[patch 1/2] x86, ptrace: support for branch trace store(BTS)
From: Markus Metzger
Date: Tue Dec 04 2007 - 13:04:47 EST
Changes to the last version:
- split implementation into two layers: ds/bts and ptrace
- renamed TIF's
- save/restore ds save area msr in __switch_to_xtra()
- make block-stepping only look at BTF bit
Signed-off-by: Markus Metzger <markus.t.metzger@xxxxxxxxx>
Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
---
Index: linux-2.6-x86/arch/x86/kernel/process_32.c
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/process_32.c 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/process_32.c 2007-12-04 18:12:42.%N +0100
@@ -594,11 +594,21 @@
struct tss_struct *tss)
{
struct thread_struct *prev, *next;
+ unsigned long debugctl;
prev = &prev_p->thread;
next = &next_p->thread;
- if (next->debugctlmsr != prev->debugctlmsr)
+ debugctl = prev->debugctlmsr;
+ if (next->ds_area_msr != prev->ds_area_msr) {
+ /* we clear debugctl to make sure DS
+ * is not in use when we change it */
+ debugctl = 0;
+ wrmsrl(MSR_IA32_DEBUGCTLMSR, 0);
+ wrmsr(MSR_IA32_DS_AREA, next->ds_area_msr, 0);
+ }
+
+ if (next->debugctlmsr != debugctl)
wrmsr(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr, 0);
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
@@ -622,6 +632,13 @@
}
#endif
+ 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);
+
+
if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
/*
* Disable the bitmap via an invalid offset. We still cache
Index: linux-2.6-x86/include/asm-x86/ptrace-abi.h
===================================================================
--- linux-2.6-x86.orig/include/asm-x86/ptrace-abi.h 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/include/asm-x86/ptrace-abi.h 2007-12-04 17:21:28.%N +0100
@@ -80,4 +80,56 @@
#define PTRACE_SINGLEBLOCK 33 /* resume execution until next branch */
+/* Return maximal BTS buffer size in number of records,
+ if successuf; -1, otherwise.
+ EOPNOTSUPP...processor does not support bts tracing */
+#define PTRACE_BTS_MAX_BUFFER_SIZE 40
+
+/* Allocate new bts buffer (free old one, if exists) of size DATA bts records;
+ parameter ADDR is ignored.
+ Return 0, if successful; -1, otherwise.
+ EOPNOTSUPP...processor does not support bts tracing
+ EINVAL.......invalid size in records
+ ENOMEM.......out of memory */
+#define PTRACE_BTS_ALLOCATE_BUFFER 41
+
+/* Return the size of the bts buffer in number of bts records,
+ if successful; -1, otherwise.
+ EOPNOTSUPP...processor does not support bts tracing
+ ENXIO........no buffer allocated */
+#define PTRACE_BTS_GET_BUFFER_SIZE 42
+
+/* Return the index of the next bts record to be written,
+ if successful; -1, otherwise.
+ EOPNOTSUPP...processor does not support bts tracing
+ ENXIO........no buffer allocated
+ After the first warp-around, this is the start of the circular bts
buffer. */
+#define PTRACE_BTS_GET_INDEX 43
+
+/* Read the DATA'th bts record into a ptrace_bts_record buffer
provided in ADDR.
+ Return 0, if successful; -1, otherwise
+ EOPNOTSUPP...processor does not support bts tracing
+ ENXIO........no buffer allocated
+ EINVAL.......invalid index */
+#define PTRACE_BTS_READ_RECORD 44
+
+/* Configure last branch trace; the configuration is given as a bit-mask of
+ PTRACE_BTS_O_* options in DATA; parameter ADDR is ignored.
+ Return 0, if successful; -1, otherwise
+ EOPNOTSUPP...processor does not support bts tracing
+ ENXIO........no buffer allocated */
+#define PTRACE_BTS_CONFIG 45
+
+/* Return the configuration as bit-mask of PTRACE_BTS_O_* options
+ if successful; -1, otherwise.
+ EOPNOTSUPP...processor does not support bts tracing
+ ENXIO........no buffer allocated */
+#define PTRACE_BTS_STATUS 46
+
+/* Trace configuration options */
+/* Collect last branch trace */
+#define PTRACE_BTS_O_TRACE_TASK 0x1
+/* Take timestamps when the task arrives and departs */
+#define PTRACE_BTS_O_TIMESTAMPS 0x2
+
#endif
Index: linux-2.6-x86/include/asm-x86/ptrace.h
===================================================================
--- linux-2.6-x86.orig/include/asm-x86/ptrace.h 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/include/asm-x86/ptrace.h 2007-12-04 18:17:52.%N +0100
@@ -4,8 +4,19 @@
#include <linux/compiler.h> /* For __user */
#include <asm/ptrace-abi.h>
+
#ifndef __ASSEMBLY__
+#ifdef __KERNEL__
+
+#include <asm/ds.h>
+
+struct task_struct;
+extern void ptrace_bts_take_timestamp(struct task_struct *, enum
bts_qualifier);
+
+#endif /* __KERNEL__ */
+
+
#ifdef __i386__
/* this struct defines the way the registers are stored on the
stack during a system call. */
Index: linux-2.6-x86/arch/x86/kernel/Makefile_32
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/Makefile_32 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/Makefile_32 2007-12-04 17:21:28.%N +0100
@@ -11,6 +11,7 @@
quirks.o i8237.o topology.o alternative.o i8253.o tsc_32.o rtc.o
obj-y += ptrace.o
+obj-y += ds.o
obj-y += tls.o
obj-y += step.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
Index: linux-2.6-x86/include/asm-x86/thread_info_32.h
===================================================================
--- linux-2.6-x86.orig/include/asm-x86/thread_info_32.h 2007-12-04
16:44:47.%N +0100
+++ linux-2.6-x86/include/asm-x86/thread_info_32.h 2007-12-04 17:21:28.%N +0100
@@ -139,6 +139,8 @@
#define TIF_NOTSC 20 /* TSC is not accessible in userland */
#define TIF_FORCED_TF 21 /* true if TF in eflags artificially */
#define TIF_DEBUGCTLMSR 22 /* uses thread_struct.debugctlmsr */
+#define TIF_DS_AREA_MSR 23 /* uses thread_struct.ds_area_msr */
+#define TIF_BTS_TRACE_TS 24 /* record scheduling event
timestamps */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
@@ -155,6 +157,8 @@
#define _TIF_NOTSC (1<<TIF_NOTSC)
#define _TIF_FORCED_TF (1<<TIF_FORCED_TF)
#define _TIF_DEBUGCTLMSR (1<<TIF_DEBUGCTLMSR)
+#define _TIF_DS_AREA_MSR (1<<TIF_DS_AREA_MSR)
+#define _TIF_BTS_TRACE_TS (1<<TIF_BTS_TRACE_TS)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
@@ -164,8 +168,12 @@
#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
/* flags to check in __switch_to() */
-#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC |
_TIF_DEBUG | _TIF_DEBUGCTLMSR)
-#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUGCTLMSR)
+#define _TIF_WORK_CTXSW \
+ (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUGCTLMSR | \
+ _TIF_DS_AREA_MSR | _TIF_BTS_TRACE_TS)
+#define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW
+#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW | _TIF_DEBUG)
+
/*
* Thread-synchronous status.
Index: linux-2.6-x86/include/asm-x86/processor_32.h
===================================================================
--- linux-2.6-x86.orig/include/asm-x86/processor_32.h 2007-12-04
16:44:47.%N +0100
+++ linux-2.6-x86/include/asm-x86/processor_32.h 2007-12-04 17:21:28.%N +0100
@@ -360,6 +360,9 @@
unsigned long 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;
};
#define INIT_THREAD { \
Index: linux-2.6-x86/arch/x86/kernel/process_64.c
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/process_64.c 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/process_64.c 2007-12-04 18:13:10.%N +0100
@@ -550,11 +550,21 @@
struct tss_struct *tss)
{
struct thread_struct *prev, *next;
+ unsigned long debugctl;
prev = &prev_p->thread,
next = &next_p->thread;
- if (next->debugctlmsr != prev->debugctlmsr)
+ debugctl = prev->debugctlmsr;
+ if (next->ds_area_msr != prev->ds_area_msr) {
+ /* we clear debugctl to make sure DS
+ * is not in use when we change it */
+ debugctl = 0;
+ wrmsrl(MSR_IA32_DEBUGCTLMSR, 0);
+ wrmsrl(MSR_IA32_DS_AREA, next->ds_area_msr);
+ }
+
+ if (next->debugctlmsr != debugctl)
wrmsrl(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr);
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
@@ -580,6 +590,16 @@
*/
memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
}
+
+ /*
+ * Last branch recording recofiguration of trace hardware and
+ * disentangling of trace data per task.
+ */
+ 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);
}
/*
@@ -683,8 +703,8 @@
/*
* Now maybe reload the debug registers and handle I/O bitmaps
*/
- if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW))
- || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP))
+ if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
+ task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
__switch_to_xtra(prev_p, next_p, tss);
/* If the task has used fpu the last 5 timeslices, just do a full
Index: linux-2.6-x86/include/asm-x86/processor_64.h
===================================================================
--- linux-2.6-x86.orig/include/asm-x86/processor_64.h 2007-12-04
16:44:47.%N +0100
+++ linux-2.6-x86/include/asm-x86/processor_64.h 2007-12-04 17:21:28.%N +0100
@@ -240,6 +240,9 @@
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;
/* cached TLS descriptors. */
u64 tls_array[GDT_ENTRY_TLS_ENTRIES];
} __attribute__((aligned(16)));
Index: linux-2.6-x86/include/asm-x86/thread_info_64.h
===================================================================
--- linux-2.6-x86.orig/include/asm-x86/thread_info_64.h 2007-12-04
16:44:47.%N +0100
+++ linux-2.6-x86/include/asm-x86/thread_info_64.h 2007-12-04 17:21:28.%N +0100
@@ -121,6 +121,8 @@
#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
#define TIF_FREEZE 23 /* is freezing for suspend */
#define TIF_DEBUGCTLMSR 24 /* uses thread_struct.debugctlmsr */
+#define TIF_DS_AREA_MSR 25 /* uses thread_struct.ds_area_msr */
+#define TIF_BTS_TRACE_TS 26 /* record scheduling event timestamps */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
@@ -139,6 +141,8 @@
#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
#define _TIF_FREEZE (1<<TIF_FREEZE)
#define _TIF_DEBUGCTLMSR (1<<TIF_DEBUGCTLMSR)
+#define _TIF_DS_AREA_MSR (1<<TIF_DS_AREA_MSR)
+#define _TIF_BTS_TRACE_TS (1<<TIF_BTS_TRACE_TS)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
@@ -147,7 +151,10 @@
#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
/* flags to check in __switch_to() */
-#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR)
+#define _TIF_WORK_CTXSW \
+ (_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS)
+#define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW
+#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)
#define PREEMPT_ACTIVE 0x10000000
Index: linux-2.6-x86/arch/x86/kernel/cpu/intel.c
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/cpu/intel.c 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/cpu/intel.c 2007-12-04 17:21:28.%N +0100
@@ -11,6 +11,8 @@
#include <asm/pgtable.h>
#include <asm/msr.h>
#include <asm/uaccess.h>
+#include <asm/ptrace.h>
+#include <asm/ds.h>
#include "cpu.h"
@@ -219,6 +221,9 @@
if (!(l1 & (1<<12)))
set_bit(X86_FEATURE_PEBS, c->x86_capability);
}
+
+ if (cpu_has_bts)
+ ds_init_intel(c);
}
static unsigned int __cpuinit intel_size_cache(struct cpuinfo_x86 *
c, unsigned int size)
Index: linux-2.6-x86/arch/x86/kernel/setup_64.c
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/setup_64.c 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/setup_64.c 2007-12-04 17:21:28.%N +0100
@@ -60,6 +60,7 @@
#include <asm/dmi.h>
#include <asm/cacheflush.h>
#include <asm/mce.h>
+#include <asm/ds.h>
/*
* Machine setup..
@@ -850,6 +851,10 @@
set_cpu_cap(c, X86_FEATURE_PEBS);
}
+
+ if (cpu_has_bts)
+ ds_init_intel(c);
+
n = c->extended_cpuid_level;
if (n >= 0x80000008) {
unsigned eax = cpuid_eax(0x80000008);
Index: linux-2.6-x86/arch/x86/kernel/ptrace.c
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/ptrace.c 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/ptrace.c 2007-12-04 18:13:37.%N +0100
@@ -2,6 +2,9 @@
/*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@xxxxxxxxxxx>, May 2000
+ *
+ * BTS tracing
+ * Markus Metzger <markus.t.metzger@xxxxxxxxx>, Dec 2007
*/
#include <linux/kernel.h>
@@ -26,6 +29,14 @@
#include <asm/desc.h>
#include <asm/prctl.h>
#include <asm/proto.h>
+#include <asm/ds.h>
+
+
+/*
+ * The maximal size of a BTS buffer per traced task in number of BTS
+ * records.
+ */
+#define PTRACE_BTS_BUFFER_MAX 4000
/*
* does not yet catch signals sent when the child dies.
@@ -455,6 +466,165 @@
return 0;
}
+static int ptrace_bts_max_buffer_size(void)
+{
+ return PTRACE_BTS_BUFFER_MAX;
+}
+
+static int ptrace_bts_get_buffer_size(struct task_struct *child)
+{
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ return ds_get_bts_size((void *)child->thread.ds_area_msr);
+}
+
+static int ptrace_bts_get_index(struct task_struct *child)
+{
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ return ds_get_bts_index((void *)child->thread.ds_area_msr);
+}
+
+static int ptrace_bts_read_record(struct task_struct *child,
+ long index,
+ struct bts_struct __user *out)
+{
+ struct bts_struct ret;
+ int retval;
+
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ retval = ds_read_bts((void *)child->thread.ds_area_msr,
+ index, &ret);
+ if (retval)
+ return retval;
+
+ if (copy_to_user(out, &ret, sizeof(ret)))
+ return -EFAULT;
+
+ return sizeof(ret);
+}
+
+static int ptrace_bts_write_record(struct task_struct *child,
+ const struct bts_struct *in)
+{
+ int retval;
+
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ retval = ds_write_bts((void *)child->thread.ds_area_msr, in);
+ if (retval)
+ return retval;
+
+ return sizeof(*in);
+}
+
+static int ptrace_bts_config(struct task_struct *child,
+ unsigned long options)
+{
+ unsigned long debugctl_mask = ds_debugctl_mask();
+ int retval;
+
+ retval = ptrace_bts_get_buffer_size(child);
+ if (retval < 0)
+ return retval;
+ if (retval == 0)
+ return -ENXIO;
+
+ if (options & PTRACE_BTS_O_TRACE_TASK) {
+ child->thread.debugctlmsr |= debugctl_mask;
+ set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
+ } else {
+ /* there is no way for us to check whether we 'own'
+ * the respective bits in the DEBUGCTL MSR, we're
+ * about to clear */
+ child->thread.debugctlmsr &= ~debugctl_mask;
+
+ if (!child->thread.debugctlmsr)
+ clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
+ }
+
+ if (options & PTRACE_BTS_O_TIMESTAMPS)
+ set_tsk_thread_flag(child, TIF_BTS_TRACE_TS);
+ else
+ clear_tsk_thread_flag(child, TIF_BTS_TRACE_TS);
+
+ return 0;
+}
+
+static int ptrace_bts_status(struct task_struct *child)
+{
+ unsigned long debugctl_mask = ds_debugctl_mask();
+ int retval, status = 0;
+
+ retval = ptrace_bts_get_buffer_size(child);
+ if (retval < 0)
+ return retval;
+ if (retval == 0)
+ return -ENXIO;
+
+ if (ptrace_bts_get_buffer_size(child) <= 0)
+ return -ENXIO;
+
+ if (test_tsk_thread_flag(child, TIF_DEBUGCTLMSR) &&
+ child->thread.debugctlmsr & debugctl_mask)
+ status |= PTRACE_BTS_O_TRACE_TASK;
+ if (test_tsk_thread_flag(child, TIF_BTS_TRACE_TS))
+ status |= PTRACE_BTS_O_TIMESTAMPS;
+
+ return status;
+}
+
+static int ptrace_bts_allocate_bts(struct task_struct *child,
+ int size_in_records)
+{
+ int retval = 0;
+ void *ds;
+
+ if (size_in_records < 0)
+ return -EINVAL;
+
+ if (size_in_records > ptrace_bts_max_buffer_size())
+ return -EINVAL;
+
+ if (size_in_records == 0) {
+ ptrace_bts_config(child, /* options = */ 0);
+ } else {
+ retval = ds_allocate(&ds, size_in_records);
+ if (retval)
+ return retval;
+ }
+
+ if (child->thread.ds_area_msr)
+ ds_free((void **)&child->thread.ds_area_msr);
+
+ child->thread.ds_area_msr = (unsigned long)ds;
+ if (child->thread.ds_area_msr)
+ set_tsk_thread_flag(child, TIF_DS_AREA_MSR);
+ else
+ clear_tsk_thread_flag(child, TIF_DS_AREA_MSR);
+
+ return retval;
+}
+
+void ptrace_bts_take_timestamp(struct task_struct *tsk,
+ enum bts_qualifier qualifier)
+{
+ struct bts_struct rec = {
+ .qualifier = qualifier,
+ .variant.timestamp = sched_clock()
+ };
+
+ if (ptrace_bts_get_buffer_size(tsk) <= 0)
+ return;
+
+ ptrace_bts_write_record(tsk, &rec);
+}
+
/*
* Called by kernel/ptrace.c when detaching..
*
@@ -466,6 +636,11 @@
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif
+ ptrace_bts_config(child, /* options = */ 0);
+ if (child->thread.ds_area_msr) {
+ ds_free((void **)&child->thread.ds_area_msr);
+ clear_tsk_thread_flag(child, TIF_DS_AREA_MSR);
+ }
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
@@ -626,6 +801,36 @@
break;
#endif
+ case PTRACE_BTS_MAX_BUFFER_SIZE:
+ ret = ptrace_bts_max_buffer_size();
+ break;
+
+ case PTRACE_BTS_ALLOCATE_BUFFER:
+ ret = ptrace_bts_allocate_bts(child, data);
+ break;
+
+ case PTRACE_BTS_GET_BUFFER_SIZE:
+ ret = ptrace_bts_get_buffer_size(child);
+ break;
+
+ case PTRACE_BTS_GET_INDEX:
+ ret = ptrace_bts_get_index(child);
+ break;
+
+ case PTRACE_BTS_READ_RECORD:
+ ret = ptrace_bts_read_record
+ (child, data,
+ (struct bts_struct __user *) addr);
+ break;
+
+ case PTRACE_BTS_CONFIG:
+ ret = ptrace_bts_config(child, data);
+ break;
+
+ case PTRACE_BTS_STATUS:
+ ret = ptrace_bts_status(child);
+ break;
+
default:
ret = ptrace_request(child, request, addr, data);
break;
@@ -809,6 +1014,13 @@
case PTRACE_SETOPTIONS:
case PTRACE_SET_THREAD_AREA:
case PTRACE_GET_THREAD_AREA:
+ case PTRACE_BTS_MAX_BUFFER_SIZE:
+ case PTRACE_BTS_ALLOCATE_BUFFER:
+ case PTRACE_BTS_GET_BUFFER_SIZE:
+ case PTRACE_BTS_GET_INDEX:
+ case PTRACE_BTS_READ_RECORD:
+ case PTRACE_BTS_CONFIG:
+ case PTRACE_BTS_STATUS:
return sys_ptrace(request, pid, addr, data);
default:
Index: linux-2.6-x86/arch/x86/kernel/Makefile_64
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/Makefile_64 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/Makefile_64 2007-12-04 17:21:28.%N +0100
@@ -13,6 +13,7 @@
i8253.o rtc.o
obj-y += ptrace.o
+obj-y += ds.o
obj-y += step.o
obj-$(CONFIG_IA32_EMULATION) += tls.o
Index: linux-2.6-x86/arch/x86/kernel/step.c
===================================================================
--- linux-2.6-x86.orig/arch/x86/kernel/step.c 2007-12-04 16:44:47.%N +0100
+++ linux-2.6-x86/arch/x86/kernel/step.c 2007-12-04 17:21:28.%N +0100
@@ -169,9 +169,14 @@
*/
if (enable_single_step(child) && block) {
set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
- write_debugctlmsr(child, DEBUGCTLMSR_BTF);
- } else if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR)) {
- write_debugctlmsr(child, 0);
+ write_debugctlmsr(child,
+ child->thread.debugctlmsr | DEBUGCTLMSR_BTF);
+ } else {
+ write_debugctlmsr(child,
+ child->thread.debugctlmsr & ~TIF_DEBUGCTLMSR);
+
+ if (!child->thread.debugctlmsr)
+ clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
}
}
@@ -190,8 +195,11 @@
/*
* Make sure block stepping (BTF) is disabled.
*/
- if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR))
- write_debugctlmsr(child, 0);
+ write_debugctlmsr(child,
+ child->thread.debugctlmsr & ~TIF_DEBUGCTLMSR);
+
+ if (!child->thread.debugctlmsr)
+ clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
/* Always clear TIF_SINGLESTEP... */
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
Index: linux-2.6-x86/arch/x86/kernel/ds.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6-x86/arch/x86/kernel/ds.c 2007-12-04 17:21:28.%N +0100
@@ -0,0 +1,429 @@
+/*
+ * Debug Store support
+ *
+ * This provides a low-level interface to the hardware's Debug Store
+ * feature that is used for last branch recording (LBR) and
+ * precise-event based sampling (PEBS).
+ *
+ * Different architectures use a different DS layout/pointer size.
+ * The below functions therefore work on a void*.
+ *
+ *
+ * Since there is no user for PEBS, yet, only LBR (or branch
+ * trace store, BTS) is supported.
+ *
+ *
+ * Copyright (C) 2007 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@xxxxxxxxx>, Dec 2007
+ */
+
+#include <asm/ds.h>
+
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+
+
+/*
+ * Debug Store (DS) save area configuration (see Intel64 and IA32
+ * Architectures Software Developer's Manual, section 18.5)
+ *
+ * The DS configuration consists of the following fields; different
+ * architetures vary in the size of those fields.
+ * - double-word aligned base linear address of the BTS buffer
+ * - write pointer into the BTS buffer
+ * - end linear address of the BTS buffer (one byte beyond the end of
+ * the buffer)
+ * - interrupt pointer into BTS buffer
+ * (interrupt occurs when write pointer passes interrupt pointer)
+ * - double-word aligned base linear address of the PEBS buffer
+ * - write pointer into the PEBS buffer
+ * - end linear address of the PEBS buffer (one byte beyond the end of
+ * the buffer)
+ * - interrupt pointer into PEBS buffer
+ * (interrupt occurs when write pointer passes interrupt pointer)
+ * - value to which counter is reset following counter overflow
+ *
+ * On later architectures, the last branch recording hardware uses
+ * 64bit pointers even in 32bit mode.
+ *
+ *
+ * Branch Trace Store (BTS) records store information about control
+ * flow changes. They at least provide the following information:
+ * - source linear address
+ * - destination linear address
+ *
+ * Netburst supported a predicated bit that had been dropped in later
+ * architectures. We do not suppor it.
+ *
+ *
+ * In order to abstract from the actual DS and BTS layout, we describe
+ * the access to the relevant fields.
+ * Thanks to Andi Kleen for proposing this design.
+ *
+ * The implementation, however, is not as general as it might seem. In
+ * order to stay somewhat simple and efficient, we assume an
+ * underlying unsigned type (mostly a pointer type) and we expect the
+ * field to be at least as big as that type.
+ */
+
+/*
+ * A special from_ip address to indicate that the BTS record is an
+ * info record that needs to be interpreted or skipped.
+ */
+#define BTS_ESCAPE_ADDRESS (-1)
+
+/*
+ * A field access descriptor
+ */
+struct access_desc {
+ unsigned char offset;
+ unsigned char size;
+};
+
+/*
+ * The configuration for a particular DS/BTS hardware implementation.
+ */
+struct ds_configuration {
+ /* the DS configuration */
+ unsigned char sizeof_ds;
+ struct access_desc bts_buffer_base;
+ struct access_desc bts_index;
+ struct access_desc bts_absolute_maximum;
+ struct access_desc bts_interrupt_threshold;
+ /* the BTS configuration */
+ unsigned char sizeof_bts;
+ struct access_desc from_ip;
+ struct access_desc to_ip;
+ /* BTS variants used to store additional information like
+ timestamps */
+ struct access_desc info_type;
+ struct access_desc info_data;
+ unsigned long debugctl_mask;
+};
+
+/*
+ * The global configuration used by the below accessor functions
+ */
+static struct ds_configuration ds_cfg;
+
+/*
+ * Accessor functions for some DS and BTS fields using the above
+ * global ptrace_bts_cfg.
+ */
+static inline void *get_bts_buffer_base(char *base)
+{
+ return *(void **)(base + ds_cfg.bts_buffer_base.offset);
+}
+static inline void set_bts_buffer_base(char *base, void *value)
+{
+ (*(void **)(base + ds_cfg.bts_buffer_base.offset)) = value;
+}
+static inline void *get_bts_index(char *base)
+{
+ return *(void **)(base + ds_cfg.bts_index.offset);
+}
+static inline void set_bts_index(char *base, void *value)
+{
+ (*(void **)(base + ds_cfg.bts_index.offset)) = value;
+}
+static inline void *get_bts_absolute_maximum(char *base)
+{
+ return *(void **)(base + ds_cfg.bts_absolute_maximum.offset);
+}
+static inline void set_bts_absolute_maximum(char *base, void *value)
+{
+ (*(void **)(base + ds_cfg.bts_absolute_maximum.offset)) = value;
+}
+static inline void *get_bts_interrupt_threshold(char *base)
+{
+ return *(void **)(base + ds_cfg.bts_interrupt_threshold.offset);
+}
+static inline void set_bts_interrupt_threshold(char *base, void *value)
+{
+ (*(void **)(base + ds_cfg.bts_interrupt_threshold.offset)) = value;
+}
+static inline long get_from_ip(char *base)
+{
+ return *(long *)(base + ds_cfg.from_ip.offset);
+}
+static inline void set_from_ip(char *base, long value)
+{
+ (*(long *)(base + ds_cfg.from_ip.offset)) = value;
+}
+static inline long get_to_ip(char *base)
+{
+ return *(long *)(base + ds_cfg.to_ip.offset);
+}
+static inline void set_to_ip(char *base, long value)
+{
+ (*(long *)(base + ds_cfg.to_ip.offset)) = value;
+}
+static inline unsigned char get_info_type(char *base)
+{
+ return *(unsigned char *)(base + ds_cfg.info_type.offset);
+}
+static inline void set_info_type(char *base, unsigned char value)
+{
+ (*(unsigned char *)(base + ds_cfg.info_type.offset)) = value;
+}
+/*
+ * The info data might overlap with the info type on some architectures.
+ * We therefore read and write the exact number of bytes.
+ */
+static inline unsigned long long get_info_data(char *base)
+{
+ unsigned long long value = 0;
+ memcpy(&value,
+ base + ds_cfg.info_data.offset,
+ ds_cfg.info_data.size);
+ return value;
+}
+static inline void set_info_data(char *base, unsigned long long value)
+{
+ memcpy(base + ds_cfg.info_data.offset,
+ &value,
+ ds_cfg.info_data.size);
+}
+
+
+int ds_allocate(void **dsp, size_t bts_size_in_records)
+{
+ size_t bts_size_in_bytes = 0;
+ void *bts = 0;
+ void *ds = 0;
+
+ if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
+ return -EOPNOTSUPP;
+
+ if (bts_size_in_records < 0)
+ return -EINVAL;
+
+ bts_size_in_bytes =
+ bts_size_in_records * ds_cfg.sizeof_bts;
+
+ if (bts_size_in_bytes <= 0)
+ return -EINVAL;
+
+ bts = kzalloc(bts_size_in_bytes, GFP_KERNEL);
+
+ if (!bts)
+ return -ENOMEM;
+
+ ds = kzalloc(ds_cfg.sizeof_ds, GFP_KERNEL);
+
+ if (!ds) {
+ kfree(bts);
+ return -ENOMEM;
+ }
+
+ set_bts_buffer_base(ds, bts);
+ set_bts_index(ds, bts);
+ set_bts_absolute_maximum(ds, bts + bts_size_in_bytes);
+ set_bts_interrupt_threshold(ds, bts + bts_size_in_bytes + 1);
+
+ *dsp = ds;
+ return 0;
+}
+
+int ds_free(void **dsp)
+{
+ if (*dsp)
+ kfree(get_bts_buffer_base(*dsp));
+ kfree(*dsp);
+ *dsp = 0;
+
+ return 0;
+}
+
+int ds_get_bts_size(void *ds)
+{
+ size_t size_in_bytes;
+
+ if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
+ return -EOPNOTSUPP;
+
+ size_in_bytes =
+ get_bts_absolute_maximum(ds) -
+ get_bts_buffer_base(ds);
+
+ return size_in_bytes / ds_cfg.sizeof_bts;
+}
+
+int ds_get_bts_index(void *ds)
+{
+ size_t index_offset_in_bytes;
+
+ if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
+ return -EOPNOTSUPP;
+
+ index_offset_in_bytes =
+ get_bts_index(ds) -
+ get_bts_buffer_base(ds);
+
+ return index_offset_in_bytes / ds_cfg.sizeof_bts;
+}
+
+int ds_read_bts(void *ds, size_t index, struct bts_struct *out)
+{
+ void *bts;
+
+ if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
+ return -EOPNOTSUPP;
+
+ if (index < 0)
+ return -EINVAL;
+
+ if (index >= ds_get_bts_size(ds))
+ return -EINVAL;
+
+ bts = get_bts_buffer_base(ds);
+ bts = (char *)bts + (index * ds_cfg.sizeof_bts);
+
+ memset(out, 0, sizeof(*out));
+ if (get_from_ip(bts) == BTS_ESCAPE_ADDRESS) {
+ out->qualifier = get_info_type(bts);
+ out->variant.timestamp = get_info_data(bts);
+ } else {
+ out->qualifier = BTS_BRANCH;
+ out->variant.lbr.from_ip = get_from_ip(bts);
+ out->variant.lbr.to_ip = get_to_ip(bts);
+ }
+
+ return 0;
+}
+
+int ds_write_bts(void *ds, const struct bts_struct *in)
+{
+ void *bts;
+
+ if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
+ return -EOPNOTSUPP;
+
+ if (ds_get_bts_size(ds) <= 0)
+ return -ENXIO;
+
+ bts = get_bts_index(ds);
+
+ memset(bts, 0, ds_cfg.sizeof_bts);
+ switch (in->qualifier) {
+ case BTS_INVALID:
+ break;
+
+ case BTS_BRANCH:
+ set_from_ip(bts, in->variant.lbr.from_ip);
+ set_to_ip(bts, in->variant.lbr.to_ip);
+ break;
+
+ case BTS_TASK_ARRIVES:
+ case BTS_TASK_DEPARTS:
+ set_from_ip(bts, BTS_ESCAPE_ADDRESS);
+ set_info_type(bts, in->qualifier);
+ set_info_data(bts, in->variant.timestamp);
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ bts = (char *)bts + ds_cfg.sizeof_bts;
+ if (bts >= get_bts_absolute_maximum(ds))
+ bts = get_bts_buffer_base(ds);
+ set_bts_index(ds, bts);
+
+ return 0;
+}
+
+unsigned long ds_debugctl_mask(void)
+{
+ return ds_cfg.debugctl_mask;
+}
+
+#ifdef __i386__
+static const struct ds_configuration ds_cfg_netburst = {
+ .sizeof_ds = 9 * 4,
+ .bts_buffer_base = { 0, 4 },
+ .bts_index = { 4, 4 },
+ .bts_absolute_maximum = { 8, 4 },
+ .bts_interrupt_threshold = { 12, 4 },
+ .sizeof_bts = 3 * 4,
+ .from_ip = { 0, 4 },
+ .to_ip = { 4, 4 },
+ .info_type = { 4, 1 },
+ .info_data = { 5, 7 },
+ .debugctl_mask = (1<<2)|(1<<3)
+};
+
+static const struct ds_configuration ds_cfg_pentium_m = {
+ .sizeof_ds = 9 * 4,
+ .bts_buffer_base = { 0, 4 },
+ .bts_index = { 4, 4 },
+ .bts_absolute_maximum = { 8, 4 },
+ .bts_interrupt_threshold = { 12, 4 },
+ .sizeof_bts = 3 * 4,
+ .from_ip = { 0, 4 },
+ .to_ip = { 4, 4 },
+ .info_type = { 4, 1 },
+ .info_data = { 5, 7 },
+ .debugctl_mask = (1<<6)|(1<<7)
+};
+#endif /* _i386_ */
+
+static const struct ds_configuration ds_cfg_core2 = {
+ .sizeof_ds = 9 * 8,
+ .bts_buffer_base = { 0, 8 },
+ .bts_index = { 8, 8 },
+ .bts_absolute_maximum = { 16, 8 },
+ .bts_interrupt_threshold = { 24, 8 },
+ .sizeof_bts = 3 * 8,
+ .from_ip = { 0, 8 },
+ .to_ip = { 8, 8 },
+ .info_type = { 8, 1 },
+ .info_data = { 9, 7 },
+ .debugctl_mask = (1<<6)|(1<<7)|(1<<9)
+};
+
+static inline void
+ds_configure(const struct ds_configuration *cfg)
+{
+ ds_cfg = *cfg;
+}
+
+void __cpuinit ds_init_intel(struct cpuinfo_x86 *c)
+{
+ switch (c->x86) {
+ case 0x6:
+ switch (c->x86_model) {
+#ifdef __i386__
+ case 0xD:
+ case 0xE: /* Pentium M */
+ ds_configure(&ds_cfg_pentium_m);
+ break;
+#endif /* _i386_ */
+ case 0xF: /* Core2 */
+ ds_configure(&ds_cfg_core2);
+ break;
+ default:
+ /* sorry, don't know about them */
+ break;
+ }
+ break;
+ case 0xF:
+ switch (c->x86_model) {
+#ifdef __i386__
+ case 0x0:
+ case 0x1:
+ case 0x2: /* Netburst */
+ ds_configure(&ds_cfg_netburst);
+ break;
+#endif /* _i386_ */
+ default:
+ /* sorry, don't know about them */
+ break;
+ }
+ break;
+ default:
+ /* sorry, don't know about them */
+ break;
+ }
+}
Index: linux-2.6-x86/include/asm-x86/ds.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6-x86/include/asm-x86/ds.h 2007-12-04 18:18:55.%N +0100
@@ -0,0 +1,65 @@
+/*
+ * Debug Store (DS) support
+ *
+ * This provides a low-level interface to the hardware's Debug Store
+ * feature that is used for last branch recording (LBR) and
+ * precise-event based sampling (PEBS).
+ *
+ * Different architectures use a different DS layout/pointer size.
+ * The below functions therefore work on a void*.
+ *
+ *
+ * Since there is no user for PEBS, yet, only LBR (or branch
+ * trace store, BTS) is supported.
+ *
+ *
+ * Copyright (C) 2007 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@xxxxxxxxx>, Dec 2007
+ */
+
+#ifndef _ASM_X86_DS_H
+#define _ASM_X86_DS_H
+
+#include <linux/types.h>
+#include <linux/init.h>
+
+struct cpuinfo_x86;
+
+
+/* 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 {
+ enum bts_qualifier qualifier;
+ union {
+ /* BTS_BRANCH */
+ struct {
+ long from_ip;
+ long to_ip;
+ } lbr;
+ /* BTS_TASK_ARRIVES or
+ BTS_TASK_DEPARTS */
+ unsigned long long timestamp;
+ } variant;
+};
+
+
+extern int ds_allocate(void **, size_t);
+extern int ds_free(void **);
+extern int ds_get_bts_size(void *);
+extern int ds_get_bts_index(void *);
+extern int ds_read_bts(void *, size_t, struct bts_struct *);
+extern int ds_write_bts(void *, const struct bts_struct *);
+extern unsigned long ds_debugctl_mask(void);
+extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *c);
+
+#endif /* _ASM_X86_DS_H */
--
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