linux/arch/x86/events
Andrea Arcangeli 74c504a6d7 x86: retpolines: eliminate retpoline from msr event handlers
It's enough to check the value and issue the direct call.

After this commit is applied, here the most common retpolines executed
under a high resolution timer workload in the guest on a VMX host:

[..]
@[
    trace_retpoline+1
    __trace_retpoline+30
    __x86_indirect_thunk_rax+33
    do_syscall_64+89
    entry_SYSCALL_64_after_hwframe+68
]: 267
@[]: 2256
@[
    trace_retpoline+1
    __trace_retpoline+30
    __x86_indirect_thunk_rax+33
    __kvm_wait_lapic_expire+284
    vmx_vcpu_run.part.97+1091
    vcpu_enter_guest+377
    kvm_arch_vcpu_ioctl_run+261
    kvm_vcpu_ioctl+559
    do_vfs_ioctl+164
    ksys_ioctl+96
    __x64_sys_ioctl+22
    do_syscall_64+89
    entry_SYSCALL_64_after_hwframe+68
]: 2390
@[]: 33410

@total: 315707

Note the highest hit above is __delay so probably not worth optimizing
even if it would be more frequent than 2k hits per sec.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-11-15 11:43:58 +01:00
..
amd perf/x86/amd: Change/fix NMI latency mitigation to use a timestamp 2019-10-09 12:44:14 +02:00
intel x86: retpolines: eliminate retpoline from msr event handlers 2019-11-15 11:43:58 +01:00
core.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-16 19:21:34 -07:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile perf/x86: Add MSR probe interface 2019-06-24 19:28:31 +02:00
msr.c perf/x86/msr: Add Tiger Lake CPU support 2019-10-12 15:13:09 +02:00
perf_event.h perf/x86/intel: Support PEBS output to PT 2019-08-28 11:29:39 +02:00
probe.c perf/x86: Add MSR probe interface 2019-06-24 19:28:31 +02:00
probe.h perf/x86: Add MSR probe interface 2019-06-24 19:28:31 +02:00