Messages in this thread Patch in this message | | | Date | Thu, 19 Apr 2018 11:37:12 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCH] perf tools: set kernel end address properly |
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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.
> > > 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 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?
Thanks, Namhyung
---8<---
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index be328416de61..0f3c4bc7b90f 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -1228,7 +1228,6 @@ int machine__create_kernel_maps(struct machine *machine) const char *name = NULL; struct map *map; u64 addr = 0; - u64 end = ~0ULL; int ret; if (kernel == NULL) @@ -1254,14 +1253,25 @@ int machine__create_kernel_maps(struct machine *machine) machine__destroy_kernel_maps(machine); return -1; } + + /* we have a real start address now, so re-order the kmaps */ + map = machine__kernel_map(machine); + + map__get(map); + map_groups__remove(&machine->kmaps, map); + + /* assume it's the last in the kmaps */ + machine__set_kernel_mmap(machine, addr, ~0ULL); + + map_groups__insert(&machine->kmaps, map); + map__put(map); } /* update end address of the kernel map using adjacent module address */ map = map__next(machine__kernel_map(machine)); if (map) - end = map->start; + machine__set_kernel_mmap(machine, addr, map->start); - machine__set_kernel_mmap(machine, addr, end); return 0; }
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