Commit-ID: 32caa06091cc59651222cdc971dc21eaab36b097
Gitweb: http://git.kernel.org/tip/32caa06091cc59651222cdc971dc21eaab36b097
Author: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
AuthorDate: Fri, 10 Apr 2015 15:06:58 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sat, 11 Apr 2015 13:08:53 +0200
perf/x86/64: Simplify regs_user->abi setting code in get_regs_user()
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@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1428671219-29341-3-git-send-email-dvlasenk@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|