On Sat, Apr 20, 2013 at 06:53:34PM +0200, Oleg Nesterov wrote: > On 04/09, Jacob Shin wrote: > > > > The following patchset adds address masks to existing perf hardware > > breakpoint mechanism to allow trapping on an address range (currently > > only single address) on supported architectures. > > > > perf uapi is updated, x86 AMD implementation (for AMD Family 16h and > > beyond) is provided, and perf tool has been extended to do: > > > > $ perf stat -e mem:0x1000:w:0xf a.out > > ^^^ > > "don't care" bit mask > > > > which will count writes to [0x1000 ~ 0x1010) > > Please help me understand... > > Assuming that cpu_has_bpext == T, suppose that > > bp_addr = 0x1001; > bp_bp_addr_mask = 0xf; > > Is it the same as 0x1000/0xf above? > > IOW, what exactly this mask means? I guess, mem:ADDR:w:MASK > should trigger the trap if CPU writes to the addr and > > (addr & ~MASK) == (ADDR & ~MASK) > > correct?
Yes that is correct. > > And does attr.bp_len "contribute" to the mask? > > I mean, if bp_len == X86_BREAKPOINT_LEN_8, does this mean that > bp_bp_addr_mask and (bp_bp_addr_mask | 7) have the same effect? Yes it has the same effect. Thanks, -Jacob -- 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/
