On Tue, 10 Jan 2017 10:18:35 -0300 Arnaldo Carvalho de Melo <a...@kernel.org> wrote:
> Em Sat, Jan 07, 2017 at 02:25:09PM +0900, Masami Hiramatsu escreveu: > > Fix to show correct locations for events on modules by > > relocating given address. Currently the relocation is > > done when we failed to find the address in debuginfo, > > but for modules it always makes a mistakes. > > Try to provide precise instructions on how to reproduce, for instance, > here I'm not being able to reproduce: > > [root@jouet ~]# perf probe -m i915 chv_prepare_pll > Added new event: > probe:chv_prepare_pll (on chv_prepare_pll in i915) > > You can now use it in all perf tools, such as: > > perf record -e probe:chv_prepare_pll -aR sleep 1 > > [root@jouet ~]# perf probe -l > probe:chv_prepare_pll (on chv_prepare_pll in i915) > probe:e1000_xmit_frame (on > e1000_get_link_up_info_80003es2lan:7@intel/e1000e/80003es2lan.c in e1000e) > [root@jouet ~]# > > So it doesn't seem to "always make mistakes", what are the precise > conditions to reproduce this problem? OK, I found mymistakes. chv_prepare_pll in my i915 module is optimized and have isra.X suffix, so perf ends up with searching it in map. (That issue is fixed in [3/4] in this series as you may know) This happens when the module text size is enough big, bigger than sh_addr, because original code retries with given address + sh_addr if it failed to find CU DIE at the given address. Any address smaller than sh_addr always fails and it retries. On my environment, the sh_addr of ".text" section is 0x10030. Since i915 is a huge kernel module, we can see this issue as below. $ grep "[Tt] .*\[i915\]" /proc/kallsyms | sort | head -n1 ffffffffc0270000 t i915_switcheroo_can_switch [i915] ffffffffc0270000 + 0x10030 = ffffffffc0280030, so we'll check symbols cross this boundary. $ grep "[Tt] .*\[i915\]" /proc/kallsyms | grep -B1 ^ffffffffc028 | head -n 2 ffffffffc027ff80 t haswell_init_clock_gating [i915] ffffffffc0280110 t valleyview_init_clock_gating [i915] So setup probes on both function and see what happen. $ sudo ./perf probe -m i915 -a haswell_init_clock_gating -a valleyview_init_clock_gating Added new events: probe:haswell_init_clock_gating (on haswell_init_clock_gating in i915) probe:valleyview_init_clock_gating (on valleyview_init_clock_gating in i915) You can now use it in all perf tools, such as: perf record -e probe:valleyview_init_clock_gating -aR sleep 1 $ sudo ./perf probe -l probe:haswell_init_clock_gating (on haswell_init_clock_gating@gpu/drm/i915/intel_pm.c in i915) probe:valleyview_init_clock_gating (on i915_vga_set_decode:4@gpu/drm/i915/i915_drv.c in i915) As you can see, haswell_init_clock_gating is correctly shown, but valleyview_init_clock_gating is not. With this patch, both events shown correctly. $ sudo ./perf probe -l probe:haswell_init_clock_gating (on haswell_init_clock_gating@gpu/drm/i915/intel_pm.c in i915) probe:valleyview_init_clock_gating (on valleyview_init_clock_gating@gpu/drm/i915/intel_pm.c in i915) I'll update patch description and resend with fix of [4/4]. Thank you, -- Masami Hiramatsu <mhira...@kernel.org>