From 0722db015c246204044299eae3b02d18d3ca4faf Mon Sep 17 00:00:00 2001 From: "K.Prasad" Date: Mon, 1 Jun 2009 23:46:40 +0530 Subject: hw-breakpoints: ftrace plugin for kernel symbol tracing using HW Breakpoint interfaces This patch adds an ftrace plugin to detect and profile memory access over kernel variables. It uses HW Breakpoint interfaces to 'watch memory addresses. Signed-off-by: K.Prasad Signed-off-by: Frederic Weisbecker --- kernel/trace/trace.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 6e735d4771f8..7d5cc37b8fca 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -15,6 +15,10 @@ #include #include +#ifdef CONFIG_KSYM_TRACER +#include +#endif + enum trace_type { __TRACE_FIRST_TYPE = 0, @@ -40,6 +44,7 @@ enum trace_type { TRACE_KMEM_FREE, TRACE_POWER, TRACE_BLK, + TRACE_KSYM, __TRACE_LAST_TYPE, }; @@ -207,6 +212,21 @@ struct syscall_trace_exit { unsigned long ret; }; +#define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy" +extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr); + +struct trace_ksym { + struct trace_entry ent; + struct hw_breakpoint *ksym_hbp; + unsigned long ksym_addr; + unsigned long ip; +#ifdef CONFIG_PROFILE_KSYM_TRACER + unsigned long counter; +#endif + struct hlist_node ksym_hlist; + char ksym_name[KSYM_NAME_LEN]; + char p_name[TASK_COMM_LEN]; +}; /* * trace_flag_type is an enumeration that holds different @@ -323,6 +343,7 @@ extern void __ftrace_bad_type(void); TRACE_SYSCALL_ENTER); \ IF_ASSIGN(var, ent, struct syscall_trace_exit, \ TRACE_SYSCALL_EXIT); \ + IF_ASSIGN(var, ent, struct trace_ksym, TRACE_KSYM); \ __ftrace_bad_type(); \ } while (0) @@ -540,6 +561,8 @@ extern int trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr); extern int trace_selftest_startup_hw_branches(struct tracer *trace, struct trace_array *tr); +extern int trace_selftest_startup_ksym(struct tracer *trace, + struct trace_array *tr); #endif /* CONFIG_FTRACE_STARTUP_TEST */ extern void *head_page(struct trace_array_cpu *data); -- cgit v1.2.3 From db59504d89db1462a5281fb55b1d962cb74a398f Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Tue, 7 Jul 2009 13:52:36 +0800 Subject: ksym_tracer: Extract trace entry from struct trace_ksym struct trace_ksym is used as an entry in hbp list, and is also used as trace_entry stored in ring buffer. This is not necessary and is a waste of memory in ring buffer. There is also a bug that dereferencing field->ksym_hbp in ksym_trace_output() can be invalid. Signed-off-by: Li Zefan Acked-by: Frederic Weisbecker Cc: "K.Prasad" Cc: Alan Stern Cc: Steven Rostedt LKML-Reference: <4A52E2A4.4050007@cn.fujitsu.com> Signed-off-by: Ingo Molnar --- kernel/trace/trace.h | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 7d5cc37b8fca..ff1ef411a176 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -215,17 +215,12 @@ struct syscall_trace_exit { #define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy" extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr); -struct trace_ksym { +struct ksym_trace_entry { struct trace_entry ent; - struct hw_breakpoint *ksym_hbp; - unsigned long ksym_addr; unsigned long ip; -#ifdef CONFIG_PROFILE_KSYM_TRACER - unsigned long counter; -#endif - struct hlist_node ksym_hlist; + unsigned char type; char ksym_name[KSYM_NAME_LEN]; - char p_name[TASK_COMM_LEN]; + char cmd[TASK_COMM_LEN]; }; /* @@ -343,7 +338,7 @@ extern void __ftrace_bad_type(void); TRACE_SYSCALL_ENTER); \ IF_ASSIGN(var, ent, struct syscall_trace_exit, \ TRACE_SYSCALL_EXIT); \ - IF_ASSIGN(var, ent, struct trace_ksym, TRACE_KSYM); \ + IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\ __ftrace_bad_type(); \ } while (0) -- cgit v1.2.3 From 24f1e32c60c45c89a997c73395b69c8af6f0a84e Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 9 Sep 2009 19:22:48 +0200 Subject: 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 Cc: Prasad Cc: Alan Stern Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Steven Rostedt Cc: Ingo Molnar Cc: Jan Kiszka Cc: Jiri Slaby Cc: Li Zefan Cc: Avi Kivity Cc: Paul Mackerras Cc: Mike Galbraith Cc: Masami Hiramatsu Cc: Paul Mundt --- kernel/trace/trace.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 91c3d0e9a5a1..d72f06ff263f 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -11,14 +11,11 @@ #include #include #include +#include #include #include -#ifdef CONFIG_KSYM_TRACER -#include -#endif - enum trace_type { __TRACE_FIRST_TYPE = 0, -- cgit v1.2.3 From 30ff21e31fe5c8b7b1b7d30cc41e32bc4ee9f175 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Thu, 10 Sep 2009 09:35:20 +0800 Subject: ksym_tracer: Remove KSYM_SELFTEST_ENTRY The macro used to be used in both trace_selftest.c and trace_ksym.c, but no longer, so remove it from header file. Signed-off-by: Li Zefan Cc: Prasad Signed-off-by: Frederic Weisbecker --- kernel/trace/trace.h | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index d72f06ff263f..ee00475742eb 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -367,7 +367,6 @@ int register_tracer(struct tracer *type); void unregister_tracer(struct tracer *type); int is_tracing_stopped(void); -#define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy" extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr); extern unsigned long nsecs_to_usecs(unsigned long nsecs); -- cgit v1.2.3