Messages in this thread | | | Date | Thu, 19 Apr 2018 18:20:24 -0500 | From | Kim Phillips <> | Subject | Re: [PATCH] perf tools: set kernel end address properly |
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On Thu, 19 Apr 2018 11:37:12 +0900 Namhyung Kim <namhyung@kernel.org> wrote:
> On Wed, Apr 18, 2018 at 07:37:59PM -0500, Kim Phillips wrote: > > On Tue, 17 Apr 2018 11:27:26 +0900 > > Namhyung Kim <namhyung@kernel.org> wrote: > > > On Mon, Apr 16, 2018 at 05:48:11PM -0500, Kim Phillips wrote: > > > > > a perf/urgent from last week (commit 918965d4897) + this patch: > > > > > > > > > > $ sudo ./perf test -vv 1 |& head > > > > > 1: vmlinux symtab matches kallsyms : > > > > > --- start --- > > > > > test child forked, pid 6194 > > > > > Looking at the vmlinux_path (8 entries long) > > > > > Using /lib/modules/4.16.0+/build/vmlinux for symbols > > > > > ERR : 0xffff200008081000: do_undefinstr not on kallsyms > > > > > ERR : 0xffff2000080810b8: do_sysinstr not on kallsyms > > > > > ERR : 0xffff200008081258: do_debug_exception not on kallsyms > > > > > ERR : 0xffff200008081648: do_mem_abort not on kallsyms > > > > > ERR : 0xffff2000080818b8: do_el0_irq_bp_hardening not on kallsyms > > > > > $ sudo ./perf test -vv 1 |& tail > > > > > ERR : 0xffff20000a1d37c8: tramp_exit_native not on kallsyms > > > > > ERR : 0xffff20000a1d37e8: tramp_exit_compat not on kallsyms > > > > > ERR : 0xffff20000a1d4000: __entry_tramp_text_end not on kallsyms > > > > > WARN: Maps only in vmlinux: > > > > > ffff200008080000-ffff200008081000 10000 [kernel].head.text > > > > > ffff20000aec0000-ffff20000aff7548 2e50000 [kernel].init.text > > > > > ffff20000aff7548-ffff20000b0126d4 2f87548 [kernel].exit.text > > > > > test child finished with -1 > > > > > ---- end ---- > > > > > vmlinux symtab matches kallsyms: FAILED! > > > > > > > > this patch's advertised "If there's no module after the kernel map, the > > > > end address will be ~0ULL." doesn't seem to be working: the value it > > > > gets for 'end' is 0xffff200008080000. > > > > > > For the vmlinux, right? > > > > yes, map__next(machine__kernel_map(machine)) has the start address > > of the single module currently loaded: > > > > ffff200002290000 t $x [arm_ccn] > > ffff200002290000 t arm_ccn_pmu_events_is_visible [arm_ccn] > > > > The beginning of the kernel is..later: > > > > ffff200008080000 t _head > > ffff200008080000 T _text > > > > and its end according to grep -w _end /proc/kallsyms is: > > > > ffff20000d5f9000 B _end > > > > but end was assigned to the beginning of arm_ccn (0xffff200002290000), > > which is upside-down. > > So ARM64 has modules below the kernel.
right.
> > > To be precise, it should be "If there's no map after the kernel map". > > > > In numerical address order, in maps in map_groups__insert order, or > > some other order? > > The map_groups__insert() also sorts the map by address, so they should
Had missed that, sorry.
> be identical. I think the problem is perf assumes the kernel is the > first map in the kmaps. When it calls maps_groups__insert() it uses > start address of 0 for the kernel map. It seems always true for x86 > but not for ARM64. > > While it changes the start address in machine__set_kernel_mmap() it > doesn't change the order in the kmaps. > > Could you please test below patch (on top) then?
Much better, thank you! Together with the "module_emit_adrp_veneer not on kallsyms" mitigation diff, test 1 now passes on arm64 systems both with modules loaded, and without, and with and without RANDOMIZE_BASE.
I would send a patch (From: you), but I think you'd do a better job on writing the commit text, so would you care to, please?
Thanks,
Kim
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