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Commit 57d1c0c0 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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perf/x86: Fix PEBS instruction unwind 



Masami spotted that we always try to decode the instruction stream as
64bit instructions when running a 64bit kernel, this doesn't work for
ia32-compat proglets.

Use TIF_IA32 to detect if we need to use the 32bit instruction
decoder.

Reported-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: stable@kernel.org
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7f80850d

arch/x86/kernel/cpu/perf_event_intel_ds.c

+5 −1
Original line number Diff line number Diff line
@@ -493,6 +493,7 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) 
	unsigned long from = cpuc->lbr_entries[0].from;

	unsigned long old_to, to = cpuc->lbr_entries[0].to;

	unsigned long ip = regs->ip;

	int is_64bit = 0;



	/*

	 * We don't need to fixup if the PEBS assist is fault like
@@ -544,7 +545,10 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) 
		} else

			kaddr = (void *)to;



		kernel_insn_init(&insn, kaddr);

#ifdef CONFIG_X86_64

		is_64bit = kernel_ip(to) || !test_thread_flag(TIF_IA32);

#endif

		insn_init(&insn, kaddr, is_64bit);

		insn_get_length(&insn);

		to += insn.length;

	} while (to < ip);