This is a note to let you know that I've just added the patch titled perf regs: Make perf_reg_name() return "unknown" instead of NULL to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: perf-regs-make-perf_reg_name-return-unknown-instead-.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 97359b809195c2fa912bc50530a466fa25525b18 Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Date: Wed Nov 27 10:13:34 2019 -0300 perf regs: Make perf_reg_name() return "unknown" instead of NULL [ Upstream commit 5b596e0ff0e1852197d4c82d3314db5e43126bf7 ] To avoid breaking the build on arches where this is not wired up, at least all the other features should be made available and when using this specific routine, the "unknown" should point the user/developer to the need to wire this up on this particular hardware architecture. Detected in a container mipsel debian cross build environment, where it shows up as: In file included from /usr/mipsel-linux-gnu/include/stdio.h:867, from /git/linux/tools/perf/lib/include/perf/cpumap.h:6, from util/session.c:13: In function 'printf', inlined from 'regs_dump__printf' at util/session.c:1103:3, inlined from 'regs__printf' at util/session.c:1131:2: /usr/mipsel-linux-gnu/include/bits/stdio2.h:107:10: error: '%-5s' directive argument is null [-Werror=format-overflow=] 107 | return __printf_chk (__USE_FORTIFY_LEVEL - 1, __fmt, __va_arg_pack ()); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cross compiler details: mipsel-linux-gnu-gcc (Debian 9.2.1-8) 9.2.1 20190909 Also on mips64: In file included from /usr/mips64-linux-gnuabi64/include/stdio.h:867, from /git/linux/tools/perf/lib/include/perf/cpumap.h:6, from util/session.c:13: In function 'printf', inlined from 'regs_dump__printf' at util/session.c:1103:3, inlined from 'regs__printf' at util/session.c:1131:2, inlined from 'regs_user__printf' at util/session.c:1139:3, inlined from 'dump_sample' at util/session.c:1246:3, inlined from 'machines__deliver_event' at util/session.c:1421:3: /usr/mips64-linux-gnuabi64/include/bits/stdio2.h:107:10: error: '%-5s' directive argument is null [-Werror=format-overflow=] 107 | return __printf_chk (__USE_FORTIFY_LEVEL - 1, __fmt, __va_arg_pack ()); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In function 'printf', inlined from 'regs_dump__printf' at util/session.c:1103:3, inlined from 'regs__printf' at util/session.c:1131:2, inlined from 'regs_intr__printf' at util/session.c:1147:3, inlined from 'dump_sample' at util/session.c:1249:3, inlined from 'machines__deliver_event' at util/session.c:1421:3: /usr/mips64-linux-gnuabi64/include/bits/stdio2.h:107:10: error: '%-5s' directive argument is null [-Werror=format-overflow=] 107 | return __printf_chk (__USE_FORTIFY_LEVEL - 1, __fmt, __va_arg_pack ()); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cross compiler details: mips64-linux-gnuabi64-gcc (Debian 9.2.1-8) 9.2.1 20190909 Fixes: 2bcd355b71da ("perf tools: Add interface to arch registers sets") Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Link: https://lkml.kernel.org/n/tip-95wjyv4o65nuaeweq31t7l1s@xxxxxxxxxxxxxx Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/tools/perf/util/perf_regs.h b/tools/perf/util/perf_regs.h index 679d6e493962..e6324397b295 100644 --- a/tools/perf/util/perf_regs.h +++ b/tools/perf/util/perf_regs.h @@ -26,7 +26,7 @@ int perf_reg_value(u64 *valp, struct regs_dump *regs, int id); static inline const char *perf_reg_name(int id __maybe_unused) { - return NULL; + return "unknown"; } static inline int perf_reg_value(u64 *valp __maybe_unused,