From cdbe61bfe70440939e457fb4a8d0995eaaed17de Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 5 May 2011 21:14:55 -0400 Subject: ftrace: Allow dynamically allocated function tracers Now that functions may be selected individually, it only makes sense that we should allow dynamically allocated trace structures to be traced. This will allow perf to allocate a ftrace_ops structure at runtime and use it to pick and choose which functions that structure will trace. Note, a dynamically allocated ftrace_ops will always be called indirectly instead of being called directly from the mcount in entry.S. This is because there's no safe way to prevent mcount from being preempted before calling the function, unless we modify every entry.S to do so (not likely). Thus, dynamically allocated functions will now be called by the ftrace_ops_list_func() that loops through the ops that are allocated if there are more than one op allocated at a time. This loop is protected with a preempt_disable. To determine if an ftrace_ops structure is allocated or not, a new util function was added to the kernel/extable.c called core_kernel_data(), which returns 1 if the address is between _sdata and _edata. Cc: Paul E. McKenney Signed-off-by: Steven Rostedt --- kernel/extable.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel/extable.c') diff --git a/kernel/extable.c b/kernel/extable.c index 7f8f263f8524..c2d625fcda77 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -72,6 +72,14 @@ int core_kernel_text(unsigned long addr) return 0; } +int core_kernel_data(unsigned long addr) +{ + if (addr >= (unsigned long)_sdata && + addr < (unsigned long)_edata) + return 1; + return 0; +} + int __kernel_text_address(unsigned long addr) { if (core_kernel_text(addr)) -- cgit v1.2.2 From c5fc472171ec4f96d06d1ac039d88f9b89bb95db Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 20 May 2011 01:22:14 +0200 Subject: core_kernel_data(): Fix architectures that do not define _sdata Some architectures such as Alpha do not define _sdata but _data: kernel/built-in.o: In function `core_kernel_data': kernel/extable.c:77: undefined reference to `_sdata' So expand the scope of the data range to the text addresses too, this might be more correct anyway because this way we can cover readonly variables as well. Cc: Paul E. McKenney Cc: Steven Rostedt Link: http://lkml.kernel.org/n/tip-i878c8a0e0g0ep4v7i6vxnhz@git.kernel.org Signed-off-by: Ingo Molnar --- kernel/extable.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/extable.c') diff --git a/kernel/extable.c b/kernel/extable.c index c2d625fcda77..d44aac0c3faa 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -74,7 +74,7 @@ int core_kernel_text(unsigned long addr) int core_kernel_data(unsigned long addr) { - if (addr >= (unsigned long)_sdata && + if (addr >= (unsigned long)_stext && addr < (unsigned long)_edata) return 1; return 0; -- cgit v1.2.2 From a2d063ac216c1618bfc2b4d40b7176adffa63511 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 19 May 2011 21:34:58 -0400 Subject: extable, core_kernel_data(): Make sure all archs define _sdata A new utility function (core_kernel_data()) is used to determine if a passed in address is part of core kernel data or not. It may or may not return true for RO data, but this utility must work for RW data. Thus both _sdata and _edata must be defined and continuous, without .init sections that may later be freed and replaced by volatile memory (memory that can be freed). This utility function is used to determine if data is safe from ever being freed. Thus it should return true for all RW global data that is not in a module or has been allocated, or false otherwise. Also change core_kernel_data() back to the more precise _sdata condition and document the function. Signed-off-by: Steven Rostedt Acked-by: Ralf Baechle Acked-by: Hirokazu Takata Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Geert Uytterhoeven Cc: Roman Zippel Cc: linux-m68k@lists.linux-m68k.org Cc: Kyle McMartin Cc: Helge Deller Cc: JamesE.J.Bottomley Link: http://lkml.kernel.org/r/1305855298.1465.19.camel@gandalf.stny.rr.com Signed-off-by: Ingo Molnar ---- arch/alpha/kernel/vmlinux.lds.S | 1 + arch/m32r/kernel/vmlinux.lds.S | 1 + arch/m68k/kernel/vmlinux-std.lds | 2 ++ arch/m68k/kernel/vmlinux-sun3.lds | 1 + arch/mips/kernel/vmlinux.lds.S | 1 + arch/parisc/kernel/vmlinux.lds.S | 3 +++ kernel/extable.c | 12 +++++++++++- 7 files changed, 20 insertions(+), 1 deletion(-) --- kernel/extable.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'kernel/extable.c') diff --git a/kernel/extable.c b/kernel/extable.c index d44aac0c3faa..5339705b8241 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -72,9 +72,19 @@ int core_kernel_text(unsigned long addr) return 0; } +/** + * core_kernel_data - tell if addr points to kernel data + * @addr: address to test + * + * Returns true if @addr passed in is from the core kernel data + * section. + * + * Note: On some archs it may return true for core RODATA, and false + * for others. But will always be true for core RW data. + */ int core_kernel_data(unsigned long addr) { - if (addr >= (unsigned long)_stext && + if (addr >= (unsigned long)_sdata && addr < (unsigned long)_edata) return 1; return 0; -- cgit v1.2.2