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authorFrederic Weisbecker <fweisbec@gmail.com>2009-09-09 13:22:48 -0400
committerFrederic Weisbecker <fweisbec@gmail.com>2009-11-08 09:34:42 -0500
commit24f1e32c60c45c89a997c73395b69c8af6f0a84e (patch)
tree4f30f16e18cb4abbcf96b3b331e6a3f01bfa26e6 /include/linux/hw_breakpoint.h
parent2da3e160cb3d226d87b907fab26850d838ed8d7c (diff)
hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events
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 Changes in v3: - Fix broken CONFIG_KVM, we need to propagate the breakpoint api changes to kvm when we exit the guest and restore the bp registers to the host. Changes in v4: - Drop the hw_breakpoint_restore() stub as it is only used by KVM - EXPORT_SYMBOL_GPL hw_breakpoint_restore() as KVM can be built as a module - Restore the breakpoints unconditionally on kvm guest exit: TIF_DEBUG_THREAD doesn't anymore cover every cases of running breakpoints and vcpu->arch.switch_db_regs might not always be set when the guest used debug registers. (Waiting for a reliable optimization) Changes in v5: - Split-up the asm-generic/hw-breakpoint.h moving to linux/hw_breakpoint.h into a separate patch - Optimize the breakpoints restoring while switching from kvm guest to host. We only want to restore the state if we have active breakpoints to the host, otherwise we don't care about messed-up address registers. - Add asm/hw_breakpoint.h to Kbuild - Fix bad breakpoint type in trace_selftest.c Changes in v6: - Fix wrong header inclusion in trace.h (triggered a build error with CONFIG_FTRACE_SELFTEST 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>
Diffstat (limited to 'include/linux/hw_breakpoint.h')
-rw-r--r--include/linux/hw_breakpoint.h243
1 files changed, 119 insertions, 124 deletions
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index 61ccc8f17eac..7eba9b92e5f3 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -1,136 +1,131 @@
1#ifndef _LINUX_HW_BREAKPOINT_H 1#ifndef _LINUX_HW_BREAKPOINT_H
2#define _LINUX_HW_BREAKPOINT_H 2#define _LINUX_HW_BREAKPOINT_H
3 3
4#include <linux/perf_event.h>
4 5
5#ifdef __KERNEL__ 6enum {
6#include <linux/list.h> 7 HW_BREAKPOINT_LEN_1 = 1,
7#include <linux/types.h> 8 HW_BREAKPOINT_LEN_2 = 2,
8#include <linux/kallsyms.h> 9 HW_BREAKPOINT_LEN_4 = 4,
9 10 HW_BREAKPOINT_LEN_8 = 8,
10/**
11 * struct hw_breakpoint - unified kernel/user-space hardware breakpoint
12 * @triggered: callback invoked after target address access
13 * @info: arch-specific breakpoint info (address, length, and type)
14 *
15 * %hw_breakpoint structures are the kernel's way of representing
16 * hardware breakpoints. These are data breakpoints
17 * (also known as "watchpoints", triggered on data access), and the breakpoint's
18 * target address can be located in either kernel space or user space.
19 *
20 * The breakpoint's address, length, and type are highly
21 * architecture-specific. The values are encoded in the @info field; you
22 * specify them when registering the breakpoint. To examine the encoded
23 * values use hw_breakpoint_get_{kaddress,uaddress,len,type}(), declared
24 * below.
25 *
26 * The address is specified as a regular kernel pointer (for kernel-space
27 * breakponts) or as an %__user pointer (for user-space breakpoints).
28 * With register_user_hw_breakpoint(), the address must refer to a
29 * location in user space. The breakpoint will be active only while the
30 * requested task is running. Conversely with
31 * register_kernel_hw_breakpoint(), the address must refer to a location
32 * in kernel space, and the breakpoint will be active on all CPUs
33 * regardless of the current task.
34 *
35 * The length is the breakpoint's extent in bytes, which is subject to
36 * certain limitations. include/asm/hw_breakpoint.h contains macros
37 * defining the available lengths for a specific architecture. Note that
38 * the address's alignment must match the length. The breakpoint will
39 * catch accesses to any byte in the range from address to address +
40 * (length - 1).
41 *
42 * The breakpoint's type indicates the sort of access that will cause it
43 * to trigger. Possible values may include:
44 *
45 * %HW_BREAKPOINT_RW (triggered on read or write access),
46 * %HW_BREAKPOINT_WRITE (triggered on write access), and
47 * %HW_BREAKPOINT_READ (triggered on read access).
48 *
49 * Appropriate macros are defined in include/asm/hw_breakpoint.h; not all
50 * possibilities are available on all architectures. Execute breakpoints
51 * must have length equal to the special value %HW_BREAKPOINT_LEN_EXECUTE.
52 *
53 * When a breakpoint gets hit, the @triggered callback is
54 * invoked in_interrupt with a pointer to the %hw_breakpoint structure and the
55 * processor registers.
56 * Data breakpoints occur after the memory access has taken place.
57 * Breakpoints are disabled during execution @triggered, to avoid
58 * recursive traps and allow unhindered access to breakpointed memory.
59 *
60 * This sample code sets a breakpoint on pid_max and registers a callback
61 * function for writes to that variable. Note that it is not portable
62 * as written, because not all architectures support HW_BREAKPOINT_LEN_4.
63 *
64 * ----------------------------------------------------------------------
65 *
66 * #include <asm/hw_breakpoint.h>
67 *
68 * struct hw_breakpoint my_bp;
69 *
70 * static void my_triggered(struct hw_breakpoint *bp, struct pt_regs *regs)
71 * {
72 * printk(KERN_DEBUG "Inside triggered routine of breakpoint exception\n");
73 * dump_stack();
74 * .......<more debugging output>........
75 * }
76 *
77 * static struct hw_breakpoint my_bp;
78 *
79 * static int init_module(void)
80 * {
81 * ..........<do anything>............
82 * my_bp.info.type = HW_BREAKPOINT_WRITE;
83 * my_bp.info.len = HW_BREAKPOINT_LEN_4;
84 *
85 * my_bp.installed = (void *)my_bp_installed;
86 *
87 * rc = register_kernel_hw_breakpoint(&my_bp);
88 * ..........<do anything>............
89 * }
90 *
91 * static void cleanup_module(void)
92 * {
93 * ..........<do anything>............
94 * unregister_kernel_hw_breakpoint(&my_bp);
95 * ..........<do anything>............
96 * }
97 *
98 * ----------------------------------------------------------------------
99 */
100struct hw_breakpoint {
101 void (*triggered)(struct hw_breakpoint *, struct pt_regs *);
102 struct arch_hw_breakpoint info;
103}; 11};
104 12
105/* 13enum {
106 * len and type values are defined in include/asm/hw_breakpoint.h. 14 HW_BREAKPOINT_R = 1,
107 * Available values vary according to the architecture. On i386 the 15 HW_BREAKPOINT_W = 2,
108 * possibilities are: 16 HW_BREAKPOINT_X = 4,
109 * 17};
110 * HW_BREAKPOINT_LEN_1 18
111 * HW_BREAKPOINT_LEN_2 19static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
112 * HW_BREAKPOINT_LEN_4 20{
113 * HW_BREAKPOINT_RW 21 return &bp->hw.info;
114 * HW_BREAKPOINT_READ 22}
115 * 23
116 * On other architectures HW_BREAKPOINT_LEN_8 may be available, and the 24static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
117 * 1-, 2-, and 4-byte lengths may be unavailable. There also may be 25{
118 * HW_BREAKPOINT_WRITE. You can use #ifdef to check at compile time. 26 return bp->attr.bp_addr;
119 */ 27}
28
29static inline int hw_breakpoint_type(struct perf_event *bp)
30{
31 return bp->attr.bp_type;
32}
33
34static inline int hw_breakpoint_len(struct perf_event *bp)
35{
36 return bp->attr.bp_len;
37}
38
39#ifdef CONFIG_HAVE_HW_BREAKPOINT
40extern struct perf_event *
41register_user_hw_breakpoint(unsigned long addr,
42 int len,
43 int type,
44 perf_callback_t triggered,
45 struct task_struct *tsk,
46 bool active);
47
48/* FIXME: only change from the attr, and don't unregister */
49extern struct perf_event *
50modify_user_hw_breakpoint(struct perf_event *bp,
51 unsigned long addr,
52 int len,
53 int type,
54 perf_callback_t triggered,
55 struct task_struct *tsk,
56 bool active);
120 57
121extern int register_user_hw_breakpoint(struct task_struct *tsk,
122 struct hw_breakpoint *bp);
123extern int modify_user_hw_breakpoint(struct task_struct *tsk,
124 struct hw_breakpoint *bp);
125extern void unregister_user_hw_breakpoint(struct task_struct *tsk,
126 struct hw_breakpoint *bp);
127/* 58/*
128 * Kernel breakpoints are not associated with any particular thread. 59 * Kernel breakpoints are not associated with any particular thread.
129 */ 60 */
130extern int register_kernel_hw_breakpoint(struct hw_breakpoint *bp); 61extern struct perf_event *
131extern void unregister_kernel_hw_breakpoint(struct hw_breakpoint *bp); 62register_wide_hw_breakpoint_cpu(unsigned long addr,
63 int len,
64 int type,
65 perf_callback_t triggered,
66 int cpu,
67 bool active);
68
69extern struct perf_event **
70register_wide_hw_breakpoint(unsigned long addr,
71 int len,
72 int type,
73 perf_callback_t triggered,
74 bool active);
75
76extern int register_perf_hw_breakpoint(struct perf_event *bp);
77extern int __register_perf_hw_breakpoint(struct perf_event *bp);
78extern void unregister_hw_breakpoint(struct perf_event *bp);
79extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);
80
81extern int reserve_bp_slot(struct perf_event *bp);
82extern void release_bp_slot(struct perf_event *bp);
83
84extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
85
86#else /* !CONFIG_HAVE_HW_BREAKPOINT */
87
88static inline struct perf_event *
89register_user_hw_breakpoint(unsigned long addr,
90 int len,
91 int type,
92 perf_callback_t triggered,
93 struct task_struct *tsk,
94 bool active) { return NULL; }
95static inline struct perf_event *
96modify_user_hw_breakpoint(struct perf_event *bp,
97 unsigned long addr,
98 int len,
99 int type,
100 perf_callback_t triggered,
101 struct task_struct *tsk,
102 bool active) { return NULL; }
103static inline struct perf_event *
104register_wide_hw_breakpoint_cpu(unsigned long addr,
105 int len,
106 int type,
107 perf_callback_t triggered,
108 int cpu,
109 bool active) { return NULL; }
110static inline struct perf_event **
111register_wide_hw_breakpoint(unsigned long addr,
112 int len,
113 int type,
114 perf_callback_t triggered,
115 bool active) { return NULL; }
116static inline int
117register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
118static inline int
119__register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
120static inline void unregister_hw_breakpoint(struct perf_event *bp) { }
121static inline void
122unregister_wide_hw_breakpoint(struct perf_event **cpu_events) { }
123static inline int
124reserve_bp_slot(struct perf_event *bp) {return -ENOSYS; }
125static inline void release_bp_slot(struct perf_event *bp) { }
126
127static inline void flush_ptrace_hw_breakpoint(struct task_struct *tsk) { }
132 128
133extern unsigned int hbp_kernel_pos; 129#endif /* CONFIG_HAVE_HW_BREAKPOINT */
134 130
135#endif /* __KERNEL__ */ 131#endif /* _LINUX_HW_BREAKPOINT_H */
136#endif /* _LINUX_HW_BREAKPOINT_H */
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