Kan Liang 023036e389 perf/core: Fix the same task check in perf_event_set_output ... [ Upstream commit 24d3ae2f37d8bc3c14b31d353c5d27baf582b6a6 ] The same task check in perf_event_set_output has some potential issues for some usages. For the current perf code, there is a problem if using of perf_event_open() to have multiple samples getting into the same mmap’d memory when they are both attached to the same process. https://lore.kernel.org/all/92645262-D319-4068-9C44-2409EF44888E@gmail.com/ Because the event->ctx is not ready when the perf_event_set_output() is invoked in the perf_event_open(). Besides the above issue, before the commit bd2756811766 ("perf: Rewrite core context handling"), perf record can errors out when sampling with a hardware event and a software event as below. $ perf record -e cycles,dummy --per-thread ls failed to mmap with 22 (Invalid argument) That's because that prior to the commit a hardware event and a software event are from different task context. The problem should be a long time issue since commit c3f00c7027 ("perk: Separate find_get_context() from event initialization"). The task struct is stored in the event->hw.target for each per-thread event. It is a more reliable way to determine whether two events are attached to the same task. The event->hw.target was also introduced several years ago by the commit 50f16a8bf9 ("perf: Remove type specific target pointers"). It can not only be used to fix the issue with the current code, but also back port to fix the issues with an older kernel. Note: The event->hw.target was introduced later than commit c3f00c7027. The patch may cannot be applied between the commit c3f00c7027 and commit 50f16a8bf9. Anybody that wants to back-port this at that period may have to find other solutions. Fixes: c3f00c7027 ("perf: Separate find_get_context() from event initialization") Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Zhengjun Xing <zhengjun.xing@linux.intel.com> Link: https://lkml.kernel.org/r/20230322202449.512091-1-kan.liang@linux.intel.com Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-04-13 16:55:32 +02:00
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callchain.c	uaccess: remove CONFIG_SET_FS	2022-02-25 09:36:06 +01:00
core.c	perf/core: Fix the same task check in perf_event_set_output	2023-04-13 16:55:32 +02:00
hw_breakpoint.c	perf/hw_breakpoint: Annotate tsk->perf_event_mutex vs ctx->mutex	2022-10-04 13:32:09 +02:00
hw_breakpoint_test.c	perf/hw_breakpoint: test: Skip the test if dependencies unmet	2022-11-02 12:22:05 +01:00
internal.h	perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled	2022-04-19 21:15:42 +02:00
Makefile	perf/hw_breakpoint: Add KUnit test for constraints accounting	2022-08-30 10:56:20 +02:00
ring_buffer.c	perf: Fix missing SIGTRAPs	2022-10-17 16:32:05 +02:00
uprobes.c	mm/madvise: add file and shmem support to MADV_COLLAPSE	2022-10-03 14:03:33 -07:00