Messages in this thread Patch in this message | | | From | Denys Vlasenko <> | Subject | [PATCH 3/4] perf/x86_64: get_regs_user: Simplify regs_user->abi setting code | Date | Fri, 10 Apr 2015 15:06:58 +0200 |
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user_64bit_mode(regs) basically checks regs->cs to point to a 64-bit segment. This check used to be unreliable here because regs->cs was not always correct in syscalls.
Now regs->cs is always correct: in syscalls, in interrupts, in exceptions. No need to emply heuristics here.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> CC: Jiri Olsa <jolsa@redhat.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Paul Mackerras <paulus@samba.org> CC: Ingo Molnar <mingo@redhat.com> CC: Arnaldo Carvalho de Melo <acme@kernel.org> CC: x86@kernel.org CC: linux-kernel@vger.kernel.org --- arch/x86/kernel/perf_regs.c | 18 ++---------------- 1 file changed, 2 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c index a8d4e48..8157d39 100644 --- a/arch/x86/kernel/perf_regs.c +++ b/arch/x86/kernel/perf_regs.c @@ -166,22 +166,8 @@ void perf_get_regs_user(struct perf_regs *regs_user, * be careful not to look at any other percpu variables that might * change during context switches. */ - if (IS_ENABLED(CONFIG_IA32_EMULATION) && - task_thread_info(current)->status & TS_COMPAT) { - /* Easy case: we're in a compat syscall. */ - regs_user->abi = PERF_SAMPLE_REGS_ABI_32; - } else if (user_regs->orig_ax != -1) { - /* - * We're probably in a 64-bit syscall. - * Warning: this code is severely racy. At least it's better - * than just blindly copying user_regs. - */ - regs_user->abi = PERF_SAMPLE_REGS_ABI_64; - } else { - /* We're probably in an interrupt or exception. */ - regs_user->abi = user_64bit_mode(user_regs) ? - PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32; - } + regs_user->abi = user_64bit_mode(user_regs) ? + PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32; regs_user->regs = regs_user_copy; } -- 1.8.1.4
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