(&attr, ptrace_triggered, NULL, child);
-	thread->ptrace_bps[0] = bp;
+	thread->ptrace_bps[i] = bp;
 	if (IS_ERR(bp)) {
-		thread->ptrace_bps[0] = NULL;
+		thread->ptrace_bps[i] = NULL;
 		return PTR_ERR(bp);
 	}
 
-	return 1;
+	return i + 1;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 
 	if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
@@ -263,10 +277,10 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
 		return -EINVAL;
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-	bp = thread->ptrace_bps[0];
+	bp = thread->ptrace_bps[data - 1];
 	if (bp) {
 		unregister_hw_breakpoint(bp);
-		thread->ptrace_bps[0] = NULL;
+		thread->ptrace_bps[data - 1] = NULL;
 	} else {
 		ret = -ENOENT;
 	}
-- 
2.21.1

[PATCH v2 11/16] powerpc/watchpoint: Introduce is_ptrace_bp() function

[Ravi Bangoria]

Introduce is_ptrace_bp() function and move the check inside the
function. We will utilize it more in later set of patches.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/kernel/hw_breakpoint.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 6daa95b8bb88..8d3f7d87d790 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -90,6 +90,11 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
 	hw_breakpoint_disable();
 }
 
+static bool is_ptrace_bp(struct perf_event *bp)
+{
+	return bp->overflow_handler == ptrace_triggered;
+}
+
 /*
  * Perform cleanup of arch-specific counters during unregistration
  * of the perf-event
@@ -324,7 +329,7 @@ int hw_breakpoint_handler(struct die_args *args)
 	 * one-shot mode. The ptrace-ed process will receive the SIGTRAP signal
 	 * generated in do_dabr().
 	 */
-	if (bp->overflow_handler == ptrace_triggered) {
+	if (is_ptrace_bp(bp)) {
 		perf_bp_event(bp, regs);
 		rc = NOTIFY_DONE;
 		goto out;
-- 
2.21.1

[PATCH v2 12/16] powerpc/watchpoint: Use builtin ALIGN*() macros

[Ravi Bangoria]

Currently we calculate hw aligned start and end addresses manually.
Replace them with builtin ALIGN_DOWN() and ALIGN() macros.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/hw_breakpoint.h  | 5 +++--
 arch/powerpc/kernel/hw_breakpoint.c       | 6 +++---
 arch/powerpc/kernel/process.c             | 4 ++--
 arch/powerpc/kernel/ptrace/ptrace-noadv.c | 2 +-
 4 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index fae33c729ba9..abc4603c0efe 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -34,10 +34,11 @@ struct arch_hw_breakpoint {
 #define HW_BRK_TYPE_PRIV_ALL	(HW_BRK_TYPE_USER | HW_BRK_TYPE_KERNEL | \
 				 HW_BRK_TYPE_HYP)
 
+/* Minimum granularity */
 #ifdef CONFIG_PPC_8xx
-#define HW_BREAKPOINT_ALIGN 0x3
+#define HW_BREAKPOINT_SIZE  0x4
 #else
-#define HW_BREAKPOINT_ALIGN 0x7
+#define HW_BREAKPOINT_SIZE  0x8
 #endif
 
 #define DABR_MAX_LEN	8
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 8d3f7d87d790..71274fbbac38 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -145,7 +145,7 @@ int arch_bp_generic_fields(int type, int *gen_bp_type)
  *    <---8 bytes--->
  *
  * In this case, we should configure hw as:
- *   start_addr = address & ~HW_BREAKPOINT_ALIGN
+ *   start_addr = address & ~(HW_BREAKPOINT_SIZE - 1)
  *   len = 16 bytes
  *
  * @start_addr and @end_addr are inclusive.
@@ -156,8 +156,8 @@ static int hw_breakpoint_validate_len(struct arch_hw_breakpoint *hw)
 	u16 hw_len;
 	unsigned long start_addr, end_addr;
 
-	start_addr = hw->address & ~HW_BREAKPOINT_ALIGN;
-	end_addr = (hw->address + hw->len - 1) | HW_BREAKPOINT_ALIGN;
+	start_addr = ALIGN_DOWN(hw->address, HW_BREAKPOINT_SIZE);
+	end_addr = ALIGN(hw->address + hw->len, HW_BREAKPOINT_SIZE) - 1;
 	hw_len = end_addr - start_addr + 1;
 
 	if (dawr_enabled()) {
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 73c0800f0bcf..cbd6e9b79401 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -794,8 +794,8 @@ static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)
 	unsigned long lctrl1 = LCTRL1_CTE_GT | LCTRL1_CTF_LT | LCTRL1_CRWE_RW |
 			       LCTRL1_CRWF_RW;
 	unsigned long lctrl2 = LCTRL2_LW0EN | LCTRL2_LW0LADC | LCTRL2_SLW0EN;
-	unsigned long start_addr = brk->address & ~HW_BREAKPOINT_ALIGN;
-	unsigned long end_addr = (brk->address + brk->len - 1) | HW_BREAKPOINT_ALIGN;
+	unsigned long start_addr = ALIGN_DOWN(brk->address, HW_BREAKPOINT_SIZE);
+	unsigned long end_addr = ALIGN(brk->address + brk->len, HW_BREAKPOINT_SIZE) - 1;
 
 	if (start_addr == 0)
 		lctrl2 |= LCTRL2_LW0LA_F;
diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
index 08cb8c1b504c..697c7e4b5877 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
@@ -216,7 +216,7 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
 	if ((unsigned long)bp_info->addr >= TASK_SIZE)
 		return -EIO;
 
-	brk.address = bp_info->addr & ~HW_BREAKPOINT_ALIGN;
+	brk.address = ALIGN_DOWN(bp_info->addr, HW_BREAKPOINT_SIZE);
 	brk.type = HW_BRK_TYPE_TRANSLATE;
 	brk.len = DABR_MAX_LEN;
 	if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
-- 
2.21.1

[PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint

[Ravi Bangoria]

Currently we assume that we have only one watchpoint supported by hw.
Get rid of that assumption and use dynamic loop instead. This should
make supporting more watchpoints very easy.

With more than one watchpoint, exception handler need to know which
DAWR caused the exception, and hw currently does not provide it. So
we need sw logic for the same. To figure out which DAWR caused the
exception, check all different combinations of user specified range,
dawr address range, actual access range and dawrx constrains. For ex,
if user specified range and actual access range overlaps but dawrx is
configured for readonly watchpoint and the instruction is store, this
DAWR must not have caused exception.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/processor.h |   2 +-
 arch/powerpc/include/asm/sstep.h     |   2 +
 arch/powerpc/kernel/hw_breakpoint.c  | 396 +++++++++++++++++++++------
 arch/powerpc/kernel/process.c        |   3 -
 4 files changed, 313 insertions(+), 90 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 65b03162cd67..4bc4e4a99166 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -185,7 +185,7 @@ struct thread_struct {
 	 * Helps identify source of single-step exception and subsequent
 	 * hw-breakpoint enablement
 	 */
-	struct perf_event *last_hit_ubp;
+	struct perf_event *last_hit_ubp[HBP_NUM_MAX];
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 	struct arch_hw_breakpoint hw_brk[HBP_NUM_MAX]; /* hardware breakpoint info */
 	unsigned long	trap_nr;	/* last trap # on this thread */
diff --git a/arch/powerpc/include/asm/sstep.h b/arch/powerpc/include/asm/sstep.h
index 769f055509c9..38919b27a6fa 100644
--- a/arch/powerpc/include/asm/sstep.h
+++ b/arch/powerpc/include/asm/sstep.h
@@ -48,6 +48,8 @@ enum instruction_type {
 
 #define INSTR_TYPE_MASK	0x1f
 
+#define OP_IS_LOAD(type)	((LOAD <= (type) && (type) <= LOAD_VSX) || (type) == LARX)
+#define OP_IS_STORE(type)	((STORE <= (type) && (type) <= STORE_VSX) || (type) == STCX)
 #define OP_IS_LOAD_STORE(type)	(LOAD <= (type) && (type) <= STCX)
 
 /* Compute flags, ORed in with type */
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 71274fbbac38..07a6cdea84ed 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -30,7 +30,7 @@
  * Stores the breakpoints currently in use on each breakpoint address
  * register for every cpu
  */
-static DEFINE_PER_CPU(struct perf_event *, bp_per_reg);
+static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM_MAX]);
 
 /*
  * Returns total number of data or instruction breakpoints available.
@@ -42,6 +42,17 @@ int hw_breakpoint_slots(int type)
 	return 0;		/* no instruction breakpoints available */
 }
 
+static bool single_step_pending(void)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (current->thread.last_hit_ubp[i])
+			return true;
+	}
+	return false;
+}
+
 /*
  * Install a perf counter breakpoint.
  *
@@ -54,16 +65,26 @@ int hw_breakpoint_slots(int type)
 int arch_install_hw_breakpoint(struct perf_event *bp)
 {
 	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
-	struct perf_event **slot = this_cpu_ptr(&bp_per_reg);
+	struct perf_event **slot;
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		slot = this_cpu_ptr(&bp_per_reg[i]);
+		if (!*slot) {
+			*slot = bp;
+			break;
+		}
+	}
 
-	*slot = bp;
+	if (WARN_ONCE(i == nr_wp_slots(), "Can't find any breakpoint slot"))
+		return -EBUSY;
 
 	/*
 	 * Do not install DABR values if the instruction must be single-stepped.
 	 * If so, DABR will be populated in single_step_dabr_instruction().
 	 */
-	if (current->thread.last_hit_ubp != bp)
-		__set_breakpoint(info, 0);
+	if (!single_step_pending())
+		__set_breakpoint(info, i);
 
 	return 0;
 }
@@ -79,15 +100,22 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
  */
 void arch_uninstall_hw_breakpoint(struct perf_event *bp)
 {
-	struct perf_event **slot = this_cpu_ptr(&bp_per_reg);
+	struct arch_hw_breakpoint null_brk = {0};
+	struct perf_event **slot;
+	int i;
 
-	if (*slot != bp) {
-		WARN_ONCE(1, "Can't find the breakpoint");
-		return;
+	for (i = 0; i < nr_wp_slots(); i++) {
+		slot = this_cpu_ptr(&bp_per_reg[i]);
+		if (*slot == bp) {
+			*slot = NULL;
+			break;
+		}
 	}
 
-	*slot = NULL;
-	hw_breakpoint_disable();
+	if (WARN_ONCE(i == nr_wp_slots(), "Can't find any breakpoint slot"))
+		return;
+
+	__set_breakpoint(&null_brk, i);
 }
 
 static bool is_ptrace_bp(struct perf_event *bp)
@@ -101,14 +129,20 @@ static bool is_ptrace_bp(struct perf_event *bp)
  */
 void arch_unregister_hw_breakpoint(struct perf_event *bp)
 {
+	int i;
+
 	/*
 	 * If the breakpoint is unregistered between a hw_breakpoint_handler()
 	 * and the single_step_dabr_instruction(), then cleanup the breakpoint
 	 * restoration variables to prevent dangling pointers.
 	 * FIXME, this should not be using bp->ctx at all! Sayeth peterz.
 	 */
-	if (bp->ctx && bp->ctx->task && bp->ctx->task != ((void *)-1L))
-		bp->ctx->task->thread.last_hit_ubp = NULL;
+	if (bp->ctx && bp->ctx->task && bp->ctx->task != ((void *)-1L)) {
+		for (i = 0; i < nr_wp_slots(); i++) {
+			if (bp->ctx->task->thread.last_hit_ubp[i] == bp)
+				bp->ctx->task->thread.last_hit_ubp[i] = NULL;
+		}
+	}
 }
 
 /*
@@ -220,90 +254,215 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
 {
 	struct arch_hw_breakpoint *info;
+	int i;
 
-	if (likely(!tsk->thread.last_hit_ubp))
-		return;
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (unlikely(tsk->thread.last_hit_ubp[i]))
+			goto reset;
+	}
+	return;
 
-	info = counter_arch_bp(tsk->thread.last_hit_ubp);
+reset:
 	regs->msr &= ~MSR_SE;
-	__set_breakpoint(info, 0);
-	tsk->thread.last_hit_ubp = NULL;
+	for (i = 0; i < nr_wp_slots(); i++) {
+		info = counter_arch_bp(__this_cpu_read(bp_per_reg[i]));
+		__set_breakpoint(info, i);
+		tsk->thread.last_hit_ubp[i] = NULL;
+	}
 }
 
-static bool dar_within_range(unsigned long dar, struct arch_hw_breakpoint *info)
+static bool dar_in_user_range(unsigned long dar, struct arch_hw_breakpoint *info)
 {
 	return ((info->address <= dar) && (dar - info->address < info->len));
 }
 
-static bool
-dar_range_overlaps(unsigned long dar, int size, struct arch_hw_breakpoint *info)
+static bool dar_user_range_overlaps(unsigned long dar, int size,
+				    struct arch_hw_breakpoint *info)
 {
 	return ((dar <= info->address + info->len - 1) &&
 		(dar + size - 1 >= info->address));
 }
 
+static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info)
+{
+	unsigned long hw_start_addr, hw_end_addr;
+
+	hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
+	hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE) - 1;
+
+	return ((hw_start_addr <= dar) && (hw_end_addr >= dar));
+}
+
+static bool dar_hw_range_overlaps(unsigned long dar, int size,
+				  struct arch_hw_breakpoint *info)
+{
+	unsigned long hw_start_addr, hw_end_addr;
+
+	hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
+	hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE) - 1;
+
+	return ((dar <= hw_end_addr) && (dar + size - 1 >= hw_start_addr));
+}
+
 /*
- * Handle debug exception notifications.
+ * If hw has multiple DAWR registers, we also need to check all
+ * dawrx constraint bits to confirm this is _really_ a valid event.
  */
-static bool stepping_handler(struct pt_regs *regs, struct perf_event *bp,
-			     struct arch_hw_breakpoint *info)
+static bool check_dawrx_constraints(struct pt_regs *regs, int type,
+				    struct arch_hw_breakpoint *info)
 {
-	unsigned int instr = 0;
-	int ret, type, size;
-	struct instruction_op op;
-	unsigned long addr = info->address;
+	if (OP_IS_LOAD(type) && !(info->type & HW_BRK_TYPE_READ))
+		return false;
 
-	if (__get_user_inatomic(instr, (unsigned int *)regs->nip))
-		goto fail;
+	if (OP_IS_STORE(type) && !(info->type & HW_BRK_TYPE_WRITE))
+		return false;
 
-	ret = analyse_instr(&op, regs, instr);
-	type = GETTYPE(op.type);
-	size = GETSIZE(op.type);
+	if (is_kernel_addr(regs->nip) && !(info->type & HW_BRK_TYPE_KERNEL))
+		return false;
 
-	if (!ret && (type == LARX || type == STCX)) {
-		printk_ratelimited("Breakpoint hit on instruction that can't be emulated."
-				   " Breakpoint at 0x%lx will be disabled.\n", addr);
-		goto disable;
-	}
+	if (user_mode(regs) && !(info->type & HW_BRK_TYPE_USER))
+		return false;
+
+	return true;
+}
+
+/*
+ * Returns true if the event is valid wrt dawr configuration,
+ * including extraneous exception. Otherwise return false.
+ */
+static bool check_constraints(struct pt_regs *regs, unsigned int instr,
+			      int type, int size,
+			      struct arch_hw_breakpoint *info)
+{
+	bool in_user_range = dar_in_user_range(regs->dar, info);
+	bool dawrx_constraints;
 
 	/*
-	 * If it's extraneous event, we still need to emulate/single-
-	 * step the instruction, but we don't generate an event.
+	 * 8xx supports only one breakpoint and thus we can
+	 * unconditionally return true.
 	 */
-	if (size && !dar_range_overlaps(regs->dar, size, info))
-		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+	if (IS_ENABLED(CONFIG_PPC_8xx)) {
+		if (!in_user_range)
+			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+		return true;
+	}
 
-	/* Do not emulate user-space instructions, instead single-step them */
-	if (user_mode(regs)) {
-		current->thread.last_hit_ubp = bp;
-		regs->msr |= MSR_SE;
+	if (unlikely(instr == -1)) {
+		if (in_user_range)
+			return true;
+
+		if (dar_in_hw_range(regs->dar, info)) {
+			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+			return true;
+		}
 		return false;
 	}
 
-	if (!emulate_step(regs, instr))
-		goto fail;
+	dawrx_constraints = check_dawrx_constraints(regs, type, info);
 
-	return true;
+	if (dar_user_range_overlaps(regs->dar, size, info))
+		return dawrx_constraints;
+
+	if (dar_hw_range_overlaps(regs->dar, size, info)) {
+		if (dawrx_constraints) {
+			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+			return true;
+		}
+	}
+	return false;
+}
+
+static int get_instr_detail(struct pt_regs *regs, int *type, int *size,
+			    bool *larx_stcx)
+{
+	unsigned int instr = 0;
+	struct instruction_op op;
+
+	if (__get_user_inatomic(instr, (unsigned int *)regs->nip))
+		return -1;
+
+	analyse_instr(&op, regs, instr);
 
-fail:
 	/*
-	 * We've failed in reliably handling the hw-breakpoint. Unregister
-	 * it and throw a warning message to let the user know about it.
+	 * Set size = 8 if analyse_instr() fails. If it's a userspace
+	 * watchpoint(valid or extraneous), we can notify user about it.
+	 * If it's a kernel watchpoint, instruction  emulation will fail
+	 * in stepping_handler() and watchpoint will be disabled.
 	 */
-	WARN(1, "Unable to handle hardware breakpoint. Breakpoint at "
-		"0x%lx will be disabled.", addr);
+	*type = GETTYPE(op.type);
+	*size = !(*type == UNKNOWN) ? GETSIZE(op.type) : 8;
+	*larx_stcx = (*type == LARX || *type == STCX);
 
-disable:
+	return instr;
+}
+
+/*
+ * We've failed in reliably handling the hw-breakpoint. Unregister
+ * it and throw a warning message to let the user know about it.
+ */
+static void handler_error(struct perf_event *bp, struct arch_hw_breakpoint *info)
+{
+	WARN(1, "Unable to handle hardware breakpoint."
+		"Breakpoint at 0x%lx will be disabled.",
+		info->address);
+	perf_event_disable_inatomic(bp);
+}
+
+static void larx_stcx_err(struct perf_event *bp, struct arch_hw_breakpoint *info)
+{
+	printk_ratelimited("Breakpoint hit on instruction that can't "
+			   "be emulated. Breakpoint at 0x%lx will be "
+			   "disabled.\n", info->address);
 	perf_event_disable_inatomic(bp);
-	return false;
+}
+
+static bool stepping_handler(struct pt_regs *regs, struct perf_event **bp,
+			     struct arch_hw_breakpoint **info, int *hit,
+			     unsigned int instr)
+{
+	int i;
+	int stepped;
+
+	/* Do not emulate user-space instructions, instead single-step them */
+	if (user_mode(regs)) {
+		for (i = 0; i < nr_wp_slots(); i++) {
+			if (!hit[i])
+				continue;
+			current->thread.last_hit_ubp[i] = bp[i];
+			info[i] = NULL;
+		}
+		regs->msr |= MSR_SE;
+		return false;
+	}
+
+	stepped = emulate_step(regs, instr);
+	if (!stepped) {
+		for (i = 0; i < nr_wp_slots(); i++) {
+			if (!hit[i])
+				continue;
+			handler_error(bp[i], info[i]);
+			info[i] = NULL;
+		}
+		return false;
+	}
+	return true;
 }
 
 int hw_breakpoint_handler(struct die_args *args)
 {
+	bool err = false;
 	int rc = NOTIFY_STOP;
-	struct perf_event *bp;
+	struct perf_event *bp[HBP_NUM_MAX] = {0};
 	struct pt_regs *regs = args->regs;
-	struct arch_hw_breakpoint *info;
+	struct arch_hw_breakpoint *info[HBP_NUM_MAX] = {0};
+	int i;
+	int hit[HBP_NUM_MAX] = {0};
+	int nr_hit = 0;
+	bool ptrace_bp = false;
+	unsigned int instr = 0;
+	int type = 0;
+	int size = 0;
+	bool larx_stcx = false;
 
 	/* Disable breakpoints during exception handling */
 	hw_breakpoint_disable();
@@ -316,12 +475,39 @@ int hw_breakpoint_handler(struct die_args *args)
 	 */
 	rcu_read_lock();
 
-	bp = __this_cpu_read(bp_per_reg);
-	if (!bp) {
+	if (!IS_ENABLED(CONFIG_PPC_8xx))
+		instr = get_instr_detail(regs, &type, &size, &larx_stcx);
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		bp[i] = __this_cpu_read(bp_per_reg[i]);
+		if (!bp[i])
+			continue;
+
+		info[i] = counter_arch_bp(bp[i]);
+		info[i]->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
+
+		if (check_constraints(regs, instr, type, size, info[i])) {
+			if (!IS_ENABLED(CONFIG_PPC_8xx) && instr == -1) {
+				handler_error(bp[i], info[i]);
+				info[i] = NULL;
+				err = 1;
+				continue;
+			}
+
+			if (is_ptrace_bp(bp[i]))
+				ptrace_bp = true;
+			hit[i] = 1;
+			nr_hit++;
+		}
+	}
+
+	if (err)
+		goto reset;
+
+	if (!nr_hit) {
 		rc = NOTIFY_DONE;
 		goto out;
 	}
-	info = counter_arch_bp(bp);
 
 	/*
 	 * Return early after invoking user-callback function without restoring
@@ -329,29 +515,50 @@ int hw_breakpoint_handler(struct die_args *args)
 	 * one-shot mode. The ptrace-ed process will receive the SIGTRAP signal
 	 * generated in do_dabr().
 	 */
-	if (is_ptrace_bp(bp)) {
-		perf_bp_event(bp, regs);
+	if (ptrace_bp) {
+		for (i = 0; i < nr_wp_slots(); i++) {
+			if (!hit[i])
+				continue;
+			perf_bp_event(bp[i], regs);
+			info[i] = NULL;
+		}
 		rc = NOTIFY_DONE;
-		goto out;
+		goto reset;
 	}
 
-	info->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
-	if (IS_ENABLED(CONFIG_PPC_8xx)) {
-		if (!dar_within_range(regs->dar, info))
-			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
-	} else {
-		if (!stepping_handler(regs, bp, info))
-			goto out;
+	if (!IS_ENABLED(CONFIG_PPC_8xx)) {
+		if (larx_stcx) {
+			for (i = 0; i < nr_wp_slots(); i++) {
+				if (!hit[i])
+					continue;
+				larx_stcx_err(bp[i], info[i]);
+				info[i] = NULL;
+			}
+			goto reset;
+		}
+
+		if (!stepping_handler(regs, bp, info, hit, instr))
+			goto reset;
 	}
 
 	/*
 	 * As a policy, the callback is invoked in a 'trigger-after-execute'
 	 * fashion
 	 */
-	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
-		perf_bp_event(bp, regs);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!hit[i])
+			continue;
+		if (!(info[i]->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
+			perf_bp_event(bp[i], regs);
+	}
+
+reset:
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!info[i])
+			continue;
+		__set_breakpoint(info[i], i);
+	}
 
-	__set_breakpoint(info, 0);
 out:
 	rcu_read_unlock();
 	return rc;
@@ -366,26 +573,43 @@ static int single_step_dabr_instruction(struct die_args *args)
 	struct pt_regs *regs = args->regs;
 	struct perf_event *bp = NULL;
 	struct arch_hw_breakpoint *info;
+	int i;
+	bool found = false;
 
-	bp = current->thread.last_hit_ubp;
 	/*
 	 * Check if we are single-stepping as a result of a
 	 * previous HW Breakpoint exception
 	 */
-	if (!bp)
-		return NOTIFY_DONE;
+	for (i = 0; i < nr_wp_slots(); i++) {
+		bp = current->thread.last_hit_ubp[i];
+
+		if (!bp)
+			continue;
+
+		found = true;
+		info = counter_arch_bp(bp);
+
+		/*
+		 * We shall invoke the user-defined callback function in the
+		 * single stepping handler to confirm to 'trigger-after-execute'
+		 * semantics
+		 */
+		if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
+			perf_bp_event(bp, regs);
+		current->thread.last_hit_ubp[i] = NULL;
+	}
 
-	info = counter_arch_bp(bp);
+	if (!found)
+		return NOTIFY_DONE;
 
-	/*
-	 * We shall invoke the user-defined callback function in the single
-	 * stepping handler to confirm to 'trigger-after-execute' semantics
-	 */
-	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
-		perf_bp_event(bp, regs);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		bp = __this_cpu_read(bp_per_reg[i]);
+		if (!bp)
+			continue;
 
-	__set_breakpoint(info, 0);
-	current->thread.last_hit_ubp = NULL;
+		info = counter_arch_bp(bp);
+		__set_breakpoint(info, i);
+	}
 
 	/*
 	 * If the process was being single-stepped by ptrace, let the
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index cbd6e9b79401..7c64299b001a 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -622,9 +622,6 @@ void do_break (struct pt_regs *regs, unsigned long address,
 	if (debugger_break_match(regs))
 		return;
 
-	/* Clear the breakpoint */
-	hw_breakpoint_disable();
-
 	/* Deliver the signal to userspace */
 	force_sig_fault(SIGTRAP, TRAP_HWBKPT, (void __user *)address);
 }
-- 
2.21.1

[PATCH v2 14/16] powerpc/watchpoint: Don't allow concurrent perf and ptrace events

[Ravi Bangoria]

With Book3s DAWR, ptrace and perf watchpoints on powerpc behaves
differently. Ptrace watchpoint works in one-shot mode and generates
signal before executing instruction. It's ptrace user's job to
single-step the instruction and re-enable the watchpoint. OTOH, in
case of perf watchpoint, kernel emulates/single-steps the instruction
and then generates event. If perf and ptrace creates two events with
same or overlapping address ranges, it's ambiguous to decide who
should single-step the instruction. Because of this issue, don't
allow perf and ptrace watchpoint at the same time if their address
range overlaps.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/include/asm/hw_breakpoint.h |   2 +
 arch/powerpc/kernel/hw_breakpoint.c      | 222 +++++++++++++++++++++++
 kernel/events/hw_breakpoint.c            |  16 ++
 3 files changed, 240 insertions(+)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index abc4603c0efe..9d3bd1169591 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -70,6 +70,8 @@ extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
 						unsigned long val, void *data);
 int arch_install_hw_breakpoint(struct perf_event *bp);
 void arch_uninstall_hw_breakpoint(struct perf_event *bp);
+int arch_reserve_bp_slot(struct perf_event *bp);
+void arch_release_bp_slot(struct perf_event *bp);
 void arch_unregister_hw_breakpoint(struct perf_event *bp);
 void hw_breakpoint_pmu_read(struct perf_event *bp);
 extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 07a6cdea84ed..f813acb0d9f0 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -123,6 +123,228 @@ static bool is_ptrace_bp(struct perf_event *bp)
 	return bp->overflow_handler == ptrace_triggered;
 }
 
+struct breakpoint {
+	struct list_head list;
+	struct perf_event *bp;
+	bool ptrace_bp;
+};
+
+static DEFINE_PER_CPU(struct breakpoint *, cpu_bps[HBP_NUM_MAX]);
+static LIST_HEAD(task_bps);
+
+static struct breakpoint *alloc_breakpoint(struct perf_event *bp)
+{
+	struct breakpoint *tmp;
+
+	tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
+	if (!tmp)
+		return ERR_PTR(-ENOMEM);
+	tmp->bp = bp;
+	tmp->ptrace_bp = is_ptrace_bp(bp);
+	return tmp;
+}
+
+static bool bp_addr_range_overlap(struct perf_event *bp1, struct perf_event *bp2)
+{
+	__u64 bp1_saddr, bp1_eaddr, bp2_saddr, bp2_eaddr;
+
+	bp1_saddr = ALIGN_DOWN(bp1->attr.bp_addr, HW_BREAKPOINT_SIZE);
+	bp1_eaddr = ALIGN(bp1->attr.bp_addr + bp1->attr.bp_len, HW_BREAKPOINT_SIZE) - 1;
+	bp2_saddr = ALIGN_DOWN(bp2->attr.bp_addr, HW_BREAKPOINT_SIZE);
+	bp2_eaddr = ALIGN(bp2->attr.bp_addr + bp2->attr.bp_len, HW_BREAKPOINT_SIZE) - 1;
+
+	return (bp1_saddr <= bp2_eaddr && bp1_eaddr >= bp2_saddr);
+}
+
+static bool alternate_infra_bp(struct breakpoint *b, struct perf_event *bp)
+{
+	return is_ptrace_bp(bp) ? !b->ptrace_bp : b->ptrace_bp;
+}
+
+static bool can_co_exist(struct breakpoint *b, struct perf_event *bp)
+{
+	return !(alternate_infra_bp(b, bp) && bp_addr_range_overlap(b->bp, bp));
+}
+
+static int task_bps_add(struct perf_event *bp)
+{
+	struct breakpoint *tmp;
+
+	tmp = alloc_breakpoint(bp);
+	if (IS_ERR(tmp))
+		return PTR_ERR(tmp);
+
+	list_add(&tmp->list, &task_bps);
+	return 0;
+}
+
+static void task_bps_remove(struct perf_event *bp)
+{
+	struct list_head *pos, *q;
+	struct breakpoint *tmp;
+
+	list_for_each_safe(pos, q, &task_bps) {
+		tmp = list_entry(pos, struct breakpoint, list);
+
+		if (tmp->bp == bp) {
+			list_del(&tmp->list);
+			kfree(tmp);
+			break;
+		}
+	}
+}
+
+/*
+ * If any task has breakpoint from alternate infrastructure,
+ * return true. Otherwise return false.
+ */
+static bool all_task_bps_check(struct perf_event *bp)
+{
+	struct breakpoint *tmp;
+
+	list_for_each_entry(tmp, &task_bps, list) {
+		if (!can_co_exist(tmp, bp))
+			return true;
+	}
+	return false;
+}
+
+/*
+ * If same task has breakpoint from alternate infrastructure,
+ * return true. Otherwise return false.
+ */
+static bool same_task_bps_check(struct perf_event *bp)
+{
+	struct breakpoint *tmp;
+
+	list_for_each_entry(tmp, &task_bps, list) {
+		if (tmp->bp->hw.target == bp->hw.target &&
+		    !can_co_exist(tmp, bp))
+			return true;
+	}
+	return false;
+}
+
+static int cpu_bps_add(struct perf_event *bp)
+{
+	struct breakpoint **cpu_bp;
+	struct breakpoint *tmp;
+	int i = 0;
+
+	tmp = alloc_breakpoint(bp);
+	if (IS_ERR(tmp))
+		return PTR_ERR(tmp);
+
+	cpu_bp = per_cpu_ptr(cpu_bps, bp->cpu);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!cpu_bp[i]) {
+			cpu_bp[i] = tmp;
+			break;
+		}
+	}
+	return 0;
+}
+
+static void cpu_bps_remove(struct perf_event *bp)
+{
+	struct breakpoint **cpu_bp;
+	int i = 0;
+
+	cpu_bp = per_cpu_ptr(cpu_bps, bp->cpu);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!cpu_bp[i])
+			continue;
+
+		if (cpu_bp[i]->bp == bp) {
+			kfree(cpu_bp[i]);
+			cpu_bp[i] = NULL;
+			break;
+		}
+	}
+}
+
+static bool cpu_bps_check(int cpu, struct perf_event *bp)
+{
+	struct breakpoint **cpu_bp;
+	int i;
+
+	cpu_bp = per_cpu_ptr(cpu_bps, cpu);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (cpu_bp[i] && !can_co_exist(cpu_bp[i], bp))
+			return true;
+	}
+	return false;
+}
+
+static bool all_cpu_bps_check(struct perf_event *bp)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		if (cpu_bps_check(cpu, bp))
+			return true;
+	}
+	return false;
+}
+
+/*
+ * We don't use any locks to serialize accesses to cpu_bps or task_bps
+ * because are already inside nr_bp_mutex.
+ */
+int arch_reserve_bp_slot(struct perf_event *bp)
+{
+	int ret;
+
+	/* ptrace breakpoint */
+	if (is_ptrace_bp(bp)) {
+		if (all_cpu_bps_check(bp))
+			return -ENOSPC;
+
+		if (same_task_bps_check(bp))
+			return -ENOSPC;
+
+		return task_bps_add(bp);
+	}
+
+	/* perf breakpoint */
+	if (is_kernel_addr(bp->attr.bp_addr))
+		return 0;
+
+	if (bp->hw.target && bp->cpu == -1) {
+		if (same_task_bps_check(bp))
+			return -ENOSPC;
+
+		return task_bps_add(bp);
+	} else if (!bp->hw.target && bp->cpu != -1) {
+		if (all_task_bps_check(bp))
+			return -ENOSPC;
+
+		return cpu_bps_add(bp);
+	}
+
+	if (same_task_bps_check(bp))
+		return -ENOSPC;
+
+	ret = cpu_bps_add(bp);
+	if (ret)
+		return ret;
+	ret = task_bps_add(bp);
+	if (ret)
+		cpu_bps_remove(bp);
+
+	return ret;
+}
+
+void arch_release_bp_slot(struct perf_event *bp)
+{
+	if (!is_kernel_addr(bp->attr.bp_addr)) {
+		if (bp->hw.target)
+			task_bps_remove(bp);
+		if (bp->cpu != -1)
+			cpu_bps_remove(bp);
+	}
+}
+
 /*
  * Perform cleanup of arch-specific counters during unregistration
  * of the perf-event
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 3cc8416ec844..b48d7039a015 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -213,6 +213,15 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
 		list_del(&bp->hw.bp_list);
 }
 
+__weak int arch_reserve_bp_slot(struct perf_event *bp)
+{
+	return 0;
+}
+
+__weak void arch_release_bp_slot(struct perf_event *bp)
+{
+}
+
 /*
  * Function to perform processor-specific cleanup during unregistration
  */
@@ -270,6 +279,7 @@ static int __reserve_bp_slot(struct perf_event *bp, u64 bp_type)
 	struct bp_busy_slots slots = {0};
 	enum bp_type_idx type;
 	int weight;
+	int ret;
 
 	/* We couldn't initialize breakpoint constraints on boot */
 	if (!constraints_initialized)
@@ -294,6 +304,10 @@ static int __reserve_bp_slot(struct perf_event *bp, u64 bp_type)
 	if (slots.pinned + (!!slots.flexible) > nr_slots[type])
 		return -ENOSPC;
 
+	ret = arch_reserve_bp_slot(bp);
+	if (ret)
+		return ret;
+
 	toggle_bp_slot(bp, true, type, weight);
 
 	return 0;
@@ -317,6 +331,8 @@ static void __release_bp_slot(struct perf_event *bp, u64 bp_type)
 	enum bp_type_idx type;
 	int weight;
 
+	arch_release_bp_slot(bp);
+
 	type = find_slot_idx(bp_type);
 	weight = hw_breakpoint_weight(bp);
 	toggle_bp_slot(bp, false, type, weight);
-- 
2.21.1

[PATCH v2 15/16] powerpc/watchpoint/xmon: Don't allow breakpoint overwriting

[Ravi Bangoria]

Xmon allows overwriting breakpoints because it's supported by only
one dawr. But with multiple dawrs, overwriting becomes ambiguous
or unnecessary complicated. So let's not allow it.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/xmon/xmon.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 508d353e7f06..a1e36501af25 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -1382,6 +1382,10 @@ bpt_cmds(void)
 			printf("Hardware data breakpoint not supported on this cpu\n");
 			break;
 		}
+		if (dabr.enabled) {
+			printf("Couldn't find free breakpoint register\n");
+			break;
+		}
 		mode = 7;
 		cmd = inchar();
 		if (cmd == 'r')
-- 
2.21.1

[PATCH v2 16/16] powerpc/watchpoint/xmon: Support 2nd dawr

[Ravi Bangoria]

Add support for 2nd DAWR in xmon. With this, we can have two
simultaneous breakpoints from xmon.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/xmon/xmon.c | 101 ++++++++++++++++++++++++++-------------
 1 file changed, 69 insertions(+), 32 deletions(-)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index a1e36501af25..4f2c8d4cbc38 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -111,7 +111,7 @@ struct bpt {
 
 #define NBPTS	256
 static struct bpt bpts[NBPTS];
-static struct bpt dabr;
+static struct bpt dabr[HBP_NUM_MAX];
 static struct bpt *iabr;
 static unsigned bpinstr = 0x7fe00008;	/* trap */
 
@@ -787,10 +787,17 @@ static int xmon_sstep(struct pt_regs *regs)
 
 static int xmon_break_match(struct pt_regs *regs)
 {
+	int i;
+
 	if ((regs->msr & (MSR_IR|MSR_PR|MSR_64BIT)) != (MSR_IR|MSR_64BIT))
 		return 0;
-	if (dabr.enabled == 0)
-		return 0;
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (dabr[i].enabled)
+			goto found;
+	}
+	return 0;
+
+found:
 	xmon_core(regs, 0);
 	return 1;
 }
@@ -929,13 +936,16 @@ static void insert_bpts(void)
 
 static void insert_cpu_bpts(void)
 {
+	int i;
 	struct arch_hw_breakpoint brk;
 
-	if (dabr.enabled) {
-		brk.address = dabr.address;
-		brk.type = (dabr.enabled & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
-		brk.len = DABR_MAX_LEN;
-		__set_breakpoint(&brk, 0);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (dabr[i].enabled) {
+			brk.address = dabr[i].address;
+			brk.type = (dabr[i].enabled & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
+			brk.len = 8;
+			__set_breakpoint(&brk, i);
+		}
 	}
 
 	if (iabr)
@@ -1349,6 +1359,35 @@ static long check_bp_loc(unsigned long addr)
 	return 1;
 }
 
+static int find_free_data_bpt(void)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!dabr[i].enabled)
+			return i;
+	}
+	printf("Couldn't find free breakpoint register\n");
+	return -1;
+}
+
+static void print_data_bpts(void)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!dabr[i].enabled)
+			continue;
+
+		printf("   data   "REG"  [", dabr[i].address);
+		if (dabr[i].enabled & 1)
+			printf("r");
+		if (dabr[i].enabled & 2)
+			printf("w");
+		printf("]\n");
+	}
+}
+
 static char *breakpoint_help_string =
     "Breakpoint command usage:\n"
     "b                show breakpoints\n"
@@ -1382,10 +1421,9 @@ bpt_cmds(void)
 			printf("Hardware data breakpoint not supported on this cpu\n");
 			break;
 		}
-		if (dabr.enabled) {
-			printf("Couldn't find free breakpoint register\n");
+		i = find_free_data_bpt();
+		if (i < 0)
 			break;
-		}
 		mode = 7;
 		cmd = inchar();
 		if (cmd == 'r')
@@ -1394,15 +1432,15 @@ bpt_cmds(void)
 			mode = 6;
 		else
 			termch = cmd;
-		dabr.address = 0;
-		dabr.enabled = 0;
-		if (scanhex(&dabr.address)) {
-			if (!is_kernel_addr(dabr.address)) {
+		dabr[i].address = 0;
+		dabr[i].enabled = 0;
+		if (scanhex(&dabr[i].address)) {
+			if (!is_kernel_addr(dabr[i].address)) {
 				printf(badaddr);
 				break;
 			}
-			dabr.address &= ~HW_BRK_TYPE_DABR;
-			dabr.enabled = mode | BP_DABR;
+			dabr[i].address &= ~HW_BRK_TYPE_DABR;
+			dabr[i].enabled = mode | BP_DABR;
 		}
 
 		force_enable_xmon();
@@ -1441,7 +1479,9 @@ bpt_cmds(void)
 			for (i = 0; i < NBPTS; ++i)
 				bpts[i].enabled = 0;
 			iabr = NULL;
-			dabr.enabled = 0;
+			for (i = 0; i < nr_wp_slots(); i++)
+				dabr[i].enabled = 0;
+
 			printf("All breakpoints cleared\n");
 			break;
 		}
@@ -1475,14 +1515,7 @@ bpt_cmds(void)
 		if (xmon_is_ro || !scanhex(&a)) {
 			/* print all breakpoints */
 			printf("   type            address\n");
-			if (dabr.enabled) {
-				printf("   data   "REG"  [", dabr.address);
-				if (dabr.enabled & 1)
-					printf("r");
-				if (dabr.enabled & 2)
-					printf("w");
-				printf("]\n");
-			}
+			print_data_bpts();
 			for (bp = bpts; bp < &bpts[NBPTS]; ++bp) {
 				if (!bp->enabled)
 					continue;
@@ -1942,8 +1975,13 @@ static void dump_207_sprs(void)
 
 	printf("hfscr  = %.16lx  dhdes = %.16lx rpr    = %.16lx\n",
 		mfspr(SPRN_HFSCR), mfspr(SPRN_DHDES), mfspr(SPRN_RPR));
-	printf("dawr   = %.16lx  dawrx = %.16lx ciabr  = %.16lx\n",
-		mfspr(SPRN_DAWR0), mfspr(SPRN_DAWRX0), mfspr(SPRN_CIABR));
+	printf("dawr0  = %.16lx dawrx0 = %.16lx\n",
+	       mfspr(SPRN_DAWR0), mfspr(SPRN_DAWRX0));
+	if (nr_wp_slots() > 1) {
+		printf("dawr1  = %.16lx dawrx1 = %.16lx\n",
+		       mfspr(SPRN_DAWR1), mfspr(SPRN_DAWRX1));
+	}
+	printf("ciabr  = %.16lx\n", mfspr(SPRN_CIABR));
 #endif
 }
 
@@ -3868,10 +3906,9 @@ static void clear_all_bpt(void)
 		bpts[i].enabled = 0;
 
 	/* Clear any data or iabr breakpoints */
-	if (iabr || dabr.enabled) {
-		iabr = NULL;
-		dabr.enabled = 0;
-	}
+	iabr = NULL;
+	for (i = 0; i < nr_wp_slots(); i++)
+		dabr[i].enabled = 0;
 }
 
 #ifdef CONFIG_DEBUG_FS
-- 
2.21.1

Re: [PATCH v2 03/16] powerpc/watchpoint: Introduce function to get nr watchpoints dynamically

[Christophe Leroy]

Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
> So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
> But future Power architecture 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.


Everywhere else in the code, it is called 'breakpoint', not 'watchpoint'.

Wouldn't it be more consistent to call the function nr_bp_slots() 
instead of nr_wp_slots() ?

Especially as we are likely going to extend your changes to support 
DABR2 in addition to DABR on BOOK3S/32.

Christophe

> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/include/asm/cputable.h      | 6 +++++-
>   arch/powerpc/include/asm/hw_breakpoint.h | 5 +++++
>   arch/powerpc/include/asm/processor.h     | 2 +-
>   arch/powerpc/kernel/hw_breakpoint.c      | 2 +-
>   4 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 40a4d3c6fd99..c67b94f3334c 100644
> --- 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 f2f8d8aa8e3b..518b41eef924 100644
> --- 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 eedcbfb9a6ff..90f6dbc7ff00 100644
> --- 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 72f461bd70fb..4120349e2abe 100644
> --- a/arch/powerpc/kernel/hw_breakpoint.c
> +++ b/arch/powerpc/kernel/hw_breakpoint.c
> @@ -38,7 +38,7 @@ 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 */
>   }
>   
> 

Re: [PATCH v2 07/16] powerpc/watchpoint: Get watchpoint count dynamically while disabling them

[Christophe Leroy]

Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
> Instead of disabling only one watchpoint, get num of available
> watchpoints dynamically and disable all of them.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/include/asm/hw_breakpoint.h | 15 +++++++--------
>   1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
> index 4e4976c3248b..fae33c729ba9 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -78,14 +78,13 @@ extern void ptrace_triggered(struct perf_event *bp,
>   			struct perf_sample_data *data, struct pt_regs *regs);
>   static inline void hw_breakpoint_disable(void)
>   {
> -	struct arch_hw_breakpoint brk;
> -
> -	brk.address = 0;
> -	brk.type = 0;
> -	brk.len = 0;
> -	brk.hw_len = 0;
> -	if (ppc_breakpoint_available())
> -		__set_breakpoint(&brk, 0);
> +	int i;
> +	struct arch_hw_breakpoint null_brk = {0};

Those declaration should be in the block unsigned them below.

> +
> +	if (ppc_breakpoint_available()) {
> +		for (i = 0; i < nr_wp_slots(); i++)
> +			__set_breakpoint(&null_brk, i);
> +	}

I would have had a preference to the following, but that's detail I guess:

	int i;
	struct arch_hw_breakpoint null_brk = {0};

	if (!ppc_breakpoint_available())
		return;

	for (i = 0; i < nr_wp_slots(); i++)
		__set_breakpoint(&null_brk, i);

>   }
>   extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
>   int hw_breakpoint_handler(struct die_args *args);
> 

Christophe

Re: [PATCH v2 08/16] powerpc/watchpoint: Disable all available watchpoints when !dawr_force_enable

[Christophe Leroy]

Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
> Instead of disabling only first watchpoint, disable all available
> watchpoints while clearing dawr_force_enable.

Can you also explain why you change the function name ?

> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/kernel/dawr.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/dawr.c b/arch/powerpc/kernel/dawr.c
> index 311e51ee09f4..5c882f07ac7d 100644
> --- a/arch/powerpc/kernel/dawr.c
> +++ b/arch/powerpc/kernel/dawr.c
> @@ -50,9 +50,13 @@ int set_dawr(struct arch_hw_breakpoint *brk, int nr)
>   	return 0;
>   }
>   
> -static void set_dawr_cb(void *info)
> +static void disable_dawrs(void *info)

Wouldn't it be better to keep _cb at the end of the function ?

>   {
> -	set_dawr(info, 0);
> +	struct arch_hw_breakpoint null_brk = {0};
> +	int i;
> +
> +	for (i = 0; i < nr_wp_slots(); i++)
> +		set_dawr(&null_brk, i);
>   }
>   
>   static ssize_t dawr_write_file_bool(struct file *file,
> @@ -74,7 +78,7 @@ static ssize_t dawr_write_file_bool(struct file *file,
>   
>   	/* If we are clearing, make sure all CPUs have the DAWR cleared */
>   	if (!dawr_force_enable)
> -		smp_call_function(set_dawr_cb, &null_brk, 0);
> +		smp_call_function(disable_dawrs, NULL, 0);
>   
>   	return rc;
>   }
> 

Christophe

Re: [PATCH v2 09/16] powerpc/watchpoint: Convert thread_struct->hw_brk to an array

[Christophe Leroy]

Le 01/04/2020 à 08:13, 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.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/include/asm/processor.h      |  2 +-
>   arch/powerpc/kernel/process.c             | 61 ++++++++++++++---------
>   arch/powerpc/kernel/ptrace/ptrace-noadv.c | 40 +++++++++++----
>   arch/powerpc/kernel/ptrace/ptrace32.c     |  4 +-
>   arch/powerpc/kernel/signal.c              |  9 +++-
>   5 files changed, 77 insertions(+), 39 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
> index 90f6dbc7ff00..65b03162cd67 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -187,7 +187,7 @@ 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 e0275fcd0c55..f5b4f21e822b 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -704,21 +704,50 @@ 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++) {

Maybe you could add the following that you added other places:

	struct arch_hw_breakpoint null_brk = {0};

Then do

	thread->hw_brk[i] = null_brk;

> +		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);
> +	}
> +}
> +
> +static inline bool hw_brk_match(struct arch_hw_breakpoint *a,
> +				struct arch_hw_breakpoint *b)
> +{
> +	if (a->address != b->address)
> +		return false;
> +	if (a->type != b->type)
> +		return false;
> +	if (a->len != b->len)
> +		return false;
> +	/* no need to check hw_len. it's calculated from address and len */
> +	return true;
> +}
> +
> +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);
> +		}

Or could be:

		if (likely(hw_brk_match(this_cpu_ptr(&current_brk[i]),
					&new->thread.hw_brk[i])))
			continue;
		__set_breakpoint(&new->thread.hw_brk[i], i);


> +	}
>   }
>   #endif /* !CONFIG_HAVE_HW_BREAKPOINT */
>   #endif	/* CONFIG_PPC_ADV_DEBUG_REGS */
> @@ -822,19 +851,6 @@ bool ppc_breakpoint_available(void)
>   }
>   EXPORT_SYMBOL_GPL(ppc_breakpoint_available);
>   
> -static inline bool hw_brk_match(struct arch_hw_breakpoint *a,
> -			      struct arch_hw_breakpoint *b)
> -{
> -	if (a->address != b->address)
> -		return false;
> -	if (a->type != b->type)
> -		return false;
> -	if (a->len != b->len)
> -		return false;
> -	/* no need to check hw_len. it's calculated from address and len */
> -	return true;
> -}
> -
>   #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
>   
>   static inline bool tm_enabled(struct task_struct *tsk)
> @@ -1167,8 +1183,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
>    * 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);
> +	switch_hw_breakpoint(new);
>   #endif /* CONFIG_HAVE_HW_BREAKPOINT */
>   #endif
>   
> diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
> index 12962302d6a4..0dbb35392dd2 100644
> --- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
> +++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
> @@ -67,11 +67,16 @@ int ptrace_get_debugreg(struct task_struct *child, unsigned long addr,
>   	/* We only support one DABR and no IABRS at the moment */
>   	if (addr > 0)
>   		return -EINVAL;
> -	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));
>   	return put_user(dabr_fake, datalp);
>   }
>   
> +/*
> + * 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.
> + */
>   int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned long data)
>   {
>   #ifdef CONFIG_HAVE_HW_BREAKPOINT
> @@ -137,7 +142,7 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
>   			return ret;
>   
>   		thread->ptrace_bps[0] = bp;
> -		thread->hw_brk = hw_brk;
> +		thread->hw_brk[0] = hw_brk;
>   		return 0;
>   	}
>   
> @@ -159,12 +164,24 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
>   	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;
>   	return 0;
>   }
>   
> +static int find_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;
> +}
> +
>   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;
> @@ -223,15 +240,16 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
>   	if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
>   		return -EINVAL;
>   
> -	if (child->thread.hw_brk.address)
> +	i = find_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;
>   }
>   
>   long ppc_del_hwdebug(struct task_struct *child, long data)
> @@ -241,7 +259,7 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
>   	struct thread_struct *thread = &child->thread;
>   	struct perf_event *bp;
>   #endif /* CONFIG_HAVE_HW_BREAKPOINT */
> -	if (data != 1)
> +	if (data < 1 || data > nr_wp_slots())
>   		return -EINVAL;
>   
>   #ifdef CONFIG_HAVE_HW_BREAKPOINT
> @@ -254,11 +272,11 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
>   	}
>   	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;
> diff --git a/arch/powerpc/kernel/ptrace/ptrace32.c b/arch/powerpc/kernel/ptrace/ptrace32.c
> index 7976ddf29c0e..7589a9665ffb 100644
> --- a/arch/powerpc/kernel/ptrace/ptrace32.c
> +++ b/arch/powerpc/kernel/ptrace/ptrace32.c
> @@ -259,8 +259,8 @@ 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 bbf237f072d4..b559b114d03d 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);
> +	}

thread.hwbrk also exists when CONFIG_PPC_ADV_DEBUG_REGS is selected.

You could replace the #ifndef CONFIG_PPC_ADV_DEBUG_REGS by an if 
(!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) and then no need of an ifdef 
when declaring the int i;

>   #endif
>   	/* Re-enable the breakpoints for the signal stack */
>   	thread_change_pc(tsk, tsk->thread.regs);
> 

Christophe

Re: [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint

[Christophe Leroy]

Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
> Currently we assume that we have only one watchpoint supported by hw.
> Get rid of that assumption and use dynamic loop instead. This should
> make supporting more watchpoints very easy.
> 
> With more than one watchpoint, exception handler need to know which
> DAWR caused the exception, and hw currently does not provide it. So
> we need sw logic for the same. To figure out which DAWR caused the
> exception, check all different combinations of user specified range,
> dawr address range, actual access range and dawrx constrains. For ex,
> if user specified range and actual access range overlaps but dawrx is
> configured for readonly watchpoint and the instruction is store, this
> DAWR must not have caused exception.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/include/asm/processor.h |   2 +-
>   arch/powerpc/include/asm/sstep.h     |   2 +
>   arch/powerpc/kernel/hw_breakpoint.c  | 396 +++++++++++++++++++++------
>   arch/powerpc/kernel/process.c        |   3 -
>   4 files changed, 313 insertions(+), 90 deletions(-)
> 

[...]

> -static bool
> -dar_range_overlaps(unsigned long dar, int size, struct arch_hw_breakpoint *info)
> +static bool dar_user_range_overlaps(unsigned long dar, int size,
> +				    struct arch_hw_breakpoint *info)
>   {
>   	return ((dar <= info->address + info->len - 1) &&
>   		(dar + size - 1 >= info->address));
>   }

Here and several other places, I think it would be more clear if you 
could avoid the - 1 :

	return ((dar < info->address + info->len) &&
		(dar + size > info->address));


>   
> +static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info)
> +{
> +	unsigned long hw_start_addr, hw_end_addr;
> +
> +	hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
> +	hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE) - 1;
> +
> +	return ((hw_start_addr <= dar) && (hw_end_addr >= dar));
> +}

	hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);

	return ((hw_start_addr <= dar) && (hw_end_addr > dar));

Christophe

> +
> +static bool dar_hw_range_overlaps(unsigned long dar, int size,
> +				  struct arch_hw_breakpoint *info)
> +{
> +	unsigned long hw_start_addr, hw_end_addr;
> +
> +	hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
> +	hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE) - 1;
> +
> +	return ((dar <= hw_end_addr) && (dar + size - 1 >= hw_start_addr));
> +}

Same

Christophe

Re: [PATCH v2 03/16] powerpc/watchpoint: Introduce function to get nr watchpoints dynamically

[Ravi Bangoria]

On 4/1/20 11:59 AM, Christophe Leroy wrote:
> 
> 
> Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
>> So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
>> But future Power architecture 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.
> 
> 
> Everywhere else in the code, it is called 'breakpoint', not 'watchpoint'.
> 
> Wouldn't it be more consistent to call the function nr_bp_slots() instead of nr_wp_slots() ?
> 
> Especially as we are likely going to extend your changes to support DABR2 in addition to DABR on BOOK3S/32.

Sure. I don't have strong onion for nr_wp_slots() and I can rename it to
nr_bp_slots(). but...

Even though existing code uses breakpoint and watchpoint interchangeably,
I'm using wp/watchpoint to represent data-breakpoint, to distinguish it
from instruction-breakpoint (CIABR). So IMHO, nr_wp_slots() should return
number DAWRs/DABRs and nr_bp_slots() should return number of CIABRs. Is
that okay?

Ravi

Re: [PATCH v2 14/16] powerpc/watchpoint: Don't allow concurrent perf and ptrace events

[Christophe Leroy]

Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
> With Book3s DAWR, ptrace and perf watchpoints on powerpc behaves
> differently. Ptrace watchpoint works in one-shot mode and generates
> signal before executing instruction. It's ptrace user's job to
> single-step the instruction and re-enable the watchpoint. OTOH, in
> case of perf watchpoint, kernel emulates/single-steps the instruction
> and then generates event. If perf and ptrace creates two events with
> same or overlapping address ranges, it's ambiguous to decide who
> should single-step the instruction. Because of this issue, don't
> allow perf and ptrace watchpoint at the same time if their address
> range overlaps.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/include/asm/hw_breakpoint.h |   2 +
>   arch/powerpc/kernel/hw_breakpoint.c      | 222 +++++++++++++++++++++++
>   kernel/events/hw_breakpoint.c            |  16 ++
>   3 files changed, 240 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
> index abc4603c0efe..9d3bd1169591 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -70,6 +70,8 @@ extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
>   						unsigned long val, void *data);
>   int arch_install_hw_breakpoint(struct perf_event *bp);
>   void arch_uninstall_hw_breakpoint(struct perf_event *bp);
> +int arch_reserve_bp_slot(struct perf_event *bp);
> +void arch_release_bp_slot(struct perf_event *bp);
>   void arch_unregister_hw_breakpoint(struct perf_event *bp);
>   void hw_breakpoint_pmu_read(struct perf_event *bp);
>   extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
> diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
> index 07a6cdea84ed..f813acb0d9f0 100644
> --- a/arch/powerpc/kernel/hw_breakpoint.c
> +++ b/arch/powerpc/kernel/hw_breakpoint.c
> @@ -123,6 +123,228 @@ static bool is_ptrace_bp(struct perf_event *bp)
>   	return bp->overflow_handler == ptrace_triggered;
>   }
>   
> +struct breakpoint {
> +	struct list_head list;
> +	struct perf_event *bp;
> +	bool ptrace_bp;
> +};
> +
> +static DEFINE_PER_CPU(struct breakpoint *, cpu_bps[HBP_NUM_MAX]);
> +static LIST_HEAD(task_bps);
> +
> +static struct breakpoint *alloc_breakpoint(struct perf_event *bp)
> +{
> +	struct breakpoint *tmp;
> +
> +	tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
> +	if (!tmp)
> +		return ERR_PTR(-ENOMEM);
> +	tmp->bp = bp;
> +	tmp->ptrace_bp = is_ptrace_bp(bp);
> +	return tmp;
> +}
> +
> +static bool bp_addr_range_overlap(struct perf_event *bp1, struct perf_event *bp2)
> +{
> +	__u64 bp1_saddr, bp1_eaddr, bp2_saddr, bp2_eaddr;
> +
> +	bp1_saddr = ALIGN_DOWN(bp1->attr.bp_addr, HW_BREAKPOINT_SIZE);
> +	bp1_eaddr = ALIGN(bp1->attr.bp_addr + bp1->attr.bp_len, HW_BREAKPOINT_SIZE) - 1;
> +	bp2_saddr = ALIGN_DOWN(bp2->attr.bp_addr, HW_BREAKPOINT_SIZE);
> +	bp2_eaddr = ALIGN(bp2->attr.bp_addr + bp2->attr.bp_len, HW_BREAKPOINT_SIZE) - 1;
> +
> +	return (bp1_saddr <= bp2_eaddr && bp1_eaddr >= bp2_saddr);

Could avoid the - 1 on bp1_eaddr and bp2_eaddr by doing:

	return (bp1_saddr < bp2_eaddr && bp1_eaddr > bp2_saddr);


Christophe

Re: [PATCH v2 05/16] powerpc/watchpoint: Provide DAWR number to set_dawr

[Christophe Leroy]

Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
> Introduce new parameter 'nr' to set_dawr() which indicates which DAWR
> should be programed.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/include/asm/hw_breakpoint.h |  4 ++--
>   arch/powerpc/kernel/dawr.c               | 15 ++++++++++-----
>   arch/powerpc/kernel/process.c            |  2 +-
>   3 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
> index 518b41eef924..62549007c87a 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -104,10 +104,10 @@ static inline bool dawr_enabled(void)
>   {
>   	return dawr_force_enable;
>   }
> -int set_dawr(struct arch_hw_breakpoint *brk);
> +int set_dawr(struct arch_hw_breakpoint *brk, int nr);

Wondering if it wouldn't make more sense to have nr as first argument.

Christophe

>   #else
>   static inline bool dawr_enabled(void) { return false; }
> -static inline int set_dawr(struct arch_hw_breakpoint *brk) { return -1; }
> +static inline int set_dawr(struct arch_hw_breakpoint *brk, int nr) { return -1; }
>   #endif
>   
>   #endif	/* __KERNEL__ */
> diff --git a/arch/powerpc/kernel/dawr.c b/arch/powerpc/kernel/dawr.c
> index e91b613bf137..311e51ee09f4 100644
> --- a/arch/powerpc/kernel/dawr.c
> +++ b/arch/powerpc/kernel/dawr.c
> @@ -16,7 +16,7 @@
>   bool dawr_force_enable;
>   EXPORT_SYMBOL_GPL(dawr_force_enable);
>   
> -int set_dawr(struct arch_hw_breakpoint *brk)
> +int set_dawr(struct arch_hw_breakpoint *brk, int nr)
>   {
>   	unsigned long dawr, dawrx, mrd;
>   
> @@ -39,15 +39,20 @@ int set_dawr(struct arch_hw_breakpoint *brk)
>   	if (ppc_md.set_dawr)
>   		return ppc_md.set_dawr(dawr, dawrx);
>   
> -	mtspr(SPRN_DAWR0, dawr);
> -	mtspr(SPRN_DAWRX0, dawrx);
> +	if (nr == 0) {
> +		mtspr(SPRN_DAWR0, dawr);
> +		mtspr(SPRN_DAWRX0, dawrx);
> +	} else {
> +		mtspr(SPRN_DAWR1, dawr);
> +		mtspr(SPRN_DAWRX1, dawrx);
> +	}
>   
>   	return 0;
>   }
>   
>   static void set_dawr_cb(void *info)
>   {
> -	set_dawr(info);
> +	set_dawr(info, 0);
>   }
>   
>   static ssize_t dawr_write_file_bool(struct file *file,
> @@ -60,7 +65,7 @@ static ssize_t dawr_write_file_bool(struct file *file,
>   	/* Send error to user if they hypervisor won't allow us to write DAWR */
>   	if (!dawr_force_enable &&
>   	    firmware_has_feature(FW_FEATURE_LPAR) &&
> -	    set_dawr(&null_brk) != H_SUCCESS)
> +	    set_dawr(&null_brk, 0) != H_SUCCESS)
>   		return -ENODEV;
>   
>   	rc = debugfs_write_file_bool(file, user_buf, count, ppos);
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 110db94cdf3c..b548a584e465 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -799,7 +799,7 @@ void __set_breakpoint(struct arch_hw_breakpoint *brk)
>   
>   	if (dawr_enabled())
>   		// Power8 or later
> -		set_dawr(brk);
> +		set_dawr(brk, 0);
>   	else if (IS_ENABLED(CONFIG_PPC_8xx))
>   		set_breakpoint_8xx(brk);
>   	else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
> 

Re: [PATCH v2 06/16] powerpc/watchpoint: Provide DAWR number to __set_breakpoint

[Christophe Leroy]

Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
> Introduce new parameter 'nr' to __set_breakpoint() which indicates
> which DAWR should be programed. Also convert current_brk variable
> to an array.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/include/asm/debug.h         |  2 +-
>   arch/powerpc/include/asm/hw_breakpoint.h |  2 +-
>   arch/powerpc/kernel/hw_breakpoint.c      |  8 ++++----
>   arch/powerpc/kernel/process.c            | 14 +++++++-------
>   arch/powerpc/kernel/signal.c             |  2 +-
>   arch/powerpc/xmon/xmon.c                 |  2 +-
>   6 files changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/debug.h b/arch/powerpc/include/asm/debug.h
> index 7756026b95ca..6228935a8b64 100644
> --- a/arch/powerpc/include/asm/debug.h
> +++ b/arch/powerpc/include/asm/debug.h
> @@ -45,7 +45,7 @@ static inline int debugger_break_match(struct pt_regs *regs) { return 0; }
>   static inline int debugger_fault_handler(struct pt_regs *regs) { return 0; }
>   #endif
>   
> -void __set_breakpoint(struct arch_hw_breakpoint *brk);
> +void __set_breakpoint(struct arch_hw_breakpoint *brk, int nr);

Same, I think it would make more sense to have nr as first argument.

Christophe


>   bool ppc_breakpoint_available(void);
>   #ifdef CONFIG_PPC_ADV_DEBUG_REGS
>   extern void do_send_trap(struct pt_regs *regs, unsigned long address,
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
> index 62549007c87a..4e4976c3248b 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -85,7 +85,7 @@ static inline void hw_breakpoint_disable(void)
>   	brk.len = 0;
>   	brk.hw_len = 0;
>   	if (ppc_breakpoint_available())
> -		__set_breakpoint(&brk);
> +		__set_breakpoint(&brk, 0);
>   }
>   extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
>   int hw_breakpoint_handler(struct die_args *args);
> diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
> index 4120349e2abe..7562f9ceb77e 100644
> --- a/arch/powerpc/kernel/hw_breakpoint.c
> +++ b/arch/powerpc/kernel/hw_breakpoint.c
> @@ -63,7 +63,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
>   	 * If so, DABR will be populated in single_step_dabr_instruction().
>   	 */
>   	if (current->thread.last_hit_ubp != bp)
> -		__set_breakpoint(info);
> +		__set_breakpoint(info, 0);
>   
>   	return 0;
>   }
> @@ -221,7 +221,7 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
>   
>   	info = counter_arch_bp(tsk->thread.last_hit_ubp);
>   	regs->msr &= ~MSR_SE;
> -	__set_breakpoint(info);
> +	__set_breakpoint(info, 0);
>   	tsk->thread.last_hit_ubp = NULL;
>   }
>   
> @@ -346,7 +346,7 @@ int hw_breakpoint_handler(struct die_args *args)
>   	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
>   		perf_bp_event(bp, regs);
>   
> -	__set_breakpoint(info);
> +	__set_breakpoint(info, 0);
>   out:
>   	rcu_read_unlock();
>   	return rc;
> @@ -379,7 +379,7 @@ static int single_step_dabr_instruction(struct die_args *args)
>   	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
>   		perf_bp_event(bp, regs);
>   
> -	__set_breakpoint(info);
> +	__set_breakpoint(info, 0);
>   	current->thread.last_hit_ubp = NULL;
>   
>   	/*
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index b548a584e465..e0275fcd0c55 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -630,7 +630,7 @@ void do_break (struct pt_regs *regs, unsigned long address,
>   }
>   #endif	/* CONFIG_PPC_ADV_DEBUG_REGS */
>   
> -static DEFINE_PER_CPU(struct arch_hw_breakpoint, current_brk);
> +static DEFINE_PER_CPU(struct arch_hw_breakpoint, current_brk[HBP_NUM_MAX]);
>   
>   #ifdef CONFIG_PPC_ADV_DEBUG_REGS
>   /*
> @@ -707,7 +707,7 @@ EXPORT_SYMBOL_GPL(switch_booke_debug_regs);
>   static void set_breakpoint(struct arch_hw_breakpoint *brk)
>   {
>   	preempt_disable();
> -	__set_breakpoint(brk);
> +	__set_breakpoint(brk, 0);
>   	preempt_enable();
>   }
>   
> @@ -793,13 +793,13 @@ static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)
>   	return 0;
>   }
>   
> -void __set_breakpoint(struct arch_hw_breakpoint *brk)
> +void __set_breakpoint(struct arch_hw_breakpoint *brk, int nr)
>   {
> -	memcpy(this_cpu_ptr(&current_brk), brk, sizeof(*brk));
> +	memcpy(this_cpu_ptr(&current_brk[nr]), brk, sizeof(*brk));
>   
>   	if (dawr_enabled())
>   		// Power8 or later
> -		set_dawr(brk, 0);
> +		set_dawr(brk, nr);
>   	else if (IS_ENABLED(CONFIG_PPC_8xx))
>   		set_breakpoint_8xx(brk);
>   	else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
> @@ -1167,8 +1167,8 @@ struct task_struct *__switch_to(struct task_struct *prev,
>    * schedule DABR
>    */
>   #ifndef CONFIG_HAVE_HW_BREAKPOINT
> -	if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk), &new->thread.hw_brk)))
> -		__set_breakpoint(&new->thread.hw_brk);
> +	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 */
>   #endif
>   
> diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
> index d215f9554553..bbf237f072d4 100644
> --- a/arch/powerpc/kernel/signal.c
> +++ b/arch/powerpc/kernel/signal.c
> @@ -129,7 +129,7 @@ static void do_signal(struct task_struct *tsk)
>   	 * triggered inside the kernel.
>   	 */
>   	if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
> -		__set_breakpoint(&tsk->thread.hw_brk);
> +		__set_breakpoint(&tsk->thread.hw_brk, 0);
>   #endif
>   	/* Re-enable the breakpoints for the signal stack */
>   	thread_change_pc(tsk, tsk->thread.regs);
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index 75ca41c04dd1..508d353e7f06 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -935,7 +935,7 @@ static void insert_cpu_bpts(void)
>   		brk.address = dabr.address;
>   		brk.type = (dabr.enabled & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
>   		brk.len = DABR_MAX_LEN;
> -		__set_breakpoint(&brk);
> +		__set_breakpoint(&brk, 0);
>   	}
>   
>   	if (iabr)
> 

Re: [PATCH v2 03/16] powerpc/watchpoint: Introduce function to get nr watchpoints dynamically

[Christophe Leroy]

Le 01/04/2020 à 08:50, Ravi Bangoria a écrit :
> 
> 
> On 4/1/20 11:59 AM, Christophe Leroy wrote:
>>
>>
>> Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
>>> So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
>>> But future Power architecture 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.
>>
>>
>> Everywhere else in the code, it is called 'breakpoint', not 'watchpoint'.
>>
>> Wouldn't it be more consistent to call the function nr_bp_slots() 
>> instead of nr_wp_slots() ?
>>
>> Especially as we are likely going to extend your changes to support 
>> DABR2 in addition to DABR on BOOK3S/32.
> 
> Sure. I don't have strong onion for nr_wp_slots() and I can rename it to
> nr_bp_slots(). but...
> 
> Even though existing code uses breakpoint and watchpoint interchangeably,
> I'm using wp/watchpoint to represent data-breakpoint, to distinguish it
> from instruction-breakpoint (CIABR). So IMHO, nr_wp_slots() should return
> number DAWRs/DABRs and nr_bp_slots() should return number of CIABRs. Is
> that okay?
> 


Yes that makes sense too. Up to you.

Christophe

Re: [PATCH v2 06/16] powerpc/watchpoint: Provide DAWR number to __set_breakpoint

[Ravi Bangoria]

On 4/1/20 12:33 PM, Christophe Leroy wrote:
> 
> 
> Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
>> Introduce new parameter 'nr' to __set_breakpoint() which indicates
>> which DAWR should be programed. Also convert current_brk variable
>> to an array.
>>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>> ---
>>   arch/powerpc/include/asm/debug.h         |  2 +-
>>   arch/powerpc/include/asm/hw_breakpoint.h |  2 +-
>>   arch/powerpc/kernel/hw_breakpoint.c      |  8 ++++----
>>   arch/powerpc/kernel/process.c            | 14 +++++++-------
>>   arch/powerpc/kernel/signal.c             |  2 +-
>>   arch/powerpc/xmon/xmon.c                 |  2 +-
>>   6 files changed, 15 insertions(+), 15 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/debug.h b/arch/powerpc/include/asm/debug.h
>> index 7756026b95ca..6228935a8b64 100644
>> --- a/arch/powerpc/include/asm/debug.h
>> +++ b/arch/powerpc/include/asm/debug.h
>> @@ -45,7 +45,7 @@ static inline int debugger_break_match(struct pt_regs *regs) { return 0; }
>>   static inline int debugger_fault_handler(struct pt_regs *regs) { return 0; }
>>   #endif
>> -void __set_breakpoint(struct arch_hw_breakpoint *brk);
>> +void __set_breakpoint(struct arch_hw_breakpoint *brk, int nr);
> 
> Same, I think it would make more sense to have nr as first argument.

Sorry, didn't get your point. How will that help?

Ravi

Re: [PATCH v2 08/16] powerpc/watchpoint: Disable all available watchpoints when !dawr_force_enable

[Ravi Bangoria]

On 4/1/20 12:03 PM, Christophe Leroy wrote:
> 
> 
> Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
>> Instead of disabling only first watchpoint, disable all available
>> watchpoints while clearing dawr_force_enable.
> 
> Can you also explain why you change the function name ?

Right. I should have. Will add it in next version.

> 
>>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>> ---
>>   arch/powerpc/kernel/dawr.c | 10 +++++++---
>>   1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/dawr.c b/arch/powerpc/kernel/dawr.c
>> index 311e51ee09f4..5c882f07ac7d 100644
>> --- a/arch/powerpc/kernel/dawr.c
>> +++ b/arch/powerpc/kernel/dawr.c
>> @@ -50,9 +50,13 @@ int set_dawr(struct arch_hw_breakpoint *brk, int nr)
>>       return 0;
>>   }
>> -static void set_dawr_cb(void *info)
>> +static void disable_dawrs(void *info)
> 
> Wouldn't it be better to keep _cb at the end of the function ?

Sure.

Ravi

Re: [PATCH v2 09/16] powerpc/watchpoint: Convert thread_struct->hw_brk to an array

[Ravi Bangoria]

>>   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++) {
> 
> Maybe you could add the following that you added other places:
> 
>      struct arch_hw_breakpoint null_brk = {0};
> 
> Then do
> 
>      thread->hw_brk[i] = null_brk;

Yes that's better.

[...]

>> +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);
>> +        }
> 
> Or could be:
> 
>          if (likely(hw_brk_match(this_cpu_ptr(&current_brk[i]),
>                      &new->thread.hw_brk[i])))
>              continue;
>          __set_breakpoint(&new->thread.hw_brk[i], i);
> 

Sure.

[...]

>> @@ -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);
>> +    }
> 
> thread.hwbrk also exists when CONFIG_PPC_ADV_DEBUG_REGS is selected.
> 
> You could replace the #ifndef CONFIG_PPC_ADV_DEBUG_REGS by an if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) and then no need of an ifdef when declaring the int i;

Makes sense. Will change it.

Ravi

Re: [PATCH v2 06/16] powerpc/watchpoint: Provide DAWR number to __set_breakpoint

[Christophe Leroy]

Le 01/04/2020 à 10:57, Ravi Bangoria a écrit :
> 
> 
> On 4/1/20 12:33 PM, Christophe Leroy wrote:
>>
>>
>> Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
>>> Introduce new parameter 'nr' to __set_breakpoint() which indicates
>>> which DAWR should be programed. Also convert current_brk variable
>>> to an array.
>>>
>>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>>> ---
>>>   arch/powerpc/include/asm/debug.h         |  2 +-
>>>   arch/powerpc/include/asm/hw_breakpoint.h |  2 +-
>>>   arch/powerpc/kernel/hw_breakpoint.c      |  8 ++++----
>>>   arch/powerpc/kernel/process.c            | 14 +++++++-------
>>>   arch/powerpc/kernel/signal.c             |  2 +-
>>>   arch/powerpc/xmon/xmon.c                 |  2 +-
>>>   6 files changed, 15 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/debug.h 
>>> b/arch/powerpc/include/asm/debug.h
>>> index 7756026b95ca..6228935a8b64 100644
>>> --- a/arch/powerpc/include/asm/debug.h
>>> +++ b/arch/powerpc/include/asm/debug.h
>>> @@ -45,7 +45,7 @@ static inline int debugger_break_match(struct 
>>> pt_regs *regs) { return 0; }
>>>   static inline int debugger_fault_handler(struct pt_regs *regs) { 
>>> return 0; }
>>>   #endif
>>> -void __set_breakpoint(struct arch_hw_breakpoint *brk);
>>> +void __set_breakpoint(struct arch_hw_breakpoint *brk, int nr);
>>
>> Same, I think it would make more sense to have nr as first argument.
> 
> Sorry, didn't get your point. How will that help?
> 

Well, it is a tiny detail but for me it is more natural to first tel 
which element you modify before telling how you modify it.

Christophe

Re: [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint

[Ravi Bangoria]

On 4/1/20 12:20 PM, Christophe Leroy wrote:
> 
> 
> Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
>> Currently we assume that we have only one watchpoint supported by hw.
>> Get rid of that assumption and use dynamic loop instead. This should
>> make supporting more watchpoints very easy.
>>
>> With more than one watchpoint, exception handler need to know which
>> DAWR caused the exception, and hw currently does not provide it. So
>> we need sw logic for the same. To figure out which DAWR caused the
>> exception, check all different combinations of user specified range,
>> dawr address range, actual access range and dawrx constrains. For ex,
>> if user specified range and actual access range overlaps but dawrx is
>> configured for readonly watchpoint and the instruction is store, this
>> DAWR must not have caused exception.
>>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>> ---
>>   arch/powerpc/include/asm/processor.h |   2 +-
>>   arch/powerpc/include/asm/sstep.h     |   2 +
>>   arch/powerpc/kernel/hw_breakpoint.c  | 396 +++++++++++++++++++++------
>>   arch/powerpc/kernel/process.c        |   3 -
>>   4 files changed, 313 insertions(+), 90 deletions(-)
>>
> 
> [...]
> 
>> -static bool
>> -dar_range_overlaps(unsigned long dar, int size, struct arch_hw_breakpoint *info)
>> +static bool dar_user_range_overlaps(unsigned long dar, int size,
>> +                    struct arch_hw_breakpoint *info)
>>   {
>>       return ((dar <= info->address + info->len - 1) &&
>>           (dar + size - 1 >= info->address));
>>   }
> 
> Here and several other places, I think it would be more clear if you could avoid the - 1 :
> 
>      return ((dar < info->address + info->len) &&
>          (dar + size > info->address));

Ok. see below...

> 
> 
>> +static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info)
>> +{
>> +    unsigned long hw_start_addr, hw_end_addr;
>> +
>> +    hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
>> +    hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE) - 1;
>> +
>> +    return ((hw_start_addr <= dar) && (hw_end_addr >= dar));
>> +}
> 
>      hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
> 
>      return ((hw_start_addr <= dar) && (hw_end_addr > dar));

I'm using -1 while calculating end address is to make it
inclusive. If I don't use -1, the end address points to a
location outside of actual range, i.e. it's not really an
end address.

Ravi

Re: [PATCH v2 07/16] powerpc/watchpoint: Get watchpoint count dynamically while disabling them

[Ravi Bangoria]

On 4/1/20 12:02 PM, Christophe Leroy wrote:
> 
> 
> Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
>> Instead of disabling only one watchpoint, get num of available
>> watchpoints dynamically and disable all of them.
>>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>> ---
>>   arch/powerpc/include/asm/hw_breakpoint.h | 15 +++++++--------
>>   1 file changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
>> index 4e4976c3248b..fae33c729ba9 100644
>> --- a/arch/powerpc/include/asm/hw_breakpoint.h
>> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
>> @@ -78,14 +78,13 @@ extern void ptrace_triggered(struct perf_event *bp,
>>               struct perf_sample_data *data, struct pt_regs *regs);
>>   static inline void hw_breakpoint_disable(void)
>>   {
>> -    struct arch_hw_breakpoint brk;
>> -
>> -    brk.address = 0;
>> -    brk.type = 0;
>> -    brk.len = 0;
>> -    brk.hw_len = 0;
>> -    if (ppc_breakpoint_available())
>> -        __set_breakpoint(&brk, 0);
>> +    int i;
>> +    struct arch_hw_breakpoint null_brk = {0};
> 
> Those declaration should be in the block unsigned them below.
> 
>> +
>> +    if (ppc_breakpoint_available()) {
>> +        for (i = 0; i < nr_wp_slots(); i++)
>> +            __set_breakpoint(&null_brk, i);
>> +    }
> 
> I would have had a preference to the following, but that's detail I guess:
> 
>      int i;
>      struct arch_hw_breakpoint null_brk = {0};
> 
>      if (!ppc_breakpoint_available())
>          return;
> 
>      for (i = 0; i < nr_wp_slots(); i++)
>          __set_breakpoint(&null_brk, i);

This looks more better. Will change it.

Ravi

Re: [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint

[Christophe Leroy]

Le 01/04/2020 à 11:13, Ravi Bangoria a écrit :
> 
> 
> On 4/1/20 12:20 PM, Christophe Leroy wrote:
>>
>>
>> Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
>>> Currently we assume that we have only one watchpoint supported by hw.
>>> Get rid of that assumption and use dynamic loop instead. This should
>>> make supporting more watchpoints very easy.
>>>
>>> With more than one watchpoint, exception handler need to know which
>>> DAWR caused the exception, and hw currently does not provide it. So
>>> we need sw logic for the same. To figure out which DAWR caused the
>>> exception, check all different combinations of user specified range,
>>> dawr address range, actual access range and dawrx constrains. For ex,
>>> if user specified range and actual access range overlaps but dawrx is
>>> configured for readonly watchpoint and the instruction is store, this
>>> DAWR must not have caused exception.
>>>
>>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>>> ---
>>>   arch/powerpc/include/asm/processor.h |   2 +-
>>>   arch/powerpc/include/asm/sstep.h     |   2 +
>>>   arch/powerpc/kernel/hw_breakpoint.c  | 396 +++++++++++++++++++++------
>>>   arch/powerpc/kernel/process.c        |   3 -
>>>   4 files changed, 313 insertions(+), 90 deletions(-)
>>>
>>
>> [...]
>>
>>> -static bool
>>> -dar_range_overlaps(unsigned long dar, int size, struct 
>>> arch_hw_breakpoint *info)
>>> +static bool dar_user_range_overlaps(unsigned long dar, int size,
>>> +                    struct arch_hw_breakpoint *info)
>>>   {
>>>       return ((dar <= info->address + info->len - 1) &&
>>>           (dar + size - 1 >= info->address));
>>>   }
>>
>> Here and several other places, I think it would be more clear if you 
>> could avoid the - 1 :
>>
>>      return ((dar < info->address + info->len) &&
>>          (dar + size > info->address));
> 
> Ok. see below...
> 
>>
>>
>>> +static bool dar_in_hw_range(unsigned long dar, struct 
>>> arch_hw_breakpoint *info)
>>> +{
>>> +    unsigned long hw_start_addr, hw_end_addr;
>>> +
>>> +    hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
>>> +    hw_end_addr = ALIGN(info->address + info->len, 
>>> HW_BREAKPOINT_SIZE) - 1;
>>> +
>>> +    return ((hw_start_addr <= dar) && (hw_end_addr >= dar));
>>> +}
>>
>>      hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
>>
>>      return ((hw_start_addr <= dar) && (hw_end_addr > dar));
> 
> I'm using -1 while calculating end address is to make it
> inclusive. If I don't use -1, the end address points to a
> location outside of actual range, i.e. it's not really an
> end address.

But that's what is done is several places, for instance:

https://elixir.bootlin.com/linux/v5.6/source/arch/powerpc/mm/dma-noncoherent.c#L22

https://elixir.bootlin.com/linux/v5.6/source/arch/powerpc/include/asm/book3s/32/kup.h#L92

In several places like this, end is outside of the range. My feeling is 
that is helps with readability.

Christophe

Re: [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint

[Ravi Bangoria]

On 4/1/20 2:50 PM, Christophe Leroy wrote:
> 
> 
> Le 01/04/2020 à 11:13, Ravi Bangoria a écrit :
>>
>>
>> On 4/1/20 12:20 PM, Christophe Leroy wrote:
>>>
>>>
>>> Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
>>>> Currently we assume that we have only one watchpoint supported by hw.
>>>> Get rid of that assumption and use dynamic loop instead. This should
>>>> make supporting more watchpoints very easy.
>>>>
>>>> With more than one watchpoint, exception handler need to know which
>>>> DAWR caused the exception, and hw currently does not provide it. So
>>>> we need sw logic for the same. To figure out which DAWR caused the
>>>> exception, check all different combinations of user specified range,
>>>> dawr address range, actual access range and dawrx constrains. For ex,
>>>> if user specified range and actual access range overlaps but dawrx is
>>>> configured for readonly watchpoint and the instruction is store, this
>>>> DAWR must not have caused exception.
>>>>
>>>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>>>> ---
>>>>   arch/powerpc/include/asm/processor.h |   2 +-
>>>>   arch/powerpc/include/asm/sstep.h     |   2 +
>>>>   arch/powerpc/kernel/hw_breakpoint.c  | 396 +++++++++++++++++++++------
>>>>   arch/powerpc/kernel/process.c        |   3 -
>>>>   4 files changed, 313 insertions(+), 90 deletions(-)
>>>>
>>>
>>> [...]
>>>
>>>> -static bool
>>>> -dar_range_overlaps(unsigned long dar, int size, struct arch_hw_breakpoint *info)
>>>> +static bool dar_user_range_overlaps(unsigned long dar, int size,
>>>> +                    struct arch_hw_breakpoint *info)
>>>>   {
>>>>       return ((dar <= info->address + info->len - 1) &&
>>>>           (dar + size - 1 >= info->address));
>>>>   }
>>>
>>> Here and several other places, I think it would be more clear if you could avoid the - 1 :
>>>
>>>      return ((dar < info->address + info->len) &&
>>>          (dar + size > info->address));
>>
>> Ok. see below...
>>
>>>
>>>
>>>> +static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info)
>>>> +{
>>>> +    unsigned long hw_start_addr, hw_end_addr;
>>>> +
>>>> +    hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
>>>> +    hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE) - 1;
>>>> +
>>>> +    return ((hw_start_addr <= dar) && (hw_end_addr >= dar));
>>>> +}
>>>
>>>      hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
>>>
>>>      return ((hw_start_addr <= dar) && (hw_end_addr > dar));
>>
>> I'm using -1 while calculating end address is to make it
>> inclusive. If I don't use -1, the end address points to a
>> location outside of actual range, i.e. it's not really an
>> end address.
> 
> But that's what is done is several places, for instance:
> 
> https://elixir.bootlin.com/linux/v5.6/source/arch/powerpc/mm/dma-noncoherent.c#L22
> 
> https://elixir.bootlin.com/linux/v5.6/source/arch/powerpc/include/asm/book3s/32/kup.h#L92
> 
> In several places like this, end is outside of the range. My feeling is that is helps with readability.

Agreed, it helps with readability. Will change it.
Thanks for the links.

Ravi

Re: [PATCH v2 06/16] powerpc/watchpoint: Provide DAWR number to __set_breakpoint

[Christophe Leroy]

Le 01/04/2020 à 11:11, Christophe Leroy a écrit :
> 
> 
> Le 01/04/2020 à 10:57, Ravi Bangoria a écrit :
>>
>>
>> On 4/1/20 12:33 PM, Christophe Leroy wrote:
>>>
>>>
>>> Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
>>>> Introduce new parameter 'nr' to __set_breakpoint() which indicates
>>>> which DAWR should be programed. Also convert current_brk variable
>>>> to an array.
>>>>
>>>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>>>> ---
>>>>   arch/powerpc/include/asm/debug.h         |  2 +-
>>>>   arch/powerpc/include/asm/hw_breakpoint.h |  2 +-
>>>>   arch/powerpc/kernel/hw_breakpoint.c      |  8 ++++----
>>>>   arch/powerpc/kernel/process.c            | 14 +++++++-------
>>>>   arch/powerpc/kernel/signal.c             |  2 +-
>>>>   arch/powerpc/xmon/xmon.c                 |  2 +-
>>>>   6 files changed, 15 insertions(+), 15 deletions(-)
>>>>
>>>> diff --git a/arch/powerpc/include/asm/debug.h 
>>>> b/arch/powerpc/include/asm/debug.h
>>>> index 7756026b95ca..6228935a8b64 100644
>>>> --- a/arch/powerpc/include/asm/debug.h
>>>> +++ b/arch/powerpc/include/asm/debug.h
>>>> @@ -45,7 +45,7 @@ static inline int debugger_break_match(struct 
>>>> pt_regs *regs) { return 0; }
>>>>   static inline int debugger_fault_handler(struct pt_regs *regs) { 
>>>> return 0; }
>>>>   #endif
>>>> -void __set_breakpoint(struct arch_hw_breakpoint *brk);
>>>> +void __set_breakpoint(struct arch_hw_breakpoint *brk, int nr);
>>>
>>> Same, I think it would make more sense to have nr as first argument.
>>
>> Sorry, didn't get your point. How will that help?
>>
> 
> Well, it is a tiny detail but for me it is more natural to first tel 
> which element you modify before telling how you modify it.
> 

And the second advantage is that when you have a function 
get_something() paired with you set_something(), you can then have it as 
first argument in both functions.

void set_something(int nr, type something)
type get_something(int nr)

But again, that's detail, so up to you.

Christophe