x86, ptrace: PEBS support

index fe9224c..cbffa2a 100644
@@ -222,10 +222,11 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
 			set_cpu_cap(c, X86_FEATURE_BTS);
 		if (!(l1 & (1<<12)))
 			set_cpu_cap(c, X86_FEATURE_PEBS);
+		ds_init_intel(c);
 	}
 
 	if (cpu_has_bts)
-		ds_init_intel(c);
+		ptrace_bts_init_intel(c);
 }
 
 static unsigned int __cpuinit intel_size_cache(struct cpuinfo_x86 *c, unsigned int size)

1,152 lines not on this page · raw message

index 63dca4b..eda2304 100644
@@ -426,6 +426,14 @@ void exit_thread(void)
 		tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
 		put_cpu();
 	}
+#ifdef CONFIG_X86_DS
+	/* Free any DS contexts that have not been properly released. */
+	if (unlikely(current->thread.ds_ctx)) {
+		/* we clear debugctl to make sure DS is not used. */
+		update_debugctlmsr(0);
+		ds_free(current->thread.ds_ctx);
+	}
+#endif /* CONFIG_X86_DS */
 }
 
 void flush_thread(void)

@@ -451,6 +459,16 @@ void release_thread(struct task_struct *dead_task)
 {
 	BUG_ON(dead_task->mm);
 	release_vm86_irqs(dead_task);
+
+#ifdef CONFIG_X86_DS
+	/* Free any DS contexts that have not been properly released. */
+	if (unlikely(dead_task->thread.ds_ctx)) {
+		/* we clear debugctl to make sure DS is not used. */
+		if (dead_task == current)
+			update_debugctlmsr(0);
+		ds_free(dead_task->thread.ds_ctx);
+	}
+#endif /* CONFIG_X86_DS */
 }
 
 /*

@@ -592,18 +610,27 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
 {
 	struct thread_struct *prev, *next;
 	unsigned long debugctl;
+	unsigned long ds_prev = 0, ds_next = 0;
 
 	prev = &prev_p->thread;
 	next = &next_p->thread;
 
 	debugctl = prev->debugctlmsr;
-	if (next->ds_area_msr != prev->ds_area_msr) {
+
+#ifdef CONFIG_X86_DS
+	if (prev->ds_ctx)
+		ds_prev = (unsigned long)prev->ds_ctx->ds;
+	if (next->ds_ctx)
+		ds_next = (unsigned long)next->ds_ctx->ds;
+
+	if (ds_next != ds_prev) {
 		/* we clear debugctl to make sure DS
 		 * is not in use when we change it */
 		debugctl = 0;
 		update_debugctlmsr(0);
-		wrmsr(MSR_IA32_DS_AREA, next->ds_area_msr, 0);
+		wrmsr(MSR_IA32_DS_AREA, ds_next, 0);
 	}
+#endif /* CONFIG_X86_DS */
 
 	if (next->debugctlmsr != debugctl)
 		update_debugctlmsr(next->debugctlmsr);

@@ -627,13 +654,13 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
 			hard_enable_TSC();
 	}
 
-#ifdef X86_BTS
+#ifdef CONFIG_X86_PTRACE_BTS
 	if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
 		ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
 
 	if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
 		ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
-#endif
+#endif /* CONFIG_X86_PTRACE_BTS */
 
 
 	if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {

index efa98af..24916c2 100644
@@ -400,6 +400,14 @@ void exit_thread(void)
 		t->io_bitmap_max = 0;
 		put_cpu();
 	}
+#ifdef CONFIG_X86_DS
+	/* Free any DS contexts that have not been properly released. */
+	if (unlikely(t->ds_ctx)) {
+		/* we clear debugctl to make sure DS is not used. */
+		update_debugctlmsr(0);
+		ds_free(t->ds_ctx);
+	}
+#endif /* CONFIG_X86_DS */
 }
 
 void flush_thread(void)

@@ -625,18 +633,27 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
 {
 	struct thread_struct *prev, *next;
 	unsigned long debugctl;
+	unsigned long ds_prev = 0, ds_next = 0;
 
 	prev = &prev_p->thread,
 	next = &next_p->thread;
 
 	debugctl = prev->debugctlmsr;
-	if (next->ds_area_msr != prev->ds_area_msr) {
+
+#ifdef CONFIG_X86_DS
+	if (prev->ds_ctx)
+		ds_prev = (unsigned long)prev->ds_ctx->ds;
+	if (next->ds_ctx)
+		ds_next = (unsigned long)next->ds_ctx->ds;
+
+	if (ds_next != ds_prev) {
 		/* we clear debugctl to make sure DS
 		 * is not in use when we change it */
 		debugctl = 0;
 		update_debugctlmsr(0);
-		wrmsrl(MSR_IA32_DS_AREA, next->ds_area_msr);
+		wrmsrl(MSR_IA32_DS_AREA, ds_next);
 	}
+#endif /* CONFIG_X86_DS */
 
 	if (next->debugctlmsr != debugctl)
 		update_debugctlmsr(next->debugctlmsr);

@@ -674,13 +691,13 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
 		memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
 	}
 
-#ifdef X86_BTS
+#ifdef CONFIG_X86_PTRACE_BTS
 	if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
 		ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
 
 	if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
 		ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
-#endif
+#endif /* CONFIG_X86_PTRACE_BTS */
 }
 
 /*

612 lines not on this page · raw message

index 492c6a4..cd245ef 100644
@@ -906,11 +906,12 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
 			set_cpu_cap(c, X86_FEATURE_BTS);
 		if (!(l1 & (1<<12)))
 			set_cpu_cap(c, X86_FEATURE_PEBS);
+		ds_init_intel(c);
 	}
 
 
 	if (cpu_has_bts)
-		ds_init_intel(c);
+		ptrace_bts_init_intel(c);
 
 	n = c->extended_cpuid_level;
 	if (n >= 0x80000008) {

283 lines not on this page · raw message

index e6bf92d..0b0a859 100644
@@ -23,6 +23,7 @@ struct mm_struct;
 #include <asm/msr.h>
 #include <asm/desc_defs.h>
 #include <asm/nops.h>
+#include <asm/ds.h>
 
 #include <linux/personality.h>
 #include <linux/cpumask.h>

@@ -419,9 +420,14 @@ struct thread_struct {
 	unsigned		io_bitmap_max;
 /* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set.  */
 	unsigned long	debugctlmsr;
-/* Debug Store - if not 0 points to a DS Save Area configuration;
- *               goes into MSR_IA32_DS_AREA */
-	unsigned long	ds_area_msr;
+#ifdef CONFIG_X86_DS
+/* Debug Store context; see include/asm-x86/ds.h; goes into MSR_IA32_DS_AREA */
+	struct ds_context	*ds_ctx;
+#endif /* CONFIG_X86_DS */
+#ifdef CONFIG_X86_PTRACE_BTS
+/* the signal to send on a bts buffer overflow */
+	unsigned int	bts_ovfl_signal;
+#endif /* CONFIG_X86_PTRACE_BTS */
 };
 
 static inline unsigned long native_get_debugreg(int regno)

index f224eb3..9bcaa75 100644
@@ -80,8 +80,9 @@
 
 #define PTRACE_SINGLEBLOCK	33	/* resume execution until next branch */
 
-#ifndef __ASSEMBLY__
+#ifdef CONFIG_X86_PTRACE_BTS
 
+#ifndef __ASSEMBLY__
 #include <asm/types.h>
 
 /* configuration/status structure used in PTRACE_BTS_CONFIG and

@@ -97,20 +98,20 @@ struct ptrace_bts_config {
 	/* actual size of bts_struct in bytes */
 	__u32 bts_size;
 };
-#endif
+#endif /* __ASSEMBLY__ */
 
 #define PTRACE_BTS_O_TRACE	0x1 /* branch trace */
 #define PTRACE_BTS_O_SCHED	0x2 /* scheduling events w/ jiffies */
 #define PTRACE_BTS_O_SIGNAL     0x4 /* send SIG<signal> on buffer overflow
 				       instead of wrapping around */
-#define PTRACE_BTS_O_CUT_SIZE	0x8 /* cut requested size to max available
-				       instead of failing */
+#define PTRACE_BTS_O_ALLOC	0x8 /* (re)allocate buffer */
 
 #define PTRACE_BTS_CONFIG	40
 /* Configure branch trace recording.
    ADDR points to a struct ptrace_bts_config.
    DATA gives the size of that buffer.
-   A new buffer is allocated, iff the size changes.
+   A new buffer is allocated, if requested in the flags.
+   An overflow signal may only be requested for new buffers.
    Returns the number of bytes read.
 */
 #define PTRACE_BTS_STATUS	41

@@ -119,7 +120,7 @@ struct ptrace_bts_config {
    Returns the number of bytes written.
 */
 #define PTRACE_BTS_SIZE		42
-/* Return the number of available BTS records.
+/* Return the number of available BTS records for draining.
    DATA and ADDR are ignored.
 */
 #define PTRACE_BTS_GET		43

@@ -139,5 +140,6 @@ struct ptrace_bts_config {
    BTS records are read from oldest to newest.
    Returns number of BTS records drained.
 */
+#endif /* CONFIG_X86_PTRACE_BTS */
 
 #endif

index 24ec061..f78dafc 100644
@@ -125,14 +125,48 @@ struct pt_regs {
 #endif /* __KERNEL__ */
 #endif /* !__i386__ */
 
+
+#ifdef CONFIG_X86_PTRACE_BTS
+/* a branch trace record entry
+ *
+ * In order to unify the interface between various processor versions,
+ * we use the below data structure for all processors.
+ */
+enum bts_qualifier {
+	BTS_INVALID = 0,
+	BTS_BRANCH,
+	BTS_TASK_ARRIVES,
+	BTS_TASK_DEPARTS
+};
+
+struct bts_struct {
+	__u64 qualifier;
+	union {
+		/* BTS_BRANCH */
+		struct {
+			__u64 from_ip;
+			__u64 to_ip;
+		} lbr;
+		/* BTS_TASK_ARRIVES or
+		   BTS_TASK_DEPARTS */
+		__u64 jiffies;
+	} variant;
+};
+#endif /* CONFIG_X86_PTRACE_BTS */
+
 #ifdef __KERNEL__
 
-/* the DS BTS struct is used for ptrace as well */
-#include <asm/ds.h>
+#include <linux/init.h>
 
+struct cpuinfo_x86;
 struct task_struct;
 
+#ifdef CONFIG_X86_PTRACE_BTS
+extern void __cpuinit ptrace_bts_init_intel(struct cpuinfo_x86 *);
 extern void ptrace_bts_take_timestamp(struct task_struct *, enum bts_qualifier);
+#else
+#define ptrace_bts_init_intel(config) do {} while (0)
+#endif /* CONFIG_X86_PTRACE_BTS */
 
 extern unsigned long profile_pc(struct pt_regs *regs);