On Thu, 2014-03-13 at 15:54 +0000, Will Deacon wrote: > On Thu, Mar 13, 2014 at 10:13:49AM +0000, AKASHI Takahiro wrote: > > CALLER_ADDRx returns caller's address at specified level in call stacks. > > They are used for several tracers like irqsoff and preemptoff. > > Strange to say, however, they are refered even without FTRACE. > > > > Please note that this implementation assumes that we have frame pointers. > > (which means kernel should be compiled with -fno-omit-frame-pointer.) > > How do you ensure that -fno-omit-frame-pointer is passed?
Perhaps -pg does the same thing? > > +#define HAVE_ARCH_CALLER_ADDR > > + > > +#define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0)) > > +#define CALLER_ADDR1 ((unsigned long)return_address(1)) > > +#define CALLER_ADDR2 ((unsigned long)return_address(2)) > > +#define CALLER_ADDR3 ((unsigned long)return_address(3)) > > +#define CALLER_ADDR4 ((unsigned long)return_address(4)) > > +#define CALLER_ADDR5 ((unsigned long)return_address(5)) > > +#define CALLER_ADDR6 ((unsigned long)return_address(6)) > > Could we change the core definitions of these macros (in linux/ftrace.h) to > use return_address, then provide an overridable version of return_address > that defaults to __builtin_return_address, instead of copy-pasting this > sequence? We could add a new macro: /* All archs should have this, but we define it for consistency */ #ifndef ftrace_return_address0 # define ftrace_return_address0 __builtin_return_address(0) #endif /* Archs may use other ways for ADDR1 and beyond */ #ifndef ftrace_return_address # define ftrace_return_address(n) __builtin_return_address(n) #endif And then have: #define CALLER_ADDR0 ((unsigned long)ftrace_return_address0) #define CALLER_ADDR1 ((unsigned long)ftrace_return_address(1)) [...] And then you would only need to redefine ftrace_return_address. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
