treewide: remove meaningless assignments in Makefiles

In Makefiles, $(error ), $(warning ), and $(info ) expand to the empty
string, as explained in the GNU Make manual [1]:
"The result of the expansion of this function is the empty string."

Therefore, they are no-op except for logging purposes.

$(shell ...) expands to the output of the command. It expands to the
empty string when the command does not print anything to stdout.
Hence, $(shell mkdir ...) is no-op except for creating the directory.

Remove meaningless assignments.

[1]: https://www.gnu.org/software/make/manual/make.html#Make-Control-Functions

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20240221134201.2656908-1-masahiroy@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org

perf tools: Generate mips syscalls_n64.c syscall table

Grab a copy of arch/mips/kernel/syscalls/syscall_n64.tbl and use it to
generate tools/perf/arch/mips/include/generated/asm/syscalls_n64.c file,
this is similar with commit 1b700c997500 ("perf tools: Build syscall
table .c header from kernel's syscall_64.tbl")

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Juxin Gao <gaojuxin@loongson.cn>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Cc: linux-mips@vger.kernel.org
Link: http://lore.kernel.org/lkml/1612409724-3516-4-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf tools: Support MIPS unwinding and dwarf-regs

Map perf APIs (perf_reg_name/get_arch_regstr/unwind__arch_reg_id) with
MIPS specific registers.

[ayan@wavecomp.com: repick this patch for unwinding userstack backtrace
by perf and libunwind on MIPS based CPU.]

[yangtiezhu@loongson.cn: Add sample_reg_masks[] to fix build error,
silence some checkpatch errors and warnings, and also separate the
original patches into two parts (MIPS kernel and perf tools) to merge
easily.]

The original patches:

https://lore.kernel.org/patchwork/patch/1126521/
https://lore.kernel.org/patchwork/patch/1126520/

Committer notes:

Do it as __perf_reg_name() to cope with:

067012974c8ae31a ("perf tools: Fix arm64 build error with gcc-11")

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Archer Yan <ayan@wavecomp.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jianlin Lv <Jianlin.Lv@arm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Juxin Gao <gaojuxin@loongson.cn>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org
Link: http://lore.kernel.org/lkml/1612409724-3516-3-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Archer Yan <ayan@wavecomp.com>
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>