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Adrian Hunter ce3ea6b66d perf intel-pt: Fix sample instruction bytes 
commit c954eb72b3 upstream.

The decoder reports the current instruction if it was decoded. In some
cases the current instruction is not decoded, in which case the instruction
bytes length must be set to zero. Ensure that is always done.

Note perf script can anyway get the instruction bytes for any samples where
they are not present.

Also note, that there is a redundant "ptq->insn_len = 0" statement which is
not removed until a subsequent patch in order to make this patch apply
cleanly to stable branches.

Example:

A machne that supports TSX is required. It will have flag "rtm". Kernel
parameter tsx=on may be required.

 # for w in `cat /proc/cpuinfo | grep -m1 flags `;do echo $w | grep rtm ; done
 rtm

Test program:

 #include <stdio.h>
 #include <immintrin.h>

 int main()
 {
        int x = 0;

        if (_xbegin() == _XBEGIN_STARTED) {
                x = 1;
                _xabort(1);
        } else {
                printf("x = %d\n", x);
        }
        return 0;
 }

Compile with -mrtm i.e.

 gcc -Wall -Wextra -mrtm xabort.c -o xabort

Record:

 perf record -e intel_pt/cyc/u --filter 'filter main @ ./xabort' ./xabort

Before:

 # perf script --itrace=xe -F+flags,+insn,-period --xed --ns
          xabort  1478 [007] 92161.431348581:   transactions:   x                              400b81 main+0x14 (/root/xabort)          mov $0xffffffff, %eax
          xabort  1478 [007] 92161.431348624:   transactions:   tx abrt                        400b93 main+0x26 (/root/xabort)          mov $0xffffffff, %eax

After:

 # perf script --itrace=xe -F+flags,+insn,-period --xed --ns
          xabort  1478 [007] 92161.431348581:   transactions:   x                              400b81 main+0x14 (/root/xabort)          xbegin 0x6
          xabort  1478 [007] 92161.431348624:   transactions:   tx abrt                        400b93 main+0x26 (/root/xabort)          xabort $0x1

Fixes: faaa87680b ("perf intel-pt/bts: Report instruction bytes and length in sample")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20210519074515.9262-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-03 09:00:27 +02:00
arch KVM: x86: Defer vtime accounting 'til after IRQ handling 2021-05-28 13:17:43 +02:00
block blk-mq: Swap two calls in blk_mq_exit_queue() 2021-05-19 10:13:14 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-04 11:37:59 +01:00
crypto async_xor: increase src_offs when dropping destination page 2021-05-14 09:49:59 +02:00
Documentation powerpc/64s/syscall: Use pt_regs.trap to distinguish syscall ABI difference between sc and scv syscalls 2021-05-26 12:06:53 +02:00
drivers iommu/vt-d: Fix sysfs leak in alloc_iommu() 2021-06-03 09:00:27 +02:00
fs NFSv4: Fix a NULL pointer dereference in pnfs_mark_matching_lsegs_return() 2021-06-03 09:00:27 +02:00
include NFC: nci: fix memory leak in nci_allocate_device 2021-05-28 13:17:43 +02:00
init seccomp: Fix CONFIG tests for Seccomp_filters 2021-05-14 09:50:24 +02:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel bpf: No need to simulate speculative domain for immediates 2021-05-28 13:17:43 +02:00
lib lib: stackdepot: turn depot_lock spinlock to raw_spinlock 2021-05-22 11:40:55 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/hugetlb: fix F_SEAL_FUTURE_WRITE 2021-05-19 10:13:11 +02:00
net NFC: nci: fix memory leak in nci_allocate_device 2021-05-28 13:17:43 +02:00
samples samples/bpf: Fix broken tracex1 due to kprobe argument change 2021-05-19 10:12:57 +02:00
scripts scripts: switch explicitly to Python 3 2021-05-22 11:40:55 +02:00
security KEYS: trusted: Fix memory leak on object td 2021-05-19 10:12:50 +02:00
sound ALSA: usb-audio: scarlett2: Improve driver startup messages 2021-06-03 09:00:27 +02:00
tools perf intel-pt: Fix sample instruction bytes 2021-06-03 09:00:27 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt kvm: exit halt polling on need_resched() as well 2021-05-19 10:13:12 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS f2fs: move ioctl interface definitions to separated file 2021-05-19 10:13:00 +02:00
Makefile Linux 5.10.41 2021-05-28 13:17:44 +02:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.