On Wed, Jan 15, 2014 at 10:30:48AM +0000, Jean Pihet wrote: > Hi Will, Hi Jean,
> On 6 January 2014 19:30, Will Deacon <[email protected]> wrote: > > On Mon, Dec 30, 2013 at 04:25:30PM +0000, Jean Pihet wrote: > >> From: Jean Pihet <[email protected]> > >> > >> This patch implements the functions required for the perf registers API, > >> allowing the perf tool to interface kernel register dumps with libunwind > >> in order to provide userspace backtracing. > >> Compat mode is also supported. > > > > [...] > > > >> +u64 perf_reg_value(struct pt_regs *regs, int idx) > >> +{ > >> + if (WARN_ON_ONCE((u32)idx >= PERF_REG_ARM64_MAX)) > >> + return 0; > > > > While this is probably fine, I'd feel more comfortable if you had separate > > limit checks for native and compat... > In fact in the native and compat modes the same set of registers are > accessed, based on the native regs that are registered to the perf > event core, cf. the definition of PERF_REGS_MASK in > tools/perf/arch/arm64/include/perf_regs.h. > > The regs set could be registered differently based on the binary to > trace, but unfortunately the perf core code does not allow that. > > I would leave the code as is, what do you think? Well, what business would a compat task have accessing registers beyond the compat subset? Since we don't expose the PC, we can simply lower the limit as the compat registers form a prefix of the native registers, no? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
