pm24.git/kernel/trace/trace.c, branch v5.2-rc4

tracing: Silence GCC 9 array bounds warning

2019-05-26T03:04:30Z

Starting with GCC 9, -Warray-bounds detects cases when memset is called starting on a member of a struct but the size to be cleared ends up writing over further members. Such a call happens in the trace code to clear, at once, all members after and including `seq` on struct trace_iterator: In function 'memset', inlined from 'ftrace_dump' at kernel/trace/trace.c:8914:3: ./include/linux/string.h:344:9: warning: '__builtin_memset' offset [8505, 8560] from the object at 'iter' is out of the bounds of referenced subobject 'seq' with type 'struct trace_seq' at offset 4368 [-Warray-bounds] 344 | return __builtin_memset(p, c, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ In order to avoid GCC complaining about it, we compute the address ourselves by adding the offsetof distance instead of referring directly to the member. Since there are two places doing this clear (trace.c and trace_kdb.c), take the chance to move the workaround into a single place in the internal header. Link: http://lkml.kernel.org/r/20190523124535.GA12931@gmail.com Signed-off-by: Miguel Ojeda [ Removed unnecessary parenthesis around "iter" ] Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2019-05-15T23:05:47Z

Pull tracing updates from Steven Rostedt: "The major changes in this tracing update includes: - Removal of non-DYNAMIC_FTRACE from 32bit x86 - Removal of mcount support from x86 - Emulating a call from int3 on x86_64, fixes live kernel patching - Consolidated Tracing Error logs file Minor updates: - Removal of klp_check_compiler_support() - kdb ftrace dumping output changes - Accessing and creating ftrace instances from inside the kernel - Clean up of #define if macro - Introduction of TRACE_EVENT_NOP() to disable trace events based on config options And other minor fixes and clean ups" * tag 'trace-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits) x86: Hide the int3_emulate_call/jmp functions from UML livepatch: Remove klp_check_compiler_support() ftrace/x86: Remove mcount support ftrace/x86_32: Remove support for non DYNAMIC_FTRACE tracing: Simplify "if" macro code tracing: Fix documentation about disabling options using trace_options tracing: Replace kzalloc with kcalloc tracing: Fix partial reading of trace event's id file tracing: Allow RCU to run between postponed startup tests tracing: Fix white space issues in parse_pred() function tracing: Eliminate const char[] auto variables ring-buffer: Fix mispelling of Calculate tracing: probeevent: Fix to make the type of $comm string tracing: probeevent: Do not accumulate on ret variable tracing: uprobes: Re-enable $comm support for uprobe events ftrace/x86_64: Emulate call function while updating in breakpoint handler x86_64: Allow breakpoints to emulate call instructions x86_64: Add gap to int3 to allow for call emulation tracing: kdb: Allow ftdump to skip all but the last few entries tracing: Add trace_total_entries() / trace_total_entries_cpu() ...

tracing: Fix documentation about disabling options using trace_options

2019-05-08T16:15:12Z

To disable a tracing option using the trace_options file, the option name needs to be prefixed with 'no', and not suffixed, as the README states. Fix it. Link: http://lkml.kernel.org/r/154872690031.47356.5739053380942044586.stgit@srivatsa-ubuntu Signed-off-by: Srivatsa S. Bhat (VMware) Signed-off-by: Steven Rostedt (VMware)

tracing: Allow RCU to run between postponed startup tests

2019-05-08T16:15:12Z

When building a allmodconfig kernel for arm64 and boot that in qemu, CONFIG_FTRACE_STARTUP_TEST gets enabled and that takes time so the watchdog expires and prints out a message like this: 'watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]' Depending on what the what test gets called from init_trace_selftests() it stays minutes in the loop. Rework so that function cond_resched() gets called in the init_trace_selftests loop. Link: http://lkml.kernel.org/r/20181130145622.26334-1-anders.roxell@linaro.org Co-developed-by: Arnd Bergmann Signed-off-by: Arnd Bergmann Signed-off-by: Anders Roxell Signed-off-by: Steven Rostedt (VMware)

tracing: Eliminate const char[] auto variables

2019-05-08T16:15:12Z

Automatic const char[] variables cause unnecessary code generation. For example, the this_mod variable leads to 3f04: 48 b8 5f 5f 74 68 69 73 5f 6d movabs $0x6d5f736968745f5f,%rax # __this_m 3f0e: 4c 8d 44 24 02 lea 0x2(%rsp),%r8 3f13: 48 8d 7c 24 10 lea 0x10(%rsp),%rdi 3f18: 48 89 44 24 02 mov %rax,0x2(%rsp) 3f1d: 4c 89 e9 mov %r13,%rcx 3f20: b8 65 00 00 00 mov $0x65,%eax # e 3f25: 48 c7 c2 00 00 00 00 mov $0x0,%rdx 3f28: R_X86_64_32S .rodata.str1.1+0x18d 3f2c: be 48 00 00 00 mov $0x48,%esi 3f31: c7 44 24 0a 6f 64 75 6c movl $0x6c75646f,0xa(%rsp) # odul 3f39: 66 89 44 24 0e mov %ax,0xe(%rsp) i.e., the string gets built on the stack at runtime. Similar code can be found for the other instances I'm replacing here. Putting the string in .rodata reduces the combined .text+.rodata size and saves time and stack space at runtime. The simplest fix, and what I've done for the this_mod case, is to just make the variable static. However, for the "" case where the same string is used twice, that prevents the linker from merging those two literals, so instead use a macro - that also keeps the two instances automatically in sync (instead of only the compile-time strlen expression). Finally, for the two runs of spaces, it turns out that the "build these strings on the stack" is not the worst part of what gcc does - it turns print_func_help_header_irq() into "if (tgid) { /* print_event_info + five seq_printf calls */ } else { /* print event_info + another five seq_printf */}". Taking inspiration from a suggestion from Al Viro, use %.*s to make snprintf either stop after the first two spaces or print the whole string. As a bonus, the seq_printfs now fit on single lines (at least, they are not longer than the existing ones in the function just above), making it easier to see that the ascii art lines up. x86-64 defconfig + CONFIG_FUNCTION_TRACER: $ scripts/stackdelta /tmp/stackusage.{0,1} ./kernel/trace/ftrace.c ftrace_mod_callback 152 136 -16 ./kernel/trace/trace.c trace_default_header 56 32 -24 ./kernel/trace/trace.c tracing_mark_raw_write 96 72 -24 ./kernel/trace/trace.c tracing_mark_write 104 80 -24 bloat-o-meter add/remove: 1/0 grow/shrink: 0/4 up/down: 14/-375 (-361) Function old new delta this_mod - 14 +14 ftrace_mod_callback 577 542 -35 tracing_mark_raw_write 444 374 -70 tracing_mark_write 616 540 -76 trace_default_header 600 406 -194 Link: http://lkml.kernel.org/r/20190320081757.6037-1-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes Signed-off-by: Steven Rostedt (VMware)

Merge branch 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-05-06T20:11:48Z

Pull stack trace updates from Ingo Molnar: "So Thomas looked at the stacktrace code recently and noticed a few weirdnesses, and we all know how such stories of crummy kernel code meeting German engineering perfection end: a 45-patch series to clean it all up! :-) Here's the changes in Thomas's words: 'Struct stack_trace is a sinkhole for input and output parameters which is largely pointless for most usage sites. In fact if embedded into other data structures it creates indirections and extra storage overhead for no benefit. Looking at all usage sites makes it clear that they just require an interface which is based on a storage array. That array is either on stack, global or embedded into some other data structure. Some of the stack depot usage sites are outright wrong, but fortunately the wrongness just causes more stack being used for nothing and does not have functional impact. Another oddity is the inconsistent termination of the stack trace with ULONG_MAX. It's pointless as the number of entries is what determines the length of the stored trace. In fact quite some call sites remove the ULONG_MAX marker afterwards with or without nasty comments about it. Not all architectures do that and those which do, do it inconsistenly either conditional on nr_entries == 0 or unconditionally. The following series cleans that up by: 1) Removing the ULONG_MAX termination in the architecture code 2) Removing the ULONG_MAX fixups at the call sites 3) Providing plain storage array based interfaces for stacktrace and stackdepot. 4) Cleaning up the mess at the callsites including some related cleanups. 5) Removing the struct stack_trace based interfaces This is not changing the struct stack_trace interfaces at the architecture level, but it removes the exposure to the generic code'" * 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits) x86/stacktrace: Use common infrastructure stacktrace: Provide common infrastructure lib/stackdepot: Remove obsolete functions stacktrace: Remove obsolete functions livepatch: Simplify stack trace retrieval tracing: Remove the last struct stack_trace usage tracing: Simplify stack trace retrieval tracing: Make ftrace_trace_userstack() static and conditional tracing: Use percpu stack trace buffer more intelligently tracing: Simplify stacktrace retrieval in histograms lockdep: Simplify stack trace handling lockdep: Remove save argument from check_prev_add() lockdep: Remove unused trace argument from print_circular_bug() drm: Simplify stacktrace handling dm persistent data: Simplify stack trace handling dm bufio: Simplify stack trace retrieval btrfs: ref-verify: Simplify stack trace retrieval dma/debug: Simplify stracktrace retrieval fault-inject: Simplify stacktrace retrieval mm/page_owner: Simplify stack trace handling ...

tracing: Add trace_total_entries() / trace_total_entries_cpu()

2019-05-03T01:32:31Z

These two new exported functions will be used in a future patch by kdb_ftdump() to quickly skip all but the last few trace entries. Link: http://lkml.kernel.org/r/20190319171206.97107-2-dianders@chromium.org Acked-by: Daniel Thompson Suggested-by: Steven Rostedt Signed-off-by: Douglas Anderson Signed-off-by: Steven Rostedt (VMware)

tracing: Simplify stack trace retrieval

2019-04-29T10:37:55Z

Replace the indirection through struct stack_trace by using the storage array based interfaces. Signed-off-by: Thomas Gleixner Reviewed-by: Steven Rostedt (VMware) Reviewed-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Alexander Potapenko Cc: Alexey Dobriyan Cc: Andrew Morton Cc: Christoph Lameter Cc: Pekka Enberg Cc: linux-mm@kvack.org Cc: David Rientjes Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Andrey Ryabinin Cc: kasan-dev@googlegroups.com Cc: Mike Rapoport Cc: Akinobu Mita Cc: Christoph Hellwig Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy Cc: Marek Szyprowski Cc: Johannes Thumshirn Cc: David Sterba Cc: Chris Mason Cc: Josef Bacik Cc: linux-btrfs@vger.kernel.org Cc: dm-devel@redhat.com Cc: Mike Snitzer Cc: Alasdair Kergon Cc: Daniel Vetter Cc: intel-gfx@lists.freedesktop.org Cc: Joonas Lahtinen Cc: Maarten Lankhorst Cc: dri-devel@lists.freedesktop.org Cc: David Airlie Cc: Jani Nikula Cc: Rodrigo Vivi Cc: Tom Zanussi Cc: Miroslav Benes Cc: linux-arch@vger.kernel.org Link: https://lkml.kernel.org/r/20190425094803.248604594@linutronix.de

tracing: Make ftrace_trace_userstack() static and conditional

2019-04-29T10:37:55Z

It's only used in trace.c and there is absolutely no point in compiling it in when user space stack traces are not supported. Signed-off-by: Thomas Gleixner Reviewed-by: Steven Rostedt Reviewed-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Alexander Potapenko Cc: Alexey Dobriyan Cc: Andrew Morton Cc: Christoph Lameter Cc: Pekka Enberg Cc: linux-mm@kvack.org Cc: David Rientjes Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Andrey Ryabinin Cc: kasan-dev@googlegroups.com Cc: Mike Rapoport Cc: Akinobu Mita Cc: Christoph Hellwig Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy Cc: Marek Szyprowski Cc: Johannes Thumshirn Cc: David Sterba Cc: Chris Mason Cc: Josef Bacik Cc: linux-btrfs@vger.kernel.org Cc: dm-devel@redhat.com Cc: Mike Snitzer Cc: Alasdair Kergon Cc: Daniel Vetter Cc: intel-gfx@lists.freedesktop.org Cc: Joonas Lahtinen Cc: Maarten Lankhorst Cc: dri-devel@lists.freedesktop.org Cc: David Airlie Cc: Jani Nikula Cc: Rodrigo Vivi Cc: Tom Zanussi Cc: Miroslav Benes Cc: linux-arch@vger.kernel.org Link: https://lkml.kernel.org/r/20190425094803.162400595@linutronix.de

tracing: Use percpu stack trace buffer more intelligently

2019-04-29T10:37:55Z

The per cpu stack trace buffer usage pattern is odd at best. The buffer has place for 512 stack trace entries on 64-bit and 1024 on 32-bit. When interrupts or exceptions nest after the per cpu buffer was acquired the stacktrace length is hardcoded to 8 entries. 512/1024 stack trace entries in kernel stacks are unrealistic so the buffer is a complete waste. Split the buffer into 4 nest levels, which are 128/256 entries per level. This allows nesting contexts (interrupts, exceptions) to utilize the cpu buffer for stack retrieval and avoids the fixed length allocation along with the conditional execution pathes. Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Steven Rostedt Cc: Alexander Potapenko Cc: Alexey Dobriyan Cc: Andrew Morton Cc: Christoph Lameter Cc: Pekka Enberg Cc: linux-mm@kvack.org Cc: David Rientjes Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Andrey Ryabinin Cc: kasan-dev@googlegroups.com Cc: Mike Rapoport Cc: Akinobu Mita Cc: Christoph Hellwig Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy Cc: Marek Szyprowski Cc: Johannes Thumshirn Cc: David Sterba Cc: Chris Mason Cc: Josef Bacik Cc: linux-btrfs@vger.kernel.org Cc: dm-devel@redhat.com Cc: Mike Snitzer Cc: Alasdair Kergon Cc: Daniel Vetter Cc: intel-gfx@lists.freedesktop.org Cc: Joonas Lahtinen Cc: Maarten Lankhorst Cc: dri-devel@lists.freedesktop.org Cc: David Airlie Cc: Jani Nikula Cc: Rodrigo Vivi Cc: Tom Zanussi Cc: Miroslav Benes Cc: linux-arch@vger.kernel.org Link: https://lkml.kernel.org/r/20190425094803.066064076@linutronix.de