From f29c50419c8d1998edd759f1990c4243a248f469 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 19 May 2011 14:35:33 -0400 Subject: maccess,probe_kernel: Make write/read src const void * The functions probe_kernel_write() and probe_kernel_read() do not modify the src pointer. Allow const pointers to be passed in without the need of a typecast. Acked-by: Mike Frysinger Acked-by: Heiko Carstens Acked-by: Martin Schwidefsky Signed-off-by: Steven Rostedt Link: http://lkml.kernel.org/r/1305824936.1465.4.camel@gandalf.stny.rr.com --- include/linux/uaccess.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index d512d98dfb7..5ca0951e185 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -93,8 +93,8 @@ static inline unsigned long __copy_from_user_nocache(void *to, * Safely read from address @src to the buffer at @dst. If a kernel fault * happens, handle that and return -EFAULT. */ -extern long probe_kernel_read(void *dst, void *src, size_t size); -extern long __probe_kernel_read(void *dst, void *src, size_t size); +extern long probe_kernel_read(void *dst, const void *src, size_t size); +extern long __probe_kernel_read(void *dst, const void *src, size_t size); /* * probe_kernel_write(): safely attempt to write to a location @@ -105,7 +105,7 @@ extern long __probe_kernel_read(void *dst, void *src, size_t size); * Safely write to address @dst from the buffer at @src. If a kernel fault * happens, handle that and return -EFAULT. */ -extern long notrace probe_kernel_write(void *dst, void *src, size_t size); -extern long notrace __probe_kernel_write(void *dst, void *src, size_t size); +extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); +extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size); #endif /* __LINUX_UACCESS_H__ */ -- cgit v1.2.3-70-g09d2 From 2fc1b6f0d0a719e1e2a30bf076a3a799feaf6af2 Mon Sep 17 00:00:00 2001 From: liubo Date: Tue, 19 Apr 2011 09:35:28 +0800 Subject: tracing: Add __print_symbolic_u64 to avoid warnings on 32bit machine Filesystem, like Btrfs, has some "ULL" macros, and when these macros are passed to tracepoints'__print_symbolic(), there will be 64->32 truncate WARNINGS during compiling on 32bit box. Signed-off-by: Liu Bo Link: http://lkml.kernel.org/r/4DACE6E0.7000507@cn.fujitsu.com Signed-off-by: Steven Rostedt --- include/linux/ftrace_event.h | 12 ++++++++++++ include/trace/ftrace.h | 13 +++++++++++++ kernel/trace/trace_output.c | 27 +++++++++++++++++++++++++++ 3 files changed, 52 insertions(+) (limited to 'include') diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index b5a550a39a7..59d3ef100eb 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -16,6 +16,11 @@ struct trace_print_flags { const char *name; }; +struct trace_print_flags_u64 { + unsigned long long mask; + const char *name; +}; + const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim, unsigned long flags, const struct trace_print_flags *flag_array); @@ -23,6 +28,13 @@ const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim, const char *ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val, const struct trace_print_flags *symbol_array); +#if BITS_PER_LONG == 32 +const char *ftrace_print_symbols_seq_u64(struct trace_seq *p, + unsigned long long val, + const struct trace_print_flags_u64 + *symbol_array); +#endif + const char *ftrace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int len); diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index 3e68366d485..533c49f4804 100644 --- a/include/trace/ftrace.h +++ b/include/trace/ftrace.h @@ -205,6 +205,19 @@ ftrace_print_symbols_seq(p, value, symbols); \ }) +#undef __print_symbolic_u64 +#if BITS_PER_LONG == 32 +#define __print_symbolic_u64(value, symbol_array...) \ + ({ \ + static const struct trace_print_flags_u64 symbols[] = \ + { symbol_array, { -1, NULL } }; \ + ftrace_print_symbols_seq_u64(p, value, symbols); \ + }) +#else +#define __print_symbolic_u64(value, symbol_array...) \ + __print_symbolic(value, symbol_array) +#endif + #undef __print_hex #define __print_hex(buf, buf_len) ftrace_print_hex_seq(p, buf, buf_len) diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index cf535ccedc8..e37de492a9e 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -353,6 +353,33 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val, } EXPORT_SYMBOL(ftrace_print_symbols_seq); +#if BITS_PER_LONG == 32 +const char * +ftrace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val, + const struct trace_print_flags_u64 *symbol_array) +{ + int i; + const char *ret = p->buffer + p->len; + + for (i = 0; symbol_array[i].name; i++) { + + if (val != symbol_array[i].mask) + continue; + + trace_seq_puts(p, symbol_array[i].name); + break; + } + + if (!p->len) + trace_seq_printf(p, "0x%llx", val); + + trace_seq_putc(p, 0); + + return ret; +} +EXPORT_SYMBOL(ftrace_print_symbols_seq_u64); +#endif + const char * ftrace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int buf_len) { -- cgit v1.2.3-70-g09d2 From 7f34b746f79c1e1f8fd6d09799d133263ae7a504 Mon Sep 17 00:00:00 2001 From: liubo Date: Tue, 19 Apr 2011 09:35:31 +0800 Subject: tracing: Update btrfs's tracepoints to use u64 interface To avoid 64->32 truncating WARNING, update btrfs's tracepoints. Signed-off-by: Liu Bo Link: http://lkml.kernel.org/r/4DACE6E3.8080200@cn.fujitsu.com Signed-off-by: Steven Rostedt --- include/trace/events/btrfs.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index f445cff66ab..4114129f079 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -28,7 +28,7 @@ struct extent_buffer; { BTRFS_SHARED_DATA_REF_KEY, "SHARED_DATA_REF" }) #define __show_root_type(obj) \ - __print_symbolic(obj, \ + __print_symbolic_u64(obj, \ { BTRFS_ROOT_TREE_OBJECTID, "ROOT_TREE" }, \ { BTRFS_EXTENT_TREE_OBJECTID, "EXTENT_TREE" }, \ { BTRFS_CHUNK_TREE_OBJECTID, "CHUNK_TREE" }, \ @@ -125,7 +125,7 @@ DEFINE_EVENT(btrfs__inode, btrfs_inode_evict, ); #define __show_map_type(type) \ - __print_symbolic(type, \ + __print_symbolic_u64(type, \ { EXTENT_MAP_LAST_BYTE, "LAST_BYTE" }, \ { EXTENT_MAP_HOLE, "HOLE" }, \ { EXTENT_MAP_INLINE, "INLINE" }, \ -- cgit v1.2.3-70-g09d2 From b1cff0ad1062621ae63cb6c5dc4165191fe2e9f1 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 25 May 2011 14:27:43 -0400 Subject: ftrace: Add internal recursive checks Witold reported a reboot caused by the selftests of the dynamic function tracer. He sent me a config and I used ktest to do a config_bisect on it (as my config did not cause the crash). It pointed out that the problem config was CONFIG_PROVE_RCU. What happened was that if multiple callbacks are attached to the function tracer, we iterate a list of callbacks. Because the list is managed by synchronize_sched() and preempt_disable, the access to the pointers uses rcu_dereference_raw(). When PROVE_RCU is enabled, the rcu_dereference_raw() calls some debugging functions, which happen to be traced. The tracing of the debug function would then call rcu_dereference_raw() which would then call the debug function and then... well you get the idea. I first wrote two different patches to solve this bug. 1) add a __rcu_dereference_raw() that would not do any checks. 2) add notrace to the offending debug functions. Both of these patches worked. Talking with Paul McKenney on IRC, he suggested to add recursion detection instead. This seemed to be a better solution, so I decided to implement it. As the task_struct already has a trace_recursion to detect recursion in the ring buffer, and that has a very small number it allows, I decided to use that same variable to add flags that can detect the recursion inside the infrastructure of the function tracer. I plan to change it so that the task struct bit can be checked in mcount, but as that requires changes to all archs, I will hold that off to the next merge window. Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Frederic Weisbecker Cc: Paul E. McKenney Link: http://lkml.kernel.org/r/1306348063.1465.116.camel@gandalf.stny.rr.com Reported-by: Witold Baryluk Signed-off-by: Steven Rostedt --- include/linux/sched.h | 2 +- kernel/trace/ftrace.c | 13 ++++++++++++- kernel/trace/ring_buffer.c | 10 +++++----- kernel/trace/trace.h | 15 +++++++++++++++ 4 files changed, 33 insertions(+), 7 deletions(-) (limited to 'include') diff --git a/include/linux/sched.h b/include/linux/sched.h index d8b2d0bec0d..7b78d9cad47 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1513,7 +1513,7 @@ struct task_struct { #ifdef CONFIG_TRACING /* state flags for use by tracers */ unsigned long trace; - /* bitmask of trace recursion */ + /* bitmask and counter of trace recursion */ unsigned long trace_recursion; #endif /* CONFIG_TRACING */ #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */ diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 25949b33057..1ee417fcbfa 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -109,12 +109,18 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip); static void ftrace_global_list_func(unsigned long ip, unsigned long parent_ip) { - struct ftrace_ops *op = rcu_dereference_raw(ftrace_global_list); /*see above*/ + struct ftrace_ops *op; + + if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT))) + return; + trace_recursion_set(TRACE_GLOBAL_BIT); + op = rcu_dereference_raw(ftrace_global_list); /*see above*/ while (op != &ftrace_list_end) { op->func(ip, parent_ip); op = rcu_dereference_raw(op->next); /*see above*/ }; + trace_recursion_clear(TRACE_GLOBAL_BIT); } static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip) @@ -3490,6 +3496,10 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip) { struct ftrace_ops *op; + if (unlikely(trace_recursion_test(TRACE_INTERNAL_BIT))) + return; + + trace_recursion_set(TRACE_INTERNAL_BIT); /* * Some of the ops may be dynamically allocated, * they must be freed after a synchronize_sched(). @@ -3502,6 +3512,7 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip) op = rcu_dereference_raw(op->next); }; preempt_enable_notrace(); + trace_recursion_clear(TRACE_INTERNAL_BIT); } static void clear_ftrace_swapper(void) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0ef7b4b2a1f..b0c7aa40794 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2216,7 +2216,7 @@ static noinline void trace_recursive_fail(void) printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:" "HC[%lu]:SC[%lu]:NMI[%lu]\n", - current->trace_recursion, + trace_recursion_buffer(), hardirq_count() >> HARDIRQ_SHIFT, softirq_count() >> SOFTIRQ_SHIFT, in_nmi()); @@ -2226,9 +2226,9 @@ static noinline void trace_recursive_fail(void) static inline int trace_recursive_lock(void) { - current->trace_recursion++; + trace_recursion_inc(); - if (likely(current->trace_recursion < TRACE_RECURSIVE_DEPTH)) + if (likely(trace_recursion_buffer() < TRACE_RECURSIVE_DEPTH)) return 0; trace_recursive_fail(); @@ -2238,9 +2238,9 @@ static inline int trace_recursive_lock(void) static inline void trace_recursive_unlock(void) { - WARN_ON_ONCE(!current->trace_recursion); + WARN_ON_ONCE(!trace_recursion_buffer()); - current->trace_recursion--; + trace_recursion_dec(); } #else diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 6b69c4bd306..229f8591f61 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -784,4 +784,19 @@ extern const char *__stop___trace_bprintk_fmt[]; FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print)) #include "trace_entries.h" +/* Only current can touch trace_recursion */ +#define trace_recursion_inc() do { (current)->trace_recursion++; } while (0) +#define trace_recursion_dec() do { (current)->trace_recursion--; } while (0) + +/* Ring buffer has the 10 LSB bits to count */ +#define trace_recursion_buffer() ((current)->trace_recursion & 0x3ff) + +/* for function tracing recursion */ +#define TRACE_INTERNAL_BIT (1<<11) +#define TRACE_GLOBAL_BIT (1<<12) + +#define trace_recursion_set(bit) do { (current)->trace_recursion |= (bit); } while (0) +#define trace_recursion_clear(bit) do { (current)->trace_recursion &= ~(bit); } while (0) +#define trace_recursion_test(bit) ((current)->trace_recursion & (bit)) + #endif /* _LINUX_KERNEL_TRACE_H */ -- cgit v1.2.3-70-g09d2