kernel/linux.git/tools/perf/util/machine.c, branch v5.19

perf tools: Add guest_code support

2022-05-23T13:18:38+00:00

A common case for KVM test programs is that the test program acts as the hypervisor, creating, running and destroying the virtual machine, and providing the guest object code from its own object code. In this case, the VM is not running an OS, but only the functions loaded into it by the hypervisor test program, and conveniently, loaded at the same virtual addresses. Normally to resolve addresses, MMAP events are needed to map addresses back to the object code and debug symbols for that object code. Currently, there is no way to get such mapping information from guests but, in the scenario described above, the guest has the same mappings as the hypervisor, so support for that scenario can be achieved. To support that, copy the host thread's maps to the guest thread's maps. Note, we do not discover the guest until we encounter a guest event, which works well because it is not until then that we know that the host thread's maps have been set up. Typically the main function for the guest object code is called "guest_code", hence the name chosen for this feature. Note, that is just a convention, the function could be named anything, and the tools do not care. This is primarily aimed at supporting Intel PT, or similar, where trace data can be recorded for a guest. Refer to the final patch in this series "perf intel-pt: Add guest_code support" for an example. Signed-off-by: Adrian Hunter Cc: Andi Kleen Cc: Ian Rogers Cc: Jiri Olsa Cc: Leo Yan Cc: Namhyung Kim Cc: kvm@vger.kernel.org Link: https://lore.kernel.org/r/20220517131011.6117-4-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Factor out thread__set_guest_comm()

2022-05-23T13:18:27+00:00

Factor out thread__set_guest_comm() so it can be reused. Signed-off-by: Adrian Hunter Cc: Andi Kleen Cc: Ian Rogers Cc: Jiri Olsa Cc: Leo Yan Cc: Namhyung Kim Cc: kvm@vger.kernel.org Link: https://lore.kernel.org/r/20220517131011.6117-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add machine to machines back pointer

2022-05-23T13:18:06+00:00

When dealing with guest machines, it can be necessary to get a reference to the host machine. Add a machines pointer to struct machine to make that possible. Signed-off-by: Adrian Hunter Cc: Andi Kleen Cc: Ian Rogers Cc: Jiri Olsa Cc: Leo Yan Cc: Namhyung Kim Cc: kvm@vger.kernel.org Link: https://lore.kernel.org/r/20220517131011.6117-2-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf unwind: Don't show unwind error messages when augmenting frame pointer stack

2022-04-09T15:34:29+00:00

Commit Fixes: b9f6fbb3b2c29736 ("perf arm64: Inject missing frames when using 'perf record --call-graph=fp'") intended to add a 'best effort' DWARF unwind that improved the frame pointer stack in most scenarios. It's expected that the unwind will fail sometimes, but this shouldn't be reported as an error. It only works when the return address can be determined from the contents of the link register alone. Fix the error shown when the unwinder requires extra registers by adding a new flag that suppresses error messages. This flag is not set in the normal --call-graph=dwarf unwind mode so that behavior is not changed. Fixes: b9f6fbb3b2c29736 ("perf arm64: Inject missing frames when using 'perf record --call-graph=fp'") Reported-by: John Garry Signed-off-by: James Clark Tested-by: John Garry Cc: Alexander Shishkin Cc: Alexandre Truong Cc: German Gomez Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Link: https://lore.kernel.org/r/20220406145651.1392529-1-james.clark@arm.com Signed-off-by: Arnaldo Carvalho de Melo

perf maps: Use a pointer for kmaps

2022-02-14T19:47:13+00:00

struct maps is reference counted, using a pointer is more idiomatic. Committer notes: Delay: maps = machine__kernel_maps(&vmlinux); To after: machine__init(&vmlinux, "", HOST_KERNEL_ID); To avoid this on f34: In file included from /var/home/acme/git/perf/tools/perf/util/build-id.h:10, from /var/home/acme/git/perf/tools/perf/util/dso.h:13, from tests/vmlinux-kallsyms.c:8: In function ‘machine__kernel_maps’, inlined from ‘test__vmlinux_matches_kallsyms’ at tests/vmlinux-kallsyms.c:122:22: /var/home/acme/git/perf/tools/perf/util/machine.h:86:23: error: ‘vmlinux.kmaps’ is used uninitialized [-Werror=uninitialized] 86 | return machine->kmaps; | ~~~~~~~^~~~~~~ tests/vmlinux-kallsyms.c: In function ‘test__vmlinux_matches_kallsyms’: tests/vmlinux-kallsyms.c:121:34: note: ‘vmlinux’ declared here 121 | struct machine kallsyms, vmlinux; | ^~~~~~~ cc1: all warnings being treated as errors Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexey Bayduraev Cc: Andi Kleen Cc: Andrew Morton Cc: André Almeida Cc: Andy Shevchenko Cc: Darren Hart Cc: Davidlohr Bueso Cc: Dmitriy Vyukov Cc: Eric Dumazet Cc: German Gomez Cc: Hao Luo Cc: James Clark Cc: Jin Yao Cc: Jiri Olsa Cc: John Garry Cc: Kajol Jain Cc: Kan Liang Cc: Leo Yan Cc: Madhavan Srinivasan Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Miaoqian Lin Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Riccardo Mancini Cc: Shunsuke Nakamura Cc: Song Liu Cc: Stephane Eranian Cc: Stephen Brennan Cc: Steven Rostedt (VMware) Cc: Thomas Gleixner Cc: Thomas Richter Cc: Yury Norov Link: http://lore.kernel.org/lkml/20220211103415.2737789-6-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Apply correct label to user/kernel symbols in branch mode

2022-02-06T12:03:06+00:00

In branch mode, the branch symbols were being displayed with incorrect cpumode labels. So fix this. For example, before: # perf record -b -a -- sleep 1 # perf report -b Overhead Command Source Shared Object Source Symbol Target Symbol 0.08% swapper [kernel.kallsyms] [k] rcu_idle_enter [k] cpuidle_enter_state ==> 0.08% cmd0 [kernel.kallsyms] [.] psi_group_change [.] psi_group_change 0.08% cmd1 [kernel.kallsyms] [k] psi_group_change [k] psi_group_change After: # perf report -b Overhead Command Source Shared Object Source Symbol Target Symbol 0.08% swapper [kernel.kallsyms] [k] rcu_idle_enter [k] cpuidle_enter_state 0.08% cmd0 [kernel.kallsyms] [k] psi_group_change [k] pei_group_change 0.08% cmd1 [kernel.kallsyms] [k] psi_group_change [k] psi_group_change Reviewed-by: James Clark Signed-off-by: German Gomez Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Link: https://lore.kernel.org/r/20220126105927.3411216-1-german.gomez@arm.com Signed-off-by: Arnaldo Carvalho de Melo

perf machine: Use path__join() to compose a path instead of snprintf(dir, '/', filename)

2022-01-19T16:54:57+00:00

Its more intention revealing, and if we're interested in the odd cases where this may end up truncating we can do debug checks at one centralized place. Motivation, of all the container builds, fedora rawhide started complaining of: util/machine.c: In function ‘machine__create_modules’: util/machine.c:1419:50: error: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=] 1419 | snprintf(path, sizeof(path), "%s/%s", dir_name, dent->d_name); | ^~ In file included from /usr/include/stdio.h:894, from util/branch.h:9, from util/callchain.h:8, from util/machine.c:7: In function ‘snprintf’, inlined from ‘maps__set_modules_path_dir’ at util/machine.c:1419:3, inlined from ‘machine__set_modules_path’ at util/machine.c:1473:9, inlined from ‘machine__create_modules’ at util/machine.c:1519:7: /usr/include/bits/stdio2.h:71:10: note: ‘__builtin___snprintf_chk’ output between 2 and 4352 bytes into a destination of size 4096 There are other places where we should use path__join(), but lets get rid of this one first. Cc: Adrian Hunter Cc: Ian Rogers Cc: Jiri Olsa Cc: Namhyung Kim Acked-by: Ian Rogers Link: Link: https://lore.kernel.org/r/YebZKjwgfdOz0lAs@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf arm64: Inject missing frames when using 'perf record --call-graph=fp'

2021-12-21T21:37:13+00:00

When unwinding using frame pointers on ARM64, the return address of the current function may not have been pushed into the stack when a function was interrupted, which makes perf show an incorrect call graph to the user. Consider the following example program: void leaf() { /* long computation */ } void parent() { // (1) leaf(); // (2) } ... could be compiled into (using gcc -fno-inline -fno-omit-frame-pointer): leaf: /* long computation */ nop ret parent: // (1) stp x29, x30, [sp, -16]! mov x29, sp bl parent nop ldp x29, x30, [sp], 16 // (2) ret If the program is interrupted at (1), (2), or any point in "leaf:", the call graph will skip the callers of the current function. We can unwind using the dwarf info and check if the return addr is the same as the LR register, and inject the missing frame into the call graph. Before this patch, the above example shows the following call-graph when recording using "--call-graph fp" mode in ARM64: # Children Self Command Shared Object Symbol # ........ ........ ........ ................ ...................... # 99.86% 99.86% program3 program3 [.] leaf | ---_start __libc_start_main main leaf As can be seen, the "parent" function is missing. This is specially problematic in "leaf" because for leaf functions the compiler may always omit pushing the return addr into the stack. After this patch, it shows the correct graph: # Children Self Command Shared Object Symbol # ........ ........ ........ ................ ...................... # 99.86% 99.86% program3 program3 [.] leaf | ---_start __libc_start_main main parent leaf Reviewed-by: James Clark Signed-off-by: Alexandre Truong Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: John Garry Cc: Leo Yan Cc: Mark Rutland Cc: Mathieu Poirier Cc: Namhyung Kim Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20211217154521.80603-7-german.gomez@arm.com Signed-off-by: German Gomez [ Rename machine__normalize_is() to machine__normalized_is(), as suggested by James Clark ] Signed-off-by: Arnaldo Carvalho de Melo

perf machine: Add a mechanism to inject stack frames

2021-12-21T21:35:34+00:00

Add a mechanism for platforms to inject stack frames for the leaf frame caller if there is enough information to determine a frame is missing from dwarf or other post processing mechanisms. Reviewed-by: James Clark Signed-off-by: Alexandre Truong Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: John Garry Cc: Leo Yan Cc: Mark Rutland Cc: Mathieu Poirier Cc: Namhyung Kim Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20211217154521.80603-3-german.gomez@arm.com Signed-off-by: German Gomez Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add support for PERF_RECORD_AUX_OUTPUT_HW_ID

2021-10-20T14:22:27+00:00

The PERF_RECORD_AUX_OUTPUT_HW_ID event provides a way to match AUX output data like Intel PT PEBS-via-PT back to the event that it came from, by providing a hardware ID that is present in the AUX output. Reviewed-by: Alexander Shishkin Reviewed-by: Andi Kleen Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: Kan Liang Cc: Leo Yan Cc: Mark Rutland Cc: Peter Zijlstra Cc: x86@kernel.org Link: http://lore.kernel.org/lkml/20210907163903.11820-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo