From bf26c018490c2fce7fe9b629083b96ce0e6ad019 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 7 Apr 2011 16:53:20 +0200 Subject: ptrace: Prepare to fix racy accesses on task breakpoints When a task is traced and is in a stopped state, the tracer may execute a ptrace request to examine the tracee state and get its task struct. Right after, the tracee can be killed and thus its breakpoints released. This can happen concurrently when the tracer is in the middle of reading or modifying these breakpoints, leading to dereferencing a freed pointer. Hence, to prepare the fix, create a generic breakpoint reference holding API. When a reference on the breakpoints of a task is held, the breakpoints won't be released until the last reference is dropped. After that, no more ptrace request on the task's breakpoints can be serviced for the tracer. Reported-by: Oleg Nesterov Signed-off-by: Frederic Weisbecker Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Will Deacon Cc: Prasad Cc: Paul Mundt Cc: v2.6.33.. Link: http://lkml.kernel.org/r/1302284067-7860-2-git-send-email-fweisbec@gmail.com --- kernel/exit.c | 2 +- kernel/ptrace.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index f5d2f63bae0b..8dd874181542 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1016,7 +1016,7 @@ NORET_TYPE void do_exit(long code) /* * FIXME: do that only when needed, using sched_exit tracepoint */ - flush_ptrace_hw_breakpoint(tsk); + ptrace_put_breakpoints(tsk); exit_notify(tsk, group_dead); #ifdef CONFIG_NUMA diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 0fc1eed28d27..dc7ab65f3b36 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -22,6 +22,7 @@ #include #include #include +#include /* @@ -879,3 +880,19 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, return ret; } #endif /* CONFIG_COMPAT */ + +#ifdef CONFIG_HAVE_HW_BREAKPOINT +int ptrace_get_breakpoints(struct task_struct *tsk) +{ + if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt)) + return 0; + + return -1; +} + +void ptrace_put_breakpoints(struct task_struct *tsk) +{ + if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt)) + flush_ptrace_hw_breakpoint(tsk); +} +#endif /* CONFIG_HAVE_HW_BREAKPOINT */ -- cgit v1.2.2 From 94b2c363dcf732a4edab4ed66041cb36e7f28fbf Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Sat, 30 Apr 2011 22:56:20 +0200 Subject: genirq: Fix typo CONFIG_GENIRC_IRQ_SHOW_LEVEL commit ab7798ffcf98b11a9525cf65bacdae3fd58d357f ("genirq: Expand generic show_interrupts()") added the Kconfig option GENERIC_IRQ_SHOW_LEVEL to accomodate PowerPC, but this doesn't actually enable the functionality due to a typo in the #ifdef check. Signed-off-by: Geert Uytterhoeven Cc: Linux/PPC Development Link: http://lkml.kernel.org/r/%3Calpine.DEB.2.00.1104302251370.19068%40ayla.of.borg%3E Signed-off-by: Thomas Gleixner --- kernel/irq/proc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c index dd201bd35103..834899f2500f 100644 --- a/kernel/irq/proc.c +++ b/kernel/irq/proc.c @@ -419,7 +419,7 @@ int show_interrupts(struct seq_file *p, void *v) } else { seq_printf(p, " %8s", "None"); } -#ifdef CONFIG_GENIRC_IRQ_SHOW_LEVEL +#ifdef CONFIG_GENERIC_IRQ_SHOW_LEVEL seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge"); #endif if (desc->name) -- cgit v1.2.2 From a3a4a5acd3bd2f6f1e102e1f1b9d2e2bb320a7fd Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Thu, 5 May 2011 23:55:18 -0400 Subject: Regression: partial revert "tracing: Remove lock_depth from event entry" This partially reverts commit e6e1e2593592a8f6f6380496655d8c6f67431266. That commit changed the structure layout of the trace structure, which in turn broke PowerTOP (1.9x generation) quite badly. I appreciate not wanting to expose the variable in question, and PowerTOP was not using it, so I've replaced the variable with just a padding field - that way if in the future a new field is needed it can just use this padding field. Signed-off-by: Arjan van de Ven Signed-off-by: Linus Torvalds --- kernel/trace/trace.c | 1 + kernel/trace/trace_events.c | 1 + 2 files changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d38c16a06a6f..1cb49be7c7fb 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1110,6 +1110,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags, entry->preempt_count = pc & 0xff; entry->pid = (tsk) ? tsk->pid : 0; + entry->padding = 0; entry->flags = #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) | diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index e88f74fe1d4c..2fe110341359 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -116,6 +116,7 @@ static int trace_define_common_fields(void) __common_field(unsigned char, flags); __common_field(unsigned char, preempt_count); __common_field(int, pid); + __common_field(int, padding); return ret; } -- cgit v1.2.2