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* Merge tag 'trace-v5.2' of ↵Linus Torvalds2019-05-1644-651/+1345
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace 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() ...
| * x86: Hide the int3_emulate_call/jmp functions from UMLSteven Rostedt (VMware)2019-05-111-1/+3
| | | | | | | | | | | | | | | | | | | | User Mode Linux does not have access to the ip or sp fields of the pt_regs, and accessing them causes UML to fail to build. Hide the int3_emulate_jmp() and int3_emulate_call() instructions from UML, as it doesn't need them anyway. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * livepatch: Remove klp_check_compiler_support()Jiri Kosina2019-05-104-23/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The only purpose of klp_check_compiler_support() is to make sure that we are not using ftrace on x86 via mcount (because that's executed only after prologue has already happened, and that's too late for livepatching purposes). Now that mcount is not supported by ftrace any more, there is no need for klp_check_compiler_support() either. Link: http://lkml.kernel.org/r/nycvar.YFH.7.76.1905102346100.17054@cbobk.fhfr.pm Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * ftrace/x86: Remove mcount supportSteven Rostedt (VMware)2019-05-104-66/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There's two methods of enabling function tracing in Linux on x86. One is with just "gcc -pg" and the other is "gcc -pg -mfentry". The former will use calls to a special function "mcount" after the frame is set up in all C functions. The latter will add calls to a special function called "fentry" as the very first instruction of all C functions. At compile time, there is a check to see if gcc supports, -mfentry, and if it does, it will use that, because it is more versatile and less error prone for function tracing. Starting with v4.19, the minimum gcc supported to build the Linux kernel, was raised to version 4.6. That also happens to be the first gcc version to support -mfentry. Since on x86, using gcc versions from 4.6 and beyond will unconditionally enable the -mfentry, it will no longer use mcount as the method for inserting calls into the C functions of the kernel. This means that there is no point in continuing to maintain mcount in x86. Remove support for using mcount. This makes the code less complex, and will also allow it to be simplified in the future. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * ftrace/x86_32: Remove support for non DYNAMIC_FTRACESteven Rostedt (VMware)2019-05-102-39/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When DYNAMIC_FTRACE is enabled in the kernel, all the functions that can be traced by the function tracer have a "nop" placeholder at the start of the function. When function tracing is enabled, the nop is converted into a call to the tracing infrastructure where the functions get traced. This also allows for specifying specific functions to trace, and a lot of infrastructure is built on top of this. When DYNAMIC_FTRACE is not enabled, all the functions have a call to the ftrace trampoline. A check is made to see if a function pointer is the ftrace_stub or not, and if it is not, it calls the function pointer to trace the code. This adds over 10% overhead to the kernel even when tracing is disabled. When an architecture supports DYNAMIC_FTRACE there really is no reason to use the static tracing. I have kept non DYNAMIC_FTRACE available in x86 so that the generic code for non DYNAMIC_FTRACE can be tested. There is no reason to support non DYNAMIC_FTRACE for both x86_64 and x86_32. As the non DYNAMIC_FTRACE for x86_32 does not even support fentry, and we want to remove mcount completely, there's no reason to keep non DYNAMIC_FTRACE around for x86_32. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Simplify "if" macro codeLinus Torvalds2019-05-091-17/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Peter Zijlstra noticed that with CONFIG_PROFILE_ALL_BRANCHES, the "if" macro converts the conditional to an array index. This can cause GCC to create horrible code. When there are nested ifs, the generated code uses register values to encode branching decisions. Josh Poimboeuf found that replacing the define "if" macro from using the condition as an array index and incrementing the branch statics with an if statement itself, reduced the asm complexity and shrinks the generated code quite a bit. But this can be simplified even further by replacing the internal if statement with a ternary operator. Link: https://lkml.kernel.org/r/20190307174802.46fmpysxyo35hh43@treble Link: http://lkml.kernel.org/r/CAHk-=wiALN3jRuzARpwThN62iKd476Xj-uom+YnLZ4=eqcz7xQ@mail.gmail.com Reported-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reported-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Fix documentation about disabling options using trace_optionsSrivatsa S. Bhat (VMware)2019-05-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | 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) <srivatsa@csail.mit.edu> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Replace kzalloc with kcallocGustavo A. R. Silva2019-05-081-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Replace kzalloc() function with its 2-factor argument form, kcalloc(). This patch replaces cases of: kzalloc(a * b, gfp) with: kcalloc(a, b, gfp) This code was detected with the help of Coccinelle. Link: http://lkml.kernel.org/r/20190115043408.GA23456@embeddedor Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Fix partial reading of trace event's id fileElazar Leibovich2019-05-081-3/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When reading only part of the id file, the ppos isn't tracked correctly. This is taken care by simple_read_from_buffer. Reading a single byte, and then the next byte would result EOF. While this seems like not a big deal, this breaks abstractions that reads information from files unbuffered. See for example https://github.com/golang/go/issues/29399 This code was mentioned as problematic in commit cd458ba9d5a5 ("tracing: Do not (ab)use trace_seq in event_id_read()") An example C code that show this bug is: #include <stdio.h> #include <stdint.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> int main(int argc, char **argv) { if (argc < 2) return 1; int fd = open(argv[1], O_RDONLY); char c; read(fd, &c, 1); printf("First %c\n", c); read(fd, &c, 1); printf("Second %c\n", c); } Then run with, e.g. sudo ./a.out /sys/kernel/debug/tracing/events/tcp/tcp_set_state/id You'll notice you're getting the first character twice, instead of the first two characters in the id file. Link: http://lkml.kernel.org/r/20181231115837.4932-1-elazar@lightbitslabs.com Cc: Orit Wasserman <orit.was@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Fixes: 23725aeeab10b ("ftrace: provide an id file for each event") Signed-off-by: Elazar Leibovich <elazar@lightbitslabs.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Allow RCU to run between postponed startup testsAnders Roxell2019-05-081-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <arnd@arndb.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Fix white space issues in parse_pred() functionColin Ian King2019-05-081-24/+24
| | | | | | | | | | | | | | | | | | | | Trivial fix to clean up an indentation issue, a whole chunk of code has an extra space in the indentation. Link: http://lkml.kernel.org/r/20181109132312.20994-1-colin.king@canonical.com Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Eliminate const char[] auto variablesRasmus Villemoes2019-05-082-22/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 "<faulted>" 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 <linux@rasmusvillemoes.dk> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * ring-buffer: Fix mispelling of CalculateYangtao Li2019-05-081-1/+1
| | | | | | | | | | | | | | | | | | It's not "Caculate". Link: http://lkml.kernel.org/r/20181101154640.23162-1-tiny.windzz@gmail.com Signed-off-by: Yangtao Li <tiny.windzz@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: probeevent: Fix to make the type of $comm stringMasami Hiramatsu2019-05-081-6/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix to make the type of $comm "string". If we set the other type to $comm argument, it shows meaningless value or wrong data. Currently probe events allow us to set string array type (e.g. ":string[2]"), or other digit types like x8 on $comm. But since clearly $comm is just a string data, it should not be fetched by other types including array. Link: http://lkml.kernel.org/r/155723736241.9149.14582064184468574539.stgit@devnote2 Cc: Andreas Ziegler <andreas.ziegler@fau.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: probeevent: Do not accumulate on ret variableMasami Hiramatsu2019-05-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | Do not accumulate strlen result on "ret" local variable, because it is accumulated on "total" local variable for array case. Link: http://lkml.kernel.org/r/155723735237.9149.3192150444705457531.stgit@devnote2 Fixes: 40b53b771806 ("tracing: probeevent: Add array type support") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: uprobes: Re-enable $comm support for uprobe eventsMasami Hiramatsu2019-05-082-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code") dropped the $comm support from uprobe events, this re-enables it. For $comm support, uses strlcpy() instead of strncpy_from_user() to copy current task's comm. Because it is in the kernel space, strncpy_from_user() always fails to copy the comm. This also uses strlen() instead of strnlen_user() to measure the length of the comm. Note that this uses -ECOMM as a token value to fetch the comm string. If the user-space pointer points -ECOMM, it will be translated to task->comm. Link: http://lkml.kernel.org/r/155723734162.9149.4042756162201097965.stgit@devnote2 Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code") Reported-by: Andreas Ziegler <andreas.ziegler@fau.de> Acked-by: Andreas Ziegler <andreas.ziegler@fau.de> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * ftrace/x86_64: Emulate call function while updating in breakpoint handlerPeter Zijlstra2019-05-081-5/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Nicolai Stange discovered[1] that if live kernel patching is enabled, and the function tracer started tracing the same function that was patched, the conversion of the fentry call site during the translation of going from calling the live kernel patch trampoline to the iterator trampoline, would have as slight window where it didn't call anything. As live kernel patching depends on ftrace to always call its code (to prevent the function being traced from being called, as it will redirect it). This small window would allow the old buggy function to be called, and this can cause undesirable results. Nicolai submitted new patches[2] but these were controversial. As this is similar to the static call emulation issues that came up a while ago[3]. But after some debate[4][5] adding a gap in the stack when entering the breakpoint handler allows for pushing the return address onto the stack to easily emulate a call. [1] http://lkml.kernel.org/r/20180726104029.7736-1-nstange@suse.de [2] http://lkml.kernel.org/r/20190427100639.15074-1-nstange@suse.de [3] http://lkml.kernel.org/r/3cf04e113d71c9f8e4be95fb84a510f085aa4afa.1541711457.git.jpoimboe@redhat.com [4] http://lkml.kernel.org/r/CAHk-=wh5OpheSU8Em_Q3Hg8qw_JtoijxOdPtHru6d+5K8TWM=A@mail.gmail.com [5] http://lkml.kernel.org/r/CAHk-=wjvQxY4DvPrJ6haPgAa6b906h=MwZXO6G8OtiTGe=N7_w@mail.gmail.com [ Live kernel patching is not implemented on x86_32, thus the emulate calls are only for x86_64. ] Cc: Andy Lutomirski <luto@kernel.org> Cc: Nicolai Stange <nstange@suse.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: the arch/x86 maintainers <x86@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Petr Mladek <pmladek@suse.com> Cc: Joe Lawrence <joe.lawrence@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Mimi Zohar <zohar@linux.ibm.com> Cc: Juergen Gross <jgross@suse.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Nayna Jain <nayna@linux.ibm.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org> Cc: stable@vger.kernel.org Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching") Tested-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [ Changed to only implement emulated calls for x86_64 ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * x86_64: Allow breakpoints to emulate call instructionsPeter Zijlstra2019-05-081-0/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to allow breakpoints to emulate call instructions, they need to push the return address onto the stack. The x86_64 int3 handler adds a small gap to allow the stack to grow some. Use this gap to add the return address to be able to emulate a call instruction at the breakpoint location. These helper functions are added: int3_emulate_jmp(): changes the location of the regs->ip to return there. (The next two are only for x86_64) int3_emulate_push(): to push the address onto the gap in the stack int3_emulate_call(): push the return address and change regs->ip Cc: Andy Lutomirski <luto@kernel.org> Cc: Nicolai Stange <nstange@suse.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: the arch/x86 maintainers <x86@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Petr Mladek <pmladek@suse.com> Cc: Joe Lawrence <joe.lawrence@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Mimi Zohar <zohar@linux.ibm.com> Cc: Juergen Gross <jgross@suse.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Nayna Jain <nayna@linux.ibm.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org> Cc: stable@vger.kernel.org Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching") Tested-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [ Modified to only work for x86_64 and added comment to int3_emulate_push() ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * x86_64: Add gap to int3 to allow for call emulationJosh Poimboeuf2019-05-081-2/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To allow an int3 handler to emulate a call instruction, it must be able to push a return address onto the stack. Add a gap to the stack to allow the int3 handler to push the return address and change the return from int3 to jump straight to the emulated called function target. Link: http://lkml.kernel.org/r/20181130183917.hxmti5josgq4clti@treble Link: http://lkml.kernel.org/r/20190502162133.GX2623@hirez.programming.kicks-ass.net [ Note, this is needed to allow Live Kernel Patching to not miss calling a patched function when tracing is enabled. -- Steven Rostedt ] Cc: stable@vger.kernel.org Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching") Tested-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: kdb: Allow ftdump to skip all but the last few entriesDouglas Anderson2019-05-031-14/+31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The 'ftdump' command in kdb is currently a bit of a last resort, at least if you have lots of traces turned on. It's going to print a whole boatload of data out your serial port which is probably running at 115200. This could easily take many, many minutes. Usually you're most interested in what's at the _end_ of the ftrace buffer, AKA what happened most recently. That means you've got to wait the full time for the dump. The 'ftdump' command does attempt to help you a little bit by allowing you to skip a fixed number of entries. Unfortunately it provides no way for you to know how many entries you should skip. Let's do similar to python and allow you to use a negative number to indicate that you want to skip all entries except the last few. This allows you to quickly see what you want. Note that we also change the printout in ftdump to print the (positive) number of entries actually skipped since that could be helpful to know when you've specified a negative skip count. Link: http://lkml.kernel.org/r/20190319171206.97107-3-dianders@chromium.org Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Add trace_total_entries() / trace_total_entries_cpu()Douglas Anderson2019-05-032-15/+53
| | | | | | | | | | | | | | | | | | | | | | | | 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 <daniel.thompson@linaro.org> Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: kdb: The skip_lines parameter should have been skip_entriesDouglas Anderson2019-05-031-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The things skipped by kdb's "ftdump" command when you pass it a parameter has always been entries, not lines. The difference usually doesn't matter but when the trace buffer has multi-line entries (like a stack dump) it can matter. Let's fix this both in the help text for ftdump and also in the local variable names. Link: http://lkml.kernel.org/r/20190319171206.97107-1-dianders@chromium.org Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * function_graph: Place ftrace_graph_entry_stub() prototype in ↵Steven Rostedt (VMware)2019-04-293-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | include/linux/ftrace.h ftrace_graph_entry_stub() is defined in generic code, its prototype should be in the generic header and not defined throughout architecture specific code in order to use it. Cc: Greentime Hu <green.hu@gmail.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Helge Deller <deller@gmx.de> Cc: linux-parisc@vger.kernel.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * function_graph: Have selftest also emulate tr->reset() as it did with tr->init()Steven Rostedt (VMware)2019-04-221-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The function_graph boot up self test emulates the tr->init() function in order to add a wrapper around the function graph tracer entry code to test for lock ups and such. But it does not emulate the tr->reset(), and just calls the function_graph tracer tr->reset() function which will use its own fgraph_ops to unregister function tracing with. As the fgraph_ops is becoming more meaningful with the register_ftrace_graph() and unregister_ftrace_graph() functions, the two need to be the same. The emulated tr->init() uses its own fgraph_ops descriptor, which means the unregister_ftrace_graph() must use the same ftrace_ops, which the selftest currently does not do. By emulating the tr->reset() as the selftest does with the tr->init() it will be able to pass the same fgraph_ops descriptor to the unregister_ftrace_graph() as it did with the register_ftrace_graph(). Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * ftrace: Do not process STUB functions in ftrace_ops_list_func()Steven Rostedt (VMware)2019-04-111-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | The function_graph tracer has a stub function and its ops flag has the FTRACE_OPS_FL_STUB set. As the function graph does not use the ftrace_ops->func pointer but instead is called by a separate part of the ftrace trampoline. The function_graph tracer still requires to pass in a ftrace_ops that may also hold the hash of the functions to call. But there's no reason to test that hash in the function tracing portion. Instead of testing to see if we should call the stub function, just test if the ops has FTRACE_OPS_FL_STUB set, and just skip it. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * ftrace: Remove ASSIGN_OPS_HASH() macro from ftrace.cSteven Rostedt (VMware)2019-04-101-4/+0
| | | | | | | | | | | | | | | | The ASSIGN_OPS_HASH() macro was moved to fgraph.c where it was used, but for some reason it wasn't removed from ftrace.c, as it is no longer referenced there. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * rcu: validate arguments for rcu tracepointsYafang Shao2019-04-083-67/+31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When CONFIG_RCU_TRACE is not set, all these tracepoints are defined as do-nothing macro. We'd better make those inline functions that take proper arguments. As RCU_TRACE() is defined as do-nothing marco as well when CONFIG_RCU_TRACE is not set, so we can clean it up. Link: http://lkml.kernel.org/r/1553602391-11926-4-git-send-email-laoar.shao@gmail.com Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * sched/fair: do not expose some tracepoints to user if CONFIG_SCHEDSTATS is ↵Yafang Shao2019-04-081-7/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | not set The tracepoints trace_sched_stat_{iowait, blocked, wait, sleep} should be not exposed to user if CONFIG_SCHEDSTATS is not set. Link: http://lkml.kernel.org/r/1553602391-11926-3-git-send-email-laoar.shao@gmail.com Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: introduce TRACE_EVENT_NOP()Yafang Shao2019-04-082-0/+23
| | | | | | | | | | | | | | | | | | | | | | Sometimes we want to define a tracepoint as a do-nothing function. So I introduce TRACE_EVENT_NOP, DECLARE_EVENT_CLASS_NOP and DEFINE_EVENT_NOP for this kind of usage. Link: http://lkml.kernel.org/r/1553602391-11926-2-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Add error_log to READMETom Zanussi2019-04-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | Add brief blurb about error_log to the 'Important files' section. Link: http://lkml.kernel.org/r/c81e60f9aded495081231a32d2d1023c4d043a7a.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Add tracing/error_log DocumentationTom Zanussi2019-04-082-14/+33
| | | | | | | | | | | | | | | | | | | | | | | | Move most of the hist trigger extended error documentation to ftrace.rst and expand on it to fully document tracing/error_log. Link: http://lkml.kernel.org/r/c5d53c8f643ef6844d6ad8d0200c116936730b01.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * selftests/ftrace: Add tracing/error_log testcaseTom Zanussi2019-04-081-0/+19
| | | | | | | | | | | | | | | | | | | | | | Add a testcase verifying basic tracing/error_log functionality. Link: http://lkml.kernel.org/r/bf1c0d47a24672df945331462682d96296d1ab28.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * selftests/ftrace: Remove trigger-extended-error-support testcaseTom Zanussi2019-04-081-28/+0
| | | | | | | | | | | | | | | | | | | | | | | | Error handling has been moved to the common tracing/error_log, so this test is no longer valid. Link: http://lkml.kernel.org/r/876a98b21018814cbf46f0a3605ae0906c51d53c.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * selftests/ftrace: Move kprobe/uprobe check_error() to test.d/functionsTom Zanussi2019-04-083-18/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The k/uprobe_sytax_errors test case defines a check_error() function used to run a command and check the position of the caret in the output. This would be useful for other ftrace facilities too, so move it to test.d/functions for use by anyone. In the process, rename it to ftrace_errlog_check() and parametrize it for general use. Link: http://lkml.kernel.org/r/9f88080a06f1755811f69081926afe7e5cb53178.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * selftests/ftrace: Add error_log testcase for probe errorsMasami Hiramatsu2019-04-082-0/+124
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Add error_log testcase for error logs on probe events. This tests most of error cases and checks the error position is correct. Link: http://lkml.kernel.org/r/63d695b74e0965988fa54ffa12beeb2c3475250d.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> [tom.zanussi@linux.intel.com: changed >& redirection to 2>] Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Have the error logs show up in the proper instancesSteven Rostedt (VMware)2019-04-085-23/+46
| | | | | | | | | | | | | | | | | | | | | | | | | | | | As each instance has their own error_log file, it makes more sense that the instances show the errors of their own instead of all error_logs having the same data. Make it that the errors show up in the instance error_log file that the error happens in. If no instance trace_array is available, then NULL can be passed in which will create the error in the top level instance (the one at the top of the tracefs directory). Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Have histogram code pass around trace_array for error handlingSteven Rostedt (VMware)2019-04-081-62/+80
| | | | | | | | | | | | | | | | | | | | | | Have the trace_array that associates the trace instance of the histogram passed around to functions so that error handling can display the error message in the proper instance. Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Add trace_array parameter to create_event_filter()Steven Rostedt (VMware)2019-04-083-13/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pass in the trace_array that represents the instance the filter being changed is in to create_event_filter(). This will allow for error messages that happen when writing to the filter can be displayed in the proper instance "error_log" file. Note, for calls to create_filter() (that was also modified to support create_event_filter()), that changes filters that do not exist in a instance (for perf for example), NULL may be passed in, which means that there will not be any message to log for that filter. Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Use tracing error_log with probe eventsMasami Hiramatsu2019-04-034-124/+348
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Use tracing error_log with probe events for logging error more precisely. This also makes all parse error returns -EINVAL (except for -ENOMEM), because user can see better error message in error_log file now. Link: http://lkml.kernel.org/r/6a4d90e141d138040ea61f4776b991597077451e.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Use tracing error_log with trace event filtersTom Zanussi2019-04-031-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use tracing_log_err() from the new tracing error_log mechanism to send filter parse errors to tracing/error_log. With this change, users will be able to see filter errors by looking at tracing/error_log. The same errors will also be available in the filter file, as expected. Link: http://lkml.kernel.org/r/1d942c419941539a11d78a6810fc5740a99b2974.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Use tracing error_log with hist triggersTom Zanussi2019-04-031-102/+104
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Replace hist_err() and hist_err_event() with tracing_log_err() from the new tracing error_log mechanism. Also add a couple related helper functions and remove most of the old hist_err()-related code. With this change, users no longer read the hist files for hist trigger error information, but instead look at tracing/error_log for the same information. Link: http://lkml.kernel.org/r/c98f77a97c9715d18b623eeb5741057b330d5ac0.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Save the last hist command's associated event nameTom Zanussi2019-04-031-6/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | In preparation for making use of the new trace error log, save the subsystem and event name associated with the last hist command - it will be passed as the location param in the event_log_err() calls. Link: http://lkml.kernel.org/r/eb0fd1362be8f39facb86c83eecf441b7a5876f8.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Add tracing error logTom Zanussi2019-04-032-0/+222
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce a new ftrace file, tracing/error_log, for ftrace commands to log errors. This is useful for allowing more complex commands such as hist trigger and kprobe_event commands to point out specifically where something may have gone wrong without forcing them to resort to more ad hoc methods such as tacking error messages onto existing output files. To log a tracing error, call the event_log_err() function, passing it a location string describing where it came from e.g. kprobe_events or system:event, the command that caused the error, an array of static error strings describing errors and an index within that array which describes the specific error, along with the position to place the error caret. Reading the log displays the last (currently) 8 errors logged in the following format: [timestamp] <loc>: error: <static error text> Command: <command that caused the error> ^ Memory for the error log isn't allocated unless there has been a trace event error, and the error log can be cleared and have its memory freed by writing the empty string in truncation mode to it: # echo > tracing/error_log. Link: http://lkml.kernel.org/r/0c2c82571fd38c5f3a88ca823627edff250e9416.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Suggested-by: Masami Hiramatsu <mhiramat@kernel.org> Improvements-suggested-by: Steve Rostedt <rostedt@goodmis.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * tracing: Kernel access to Ftrace instancesDivya Indi2019-04-032-24/+51
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Ftrace provides the feature “instances” that provides the capability to create multiple Ftrace ring buffers. However, currently these buffers are created/accessed via userspace only. The kernel APIs providing these features are not exported, hence cannot be used by other kernel components. This patch aims to extend this infrastructure to provide the flexibility to create/log/remove/ enable-disable existing trace events to these buffers from within the kernel. Link: http://lkml.kernel.org/r/1553106531-3281-2-git-send-email-divya.indi@oracle.com Signed-off-by: Divya Indi <divya.indi@oracle.com> Reviewed-by: Joe Jin <joe.jin@oracle.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| * ring-buffer: Fix ring buffer size in rb_write_something()YueHaibing2019-04-031-1/+1
| | | | | | | | | | | | | | | | | | 'cnt' should be used to calculate ring buffer size rather than data->cnt Link: http://lkml.kernel.org/r/1537704693-184237-1-git-send-email-yuehaibing@huawei.com Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
* | Merge tag 'kconfig-v5.2' of ↵Linus Torvalds2019-05-158-45/+89
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kconfig updates from Masahiro Yamada: - error out if a user specifies a directory instead of a file from "Save" menu of GUI interfaces - do not overwrite .config if there is no change in the configuration - create parent directories as needed when a user specifies a new file path from "Save" menu of menuconfig/nconfig - fix potential buffer overflow - some trivial cleanups * tag 'kconfig-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kconfig: make conf_get_autoconfig_name() static kconfig: use snprintf for formatting pathnames kconfig: remove useless NULL pointer check in conf_write_dep() kconfig: make parent directories for the saved .config as needed kconfig: do not write .config if the content is the same kconfig: do not accept a directory for configuration output kconfig: remove trailing whitespaces kconfig: Make nconf-cfg.sh executable
| * | kconfig: make conf_get_autoconfig_name() staticMasahiro Yamada2019-05-142-2/+1
| | | | | | | | | | | | | | | | | | This is only used in confdata.c Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * | kconfig: use snprintf for formatting pathnamesJacob Garber2019-05-142-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Valid pathnames will never exceed PATH_MAX, but these file names are unsanitized and can cause buffer overflow if set incorrectly. Use snprintf to avoid this. This was flagged during a Coverity scan of the coreboot project, which also uses kconfig for its build system. Signed-off-by: Jacob Garber <jgarber1@ualberta.ca> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * | kconfig: remove useless NULL pointer check in conf_write_dep()Masahiro Yamada2019-05-141-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | conf_write_dep() has just one caller: conf_write_dep("include/config/auto.conf.cmd"); "name" always points to a valid string. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * | kconfig: make parent directories for the saved .config as neededMasahiro Yamada2019-05-103-3/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With menuconfig / nconfig, users can input any file path from the "Save" menu, but it fails if the parent directory does not exist. Why not create the parent directory automatically. I think this is a user-friendly behavior. I changed the error messages in menuconfig / nconfig. "Nonexistent directory" is no longer the most likely reason of the failure. Perhaps, the user specified the existing directory, or attempted to write to the location without write permission. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>