Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf updates/fixes from Ingo Molnar:
 "Mostly tooling updates, but also two kernel fixes: a call chain
  handling robustness fix and an x86 PMU driver event definition fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/callchain: Force USER_DS when invoking perf_callchain_user()
  tools build: Fixup sched_getcpu feature test
  perf tests kmod-path: Don't fail if compressed modules aren't supported
  perf annotate: Fix AArch64 comment char
  perf tools: Fix spelling mistakes
  perf/x86: Fix Broadwell-EP DRAM RAPL events
  perf config: Refactor a duplicated code for obtaining config file name
  perf symbols: Allow user probes on versioned symbols
  perf symbols: Accept symbols starting at address 0
  tools lib string: Adopt prefixcmp() from perf and subcmd
  perf units: Move parse_tag_value() to units.[ch]
  perf ui gtk: Move gtk .so name to the only place where it is used
  perf tools: Move HAS_BOOL define to where perl headers are used
  perf memswap: Split the byteswap memory range wrappers from util.[ch]
  perf tools: Move event prototypes from util.h to event.h
  perf buildid: Move prototypes from util.h to build-id.h

kernel/events/callchain.c

@@ -229,12 +229,18 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
 		}
 
 		if (regs) {
+			mm_segment_t fs;
+
 			if (crosstask)
 				goto exit_put;
 
 			if (add_mark)
 				perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
+
+			fs = get_fs();
+			set_fs(USER_DS);
 			perf_callchain_user(&ctx, regs);
+			set_fs(fs);
 		}
 	}