[patch 1/2] x86, bts: fork and exit handling
From: Markus Metzger
Date: Fri Dec 19 2008 - 09:10:42 EST
Add arch_ptrace_untrace() function that is called when the tracer
detaches (either voluntarily or when the tracing task dies);
ptrace_disable() is only called on a voluntary detach.
Add ptrace_fork() and arch_ptrace_fork(). They are called when a
traced task is forked.
Clear DS and BTS related fields on fork.
Release DS resources and reclaim memory in ptrace_untrace(). This
releases resources already when the tracing task dies. We used to do
that when the traced task dies.
Signed-off-by: Markus Metzger <markus.t.metzger@xxxxxxxxx>
---
Index: ftrace/arch/x86/kernel/process_32.c
===================================================================
--- ftrace.orig/arch/x86/kernel/process_32.c 2008-12-19 12:28:23.000000000 +0100
+++ ftrace/arch/x86/kernel/process_32.c 2008-12-19 13:18:52.000000000 +0100
@@ -60,6 +60,7 @@
#include <asm/idle.h>
#include <asm/syscalls.h>
#include <asm/smp.h>
+#include <asm/ds.h>
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
@@ -251,17 +252,8 @@
tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
put_cpu();
}
-#ifdef CONFIG_X86_DS
- /* Free any BTS tracers that have not been properly released. */
- if (unlikely(current->bts)) {
- ds_release_bts(current->bts);
- current->bts = NULL;
-
- kfree(current->bts_buffer);
- current->bts_buffer = NULL;
- current->bts_size = 0;
- }
-#endif /* CONFIG_X86_DS */
+
+ ds_exit_thread(current);
}
void flush_thread(void)
@@ -343,6 +335,12 @@
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
+
+ ds_copy_thread(p, current);
+
+ clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
+ p->thread.debugctlmsr = 0;
+
return err;
}
Index: ftrace/arch/x86/kernel/process_64.c
===================================================================
--- ftrace.orig/arch/x86/kernel/process_64.c 2008-12-19 12:29:30.000000000 +0100
+++ ftrace/arch/x86/kernel/process_64.c 2008-12-19 12:29:41.000000000 +0100
@@ -54,6 +54,7 @@
#include <asm/ia32.h>
#include <asm/idle.h>
#include <asm/syscalls.h>
+#include <asm/ds.h>
asmlinkage extern void ret_from_fork(void);
@@ -248,17 +249,8 @@
t->io_bitmap_max = 0;
put_cpu();
}
-#ifdef CONFIG_X86_DS
- /* Free any BTS tracers that have not been properly released. */
- if (unlikely(current->bts)) {
- ds_release_bts(current->bts);
- current->bts = NULL;
-
- kfree(current->bts_buffer);
- current->bts_buffer = NULL;
- current->bts_size = 0;
- }
-#endif /* CONFIG_X86_DS */
+
+ ds_exit_thread(current);
}
void flush_thread(void)
@@ -388,6 +380,12 @@
if (err)
goto out;
}
+
+ ds_copy_thread(p, me);
+
+ clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
+ p->thread.debugctlmsr = 0;
+
err = 0;
out:
if (err && p->thread.io_bitmap_ptr) {
Index: ftrace/kernel/fork.c
===================================================================
--- ftrace.orig/kernel/fork.c 2008-12-19 12:29:32.000000000 +0100
+++ ftrace/kernel/fork.c 2008-12-19 12:29:41.000000000 +0100
@@ -1102,6 +1102,8 @@
#ifdef CONFIG_DEBUG_MUTEXES
p->blocked_on = NULL; /* not blocked yet */
#endif
+ if (unlikely(ptrace_reparented(current)))
+ ptrace_fork(p, clone_flags);
/* Perform scheduler related setup. Assign this task to a CPU. */
sched_fork(p, clone_flags);
Index: ftrace/arch/x86/include/asm/ds.h
===================================================================
--- ftrace.orig/arch/x86/include/asm/ds.h 2008-12-19 12:28:23.000000000 +0100
+++ ftrace/arch/x86/include/asm/ds.h 2008-12-19 12:29:41.000000000 +0100
@@ -252,12 +252,21 @@
*/
extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);
+/*
+ * Task clone/init and cleanup work
+ */
+extern void ds_copy_thread(struct task_struct *tsk, struct task_struct *father);
+extern void ds_exit_thread(struct task_struct *tsk);
+
#else /* CONFIG_X86_DS */
struct cpuinfo_x86;
static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
static inline void ds_switch_to(struct task_struct *prev,
struct task_struct *next) {}
+static inline void ds_copy_thread(struct task_struct *tsk,
+ struct task_struct *father) {}
+static inline void ds_exit_thread(struct task_struct *tsk) {}
#endif /* CONFIG_X86_DS */
#endif /* _ASM_X86_DS_H */
Index: ftrace/arch/x86/kernel/ds.c
===================================================================
--- ftrace.orig/arch/x86/kernel/ds.c 2008-12-19 12:29:30.000000000 +0100
+++ ftrace/arch/x86/kernel/ds.c 2008-12-19 12:29:41.000000000 +0100
@@ -1022,3 +1022,14 @@
update_debugctlmsr(next->thread.debugctlmsr);
}
+
+void ds_copy_thread(struct task_struct *tsk, struct task_struct *father)
+{
+ clear_tsk_thread_flag(tsk, TIF_DS_AREA_MSR);
+ tsk->thread.ds_ctx = NULL;
+}
+
+void ds_exit_thread(struct task_struct *tsk)
+{
+ WARN_ON(tsk->thread.ds_ctx);
+}
Index: ftrace/arch/x86/kernel/ptrace.c
===================================================================
--- ftrace.orig/arch/x86/kernel/ptrace.c 2008-12-19 12:28:23.000000000 +0100
+++ ftrace/arch/x86/kernel/ptrace.c 2008-12-19 13:17:47.000000000 +0100
@@ -769,8 +769,47 @@
return (trace->ds.top - trace->ds.begin) / trace->ds.size;
}
+
+static void ptrace_bts_fork(struct task_struct *tsk)
+{
+ tsk->bts = NULL;
+ tsk->bts_buffer = NULL;
+ tsk->bts_size = 0;
+ tsk->thread.bts_ovfl_signal = 0;
+}
+
+static void ptrace_bts_untrace(struct task_struct *child)
+{
+ if (unlikely(child->bts)) {
+ ds_release_bts(child->bts);
+ child->bts = NULL;
+
+ kfree(child->bts_buffer);
+ child->bts_buffer = NULL;
+ child->bts_size = 0;
+ }
+}
+
+static void ptrace_bts_detach(struct task_struct *child)
+{
+ ptrace_bts_untrace(child);
+}
+#else
+static inline void ptrace_bts_fork(struct task_struct *tsk) {}
+static inline void ptrace_bts_detach(struct task_struct *child) {}
+static inline void ptrace_bts_untrace(struct task_struct *child) {}
#endif /* CONFIG_X86_PTRACE_BTS */
+void x86_ptrace_fork(struct task_struct *child, unsigned long clone_flags)
+{
+ ptrace_bts_fork(child);
+}
+
+void x86_ptrace_untrace(struct task_struct *child)
+{
+ ptrace_bts_untrace(child);
+}
+
/*
* Called by kernel/ptrace.c when detaching..
*
@@ -782,16 +821,7 @@
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif
-#ifdef CONFIG_X86_PTRACE_BTS
- if (child->bts) {
- ds_release_bts(child->bts);
- child->bts = NULL;
-
- kfree(child->bts_buffer);
- child->bts_buffer = NULL;
- child->bts_size = 0;
- }
-#endif /* CONFIG_X86_PTRACE_BTS */
+ ptrace_bts_detach(child);
}
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
Index: ftrace/include/linux/ptrace.h
===================================================================
--- ftrace.orig/include/linux/ptrace.h 2008-12-19 12:28:23.000000000 +0100
+++ ftrace/include/linux/ptrace.h 2008-12-19 12:29:41.000000000 +0100
@@ -94,6 +94,7 @@
extern void __ptrace_link(struct task_struct *child,
struct task_struct *new_parent);
extern void __ptrace_unlink(struct task_struct *child);
+extern void ptrace_fork(struct task_struct *task, unsigned long clone_flags);
#define PTRACE_MODE_READ 1
#define PTRACE_MODE_ATTACH 2
/* Returns 0 on success, -errno on denial. */
@@ -313,6 +314,27 @@
#define arch_ptrace_stop(code, info) do { } while (0)
#endif
+#ifndef arch_ptrace_untrace
+/*
+ * Do machine-specific work before untracing child.
+ *
+ * This is called for a normal detach as well as from ptrace_exit()
+ * when the tracing task dies.
+ *
+ * Called with write_lock(&tasklist_lock) held.
+ */
+#define arch_ptrace_untrace(task) do { } while (0)
+#endif
+
+#ifndef arch_ptrace_fork
+/*
+ * Do machine-specific work to initialize a new task.
+ *
+ * This is called from copy_process().
+ */
+#define arch_ptrace_fork(child, clone_flags) do { } while (0)
+#endif
+
extern int task_current_syscall(struct task_struct *target, long *callno,
unsigned long args[6], unsigned int maxargs,
unsigned long *sp, unsigned long *pc);
Index: ftrace/kernel/ptrace.c
===================================================================
--- ftrace.orig/kernel/ptrace.c 2008-12-19 12:28:23.000000000 +0100
+++ ftrace/kernel/ptrace.c 2008-12-19 12:29:41.000000000 +0100
@@ -25,6 +25,17 @@
#include <asm/pgtable.h>
#include <asm/uaccess.h>
+
+/*
+ * Initialize a new task whose father had been ptraced.
+ *
+ * Called from copy_process().
+ */
+void ptrace_fork(struct task_struct *child, unsigned long clone_flags)
+{
+ arch_ptrace_fork(child, clone_flags);
+}
+
/*
* ptrace a task: make the debugger its new parent and
* move it to the ptrace list.
@@ -72,6 +83,7 @@
child->parent = child->real_parent;
list_del_init(&child->ptrace_entry);
+ arch_ptrace_untrace(child);
if (task_is_traced(child))
ptrace_untrace(child);
}
Index: ftrace/arch/x86/include/asm/ptrace.h
===================================================================
--- ftrace.orig/arch/x86/include/asm/ptrace.h 2008-12-19 12:28:23.000000000 +0100
+++ ftrace/arch/x86/include/asm/ptrace.h 2008-12-19 12:29:41.000000000 +0100
@@ -235,6 +235,13 @@
extern int do_set_thread_area(struct task_struct *p, int idx,
struct user_desc __user *info, int can_allocate);
+extern void x86_ptrace_untrace(struct task_struct *);
+extern void x86_ptrace_fork(struct task_struct *child,
+ unsigned long clone_flags);
+
+#define arch_ptrace_untrace(tsk) x86_ptrace_untrace(tsk)
+#define arch_ptrace_fork(child, flags) x86_ptrace_fork(child, flags)
+
#endif /* __KERNEL__ */
#endif /* !__ASSEMBLY__ */
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