kernel/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c, branch linux-5.14.y

perf intel-pt: Add a config for max loops without consuming a packet

2021-07-07T14:40:56Z

The Intel PT decoder limits the number of unconditional branches (e.g. jmps) decoded without consuming any trace packets. Generally, a loop needs a conditional branch which generates a TNT packet, whereas a "ret" instruction will generate a TIP or TNT packet. So exceeding the limit is assumed to be a never-ending loop, which can happen if there has been a decoding error putting the decoder at the wrong place in the code. Up until now, the limit of 10000 has been enough but some analytic purposes have been reported to exceed that. Increase the limit to 100000, and make it configurable via perf config intel-pt.max-loops. Also amend the "Never-ending loop" message to mention the configuration entry. Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: http://lore.kernel.org/lkml/20210701175132.3977-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

Merge remote-tracking branch 'torvalds/master' into perf/core

2021-05-25T12:13:52Z

To pick up fixes from perf/urgent. Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix transaction abort handling

2021-05-19T13:31:04Z

When adding support for power events, some handling of FUP packets was unified. That resulted in breaking reporting of TSX aborts, by not considering the associated TIP packet. Fix that. Example: A machine 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 #include 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=be -F+flags,+addr,-period,-event --ns xabort 1478 [007] 92161.431348552: tr strt 0 [unknown] ([unknown]) => 400b6d main+0x0 (/root/xabort) xabort 1478 [007] 92161.431348624: jmp 400b96 main+0x29 (/root/xabort) => 400bae main+0x41 (/root/xabort) xabort 1478 [007] 92161.431348624: return 400bb4 main+0x47 (/root/xabort) => 400b87 main+0x1a (/root/xabort) xabort 1478 [007] 92161.431348637: jcc 400b8a main+0x1d (/root/xabort) => 400b98 main+0x2b (/root/xabort) xabort 1478 [007] 92161.431348644: tr end call 400ba9 main+0x3c (/root/xabort) => 40f690 printf+0x0 (/root/xabort) xabort 1478 [007] 92161.431360859: tr strt 0 [unknown] ([unknown]) => 400bae main+0x41 (/root/xabort) xabort 1478 [007] 92161.431360882: tr end return 400bb4 main+0x47 (/root/xabort) => 401139 __libc_start_main+0x309 (/root/xabort) After: # perf script --itrace=be -F+flags,+addr,-period,-event --ns xabort 1478 [007] 92161.431348552: tr strt 0 [unknown] ([unknown]) => 400b6d main+0x0 (/root/xabort) xabort 1478 [007] 92161.431348624: tx abrt 400b93 main+0x26 (/root/xabort) => 400b87 main+0x1a (/root/xabort) xabort 1478 [007] 92161.431348637: jcc 400b8a main+0x1d (/root/xabort) => 400b98 main+0x2b (/root/xabort) xabort 1478 [007] 92161.431348644: tr end call 400ba9 main+0x3c (/root/xabort) => 40f690 printf+0x0 (/root/xabort) xabort 1478 [007] 92161.431360859: tr strt 0 [unknown] ([unknown]) => 400bae main+0x41 (/root/xabort) xabort 1478 [007] 92161.431360882: tr end return 400bb4 main+0x47 (/root/xabort) => 401139 __libc_start_main+0x309 (/root/xabort) Fixes: a472e65fc490a ("perf intel-pt: Add decoder support for ptwrite and power event packets") Signed-off-by: Adrian Hunter Cc: Andi Kleen Cc: Jiri Olsa Cc: stable@vger.kernel.org Link: http://lore.kernel.org/lkml/20210519074515.9262-2-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Add VM Time Correlation to decoder

2021-05-12T15:43:11Z

VM Time Correlation means determining if each TSC packet belongs to a VM Guest or the Host. When the trace is "in context" that is indicated by the NR flag in the PIP packet. However, when tracing kernel-only, userspace only, or using address filters, the trace can be "out of context" in which case timing packets are produced but not PIP packets. Nevertheless, it is very unlikely the VM Guest timestamps will be in the same range as the Host timestamps. Host time ranges are established by a starting side-band event timestamp, and subsequently by the buffer timestamp, written when the buffer is copied to the perf.data file. This patch supports updating the VM Guest timestamp packets, assuming an unchanging (during perf record) VMX TSC Offset and no VMX TSC scaling. Furthermore, it is possible to determine what the VMX TSC Offset is, although not necessarily at the start. The dry-run option lets that information be determined so that the user can pass it to a subsequent run. For more detail, refer to the example in the Intel PT documentation in a subsequent patch. VM Time Correlation is also performed on the TSC value in PEBs-via-PT records. Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210430070309.17624-12-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Better 7-byte timestamp wraparound logic

2021-05-12T15:43:11Z

A timestamp should not go backwards. If it does it is assumed that the 7-byte TSC packet value has wrapped. Improve that logic so that it will not allow the timestamp to go past the buffer timestamp (which is recorded when the buffer is copied out) Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210430070309.17624-11-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Pass the first timestamp to the decoder

2021-05-12T15:43:11Z

VM Time Correlation will use time ranges to determine whether a TSC packet belongs to the Host or Guest. To start, the first non-zero timestamp is needed. Pass that to the decoder. Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210430070309.17624-10-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Add a tree for VMCS information

2021-05-12T15:43:11Z

Even when VMX TSC Offset is not changing (during perf record), different virtual machines can have different TSC Offsets. There is a Virtual Machine Control Structure (VMCS) for each virtual CPU, the address of which is reported to Intel PT in the VMCS packet. We do not know which VMCS belongs to which virtual machine, so use a tree to keep track of VMCS information. Then the decoder will be able to use the current VMCS value to look up the current TSC Offset. Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210430070309.17624-9-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Let overlap detection handle VM timestamps

2021-05-12T15:43:11Z

Intel PT timestamps are affected by virtualization. While TSC packets can still be considered to be unique, the TSC values need not be in order any more. Adjust the algorithm accordingly. Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210430070309.17624-8-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Amend decoder to track the NR flag

2021-02-18T19:13:56Z

The PIP packet NR (non-root) flag indicates whether or not a virtual machine is being traced (NR=1 => VM). Add support for tracking its value. In particular note that the PIP packet (outside of PSB+) will be associated with a TIP packet from which address the NR value takes effect. At that point, there is a branch from_ip, to_ip with corresponding from_nr and to_nr. In the event of VM-Entry failure, there should still PIP and TIP packets that can be followed in the same way. Also note that this assumes that a host VMM is not employing VMX controls that affect Intel PT, e.g. to hide the host from a guest using Intel PT. Signed-off-by: Adrian Hunter Acked-by: Andi Kleen Cc: Alexander Shishkin Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210218095801.19576-5-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Retain the last PIP packet payload as is

2021-02-18T19:13:46Z

Retain the PIP packet payload as is, instead of just the CR3, because it contains also the VMX NR flag which is needed to track VM-Entry. Signed-off-by: Adrian Hunter Acked-by: Andi Kleen Cc: Alexander Shishkin Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210218095801.19576-4-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo