Commit a68c5a52 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Greg Kroah-Hartman

perf/core: Fix perf_sample_regs_user() mm check

[ Upstream commit 085ebfe937d7a7a5df1729f35a12d6d655fea68c ]

perf_sample_regs_user() uses 'current->mm' to test for the presence of
userspace, but this is insufficient, consider use_mm().

A better test is: '!(current->flags & PF_KTHREAD)', exec() clears
PF_KTHREAD after it sets the new ->mm but before it drops to userspace
for the first time.

Possibly obsoletes: bf05fc25 ("powerpc/perf: Fix oops when kthread execs user process")
Reported-by: default avatarRavi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Reported-by: default avatarYoung Xiao <92siuyang@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4018994f ("perf: Add ability to attach user level registers dump to sample")
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 555c2ac6
......@@ -5630,7 +5630,7 @@ static void perf_sample_regs_user(struct perf_regs *regs_user,
if (user_mode(regs)) {
regs_user->abi = perf_reg_abi(current);
regs_user->regs = regs;
} else if (current->mm) {
} else if (!(current->flags & PF_KTHREAD)) {
perf_get_regs_user(regs_user, regs, regs_user_copy);
} else {
regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
......
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