[PATCH 4/6] hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events

Frederic Weisbecker
2009-10-24T14:17:36Z

This patch rebase the implementation of the breakpoints API on top of
perf events instances.

Each breakpoints are now perf events that handle the
register scheduling, thread/cpu attachment, etc..

The new layering is now made as follows:

ptrace kgdb ftrace perf syscall
\ | / /
\ | / /
/
Core breakpoint API /
/
| /
| /

Breakpoints perf events

|
|

Breakpoints PMU ---- Debug Register constraints handling
(Part of core breakpoint API)
|
|

Hardware debug registers

Reasons of this rewrite:

- Use the centralized/optimized pmu registers scheduling,
implying an easier arch integration
- More powerful register handling: perf attributes (pinned/flexible
events, exclusive/non-exclusive, tunable period, etc...)

Impact:

- New perf ABI: the hardware breakpoints counters
- Ptrace breakpoints setting remains tricky and still needs some per
thread breakpoints references.

Todo (in the order):

- Support breakpoints perf counter events for perf tools (ie: implement
perf_bpcounter_event())
- Support from perf tools

Changes in v2:

- Follow the perf "event " rename
- The ptrace regression have been fixed (ptrace breakpoint perf events
weren't released when a task ended)
- Drop the struct hw_breakpoint and store generic fields in
perf_event_attr.
- Separate core and arch specific headers, drop
asm-generic/hw_breakpoint.h and create linux/hw_breakpoint.h
- Use new generic len/type for breakpoint
- Handle off case: when breakpoints api is not supported by an arch

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
---
arch/Kconfig | 3 +
arch/x86/include/asm/debugreg.h | 7 -
arch/x86/include/asm/hw_breakpoint.h | 58 +++--
arch/x86/include/asm/processor.h | 12 +-
arch/x86/kernel/hw_breakpoint.c | 376 +++++++++++++++++++-----------
arch/x86/kernel/process.c | 7 +-
arch/x86/kernel/process_32.c | 26 +--
arch/x86/kernel/process_64.c | 26 +--
arch/x86/kernel/ptrace.c | 182 ++++++++++-----
arch/x86/kernel/smpboot.c | 3 -
arch/x86/power/cpu.c | 6 -
include/asm-generic/hw_breakpoint.h | 139 -----------
include/linux/hw_breakpoint.h | 131 +++++++++++
include/linux/perf_event.h | 26 ++-
kernel/exit.c | 5 +
kernel/hw_breakpoint.c | 424 ++++++++++++++--------------------
kernel/perf_event.c | 53 ++++-
kernel/trace/trace_entries.h | 6 +-
kernel/trace/trace_ksym.c | 126 +++++------
19 files changed, 862 insertions(+), 754 deletions(-)
delete mode 100644 include/asm-generic/hw_breakpoint.h
create mode 100644 include/linux/hw_breakpoint.h

diff --git a/arch/Kconfig b/arch/Kconfig
index acb6643..eef3bbb 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -128,6 +128,9 @@ config HAVE_DEFAULT_NO_SPIN_MUTEXES

config HAVE_HW_BREAKPOINT
bool
+ depends on HAVE_PERF_EVENTS
+ select ANON_INODES
+ select PERF_EVENTS

source "kernel/gcov/Kconfig"
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index 23439fb..1062e4a 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -75,13 +75,6 @@
*/
#ifdef __KERNEL__

-/* For process management */
-extern void flush_thread_hw_breakpoint(struct task_struct *tsk);
-extern int copy_thread_hw_breakpoint(struct task_struct *tsk,
- struct task_struct *child, unsigned long clone_flags);
-
-/* For CPU management */
-extern void load_debug_registers(void);
static inline void hw_breakpoint_disable(void)
{
/* Zero the control register for HW Breakpoint */
diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h
index 1acb4d4..0675a7c 100644
--- a/arch/x86/include/asm/hw_breakpoint.h
+++ b/arch/x86/include/asm/hw_breakpoint.h
@@ -4,6 +4,11 @@
#ifdef __KERNEL__
#define __ARCH_HW_BREAKPOINT_H

+/*
+ * The name should probably be something dealt in
+ * a higher level. While dealing with the user
+ * (display/resolving)
+ */
struct arch_hw_breakpoint {
char *name; /* Contains name of the symbol to set bkpt */
unsigned long address;
@@ -12,44 +17,57 @@ struct arch_hw_breakpoint {
};

#include <linux/kdebug.h>
-#include <asm-generic/hw_breakpoint.h>
+#include <linux/percpu.h>
+#include <linux/list.h>

/* Available HW breakpoint length encodings */
-#define HW_BREAKPOINT_LEN_1 0x40
-#define HW_BREAKPOINT_LEN_2 0x44
-#define HW_BREAKPOINT_LEN_4 0x4c
-#define HW_BREAKPOINT_LEN_EXECUTE 0x40
+#define X86_BREAKPOINT_LEN_1 0x40
+#define X86_BREAKPOINT_LEN_2 0x44
+#define X86_BREAKPOINT_LEN_4 0x4c
+#define X86_BREAKPOINT_LEN_EXECUTE 0x40

#ifdef CONFIG_X86_64
-#define HW_BREAKPOINT_LEN_8 0x48
+#define X86_BREAKPOINT_LEN_8 0x48
#endif

/* Available HW breakpoint type encodings */

/* trigger on instruction execute */
-#define HW_BREAKPOINT_EXECUTE 0x80
+#define X86_BREAKPOINT_EXECUTE 0x80
/* trigger on memory write */
-#define HW_BREAKPOINT_WRITE 0x81
+#define X86_BREAKPOINT_WRITE 0x81
/* trigger on memory read or write */
-#define HW_BREAKPOINT_RW 0x83
+#define X86_BREAKPOINT_RW 0x83

/* Total number of available HW breakpoint registers */
#define HBP_NUM 4

-extern struct hw_breakpoint *hbp_kernel[HBP_NUM];
-DECLARE_PER_CPU(struct hw_breakpoint*, this_hbp_kernel[HBP_NUM]);
-extern unsigned int hbp_user_refcount[HBP_NUM];
+struct perf_event;
+struct pmu;

-extern void arch_install_thread_hw_breakpoint(struct task_struct *tsk);
-extern void arch_uninstall_thread_hw_breakpoint(void);
extern int arch_check_va_in_userspace(unsigned long va, u8 hbp_len);
-extern int arch_validate_hwbkpt_settings(struct hw_breakpoint *bp,
- struct task_struct *tsk);
-extern void arch_update_user_hw_breakpoint(int pos, struct task_struct *tsk);
-extern void arch_flush_thread_hw_breakpoint(struct task_struct *tsk);
-extern void arch_update_kernel_hw_breakpoint(void *);
+extern int arch_validate_hwbkpt_settings(struct perf_event *bp,
+ struct task_struct *tsk);
extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
- unsigned long val, void *data);
+ unsigned long val, void *data);
+
+
+int arch_install_hw_breakpoint(struct perf_event *bp);
+void arch_uninstall_hw_breakpoint(struct perf_event *bp);
+void hw_breakpoint_pmu_read(struct perf_event *bp);
+void hw_breakpoint_pmu_unthrottle(struct perf_event *bp);
+
+extern void
+arch_fill_perf_breakpoint(struct perf_event *bp);
+
+unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type);
+int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type);
+
+extern int arch_bp_generic_fields(int x86_len, int x86_type,
+ int *gen_len, int *gen_type);
+
+extern struct pmu perf_ops_bp;
+
#endif /* __KERNEL__ */
#endif /* _I386_HW_BREAKPOINT_H */

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 61aafb7..820f300 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -423,6 +423,8 @@ extern unsigned int xstate_size;
extern void free_thread_xstate(struct task_struct *);
extern struct kmem_cache *task_xstate_cachep;

+struct perf_event;
+
struct thread_struct {
/* Cached TLS descriptors: */
struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES];
@@ -444,12 +446,10 @@ struct thread_struct {
unsigned long fs;
#endif
unsigned long gs;
- /* Hardware debugging registers: */
- unsigned long debugreg[HBP_NUM];
- unsigned long debugreg6;
- unsigned long debugreg7;
- /* Hardware breakpoint info */
- struct hw_breakpoint *hbp[HBP_NUM];
+ /* Save middle states of ptrace breakpoints */
+ struct perf_event *ptrace_bps[HBP_NUM];
+ /* Debug status used for traps, single steps, etc... */
+ unsigned long debugreg6;
/* Fault info: */
unsigned long cr2;
unsigned long trap_no;
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 9316a9d..0ac7c3b 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -15,6 +15,7 @@
*
* Copyright (C) 2007 Alan Stern
* Copyright (C) 2009 IBM Corporation
+ * Copyright (C) 2009 Frederic Weisbecker <fweisbec@gmail.com>
*/

/*
@@ -22,6 +23,8 @@
* using the CPU's debug registers.
*/

+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
#include <linux/irqflags.h>
#include <linux/notifier.h>
#include <linux/kallsyms.h>
@@ -38,26 +41,21 @@
#include <asm/processor.h>
#include <asm/debugreg.h>

-/* Unmasked kernel DR7 value */
-static unsigned long kdr7;
+/* Per cpu debug control register value */
+static DEFINE_PER_CPU(unsigned long, dr7);

/*
- * Masks for the bits corresponding to registers DR0 - DR3 in DR7 register.
- * Used to clear and verify the status of bits corresponding to DR0 - DR3
+ * Stores the breakpoints currently in use on each breakpoint address
+ * register for each cpus
*/
-static const unsigned long dr7_masks[HBP_NUM] = {
- 0x000f0003, /* LEN0, R/W0, G0, L0 */
- 0x00f0000c, /* LEN1, R/W1, G1, L1 */
- 0x0f000030, /* LEN2, R/W2, G2, L2 */
- 0xf00000c0 /* LEN3, R/W3, G3, L3 */
-};
+static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);

/*
* Encode the length, type, Exact, and Enable bits for a particular breakpoint
* as stored in debug register 7.
*/
-static unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
+unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
{
unsigned long bp_info;

@@ -68,64 +66,88 @@ static unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
return bp_info;
}

-void arch_update_kernel_hw_breakpoint(void *unused)
+/*
+ * Decode the length and type bits for a particular breakpoint as
+ * stored in debug register 7. Return the "enabled" status.
+ */
+int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type)
{
- struct hw_breakpoint *bp;
- int i, cpu = get_cpu();
- unsigned long temp_kdr7 = 0;
-
- /* Don't allow debug exceptions while we update the registers */
- set_debugreg(0UL, 7);
+ int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE);

- for (i = hbp_kernel_pos; i < HBP_NUM; i++) {
- per_cpu(this_hbp_kernel[i], cpu) = bp = hbp_kernel[i];
- if (bp) {
- temp_kdr7 |= encode_dr7(i, bp->info.len, bp->info.type);
- set_debugreg(bp->info.address, i);
- }
- }
+ *len = (bp_info & 0xc) | 0x40;
+ *type = (bp_info & 0x3) | 0x80;

- /* No need to set DR6. Update the debug registers with kernel-space
- * breakpoint values from kdr7 and user-space requests from the
- * current process
- */
- kdr7 = temp_kdr7;
- set_debugreg(kdr7 | current->thread.debugreg7, 7);
- put_cpu();
+ return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3;
}

/*
- * Install the thread breakpoints in their debug registers.
+ * Install a perf counter breakpoint.
+ *
+ * We seek a free debug address register and use it for this
+ * breakpoint. Eventually we enable it in the debug control register.
+ *
+ * Atomic: we hold the counter->ctx->lock and we only handle variables
+ * and registers local to this cpu.
*/
-void arch_install_thread_hw_breakpoint(struct task_struct *tsk)
+int arch_install_hw_breakpoint(struct perf_event *bp)
{
- struct thread_struct *thread = &(tsk->thread);
-
- switch (hbp_kernel_pos) {
- case 4:
- set_debugreg(thread->debugreg[3], 3);
- case 3:
- set_debugreg(thread->debugreg[2], 2);
- case 2:
- set_debugreg(thread->debugreg[1], 1);
- case 1:
- set_debugreg(thread->debugreg[0], 0);
- default:
- break;
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned long *dr7;
+ int i;
+
+ for (i = 0; i < HBP_NUM; i++) {
+ struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+
+ if (!*slot) {
+ *slot = bp;
+ break;
+ }
}

- /* No need to set DR6 */
- set_debugreg((kdr7 | thread->debugreg7), 7);
+ if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
+ return -EBUSY;
+
+ set_debugreg(info->address, i);
+
+ dr7 = &__get_cpu_var(dr7);
+ *dr7 |= encode_dr7(i, info->len, info->type);
+
+ set_debugreg(*dr7, 7);
+
+ return 0;
}

/*
- * Install the debug register values for just the kernel, no thread.
+ * Uninstall the breakpoint contained in the given counter.
+ *
+ * First we search the debug address register it uses and then we disable
+ * it.
+ *
+ * Atomic: we hold the counter->ctx->lock and we only handle variables
+ * and registers local to this cpu.
*/
-void arch_uninstall_thread_hw_breakpoint(void)
+void arch_uninstall_hw_breakpoint(struct perf_event *bp)
{
- /* Clear the user-space portion of debugreg7 by setting only kdr7 */
- set_debugreg(kdr7, 7);
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned long *dr7;
+ int i;

+ for (i = 0; i < HBP_NUM; i++) {
+ struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+
+ if (*slot == bp) {
+ *slot = NULL;
+ break;
+ }
+ }
+
+ if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
+ return;
+
+ dr7 = &__get_cpu_var(dr7);
+ *dr7 &= ~encode_dr7(i, info->len, info->type);
+
+ set_debugreg(*dr7, 7);
}

static int get_hbp_len(u8 hbp_len)
@@ -133,17 +155,17 @@ static int get_hbp_len(u8 hbp_len)
unsigned int len_in_bytes = 0;

switch (hbp_len) {
- case HW_BREAKPOINT_LEN_1:
+ case X86_BREAKPOINT_LEN_1:
len_in_bytes = 1;
break;
- case HW_BREAKPOINT_LEN_2:
+ case X86_BREAKPOINT_LEN_2:
len_in_bytes = 2;
break;
- case HW_BREAKPOINT_LEN_4:
+ case X86_BREAKPOINT_LEN_4:
len_in_bytes = 4;
break;
#ifdef CONFIG_X86_64
- case HW_BREAKPOINT_LEN_8:
+ case X86_BREAKPOINT_LEN_8:
len_in_bytes = 8;
break;
#endif
@@ -178,67 +200,146 @@ static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
/*
* Store a breakpoint's encoded address, length, and type.
*/
-static int arch_store_info(struct hw_breakpoint *bp, struct task_struct *tsk)
+static int arch_store_info(struct perf_event *bp)
{
- /*
- * User-space requests will always have the address field populated
- * Symbol names from user-space are rejected
- */
- if (tsk && bp->info.name)
- return -EINVAL;
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
/*
* For kernel-addresses, either the address or symbol name can be
* specified.
*/
- if (bp->info.name)
- bp->info.address = (unsigned long)
- kallsyms_lookup_name(bp->info.name);
- if (bp->info.address)
+ if (info->name)
+ info->address = (unsigned long)
+ kallsyms_lookup_name(info->name);
+ if (info->address)
return 0;
+
return -EINVAL;
}

-/*
- * Validate the arch-specific HW Breakpoint register settings
- */
-int arch_validate_hwbkpt_settings(struct hw_breakpoint *bp,
- struct task_struct *tsk)
+int arch_bp_generic_fields(int x86_len, int x86_type,
+ int *gen_len, int *gen_type)
{
- unsigned int align;
- int ret = -EINVAL;
+ /* Len */
+ switch (x86_len) {
+ case X86_BREAKPOINT_LEN_1:
+ *gen_len = HW_BREAKPOINT_LEN_1;
+ break;
+ case X86_BREAKPOINT_LEN_2:
+ *gen_len = HW_BREAKPOINT_LEN_2;
+ break;
+ case X86_BREAKPOINT_LEN_4:
+ *gen_len = HW_BREAKPOINT_LEN_4;
+ break;
+#ifdef CONFIG_X86_64
+ case X86_BREAKPOINT_LEN_8:
+ *gen_len = HW_BREAKPOINT_LEN_8;
+ break;
+#endif
+ default:
+ return -EINVAL;
+ }

- switch (bp->info.type) {
- /*
- * Ptrace-refactoring code
- * For now, we'll allow instruction breakpoint only for user-space
- * addresses
- */
- case HW_BREAKPOINT_EXECUTE:
- if ((!arch_check_va_in_userspace(bp->info.address,
- bp->info.len)) &&
- bp->info.len != HW_BREAKPOINT_LEN_EXECUTE)
- return ret;
+ /* Type */
+ switch (x86_type) {
+ case X86_BREAKPOINT_EXECUTE:
+ *gen_type = HW_BREAKPOINT_X;
break;
- case HW_BREAKPOINT_WRITE:
+ case X86_BREAKPOINT_WRITE:
+ *gen_type = HW_BREAKPOINT_W;
break;
- case HW_BREAKPOINT_RW:
+ case X86_BREAKPOINT_RW:
+ *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
break;
default:
- return ret;
+ return -EINVAL;
}

- switch (bp->info.len) {
+ return 0;
+}
+
+
+static int arch_build_bp_info(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+
+ info->address = bp->attr.bp_addr;
+
+ /* Len */
+ switch (bp->attr.bp_len) {
case HW_BREAKPOINT_LEN_1:
- align = 0;
+ info->len = X86_BREAKPOINT_LEN_1;
break;
case HW_BREAKPOINT_LEN_2:
- align = 1;
+ info->len = X86_BREAKPOINT_LEN_2;
break;
case HW_BREAKPOINT_LEN_4:
- align = 3;
+ info->len = X86_BREAKPOINT_LEN_4;
break;
#ifdef CONFIG_X86_64
case HW_BREAKPOINT_LEN_8:
+ info->len = X86_BREAKPOINT_LEN_8;
+ break;
+#endif
+ default:
+ return -EINVAL;
+ }
+
+ /* Type */
+ switch (bp->attr.bp_type) {
+ case HW_BREAKPOINT_W:
+ info->type = X86_BREAKPOINT_WRITE;
+ break;
+ case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
+ info->type = X86_BREAKPOINT_RW;
+ break;
+ case HW_BREAKPOINT_X:
+ info->type = X86_BREAKPOINT_EXECUTE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+/*
+ * Validate the arch-specific HW Breakpoint register settings
+ */
+int arch_validate_hwbkpt_settings(struct perf_event *bp,
+ struct task_struct *tsk)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned int align;
+ int ret;
+
+
+ ret = arch_build_bp_info(bp);
+ if (ret)
+ return ret;
+
+ ret = -EINVAL;
+
+ if (info->type == X86_BREAKPOINT_EXECUTE)
+ /*
+ * Ptrace-refactoring code
+ * For now, we'll allow instruction breakpoint only for user-space
+ * addresses
+ */
+ if ((!arch_check_va_in_userspace(info->address, info->len)) &&
+ info->len != X86_BREAKPOINT_EXECUTE)
+ return ret;
+
+ switch (info->len) {
+ case X86_BREAKPOINT_LEN_1:
+ align = 0;
+ break;
+ case X86_BREAKPOINT_LEN_2:
+ align = 1;
+ break;
+ case X86_BREAKPOINT_LEN_4:
+ align = 3;
+ break;
+#ifdef CONFIG_X86_64
+ case X86_BREAKPOINT_LEN_8:
align = 7;
break;
#endif
@@ -246,8 +347,8 @@ int arch_validate_hwbkpt_settings(struct hw_breakpoint *bp,
return ret;
}

- if (bp->triggered)
- ret = arch_store_info(bp, tsk);
+ if (bp->callback)
+ ret = arch_store_info(bp);

if (ret < 0)
return ret;
@@ -255,43 +356,33 @@ int arch_validate_hwbkpt_settings(struct hw_breakpoint *bp,
* Check that the low-order bits of the address are appropriate
* for the alignment implied by len.
*/
- if (bp->info.address & align)
+ if (info->address & align)
return -EINVAL;

/* Check that the virtual address is in the proper range */
if (tsk) {
- if (!arch_check_va_in_userspace(bp->info.address, bp->info.len))
+ if (!arch_check_va_in_userspace(info->address, info->len))
return -EFAULT;
} else {
- if (!arch_check_va_in_kernelspace(bp->info.address,
- bp->info.len))
+ if (!arch_check_va_in_kernelspace(info->address, info->len))
return -EFAULT;
}
- return 0;
-}

-void arch_update_user_hw_breakpoint(int pos, struct task_struct *tsk)
-{
- struct thread_struct *thread = &(tsk->thread);
- struct hw_breakpoint *bp = thread->hbp[pos];
-
- thread->debugreg7 &= ~dr7_masks[pos];
- if (bp) {
- thread->debugreg[pos] = bp->info.address;
- thread->debugreg7 |= encode_dr7(pos, bp->info.len,
- bp->info.type);
- } else
- thread->debugreg[pos] = 0;
+ return 0;
}

-void arch_flush_thread_hw_breakpoint(struct task_struct *tsk)
+/*
+ * Release the user breakpoints used by ptrace
+ */
+void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
int i;
- struct thread_struct *thread = &(tsk->thread);
+ struct thread_struct *t = &tsk->thread;

- thread->debugreg7 = 0;
- for (i = 0; i < HBP_NUM; i++)
- thread->debugreg[i] = 0;
+ for (i = 0; i < HBP_NUM; i++) {
+ unregister_hw_breakpoint(t->ptrace_bps[i]);
+ t->ptrace_bps[i] = NULL;
+ }
}

/*
@@ -313,7 +404,7 @@ void arch_flush_thread_hw_breakpoint(struct task_struct *tsk)
static int __kprobes hw_breakpoint_handler(struct die_args *args)
{
int i, cpu, rc = NOTIFY_STOP;
- struct hw_breakpoint *bp;
+ struct perf_event *bp;
unsigned long dr7, dr6;
unsigned long *dr6_p;

@@ -325,10 +416,6 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
if ((dr6 & DR_TRAP_BITS) == 0)
return NOTIFY_DONE;

- /* Lazy debug register switching */
- if (!test_tsk_thread_flag(current, TIF_DEBUG))
- arch_uninstall_thread_hw_breakpoint();
-
get_debugreg(dr7, 7);
/* Disable breakpoints during exception handling */
set_debugreg(0UL, 7);
@@ -344,17 +431,18 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
for (i = 0; i < HBP_NUM; ++i) {
if (likely(!(dr6 & (DR_TRAP0 << i))))
continue;
+
/*
- * Find the corresponding hw_breakpoint structure and
- * invoke its triggered callback.
+ * The counter may be concurrently released but that can only
+ * occur from a call_rcu() path. We can then safely fetch
+ * the breakpoint, use its callback, touch its counter
+ * while we are in an rcu_read_lock() path.
*/
- if (i >= hbp_kernel_pos)
- bp = per_cpu(this_hbp_kernel[i], cpu);
- else {
- bp = current->thread.hbp[i];
- if (bp)
- rc = NOTIFY_DONE;
- }
+ rcu_read_lock();
+
+ bp = per_cpu(bp_per_reg[i], cpu);
+ if (bp)
+ rc = NOTIFY_DONE;
/*
* Reset the 'i'th TRAP bit in dr6 to denote completion of
* exception handling
@@ -362,19 +450,23 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
(*dr6_p) &= ~(DR_TRAP0 << i);
/*
* bp can be NULL due to lazy debug register switching
- * or due to the delay between updates of hbp_kernel_pos
- * and this_hbp_kernel.
+ * or due to concurrent perf counter removing.
*/
- if (!bp)
- continue;
+ if (!bp) {
+ rcu_read_unlock();
+ break;
+ }
+
+ (bp->callback)(bp, args->regs);

- (bp->triggered)(bp, args->regs);
+ rcu_read_unlock();
}
if (dr6 & (~DR_TRAP_BITS))
rc = NOTIFY_DONE;

set_debugreg(dr7, 7);
put_cpu();
+
return rc;
}

@@ -389,3 +481,13 @@ int __kprobes hw_breakpoint_exceptions_notify(

return hw_breakpoint_handler(data);
}
+
+void hw_breakpoint_pmu_read(struct perf_event *bp)
+{
+ /* TODO */
+}
+
+void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
+{
+ /* TODO */
+}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index cf8ee00..744508e 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -10,6 +10,7 @@
#include <linux/clockchips.h>
#include <linux/random.h>
#include <trace/events/power.h>
+#include <linux/hw_breakpoint.h>
#include <asm/system.h>
#include <asm/apic.h>
#include <asm/syscalls.h>
@@ -18,7 +19,6 @@
#include <asm/i387.h>
#include <asm/ds.h>
#include <asm/debugreg.h>
-#include <asm/hw_breakpoint.h>

unsigned long idle_halt;
EXPORT_SYMBOL(idle_halt);
@@ -47,8 +47,6 @@ void free_thread_xstate(struct task_struct *tsk)
kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
tsk->thread.xstate = NULL;
}
- if (unlikely(test_tsk_thread_flag(tsk, TIF_DEBUG)))
- flush_thread_hw_breakpoint(tsk);

WARN(tsk->thread.ds_ctx, "leaking DS context\n");
}
@@ -107,8 +105,7 @@ void flush_thread(void)
}
#endif

- if (unlikely(test_tsk_thread_flag(tsk, TIF_DEBUG)))
- flush_thread_hw_breakpoint(tsk);
+ flush_ptrace_hw_breakpoint(tsk);
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
/*
* Forget coprocessor state..
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 209e748..d5bd313 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -59,7 +59,6 @@
#include <asm/syscalls.h>
#include <asm/ds.h>
#include <asm/debugreg.h>
-#include <asm/hw_breakpoint.h>

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

@@ -264,9 +263,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
p->thread.io_bitmap_ptr = NULL;
tsk = current;
err = -ENOMEM;
- if (unlikely(test_tsk_thread_flag(tsk, TIF_DEBUG)))
- if (copy_thread_hw_breakpoint(tsk, p, clone_flags))
- goto out;
+
+ memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));

if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
@@ -287,13 +285,10 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
err = do_set_thread_area(p, -1,
(struct user_desc __user *)childregs->si, 0);

-out:
if (err && p->thread.io_bitmap_ptr) {
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
- if (err)
- flush_thread_hw_breakpoint(p);

clear_tsk_thread_flag(p, TIF_DS_AREA_MSR);
p->thread.ds_ctx = NULL;
@@ -437,23 +432,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
lazy_load_gs(next->gs);

percpu_write(current_task, next_p);
- /*
- * There's a problem with moving the arch_install_thread_hw_breakpoint()
- * call before current is updated. Suppose a kernel breakpoint is
- * triggered in between the two, the hw-breakpoint handler will see that
- * the 'current' task does not have TIF_DEBUG flag set and will think it
- * is leftover from an old task (lazy switching) and will erase it. Then
- * until the next context switch, no user-breakpoints will be installed.
- *
- * The real problem is that it's impossible to update both current and
- * physical debug registers at the same instant, so there will always be
- * a window in which they disagree and a breakpoint might get triggered.
- * Since we use lazy switching, we are forced to assume that a
- * disagreement means that current is correct and the exception is due
- * to lazy debug register switching.
- */
- if (unlikely(test_tsk_thread_flag(next_p, TIF_DEBUG)))
- arch_install_thread_hw_breakpoint(next_p);

return prev_p;
}
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 72edac0..5bafdec 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -53,7 +53,6 @@
#include <asm/syscalls.h>
#include <asm/ds.h>
#include <asm/debugreg.h>
-#include <asm/hw_breakpoint.h>

asmlinkage extern void ret_from_fork(void);

@@ -244,8 +243,6 @@ void release_thread(struct task_struct *dead_task)
BUG();
}
}
- if (unlikely(dead_task->thread.debugreg7))
- flush_thread_hw_breakpoint(dead_task);
}

static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
@@ -309,9 +306,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
savesegment(ds, p->thread.ds);

err = -ENOMEM;
- if (unlikely(test_tsk_thread_flag(me, TIF_DEBUG)))
- if (copy_thread_hw_breakpoint(me, p, clone_flags))
- goto out;
+ memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));

if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
@@ -351,8 +346,6 @@ out:
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
- if (err)
- flush_thread_hw_breakpoint(p);

return err;
}
@@ -508,23 +501,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
*/
if (preload_fpu)
__math_state_restore();
- /*
- * There's a problem with moving the arch_install_thread_hw_breakpoint()
- * call before current is updated. Suppose a kernel breakpoint is
- * triggered in between the two, the hw-breakpoint handler will see that
- * the 'current' task does not have TIF_DEBUG flag set and will think it
- * is leftover from an old task (lazy switching) and will erase it. Then
- * until the next context switch, no user-breakpoints will be installed.
- *
- * The real problem is that it's impossible to update both current and
- * physical debug registers at the same instant, so there will always be
- * a window in which they disagree and a breakpoint might get triggered.
- * Since we use lazy switching, we are forced to assume that a
- * disagreement means that current is correct and the exception is due
- * to lazy debug register switching.
- */
- if (unlikely(test_tsk_thread_flag(next_p, TIF_DEBUG)))
- arch_install_thread_hw_breakpoint(next_p);

return prev_p;
}
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 267cb85..e79610d 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -22,6 +22,8 @@
#include <linux/seccomp.h>
#include <linux/signal.h>
#include <linux/workqueue.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -441,54 +443,59 @@ static int genregs_set(struct task_struct *target,
return ret;
}

-/*
- * Decode the length and type bits for a particular breakpoint as
- * stored in debug register 7. Return the "enabled" status.
- */
-static int decode_dr7(unsigned long dr7, int bpnum, unsigned *len,
- unsigned *type)
-{
- int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE);
-
- *len = (bp_info & 0xc) | 0x40;
- *type = (bp_info & 0x3) | 0x80;
- return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3;
-}
-
-static void ptrace_triggered(struct hw_breakpoint *bp, struct pt_regs *regs)
+static void ptrace_triggered(struct perf_event *bp, void *data)
{
- struct thread_struct *thread = &(current->thread);
int i;
+ struct thread_struct *thread = &(current->thread);

/*
* Store in the virtual DR6 register the fact that the breakpoint
* was hit so the thread's debugger will see it.
*/
- for (i = 0; i < hbp_kernel_pos; i++)
- /*
- * We will check bp->info.address against the address stored in
- * thread's hbp structure and not debugreg[i]. This is to ensure
- * that the corresponding bit for 'i' in DR7 register is enabled
- */
- if (bp->info.address == thread->hbp[i]->info.address)
+ for (i = 0; i < HBP_NUM; i++) {
+ if (thread->ptrace_bps[i] == bp)
break;
+ }

thread->debugreg6 |= (DR_TRAP0 << i);
}

/*
+ * Walk through every ptrace breakpoints for this thread and
+ * build the dr7 value on top of their attributes.
+ *
+ */
+static unsigned long ptrace_get_dr7(struct perf_event *bp[])
+{
+ int i;
+ int dr7 = 0;
+ struct arch_hw_breakpoint *info;
+
+ for (i = 0; i < HBP_NUM; i++) {
+ if (bp[i] && !bp[i]->attr.disabled) {
+ info = counter_arch_bp(bp[i]);
+ dr7 |= encode_dr7(i, info->len, info->type);
+ }
+ }
+
+ return dr7;
+}
+
+/*
* Handle ptrace writes to debug register 7.
*/
static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
{
struct thread_struct *thread = &(tsk->thread);
- unsigned long old_dr7 = thread->debugreg7;
+ unsigned long old_dr7;
int i, orig_ret = 0, rc = 0;
int enabled, second_pass = 0;
unsigned len, type;
- struct hw_breakpoint *bp;
+ int gen_len, gen_type;
+ struct perf_event *bp;

data &= ~DR_CONTROL_RESERVED;
+ old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
restore:
/*
* Loop through all the hardware breakpoints, making the
@@ -496,11 +503,12 @@ restore:
*/
for (i = 0; i < HBP_NUM; i++) {
enabled = decode_dr7(data, i, &len, &type);
- bp = thread->hbp[i];
+ bp = thread->ptrace_bps[i];

if (!enabled) {
if (bp) {
- /* Don't unregister the breakpoints right-away,
+ /*
+ * Don't unregister the breakpoints right-away,
* unless all register_user_hw_breakpoint()
* requests have succeeded. This prevents
* any window of opportunity for debug
@@ -508,27 +516,45 @@ restore:
*/
if (!second_pass)
continue;
- unregister_user_hw_breakpoint(tsk, bp);
- kfree(bp);
+ thread->ptrace_bps[i] = NULL;
+ unregister_hw_breakpoint(bp);
}
continue;
}
+
+ /*
+ * We shoud have at least an inactive breakpoint at this
+ * slot. It means the user is writing dr7 without having
+ * written the address register first
+ */
if (!bp) {
- rc = -ENOMEM;
- bp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL);
- if (bp) {
- bp->info.address = thread->debugreg[i];
- bp->triggered = ptrace_triggered;
- bp->info.len = len;
- bp->info.type = type;
- rc = register_user_hw_breakpoint(tsk, bp);
- if (rc)
- kfree(bp);
- }
- } else
- rc = modify_user_hw_breakpoint(tsk, bp);
+ rc = -EINVAL;
+ break;
+ }
+
+ rc = arch_bp_generic_fields(len, type, &gen_len, &gen_type);
if (rc)
break;
+
+ /*
+ * This is a temporary thing as bp is unregistered/registered
+ * to simulate modification
+ */
+ bp = modify_user_hw_breakpoint(bp, bp->attr.bp_addr, gen_len,
+ gen_type, bp->callback,
+ tsk, true);
+ thread->ptrace_bps[i] = NULL;
+
+ if (!bp) { /* incorrect bp, or we have a bug in bp API */
+ rc = -EINVAL;
+ break;
+ }
+ if (IS_ERR(bp)) {
+ rc = PTR_ERR(bp);
+ bp = NULL;
+ break;
+ }
+ thread->ptrace_bps[i] = bp;
}
/*
* Make a second pass to free the remaining unused breakpoints
@@ -553,15 +579,63 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
struct thread_struct *thread = &(tsk->thread);
unsigned long val = 0;

- if (n < HBP_NUM)
- val = thread->debugreg[n];
- else if (n == 6)
+ if (n < HBP_NUM) {
+ struct perf_event *bp;
+ bp = thread->ptrace_bps[n];
+ if (!bp)
+ return 0;
+ val = bp->hw.info.address;
+ } else if (n == 6) {
val = thread->debugreg6;
- else if (n == 7)
- val = thread->debugreg7;
+ } else if (n == 7) {
+ val = ptrace_get_dr7(thread->ptrace_bps);
+ }
return val;
}

+static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
+ unsigned long addr)
+{
+ struct perf_event *bp;
+ struct thread_struct *t = &tsk->thread;
+
+ if (!t->ptrace_bps[nr]) {
+ /*
+ * Put stub len and type to register (reserve) an inactive but
+ * correct bp
+ */
+ bp = register_user_hw_breakpoint(addr, HW_BREAKPOINT_LEN_1,
+ HW_BREAKPOINT_W,
+ ptrace_triggered, tsk,
+ false);
+ } else {
+ bp = t->ptrace_bps[nr];
+ t->ptrace_bps[nr] = NULL;
+ bp = modify_user_hw_breakpoint(bp, addr, bp->attr.bp_len,
+ bp->attr.bp_type,
+ bp->callback,
+ tsk,
+ bp->attr.disabled);
+ }
+
+ if (!bp)
+ return -EIO;
+ /*
+ * CHECKME: the previous code returned -EIO if the addr wasn't a
+ * valid task virtual addr. The new one will return -EINVAL in this
+ * case.
+ * -EINVAL may be what we want for in-kernel breakpoints users, but
+ * -EIO looks better for ptrace, since we refuse a register writing
+ * for the user. And anyway this is the previous behaviour.
+ */
+ if (IS_ERR(bp))
+ return PTR_ERR(bp);
+
+ t->ptrace_bps[nr] = bp;
+
+ return 0;
+}
+
/*
* Handle PTRACE_POKEUSR calls for the debug register area.
*/
@@ -575,19 +649,13 @@ int ptrace_set_debugreg(struct task_struct *tsk, int n, unsigned long val)
return -EIO;

if (n == 6) {
- tsk->thread.debugreg6 = val;
+ thread->debugreg6 = val;
goto ret_path;
}
if (n < HBP_NUM) {
- if (thread->hbp[n]) {
- if (arch_check_va_in_userspace(val,
- thread->hbp[n]->info.len) == 0) {
- rc = -EIO;
- goto ret_path;
- }
- thread->hbp[n]->info.address = val;
- }
- thread->debugreg[n] = val;
+ rc = ptrace_set_breakpoint_addr(tsk, n, val);
+ if (rc)
+ return rc;
}
/* All that's left is DR7 */
if (n == 7)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 213a7a3..565ebc6 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -64,7 +64,6 @@
#include <asm/apic.h>
#include <asm/setup.h>
#include <asm/uv/uv.h>
-#include <asm/debugreg.h>
#include <linux/mc146818rtc.h>

#include <asm/smpboot_hooks.h>
@@ -328,7 +327,6 @@ notrace static void __cpuinit start_secondary(void *unused)
x86_cpuinit.setup_percpu_clockev();

wmb();
- load_debug_registers();
cpu_idle();
}

@@ -1269,7 +1267,6 @@ void cpu_disable_common(void)
remove_cpu_from_maps(cpu);
unlock_vector_lock();
fixup_irqs();
- hw_breakpoint_disable();
}

int native_cpu_disable(void)
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index e09a44f..0a979f3 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -105,7 +105,6 @@ static void __save_processor_state(struct saved_context *ctxt)
ctxt->cr4 = read_cr4();
ctxt->cr8 = read_cr8();
#endif
- hw_breakpoint_disable();
}

/* Needed by apm.c */
@@ -144,11 +143,6 @@ static void fix_processor_context(void)
#endif
load_TR_desc(); /* This does ltr */
load_LDT(&current->active_mm->context); /* This does lldt */
-
- /*
- * Now maybe reload the debug registers
- */
- load_debug_registers();
}

/**
diff --git a/include/asm-generic/hw_breakpoint.h b/include/asm-generic/hw_breakpoint.h
deleted file mode 100644
index 9bf2d12..0000000
--- a/include/asm-generic/hw_breakpoint.h
+++ /dev/null
@@ -1,139 +0,0 @@
-#ifndef _ASM_GENERIC_HW_BREAKPOINT_H
-#define _ASM_GENERIC_HW_BREAKPOINT_H
-
-#ifndef __ARCH_HW_BREAKPOINT_H
-#error "Please don't include this file directly"
-#endif
-
-#ifdef __KERNEL__
-#include <linux/list.h>
-#include <linux/types.h>
-#include <linux/kallsyms.h>
-
-/**
- * struct hw_breakpoint - unified kernel/user-space hardware breakpoint
- * @triggered: callback invoked after target address access
- * @info: arch-specific breakpoint info (address, length, and type)
- *
- * %hw_breakpoint structures are the kernel's way of representing
- * hardware breakpoints. These are data breakpoints
- * (also known as "watchpoints", triggered on data access), and the breakpoint's
- * target address can be located in either kernel space or user space.
- *
- * The breakpoint's address, length, and type are highly
- * architecture-specific. The values are encoded in the @info field; you
- * specify them when registering the breakpoint. To examine the encoded
- * values use hw_breakpoint_get_{kaddress,uaddress,len,type}(), declared
- * below.
- *
- * The address is specified as a regular kernel pointer (for kernel-space
- * breakponts) or as an %__user pointer (for user-space breakpoints).
- * With register_user_hw_breakpoint(), the address must refer to a
- * location in user space. The breakpoint will be active only while the
- * requested task is running. Conversely with
- * register_kernel_hw_breakpoint(), the address must refer to a location
- * in kernel space, and the breakpoint will be active on all CPUs
- * regardless of the current task.
- *
- * The length is the breakpoint's extent in bytes, which is subject to
- * certain limitations. include/asm/hw_breakpoint.h contains macros
- * defining the available lengths for a specific architecture. Note that
- * the address's alignment must match the length. The breakpoint will
- * catch accesses to any byte in the range from address to address +
- * (length - 1).
- *
- * The breakpoint's type indicates the sort of access that will cause it
- * to trigger. Possible values may include:
- *
- * %HW_BREAKPOINT_RW (triggered on read or write access),
- * %HW_BREAKPOINT_WRITE (triggered on write access), and
- * %HW_BREAKPOINT_READ (triggered on read access).
- *
- * Appropriate macros are defined in include/asm/hw_breakpoint.h; not all
- * possibilities are available on all architectures. Execute breakpoints
- * must have length equal to the special value %HW_BREAKPOINT_LEN_EXECUTE.
- *
- * When a breakpoint gets hit, the @triggered callback is
- * invoked in_interrupt with a pointer to the %hw_breakpoint structure and the
- * processor registers.
- * Data breakpoints occur after the memory access has taken place.
- * Breakpoints are disabled during execution @triggered, to avoid
- * recursive traps and allow unhindered access to breakpointed memory.
- *
- * This sample code sets a breakpoint on pid_max and registers a callback
- * function for writes to that variable. Note that it is not portable
- * as written, because not all architectures support HW_BREAKPOINT_LEN_4.
- *
- * ----------------------------------------------------------------------
- *
- * #include <asm/hw_breakpoint.h>
- *
- * struct hw_breakpoint my_bp;
- *
- * static void my_triggered(struct hw_breakpoint *bp, struct pt_regs *regs)
- * {
- * printk(KERN_DEBUG "Inside triggered routine of breakpoint exception\n");
- * dump_stack();
- * .......<more debugging output>........
- * }
- *
- * static struct hw_breakpoint my_bp;
- *
- * static int init_module(void)
- * {
- * ..........<do anything>............
- * my_bp.info.type = HW_BREAKPOINT_WRITE;
- * my_bp.info.len = HW_BREAKPOINT_LEN_4;
- *
- * my_bp.installed = (void *)my_bp_installed;
- *
- * rc = register_kernel_hw_breakpoint(&my_bp);
- * ..........<do anything>............
- * }
- *
- * static void cleanup_module(void)
- * {
- * ..........<do anything>............
- * unregister_kernel_hw_breakpoint(&my_bp);
- * ..........<do anything>............
- * }
- *
- * ----------------------------------------------------------------------
- */
-struct hw_breakpoint {
- void (*triggered)(struct hw_breakpoint *, struct pt_regs *);
- struct arch_hw_breakpoint info;
-};
-
-/*
- * len and type values are defined in include/asm/hw_breakpoint.h.
- * Available values vary according to the architecture. On i386 the
- * possibilities are:
- *
- * HW_BREAKPOINT_LEN_1
- * HW_BREAKPOINT_LEN_2
- * HW_BREAKPOINT_LEN_4
- * HW_BREAKPOINT_RW
- * HW_BREAKPOINT_READ
- *
- * On other architectures HW_BREAKPOINT_LEN_8 may be available, and the
- * 1-, 2-, and 4-byte lengths may be unavailable. There also may be
- * HW_BREAKPOINT_WRITE. You can use #ifdef to check at compile time.
- */
-
-extern int register_user_hw_breakpoint(struct task_struct *tsk,
- struct hw_breakpoint *bp);
-extern int modify_user_hw_breakpoint(struct task_struct *tsk,
- struct hw_breakpoint *bp);
-extern void unregister_user_hw_breakpoint(struct task_struct *tsk,
- struct hw_breakpoint *bp);
-/*
- * Kernel breakpoints are not associated with any particular thread.
- */
-extern int register_kernel_hw_breakpoint(struct hw_breakpoint *bp);
-extern void unregister_kernel_hw_breakpoint(struct hw_breakpoint *bp);
-
-extern unsigned int hbp_kernel_pos;
-
-#endif /* __KERNEL__ */
-#endif /* _ASM_GENERIC_HW_BREAKPOINT_H */
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
new file mode 100644
index 0000000..7eba9b9
--- /dev/null
+++ b/include/linux/hw_breakpoint.h
@@ -0,0 +1,131 @@
+#ifndef _LINUX_HW_BREAKPOINT_H
+#define _LINUX_HW_BREAKPOINT_H
+
+#include <linux/perf_event.h>
+
+enum {
+ HW_BREAKPOINT_LEN_1 = 1,
+ HW_BREAKPOINT_LEN_2 = 2,
+ HW_BREAKPOINT_LEN_4 = 4,
+ HW_BREAKPOINT_LEN_8 = 8,
+};
+
+enum {
+ HW_BREAKPOINT_R = 1,
+ HW_BREAKPOINT_W = 2,
+ HW_BREAKPOINT_X = 4,
+};
+
+static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
+{
+ return &bp->hw.info;
+}
+
+static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
+{
+ return bp->attr.bp_addr;
+}
+
+static inline int hw_breakpoint_type(struct perf_event *bp)
+{
+ return bp->attr.bp_type;
+}
+
+static inline int hw_breakpoint_len(struct perf_event *bp)
+{
+ return bp->attr.bp_len;
+}
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+extern struct perf_event *
+register_user_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active);
+
+/* FIXME: only change from the attr, and don't unregister */
+extern struct perf_event *
+modify_user_hw_breakpoint(struct perf_event *bp,
+ unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active);
+
+/*
+ * Kernel breakpoints are not associated with any particular thread.
+ */
+extern struct perf_event *
+register_wide_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ int cpu,
+ bool active);
+
+extern struct perf_event **
+register_wide_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ bool active);
+
+extern int register_perf_hw_breakpoint(struct perf_event *bp);
+extern int __register_perf_hw_breakpoint(struct perf_event *bp);
+extern void unregister_hw_breakpoint(struct perf_event *bp);
+extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);
+
+extern int reserve_bp_slot(struct perf_event *bp);
+extern void release_bp_slot(struct perf_event *bp);
+
+extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
+
+#else /* !CONFIG_HAVE_HW_BREAKPOINT */
+
+static inline struct perf_event *
+register_user_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active) { return NULL; }
+static inline struct perf_event *
+modify_user_hw_breakpoint(struct perf_event *bp,
+ unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active) { return NULL; }
+static inline struct perf_event *
+register_wide_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ int cpu,
+ bool active) { return NULL; }
+static inline struct perf_event **
+register_wide_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ bool active) { return NULL; }
+static inline int
+register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
+static inline int
+__register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
+static inline void unregister_hw_breakpoint(struct perf_event *bp) { }
+static inline void
+unregister_wide_hw_breakpoint(struct perf_event **cpu_events) { }
+static inline int
+reserve_bp_slot(struct perf_event *bp) {return -ENOSYS; }
+static inline void release_bp_slot(struct perf_event *bp) { }
+
+static inline void flush_ptrace_hw_breakpoint(struct task_struct *tsk) { }
+
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
+#endif /* _LINUX_HW_BREAKPOINT_H */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 8d54e6d..cead64e 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -18,6 +18,10 @@
#include <linux/ioctl.h>
#include <asm/byteorder.h>

+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+#include <asm/hw_breakpoint.h>
+#endif
+
/*
* User-space ABI bits:
*/
@@ -31,6 +35,7 @@ enum perf_type_id {
PERF_TYPE_TRACEPOINT = 2,
PERF_TYPE_HW_CACHE = 3,
PERF_TYPE_RAW = 4,
+ PERF_TYPE_BREAKPOINT = 5,

PERF_TYPE_MAX, /* non-ABI */
};
@@ -207,6 +212,15 @@ struct perf_event_attr {
__u32 wakeup_events; /* wakeup every n events */
__u32 wakeup_watermark; /* bytes before wakeup */
};
+
+ union {
+ struct { /* Hardware breakpoint info */
+ __u64 bp_addr;
+ __u32 bp_type;
+ __u32 bp_len;
+ };
+ };
+
__u32 __reserved_2;

__u64 __reserved_3;
@@ -476,6 +490,11 @@ struct hw_perf_event {
atomic64_t count;
struct hrtimer hrtimer;
};
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ union { /* breakpoint */
+ struct arch_hw_breakpoint info;
+ };
+#endif
};
atomic64_t prev_count;
u64 sample_period;
@@ -588,7 +607,7 @@ struct perf_event {
u64 tstamp_running;
u64 tstamp_stopped;

- struct perf_event_attr attr;
+ struct perf_event_attr attr;
struct hw_perf_event hw;

struct perf_event_context *ctx;
@@ -643,6 +662,8 @@ struct perf_event {

perf_callback_t callback;

+ perf_callback_t event_callback;
+
#endif /* CONFIG_PERF_EVENTS */
};

@@ -831,6 +852,7 @@ extern int sysctl_perf_event_sample_rate;
extern void perf_event_init(void);
extern void perf_tp_event(int event_id, u64 addr, u64 count,
void *record, int entry_size);
+extern void perf_bp_event(struct perf_event *event, void *data);

#ifndef perf_misc_flags
#define perf_misc_flags(regs) (user_mode(regs) ? PERF_RECORD_MISC_USER : \
@@ -865,6 +887,8 @@ static inline int perf_event_task_enable(void) { return -EINVAL; }
static inline void
perf_sw_event(u32 event_id, u64 nr, int nmi,
struct pt_regs *regs, u64 addr) { }
+static inline void
+perf_bp_event(struct perf_event *event, void *data) { }

static inline void perf_event_mmap(struct vm_area_struct *vma) { }
static inline void perf_event_comm(struct task_struct *tsk) { }
diff --git a/kernel/exit.c b/kernel/exit.c
index e61891f..266f892 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -49,6 +49,7 @@
#include <linux/init_task.h>
#include <linux/perf_event.h>
#include <trace/events/sched.h>
+#include <linux/hw_breakpoint.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -980,6 +981,10 @@ NORET_TYPE void do_exit(long code)
proc_exit_connector(tsk);

/*
+ * FIXME: do that only when needed, using sched_exit tracepoint
+ */
+ flush_ptrace_hw_breakpoint(tsk);
+ /*
* Flush inherited counters to the parent - before the parent
* gets woken up by child-exit notifications.
*/
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index c1f64e6..08f6d01 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -15,6 +15,7 @@
*
* Copyright (C) 2007 Alan Stern
* Copyright (C) IBM Corporation, 2009
+ * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
*/

/*
@@ -35,334 +36,242 @@
#include <linux/init.h>
#include <linux/smp.h>

-#include <asm/hw_breakpoint.h>
+#include <linux/hw_breakpoint.h>
+
#include <asm/processor.h>

#ifdef CONFIG_X86
#include <asm/debugreg.h>
#endif
-/*
- * Spinlock that protects all (un)register operations over kernel/user-space
- * breakpoint requests
- */
-static DEFINE_SPINLOCK(hw_breakpoint_lock);
-
-/* Array of kernel-space breakpoint structures */
-struct hw_breakpoint *hbp_kernel[HBP_NUM];
-
-/*
- * Per-processor copy of hbp_kernel[]. Used only when hbp_kernel is being
- * modified but we need the older copy to handle any hbp exceptions. It will
- * sync with hbp_kernel[] value after updation is done through IPIs.
- */
-DEFINE_PER_CPU(struct hw_breakpoint*, this_hbp_kernel[HBP_NUM]);
-
-/*
- * Kernel breakpoints grow downwards, starting from HBP_NUM
- * 'hbp_kernel_pos' denotes lowest numbered breakpoint register occupied for
- * kernel-space request. We will initialise it here and not in an __init
- * routine because load_debug_registers(), which uses this variable can be
- * called very early during CPU initialisation.
- */
-unsigned int hbp_kernel_pos = HBP_NUM;

-/*
- * An array containing refcount of threads using a given bkpt register
- * Accesses are synchronised by acquiring hw_breakpoint_lock
- */
-unsigned int hbp_user_refcount[HBP_NUM];
+static atomic_t bp_slot;

-/*
- * Load the debug registers during startup of a CPU.
- */
-void load_debug_registers(void)
+int reserve_bp_slot(struct perf_event *bp)
{
- unsigned long flags;
- struct task_struct *tsk = current;
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- /* Prevent IPIs for new kernel breakpoint updates */
- local_irq_save(flags);
- arch_update_kernel_hw_breakpoint(NULL);
- local_irq_restore(flags);
-
- if (test_tsk_thread_flag(tsk, TIF_DEBUG))
- arch_install_thread_hw_breakpoint(tsk);
-
- spin_unlock_bh(&hw_breakpoint_lock);
-}
+ if (atomic_inc_return(&bp_slot) == HBP_NUM) {
+ atomic_dec(&bp_slot);

-/*
- * Erase all the hardware breakpoint info associated with a thread.
- *
- * If tsk != current then tsk must not be usable (for example, a
- * child being cleaned up from a failed fork).
- */
-void flush_thread_hw_breakpoint(struct task_struct *tsk)
-{
- int i;
- struct thread_struct *thread = &(tsk->thread);
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- /* The thread no longer has any breakpoints associated with it */
- clear_tsk_thread_flag(tsk, TIF_DEBUG);
- for (i = 0; i < HBP_NUM; i++) {
- if (thread->hbp[i]) {
- hbp_user_refcount[i]--;
- kfree(thread->hbp[i]);
- thread->hbp[i] = NULL;
- }
+ return -ENOSPC;
}

- arch_flush_thread_hw_breakpoint(tsk);
-
- /* Actually uninstall the breakpoints if necessary */
- if (tsk == current)
- arch_uninstall_thread_hw_breakpoint();
- spin_unlock_bh(&hw_breakpoint_lock);
+ return 0;
}

-/*
- * Copy the hardware breakpoint info from a thread to its cloned child.
- */
-int copy_thread_hw_breakpoint(struct task_struct *tsk,
- struct task_struct *child, unsigned long clone_flags)
+void release_bp_slot(struct perf_event *bp)
{
- /*
- * We will assume that breakpoint settings are not inherited
- * and the child starts out with no debug registers set.
- * But what about CLONE_PTRACE?
- */
- clear_tsk_thread_flag(child, TIF_DEBUG);
-
- /* We will call flush routine since the debugregs are not inherited */
- arch_flush_thread_hw_breakpoint(child);
-
- return 0;
+ atomic_dec(&bp_slot);
}

-static int __register_user_hw_breakpoint(int pos, struct task_struct *tsk,
- struct hw_breakpoint *bp)
+int __register_perf_hw_breakpoint(struct perf_event *bp)
{
- struct thread_struct *thread = &(tsk->thread);
- int rc;
+ int ret;

- /* Do not overcommit. Fail if kernel has used the hbp registers */
- if (pos >= hbp_kernel_pos)
- return -ENOSPC;
+ ret = reserve_bp_slot(bp);
+ if (ret)
+ return ret;

- rc = arch_validate_hwbkpt_settings(bp, tsk);
- if (rc)
- return rc;
+ if (!bp->attr.disabled)
+ ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);

- thread->hbp[pos] = bp;
- hbp_user_refcount[pos]++;
+ return ret;
+}

- arch_update_user_hw_breakpoint(pos, tsk);
- /*
- * Does it need to be installed right now?
- * Otherwise it will get installed the next time tsk runs
- */
- if (tsk == current)
- arch_install_thread_hw_breakpoint(tsk);
+int register_perf_hw_breakpoint(struct perf_event *bp)
+{
+ bp->callback = perf_bp_event;

- return rc;
+ return __register_perf_hw_breakpoint(bp);
}

/*
- * Modify the address of a hbp register already in use by the task
- * Do not invoke this in-lieu of a __unregister_user_hw_breakpoint()
+ * Register a breakpoint bound to a task and a given cpu.
+ * If cpu is -1, the breakpoint is active for the task in every cpu
+ * If the task is -1, the breakpoint is active for every tasks in the given
+ * cpu.
*/
-static int __modify_user_hw_breakpoint(int pos, struct task_struct *tsk,
- struct hw_breakpoint *bp)
+static struct perf_event *
+register_user_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ pid_t pid,
+ int cpu,
+ bool active)
{
- struct thread_struct *thread = &(tsk->thread);
-
- if ((pos >= hbp_kernel_pos) || (arch_validate_hwbkpt_settings(bp, tsk)))
- return -EINVAL;
-
- if (thread->hbp[pos] == NULL)
- return -EINVAL;
-
- thread->hbp[pos] = bp;
+ struct perf_event_attr *attr;
+ struct perf_event *bp;
+
+ attr = kzalloc(sizeof(*attr), GFP_KERNEL);
+ if (!attr)
+ return ERR_PTR(-ENOMEM);
+
+ attr->type = PERF_TYPE_BREAKPOINT;
+ attr->size = sizeof(*attr);
+ attr->bp_addr = addr;
+ attr->bp_len = len;
+ attr->bp_type = type;
/*
- * 'pos' must be that of a hbp register already used by 'tsk'
- * Otherwise arch_modify_user_hw_breakpoint() will fail
+ * Such breakpoints are used by debuggers to trigger signals when
+ * we hit the excepted memory op. We can't miss such events, they
+ * must be pinned.
*/
- arch_update_user_hw_breakpoint(pos, tsk);
+ attr->pinned = 1;

- if (tsk == current)
- arch_install_thread_hw_breakpoint(tsk);
+ if (!active)
+ attr->disabled = 1;

- return 0;
-}
-
-static void __unregister_user_hw_breakpoint(int pos, struct task_struct *tsk)
-{
- hbp_user_refcount[pos]--;
- tsk->thread.hbp[pos] = NULL;
+ bp = perf_event_create_kernel_counter(attr, cpu, pid, triggered);
+ kfree(attr);

- arch_update_user_hw_breakpoint(pos, tsk);
-
- if (tsk == current)
- arch_install_thread_hw_breakpoint(tsk);
+ return bp;
}

/**
* register_user_hw_breakpoint - register a hardware breakpoint for user space
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
* @tsk: pointer to 'task_struct' of the process to which the address belongs
- * @bp: the breakpoint structure to register
- *
- * @bp.info->name or @bp.info->address, @bp.info->len, @bp.info->type and
- * @bp->triggered must be set properly before invocation
+ * @active: should we activate it while registering it
*
*/
-int register_user_hw_breakpoint(struct task_struct *tsk,
- struct hw_breakpoint *bp)
+struct perf_event *
+register_user_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active)
{
- struct thread_struct *thread = &(tsk->thread);
- int i, rc = -ENOSPC;
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- for (i = 0; i < hbp_kernel_pos; i++) {
- if (!thread->hbp[i]) {
- rc = __register_user_hw_breakpoint(i, tsk, bp);
- break;
- }
- }
- if (!rc)
- set_tsk_thread_flag(tsk, TIF_DEBUG);
-
- spin_unlock_bh(&hw_breakpoint_lock);
- return rc;
+ return register_user_hw_breakpoint_cpu(addr, len, type, triggered,
+ tsk->pid, -1, active);
}
EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);

/**
* modify_user_hw_breakpoint - modify a user-space hardware breakpoint
+ * @bp: the breakpoint structure to modify
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
* @tsk: pointer to 'task_struct' of the process to which the address belongs
- * @bp: the breakpoint structure to unregister
- *
+ * @active: should we activate it while registering it
*/
-int modify_user_hw_breakpoint(struct task_struct *tsk, struct hw_breakpoint *bp)
+struct perf_event *
+modify_user_hw_breakpoint(struct perf_event *bp,
+ unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active)
{
- struct thread_struct *thread = &(tsk->thread);
- int i, ret = -ENOENT;
+ /*
+ * FIXME: do it without unregistering
+ * - We don't want to lose our slot
+ * - If the new bp is incorrect, don't lose the older one
+ */
+ unregister_hw_breakpoint(bp);

- spin_lock_bh(&hw_breakpoint_lock);
- for (i = 0; i < hbp_kernel_pos; i++) {
- if (bp == thread->hbp[i]) {
- ret = __modify_user_hw_breakpoint(i, tsk, bp);
- break;
- }
- }
- spin_unlock_bh(&hw_breakpoint_lock);
- return ret;
+ return register_user_hw_breakpoint(addr, len, type, triggered,
+ tsk, active);
}
EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);

/**
- * unregister_user_hw_breakpoint - unregister a user-space hardware breakpoint
- * @tsk: pointer to 'task_struct' of the process to which the address belongs
+ * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
* @bp: the breakpoint structure to unregister
- *
*/
-void unregister_user_hw_breakpoint(struct task_struct *tsk,
- struct hw_breakpoint *bp)
+void unregister_hw_breakpoint(struct perf_event *bp)
{
- struct thread_struct *thread = &(tsk->thread);
- int i, pos = -1, hbp_counter = 0;
-
- spin_lock_bh(&hw_breakpoint_lock);
- for (i = 0; i < hbp_kernel_pos; i++) {
- if (thread->hbp[i])
- hbp_counter++;
- if (bp == thread->hbp[i])
- pos = i;
- }
- if (pos >= 0) {
- __unregister_user_hw_breakpoint(pos, tsk);
- hbp_counter--;
- }
- if (!hbp_counter)
- clear_tsk_thread_flag(tsk, TIF_DEBUG);
-
- spin_unlock_bh(&hw_breakpoint_lock);
+ if (!bp)
+ return;
+ perf_event_release_kernel(bp);
+}
+EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
+
+static struct perf_event *
+register_kernel_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ int cpu,
+ bool active)
+{
+ return register_user_hw_breakpoint_cpu(addr, len, type, triggered,
+ -1, cpu, active);
}
-EXPORT_SYMBOL_GPL(unregister_user_hw_breakpoint);

/**
- * register_kernel_hw_breakpoint - register a hardware breakpoint for kernel space
- * @bp: the breakpoint structure to register
- *
- * @bp.info->name or @bp.info->address, @bp.info->len, @bp.info->type and
- * @bp->triggered must be set properly before invocation
+ * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
+ * @active: should we activate it while registering it
*
+ * @return a set of per_cpu pointers to perf events
*/
-int register_kernel_hw_breakpoint(struct hw_breakpoint *bp)
+struct perf_event **
+register_wide_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ bool active)
{
- int rc;
+ struct perf_event **cpu_events, **pevent, *bp;
+ long err;
+ int cpu;
+
+ cpu_events = alloc_percpu(typeof(*cpu_events));
+ if (!cpu_events)
+ return ERR_PTR(-ENOMEM);

- rc = arch_validate_hwbkpt_settings(bp, NULL);
- if (rc)
- return rc;
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ bp = register_kernel_hw_breakpoint_cpu(addr, len, type,
+ triggered, cpu, active);

- spin_lock_bh(&hw_breakpoint_lock);
+ *pevent = bp;

- rc = -ENOSPC;
- /* Check if we are over-committing */
- if ((hbp_kernel_pos > 0) && (!hbp_user_refcount[hbp_kernel_pos-1])) {
- hbp_kernel_pos--;
- hbp_kernel[hbp_kernel_pos] = bp;
- on_each_cpu(arch_update_kernel_hw_breakpoint, NULL, 1);
- rc = 0;
+ if (IS_ERR(bp) || !bp) {
+ err = PTR_ERR(bp);
+ goto fail;
+ }
}

- spin_unlock_bh(&hw_breakpoint_lock);
- return rc;
+ return cpu_events;
+
+fail:
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ if (IS_ERR(*pevent) || !*pevent)
+ break;
+ unregister_hw_breakpoint(*pevent);
+ }
+ free_percpu(cpu_events);
+ /* return the error if any */
+ return ERR_PTR(err);
}
-EXPORT_SYMBOL_GPL(register_kernel_hw_breakpoint);

/**
- * unregister_kernel_hw_breakpoint - unregister a HW breakpoint for kernel space
- * @bp: the breakpoint structure to unregister
- *
- * Uninstalls and unregisters @bp.
+ * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
+ * @cpu_events: the per cpu set of events to unregister
*/
-void unregister_kernel_hw_breakpoint(struct hw_breakpoint *bp)
+void unregister_wide_hw_breakpoint(struct perf_event **cpu_events)
{
- int i, j;
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- /* Find the 'bp' in our list of breakpoints for kernel */
- for (i = hbp_kernel_pos; i < HBP_NUM; i++)
- if (bp == hbp_kernel[i])
- break;
+ int cpu;
+ struct perf_event **pevent;

- /* Check if we did not find a match for 'bp'. If so return early */
- if (i == HBP_NUM) {
- spin_unlock_bh(&hw_breakpoint_lock);
- return;
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ unregister_hw_breakpoint(*pevent);
}
-
- /*
- * We'll shift the breakpoints one-level above to compact if
- * unregistration creates a hole
- */
- for (j = i; j > hbp_kernel_pos; j--)
- hbp_kernel[j] = hbp_kernel[j-1];
-
- hbp_kernel[hbp_kernel_pos] = NULL;
- on_each_cpu(arch_update_kernel_hw_breakpoint, NULL, 1);
- hbp_kernel_pos++;
-
- spin_unlock_bh(&hw_breakpoint_lock);
+ free_percpu(cpu_events);
}
-EXPORT_SYMBOL_GPL(unregister_kernel_hw_breakpoint);
+

static struct notifier_block hw_breakpoint_exceptions_nb = {
.notifier_call = hw_breakpoint_exceptions_notify,
@@ -374,5 +283,12 @@ static int __init init_hw_breakpoint(void)
{
return register_die_notifier(&hw_breakpoint_exceptions_nb);
}
-
core_initcall(init_hw_breakpoint);
+
+
+struct pmu perf_ops_bp = {
+ .enable = arch_install_hw_breakpoint,
+ .disable = arch_uninstall_hw_breakpoint,
+ .read = hw_breakpoint_pmu_read,
+ .unthrottle = hw_breakpoint_pmu_unthrottle
+};
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 34866d0..f5bb1ae 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -29,6 +29,7 @@
#include <linux/kernel_stat.h>
#include <linux/perf_event.h>
#include <linux/ftrace_event.h>
+#include <linux/hw_breakpoint.h>

#include <asm/irq_regs.h>

@@ -4229,6 +4230,51 @@ static void perf_event_free_filter(struct perf_event *event)

#endif /* CONFIG_EVENT_PROFILE */

+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+static void bp_perf_event_destroy(struct perf_event *event)
+{
+ release_bp_slot(event);
+}
+
+static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+{
+ int err;
+ /*
+ * The breakpoint is already filled if we haven't created the counter
+ * through perf syscall
+ * FIXME: manage to get trigerred to NULL if it comes from syscalls
+ */
+ if (!bp->callback)
+ err = register_perf_hw_breakpoint(bp);
+ else
+ err = __register_perf_hw_breakpoint(bp);
+ if (err)
+ return ERR_PTR(err);
+
+ bp->destroy = bp_perf_event_destroy;
+
+ return &perf_ops_bp;
+}
+
+void perf_bp_event(struct perf_event *bp, void *regs)
+{
+ /* TODO */
+}
+#else
+static void bp_perf_event_destroy(struct perf_event *event)
+{
+}
+
+static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+{
+ return NULL;
+}
+
+void perf_bp_event(struct perf_event *bp, void *regs)
+{
+}
+#endif
+
atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];

static void sw_perf_event_destroy(struct perf_event *event)
@@ -4379,6 +4425,11 @@ perf_event_alloc(struct perf_event_attr *attr,
pmu = tp_perf_event_init(event);
break;

+ case PERF_TYPE_BREAKPOINT:
+ pmu = bp_perf_event_init(event);
+ break;
+
+
default:
break;
}
@@ -4687,7 +4738,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,

ctx = find_get_context(pid, cpu);
if (IS_ERR(ctx))
- return NULL ;
+ return NULL;

event = perf_event_alloc(attr, cpu, ctx, NULL,
NULL, callback, GFP_KERNEL);
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index e19747d..c16a08f 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -372,11 +372,11 @@ FTRACE_ENTRY(ksym_trace, ksym_trace_entry,
F_STRUCT(
__field( unsigned long, ip )
__field( unsigned char, type )
- __array( char , ksym_name, KSYM_NAME_LEN )
__array( char , cmd, TASK_COMM_LEN )
+ __field( unsigned long, addr )
),

- F_printk("ip: %pF type: %d ksym_name: %s cmd: %s",
+ F_printk("ip: %pF type: %d ksym_name: %pS cmd: %s",
(void *)__entry->ip, (unsigned int)__entry->type,
- __entry->ksym_name, __entry->cmd)
+ (void *)__entry->addr, __entry->cmd)
);
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 6d5609c..fea83ee 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -29,7 +29,11 @@
#include "trace_stat.h"
#include "trace.h"

-/* For now, let us restrict the no. of symbols traced simultaneously to number
+#include <linux/hw_breakpoint.h>
+#include <asm/hw_breakpoint.h>
+
+/*
+ * For now, let us restrict the no. of symbols traced simultaneously to number
* of available hardware breakpoint registers.
*/
#define KSYM_TRACER_MAX HBP_NUM
@@ -37,8 +41,10 @@
#define KSYM_TRACER_OP_LEN 3 /* rw- */

struct trace_ksym {
- struct hw_breakpoint *ksym_hbp;
+ struct perf_event **ksym_hbp;
unsigned long ksym_addr;
+ int type;
+ int len;
#ifdef CONFIG_PROFILE_KSYM_TRACER
unsigned long counter;
#endif
@@ -75,10 +81,11 @@ void ksym_collect_stats(unsigned long hbp_hit_addr)
}
#endif /* CONFIG_PROFILE_KSYM_TRACER */

-void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs)
+void ksym_hbp_handler(struct perf_event *hbp, void *data)
{
struct ring_buffer_event *event;
struct ksym_trace_entry *entry;
+ struct pt_regs *regs = data;
struct ring_buffer *buffer;
int pc;

@@ -96,12 +103,12 @@ void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs)

entry = ring_buffer_event_data(event);
entry->ip = instruction_pointer(regs);
- entry->type = hbp->info.type;
- strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN);
+ entry->type = hw_breakpoint_type(hbp);
+ entry->addr = hw_breakpoint_addr(hbp);
strlcpy(entry->cmd, current->comm, TASK_COMM_LEN);

#ifdef CONFIG_PROFILE_KSYM_TRACER
- ksym_collect_stats(hbp->info.address);
+ ksym_collect_stats(hw_breakpoint_addr(hbp));
#endif /* CONFIG_PROFILE_KSYM_TRACER */

trace_buffer_unlock_commit(buffer, event, 0, pc);
@@ -120,31 +127,21 @@ static int ksym_trace_get_access_type(char *str)
int access = 0;

if (str[0] == 'r')
- access += 4;
- else if (str[0] != '-')
- return -EINVAL;
+ access |= HW_BREAKPOINT_R;

if (str[1] == 'w')
- access += 2;
- else if (str[1] != '-')
- return -EINVAL;
+ access |= HW_BREAKPOINT_W;

- if (str[2] != '-')
- return -EINVAL;
+ if (str[2] == 'x')
+ access |= HW_BREAKPOINT_X;

switch (access) {
- case 6:
- access = HW_BREAKPOINT_RW;
- break;
- case 4:
- access = -EINVAL;
- break;
- case 2:
- access = HW_BREAKPOINT_WRITE;
- break;
+ case HW_BREAKPOINT_W:
+ case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
+ return access;
+ default:
+ return -EINVAL;
}
-
- return access;
}

/*
@@ -194,36 +191,33 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
if (!entry)
return -ENOMEM;

- entry->ksym_hbp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL);
- if (!entry->ksym_hbp)
- goto err;
-
- entry->ksym_hbp->info.name = kstrdup(ksymname, GFP_KERNEL);
- if (!entry->ksym_hbp->info.name)
- goto err;
-
- entry->ksym_hbp->info.type = op;
- entry->ksym_addr = entry->ksym_hbp->info.address = addr;
-#ifdef CONFIG_X86
- entry->ksym_hbp->info.len = HW_BREAKPOINT_LEN_4;
-#endif
- entry->ksym_hbp->triggered = (void *)ksym_hbp_handler;
+ entry->type = op;
+ entry->ksym_addr = addr;
+ entry->len = HW_BREAKPOINT_LEN_4;
+
+ ret = -EAGAIN;
+ entry->ksym_hbp = register_wide_hw_breakpoint(entry->ksym_addr,
+ entry->len, entry->type,
+ ksym_hbp_handler, true);
+ if (IS_ERR(entry->ksym_hbp)) {
+ entry->ksym_hbp = NULL;
+ ret = PTR_ERR(entry->ksym_hbp);
+ }

- ret = register_kernel_hw_breakpoint(entry->ksym_hbp);
- if (ret < 0) {
+ if (!entry->ksym_hbp) {
printk(KERN_INFO "ksym_tracer request failed. Try again"
" later!!\n");
- ret = -EAGAIN;
goto err;
}
+
hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head);
ksym_filter_entry_count++;
+
return 0;
+
err:
- if (entry->ksym_hbp)
- kfree(entry->ksym_hbp->info.name);
- kfree(entry->ksym_hbp);
kfree(entry);
+
return ret;
}

@@ -244,10 +238,10 @@ static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf,
mutex_lock(&ksym_tracer_mutex);

hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
- ret = trace_seq_printf(s, "%s:", entry->ksym_hbp->info.name);
- if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE)
+ ret = trace_seq_printf(s, "%pS:", (void *)entry->ksym_addr);
+ if (entry->type == HW_BREAKPOINT_W)
ret = trace_seq_puts(s, "-w-\n");
- else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW)
+ else if (entry->type == (HW_BREAKPOINT_W | HW_BREAKPOINT_R))
ret = trace_seq_puts(s, "rw-\n");
WARN_ON_ONCE(!ret);
}
@@ -269,12 +263,10 @@ static void __ksym_trace_reset(void)
mutex_lock(&ksym_tracer_mutex);
hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head,
ksym_hlist) {
- unregister_kernel_hw_breakpoint(entry->ksym_hbp);
+ unregister_wide_hw_breakpoint(entry->ksym_hbp);
ksym_filter_entry_count--;
hlist_del_rcu(&(entry->ksym_hlist));
synchronize_rcu();
- kfree(entry->ksym_hbp->info.name);
- kfree(entry->ksym_hbp);
kfree(entry);
}
mutex_unlock(&ksym_tracer_mutex);
@@ -327,7 +319,7 @@ static ssize_t ksym_trace_filter_write(struct file *file,
hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
if (entry->ksym_addr == ksym_addr) {
/* Check for malformed request: (6) */
- if (entry->ksym_hbp->info.type != op)
+ if (entry->type != op)
changed = 1;
else
goto out;
@@ -335,18 +327,21 @@ static ssize_t ksym_trace_filter_write(struct file *file,
}
}
if (changed) {
- unregister_kernel_hw_breakpoint(entry->ksym_hbp);
- entry->ksym_hbp->info.type = op;
+ unregister_wide_hw_breakpoint(entry->ksym_hbp);
+ entry->type = op;
if (op > 0) {
- ret = register_kernel_hw_breakpoint(entry->ksym_hbp);
- if (ret == 0)
+ entry->ksym_hbp =
+ register_wide_hw_breakpoint(entry->ksym_addr,
+ entry->len, entry->type,
+ ksym_hbp_handler, true);
+ if (IS_ERR(entry->ksym_hbp))
+ entry->ksym_hbp = NULL;
+ if (!entry->ksym_hbp)
goto out;
}
ksym_filter_entry_count--;
hlist_del_rcu(&(entry->ksym_hlist));
synchronize_rcu();
- kfree(entry->ksym_hbp->info.name);
- kfree(entry->ksym_hbp);
kfree(entry);
ret = 0;
goto out;
@@ -413,16 +408,16 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter)

trace_assign_type(field, entry);

- ret = trace_seq_printf(s, "%11s-%-5d [%03d] %-30s ", field->cmd,
- entry->pid, iter->cpu, field->ksym_name);
+ ret = trace_seq_printf(s, "%11s-%-5d [%03d] %pS", field->cmd,
+ entry->pid, iter->cpu, (char *)field->addr);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;

switch (field->type) {
- case HW_BREAKPOINT_WRITE:
+ case HW_BREAKPOINT_W:
ret = trace_seq_printf(s, " W ");
break;
- case HW_BREAKPOINT_RW:
+ case HW_BREAKPOINT_R | HW_BREAKPOINT_W:
ret = trace_seq_printf(s, " RW ");
break;
default:
@@ -490,14 +485,13 @@ static int ksym_tracer_stat_show(struct seq_file *m, void *v)

entry = hlist_entry(stat, struct trace_ksym, ksym_hlist);

- if (entry->ksym_hbp)
- access_type = entry->ksym_hbp->info.type;
+ access_type = entry->type;

switch (access_type) {
- case HW_BREAKPOINT_WRITE:
+ case HW_BREAKPOINT_W:
seq_puts(m, " W ");
break;
- case HW_BREAKPOINT_RW:
+ case HW_BREAKPOINT_R | HW_BREAKPOINT_W:
seq_puts(m, " RW ");
break;
default:
--
1.6.2.3