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authorLinus Torvalds <torvalds@linux-foundation.org>2018-11-30 11:31:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-11-30 11:31:48 -0800
commita1b3cf6d943800059adc262c4d839524c529db2d (patch)
treea8bdf99464f0b971dcbebf90d06af8072f218939 /kernel
parent8d9f412d51b84eafd2253a82120e218ddc53e721 (diff)
parent09d3f015d1e1b4fee7e9bbdcf54201d239393391 (diff)
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Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar: "Misc fixes: - counter freezing related regression fix - uprobes race fix - Intel PMU unusual event combination fix - .. and diverse tooling fixes" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: uprobes: Fix handle_swbp() vs. unregister() + register() race once more perf/x86/intel: Disallow precise_ip on BTS events perf/x86/intel: Add generic branch tracing check to intel_pmu_has_bts() perf/x86/intel: Move branch tracing setup to the Intel-specific source file perf/x86/intel: Fix regression by default disabling perfmon v4 interrupt handling perf tools beauty ioctl: Support new ISO7816 commands tools uapi asm-generic: Synchronize ioctls.h tools arch x86: Update tools's copy of cpufeatures.h tools headers uapi: Synchronize i915_drm.h perf tools: Restore proper cwd on return from mnt namespace tools build feature: Check if get_current_dir_name() is available perf tools: Fix crash on synthesizing the unit
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/uprobes.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 96d4bee83489..322e97bbb437 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -829,7 +829,7 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
BUG_ON((uprobe->offset & ~PAGE_MASK) +
UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
- smp_wmb(); /* pairs with rmb() in find_active_uprobe() */
+ smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */
set_bit(UPROBE_COPY_INSN, &uprobe->flags);
out:
@@ -2178,10 +2178,18 @@ static void handle_swbp(struct pt_regs *regs)
* After we hit the bp, _unregister + _register can install the
* new and not-yet-analyzed uprobe at the same address, restart.
*/
- smp_rmb(); /* pairs with wmb() in install_breakpoint() */
if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
goto out;
+ /*
+ * Pairs with the smp_wmb() in prepare_uprobe().
+ *
+ * Guarantees that if we see the UPROBE_COPY_INSN bit set, then
+ * we must also see the stores to &uprobe->arch performed by the
+ * prepare_uprobe() call.
+ */
+ smp_rmb();
+
/* Tracing handlers use ->utask to communicate with fetch methods */
if (!get_utask())
goto out;